evolutionary psychology and critical thinking

Evolutionary thinking: a new perspective on how our brains control behavior takes evolution into account

by Amanda Parker | Jul 22, 2021 | Research

We watch a ball as it falls into our glove. We hear a strange sound in another part of the house and listen intently. In neuroscience, the act of narrowing our senses in response to an environmental event is called “attention,” and it is understood that when we attend to a stimulus, we lose the ability to focus on other surrounding inputs.

“The explanation that the neuroscience community gives for this—the textbook answer—is that we have limited cognitive mechanisms,” said W. Martin Usrey, Professor of Neurobiology, Physiology and Behavior and Neurology at UC Davis, “and we have to distribute those to certain areas because there is an inherent limitation to what the cortex can do.”

But is the cortex itself inherently limited? And if so, why would this be? Assuming we evolve to better survive our environments, wouldn’t it be more useful, for example, for a mouse to be able to focus on both the owl in the sky and the rustling in the grass at the same time and with equal power?

These questions are at the heart of a perspective published on July 22 in Neuron by Usrey and University of Chicago Maurice Goldblatt Professor of Neurobiology, S. Murray Sherman.

“With the big cerebral cortex that we have, one question that’s always bothered Murray and me is why we can’t heighten our awareness of everything,” said Usrey. “The cortex has this incredible computational power. Why can’t all areas be heightened at once? Why diminish one region so that another area can be enhanced?”

Now, Sherman and Usrey argue that our inability to focus our attention on all stimuli at once is not due to a limitation in the cortex itself, but is a product of the physical constraints in which it must operate. In other words, Sherman and Usrey suggest that attention as we know it is a direct consequence of the way our brain’s structure has evolved.

The cortex and evolution

In all mammals, the brain is composed of numerous components that reflect its evolutionary heritage. The most recent component is the cerebral cortex, which is particularly large and well-developed in humans. Exceptionally intricate, the cortex contains tens of billions of interconnected neurons and underlies all our conscious perceptions and abstract thought. Importantly, the cortex functions by interacting and cooperating with the other, evolutionarily older components.

“It’s almost like you can see the history, like geologists see when they look at layers of sediment,” described Sherman. “In the brain, most of the old circuits are still there and functioning—you add things on, but you don’t throw away the old stuff.”

In other words, as the cortex emerged, the older structures of our brain did not fall away. Instead, they remained, and the cortex evolved to work with them.

“The cortex, which is the pinnacle of our evolution as far as the brain is concerned, doesn’t generally have direct access to our motor neurons to control behavior,” said Sherman. “It has to go through all these old circuits. And in doing that, it has to play nice with all the old circuits that are trying to control behavior at the same time.”

To affect behavior, the cortex must send signals through the older subcortical regions. This represents a bottleneck in the flow of signals originating in the cortex, and these subcortical structures could not function properly if all cortical area simultaneously tried to control them.

“If all cortical areas tried to take control of these subcortical structures without anything to judge what’s best, you’d have utter chaos,” said Sherman.

Not only are there physical constraints to funneling large amounts of information through smaller regions, but without any prioritization of signals, we might receive contradictory information.

“Imagine if your visual cortical areas tell you to go left and the auditory areas tell you to go right,” explained Sherman.

What we call attention, then, Sherman and Usrey suggest, is the prioritization the brain must employ to permit only appropriate cortical areas to dominate subcortical routes to behavior. And this prioritization is required due to the very process of evolution that produced the cortex.

“It’s the filtering,” said Sherman, “to determine which cortical areas or subcortical areas at any given time are going to take control of behavior, which we now think we recognize as attention.”

New ways of thinking

If attention as we know it is a product of our brain’s structural evolution, as Sherman and Usrey argue, why did it evolve this way? Why didn’t we evolve to be able to focus on all environmental stimuli at once?

“An engineer building something as complex as the brain might go through a number of different stages, said Sherman, “and when a better way of doing something is developed, the old way might be thrown out. But evolution doesn’t work that way.”

As Sherman and Usrey say in their article, “evolution is messy.” It doesn’t scrap the whole thing and start fresh when things get complicated. Instead, we change by building upon and adapting what already exists. Although we are always evolving to become better suited for our environments, that evolution is constrained by our current structure and functionality.

In the case of the brain, subcortical structures had already developed circuits for complex motor control. When the cortex subsequently evolved, instead of reproducing all the needed neural circuitry, it took advantage of what was already there.

Attention is traditionally seen as a purely cortical mechanism, which is why the “textbook answer” for why we must limit our focus has been that our cortex must have a limited supply of resources to devote. But Sherman and Usrey argue that, because of the context in which it evolved, the cortex does not function on its own.

“We hope to change the way people think about cortical functioning, writ large,” said Sherman. “If you want to understand the brain, I assert you must take evolution into consideration.”

By Amanda Parker, PhD

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20 Evolutionary Psychology

Ben Jeffares, postdoctoral fellow, Department of Philosophy, Victoria University of Wellington

Kim Sterelny School of Philosophy, Research School of Social Sciences, Australian National University, Australia

• Published: 01 May 2012
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The article presents several models of evolutionary psychology. Nativist evolutionary psychology is built around a most important insight that ordinary human decision-making has a high cognitive load. Evolutionary nativists defend a modular solution to the problem of information load on human decision-making. Human minds comprises of special purpose cognitive devices or modules. One of the modules is a language module, a module for interpreting the thoughts and intentions of others, another is a ‘naive physics’ module for causal reasoning about sticks, stones, and similar inanimate objects, a natural history module for ecological decisions, and a social exchange module for monitoring economic interactions with peers. These modules evolved in response to the distinctive, independent, and recurring problems faced by the ancestors. Domain specific modules handle information about human language, human minds, inanimate causal interactions, the biological world, and other constant adaptive demands faced by human ancestors. Nativist evolutionary psychologists have turned to moral decision making, arguing that cross-cultural moral judgments are invariant in an unexpected way. Natural selection can build and equip a special purpose module only if the information an agent needs to know is stable over evolutionary time. Automatized skills are an alternative means of coping with high-load problems. These skills are phenomenologically rather like modules, but they have very different developmental and evolutionary histories.

At its broadest, evolutionary psychology is the study of the evolved mind. It is a branch of cognitive science that takes the evolutionary history—the etiology—of minds as an important component of a complete psychology. Explaining the origins of our cognitive capacities is an important project in its own right, but many evolutionary psychologists think that an evolutionary framework helpfully guides investigations into the cognitive processes of living humans. This chapter will first sketch the historical background against which evolutionary psychology emerged, and then look at two contrasting views of evolved minds. In Section 2 , we examine the view that sees minds as collections of evolved task-specific modules: nativist evolutionary psychology. In Section 3 , we present the alternative derived directly from evolutionary theory and developmental psychology, a view that takes the role of culture as fundamental. While the truth will lie somewhere between these two views, developing and testing hypotheses will require evidence from the archaeological record. We examine that record and its role in Section 4 . Section 5 outlines the implications for cognitive science and the philosophy of mind.

1. Evolutionary Models of Mind and Behavior

The history of evolutionary psychology is as deep as that of serious evolutionary theory itself: both began with Darwin, and others continued his pioneering work on the evolution of emotion and its expression (see especially Richards 1987 ). However, evolutionary thinking in psychology essentially disappeared with the development of behaviorism. Moreover, the study of behavior was not yet fully established in zoology. This extinction was not local: the evolution of human cognition disappeared as a topic from serious science. Within the biological sciences, evolutionary psychology only returned as a side effect of the establishment of an evolutionary biology of behavior, and that development took much of the century. Early ethology, the study of animal behavior, did not focus on phenomena that extended naturally to human decision making. Many of the early paradigms were of invariant, quite rigid, often ritualized action patterns. Many examples were drawn from mating and brood care of birds, and experiments were typically designed to show that even quite complex and highly structured act sequences could be controlled by simple releasing stimuli. Action was adaptive despite its simple, cue-driven relation to the world, not because of its cognitive complexity (see, e.g., Tinbergen 1960 ). There was some speculation within ethology on how human action should be understood within this framework (see Lorenz 1966 ; Lorenz 1977 ), but these speculations were not integrated with the Tinbergen-Lorenz experimental program (Burkhardt 2005 ). Starved of models of cognitive evolution, the study of human evolution concentrated on changes in morphology and behavior. Thus much of the work of archaeologists and physical anthropologists consisted of chronicling the developments leading to full human behavior, with little informed theorizing about the underlying cognitive mechanisms. When archaeologists did speculate about human cognitive evolution, it was more mythical than methodical (Landau 1984 ).

The connections to human behavior began to be sketched out, as behavioral ecology began to replace ethology (see, e.g., Hamilton 1975 ). Behavioral ecology had a much greater emphasis on formal evolutionary modeling (including sexual selection and kin selection), and its focus shifted to social and sexual decision making. These connections became explicit in the final chapter of Wilson's synthetic overview, Sociobiology: The New Synthesis (1975), and his own subsequent and much less cautious work (1978; Lumsden and Wilson 1981 ). Wilsonian sociobiology was not explicitly a version of evolutionary psychology. Its focus was on supposedly typical forms of human social behavior : those to do with mate choice, child care, intergroup relations and the like. The Wilsonians argued that (for example) both hostility toward strangers and male sexual promiscuity are adaptations. But, while the explicit focus was on action, the Wilsonian program was implicitly committed to strong and probably implausible claims about the psychological mechanisms that generated these distinctive patterns of action. For if xenophobia, say, is an adaptation, then it must be a trait whose occurrence and intensity varies independently of the rest of an individual's behavioral phenotype (for otherwise individuals will not differ just in their xenophobic tendencies (Lewontin 1978 )). For xenophobia to be independent of other behavioral dispositions, the action pattern in question must be generated by an autonomous mechanism (Sterelny 1999 ). Moreover, this propensity must typically be inherited by an agent's offspring.

This picture of the relations between action and cognition is implausibly crude. An agent's disposition to act is dependent not just on the external environment but on the rest of one's cognitive phenotype: on motivation, emotion, and belief. So on these grounds (and others), the Wilsonian program was subject to brutal criticism (Kitcher 1985 ), and has essentially vanished, despite the title of Alcock's 2001 work, The Triumph of Sociobiology .

Even so, humans are animals, and consequently many of the critics accepted that there must be an account of the evolution of human cognition and behavior that would illuminate our current ways of life and social organization (e.g., Kitcher 2001 ; although for a sceptic, see Lewontin 1998 ). Consequently, Wilsonian sociobiology did not vanish without issue. Perhaps its most direct descendant is human behavioral ecology, which maintains the focus on behavior, and like the Wilson program, has imported most of its models from the behavioral ecology of nonhuman animals. Human behavioral ecology focuses on core, fitness-determining decision making (foraging, birth spacing, food sharing, and the like), largely in traditional environments in which the supposed problem of “adaptive lag” (of agents behaving maladaptively because they find themselves in evolutionarily novel environments) is minimized. Human behavioral ecology is focused on individual behavior, and emphasizes the adaptive flexibility of human action: the background assumption is that humans make adaptive choices in just about any social environment. So human behavioral ecologists do not echo Wilsonian sociobiology's claims about genetic constraints on individual action or human social organization, and hence it has not raised the same political suspicions as its predecessor (for reviews of human behavioral ecology that also compare it to other approaches, see Winterhalder and Smith 2000 ; Smith, Borgerhoff-Mulder, and Hill 2001 ; Laland and Brown 2002 ; Smith and Winterhalder 2003 ).

Human behavioral ecology, like Wilsonian sociobiology, says nothing explicitly about our cognitive mechanisms. Rather, it assumes that those mechanisms allow us to assess the causal structure of our environment and to recognize the likely consequences of our actions. And it presupposes that our subjective utilities track fitness. The outcomes we prefer increase fitness, while those we avoid reduce fitness. In contrast, evolutionary psychologists of sundry varieties focus on cognition and its evolution. There is plenty of disagreement among their ranks, but perhaps the most fundamental divide is on how to incorporate culture within an evolutionary framework. One group, the nativist evolutionary psychologists, minimize the role of culture within human life. While we learn much from others, and while that culturally acquired information is essential for a human life, what we learn is constrained by the innate adaptations of the mind. Just as the space of possible languages is constrained by an innate language faculty, so too the space of possible human mating systems, the space of possible folk psychologies, the space of possible folk biologies, and so forth are constrained by innate specializations. Cultural variation is constrained, and individual acquisition within that constrained space is enhanced, by our adapted mind. This model of evolutionary psychology has seized most of the headlines, and it will be our focus in Section 2 . But we will go on to show that it is not the only model of evolutionary psychology: there is a family of alternative models according to which our minds are profoundly shaped by culture and by cultural transmission—alternatives we discuss in Section 3 . Methodological issues are the focus of our final section, for it is not obvious that the historical record is rich enough to discriminate between the various alternative models of cognitive evolution.

2. Evolutionary Nativism

Nativist evolutionary psychology is built around a most important insight: ordinary human decision making has a high cognitive load . To make good decisions, agents must be sensitive to complex, subtle features of their environment. The information-hungry nature of human action first became apparent in thinking about language. Language makes intensive demands on memory. The different parties to a conversation must remember who said what to whom. It also makes intensive demands on attention. In a conversation, you must do more than recall what has been said: you must monitor and act on the effects on your utterances and those of others. You need to be alert to the signs that the conversation is going wrong. Moreover, you will often have to do this while also attending to your physical and social world, for often the point of talking is to coordinate joint action: linguistic acts interface, and are smoothly integrated, with the rest of our lives. Famously, Chomskian linguists argued that learning a first language poses an even more formidable challenge. Every child masters a complex, subtle, intricate set of rules (and a huge vocabulary). Children do so (the argument goes) on the basis of impoverished, perhaps even misleading data (this argument is expounded most brilliantly in Pinker 1994 ; for a sceptical response, see Cowie 1998 ). No wonder then that language is at the core of the cognitive revolution in psychology and is the model evolutionary nativists use in their attempts to synthesize psychology and evolutionary theory.

For, crucially, the point about the cognitive load on language use holds for human decision making generally. Hence much cognitive psychology—psychology with no professional interest in evolution—has followed Chomskian linguistics into some form of nativism: working with the idea that the human mind is specifically prewired for particular learning tasks. We are cognitively competent in the face of difficult challenges because our minds are specifically structured to meet these challenges. Nativist evolutionary psychology gives this idea of prewiring an evolutionary interpretation. Think, for example, of a social negotiation: deciding who does what in organizing a conference. The participants in such a negotiation must estimate what needs to be done and how the total package can be divided into subtasks. They must understand the relative weight of each chore, and the skill set, reliability, and motivation of their partners. Each must be sensitive to the dynamics of the negotiation itself; they must read one another's moods and intentions. We routinely manage such mixes of mindreading, social negotiation and planning, but that should not blind us to the high cognitive load of such achievements. The evolutionary nativist solution to the cognitive load problem is to appeal to special purpose adaptations. Just as we are specifically adapted for language, so too are we specifically adapted to understand our biological and social environment (Atran 1990 , 1998 ). Our minds are ensembles of special purpose devices, each of which is innately equipped to solve the information-hungry but repeated and predictable problems of human life (the classic source for this view is Barkow, Cosmides, and Tooby 1992 ; perhaps its most persuasive articulation is Pinker 1997 ).

In short, evolutionary nativists defend a modular solution to the problem of information load on human decision making. On this view, human minds are ensembles of special purpose cognitive devices: modules. We have a language module; a module for interpreting the thoughts and intentions of others; a “naive physics” module for causal reasoning about sticks, stones, and similar inanimate objects; a natural history module for ecological decisions; a social exchange module for monitoring economic interactions with our peers; and so on. The human mind is not an immensely powerful general-purpose problem-solving engine: it is an integrated array of devices, each of which solves a particular type of problem with remarkable efficiency.

These modules evolved in response to the distinctive, independent, and recurring problems our ancestors faced in their lives as Pleistocene foragers. At some stage in human evolutionary history, language became crucial to human life. In such an environment, the barely lingual would have been under an ever-increasing handicap; hence, there would have been selection for an innate language competence. The lives of human ancestors also depended on cautious cooperation—cautious because free riding would have been an ever-present temptation, and so our ancestors needed to monitor social exchange and to interpret other agents as agents. Our ancestors lived technologically enhanced foraging lives: they needed to understand the causal properties of the raw materials from which they fashioned their tools, and the nature of their biological targets. And so we have folk physics and folk biology modules. And so on.

In this view of cognition, and of cognitive evolution, we cope with the information-processing demands on human life because natural selection has pre-equipped us with both the crucial information and the task-specific processing capabilities we need. Domain specific modules handle information about human language, human minds, inanimate causal interactions, the biological world, and other constant adaptive demands faced by human ancestors (for a recent overview, see Barrett and Kurzban 2006 ).

So the empirical program of nativist evolutionary psychologists is, first, to use their model of the evolutionary demands on human cognition to develop hypotheses about the set of specific adaptations we should expect to find. Second, they use the methods of experimental cognitive psychology to test the idea that we have distinctive cognitive skills in the domains so identified. If such skills are found, this is treated as a confirmation of the evolutionary model. The results of this empirical program are very controversial. Evolutionary psychologists are very upbeat. Most famously, John Tooby and Leda Cosmides think they have evidence of distinctive reasoning about social interaction and norm violation (Cosmides and Tooby 1992 ). If the so-called “Wason selection task” is formulated as a problem of policing norm violation, subjects do well. Given logically equivalent tasks with no similar social content, subjects perform poorly. There has also been a good deal of experimental work on mate preference, the results of which have been taken to confirm nativist predictions that males and females have been under divergent selection regimes and look for different qualities in mates (Buss 1994 , 2006 ). As we see it, recent work has undermined Buss's picture in two ways. First, this work highlights the similarities between male and female choice (for example, both sexes weigh intelligence and kindness heavily), and second, mate choice is frequently that expected by behavioral ecologists, demonstrating the adaptive flexibility of mate choice given diverse local conditions (Gangestad and Simpson 2000 ; Fletcher 2002 ; Fletcher and Stenswick 2003 ; Simpson and Orina 2003 ).

As well as experimental work on adults, nativist evolutionary psychologists also take work in developmental psychology seriously, for innate capacities are expected to have a typical developmental signature, namely, early and uniform appearance. Nativist evolutionary psychologists are especially impressed by evidence of very early theory of mind skills in young toddlers, the development of so-called “theory of mind” capacities (Leslie 2000 ; Leslie, Friedman, and German 2004 ; Leslie 2005 ). Recent studies involve a “differential looking time” test. Subjects look longer at situations that surprise them, so the trick is to devise scenarios that would be surprising if and only if the subject understands mental states and their connections to action. Using these tasks, some developmental psychologists argue that very young children have theory of mind capacities (Gergely and Csibra 2003 ; Tomasello et al. 2005 ; Tomasello and Carpenter 2007 ). Indeed, some very recent work seems to show that children between two and three seem to pass nonverbal tests of sophisticated theory of mind capacities, namely understanding the role of false belief (Baillargeon et al. 2010 ). That said, these results are difficult to interpret for we need a robust account of why their capacity to understand false belief is masked in some tasks and not others.

Most recently, nativist evolutionary psychologists have turned to moral decision making, arguing that cross-cultural moral judgments are invariant in a subtle and unexpected way. Agents think foreseen but unintended consequences are morally different from foreseen and intended ones: the first, but not the second, can be tolerated as a price paid for avoiding a greater evil (Hauser 2006 ). There is a good deal of controversy about the robustness of these results and their interpretation. David Buller, in particular, is very sceptical (2005), and his scepticism has provoked a very hostile response (see, e.g., Machery and Barrett 2006 ). Even some of those broadly sympathetic to the nativist program have doubts about the flagship case of social exchange (see Sperber and Girotto 2003 ; in response see Cosmides et al. 2005 ; Cosmides and Tooby 2005 ).

We do not expect this debate to be over any time soon. We too are sceptical of the nativist program, but for different reasons. Natural selection can build and equip a special purpose module only if the information an agent needs to know is stable over evolutionary time. That sometimes happens: the causal properties of sticks, stones, and bones do not change, hence a naive physics module could well be built into human heads. So there is something to the nativist view, but it is not a general solution to the explanatory challenge posed by our capacities to cope with high cognitive-load problems for many features of human environments have not been stable. The social, physical, and cognitive environments in which we act have been extraordinarily varied. Yet we cope: that is a part of the explanation of our cosmopolitan distribution. Social worlds vary in size, family structure, economic basis, technological elaboration, extent and kinds of social hierarchy, and division of labor. They have varied physically and biologically: the world has changed very dramatically in its physical and biological state over the last few hundred thousand years as it has cycled through ice ages. Indeed, Richard Potts has argued that human evolution has been mainly shaped by increasing, and increasingly intense, climatic variability (1996). Moreover, we are now spread over virtually the whole of the globe. The variability of human environments is especially evident when we bear in mind the fact that we are incorrigible and pervasive ecological engineers: change comes not just from migration and external disturbance, but from our relentless habit of modifying our physical, biological, and social circumstances. Tools, clothes, shelter, fire, and agriculture have changed the world we live in. But so has language, ritual, and extended childhoods in which children live with and learn from their family. If many salient features of human worlds vary across time and space, information about those features cannot be engineered into human minds by natural selection. Our ability to act aptly in such worlds cannot depend on innate modules.

If the nativists are right, and general learning and problem-solving capacities are not powerful enough to solve high-load problems rapidly and accurately, we should suffer from the shock of the new far more brutally than we do. Minds adapted for mid-latitude foraging economies and small-scale social lives should short out when confronted with the cognitive and emotional challenges of (say) New York subways or Mexico City traffic. There are indeed maladaptations of modernity. Favored examples are the diseases of obesity and the restriction of family size by the urban middle class. But we are not, it seems, nearly as hopeless as we should be. Nativist evolutionary psychology seems to predict that the closer an agent's environment is to that of our ancient foraging world, the more reliably adaptive the agent's action should be. But the myth of primitive harmony is indeed a myth: there is no evidence that contemporary small-scale foraging peoples manage their lives more adaptively than, say, urban Mexicans (for a blackly comic catalog of human disaster in traditional societies, see Edgerton 1992 ; for nativist responses to this apparent paradox, see Sperber 1996 ; Carruthers 2006 ).

3. Alternative Models of Evolutionary Psychology

So the situation as we see it is this: The evolutionary nativists are right to think that many routine decision-making situations have a high cognitive load, but they are wrong to think that high-load problems can be confronted successfully only by agents with innately specified, special purpose cognitive capacities. Automatized skills are an alternative means of coping with high-load problems. Automatized skills are phenomenologically rather like modules, but they have very different developmental and evolutionary histories. Skills are slowly built, but once built they are enduring and automatic. As with the nativist psychologist's modules, once they are up and running, they are fast, reliable, automatic, and domain specific. Chess players cannot help but see a chess board and its pieces as a chess position. A birder cannot help but see a particular underwing pattern as a whistling kite. Physical skills such as riding a bicycle might be attenuated by muscular disuse, but they are not forgotten. What is more, automatized skills are often adaptive: they equip agents for the specific features of their environment. The hard-won skills of natural history and bushcraft that enable a forager to move silently, see much that is invisible to others, and find his or her way are plainly critical to survival. So too are the skills of observation, anticipation, and coordination that allow a taxi driver to negotiate the chaos that is Mexico City. But such skills are built into no one's genes. A forager's skills will be very different in an Australian aboriginal in the Pilbara, an Ache hunter-gatherer in a central American rainforest, or an Inuit seal hunter.

Such skills are not only phenomenologically similar to modules, they are also inheritable, for they can be accumulated and transmitted culturally. Children resemble their parents not just because they have inherited their parents’ genes, but also because they have inherited their parent's informational resources (and sometimes that of their parents’ social partners). Cultural transmission is reliable and of high fidelity in part because we are genetically adapted to pump information from the prior generation (Tomasello 1999 ; Alvard 2003 ; Gergely and Csibra 2005 ; Csibra and Gergely 2006 ), but also because we structure the learning environment of the next generation. We construct not just our own niche, but that of the next generation. In part, we build not just their physical and biological world, but their learning environment (Avital and Jablonka 2000 ; Laland et al. 2000 ; Sterelny 2003 , 2006 ). So there is a family of alternative models of evolutionary psychology (see, e.g., Tomasello 1999 ; Heyes 2003 ; Sterelny 2003 ; Jablonka and Lamb 2005 ; Richerson and Boyd 2005 ; Laland 2007 ). These models emphasize four factors that structure human cognition. These are: (1) Cultural inheritance: we have complex cognitive adaptations—for example, the natural history competences of foragers—that are built by cumulative selection on culturally transmitted variation. (2) We are adapted for cultural learning: Michael Tomasello, for example, thinks that joint attention is a key adaptation underpinning human cultural learning, allowing individuals to monitor (and learn from) the social and technical activities of others. (3) Human cognition is plastic: very different phenotypes emerge from the interaction between environments and inherited resources. (4) We develop in structured learning environments. We now sketch one model from this family (based on Sterelny 2003 ), and then close with the difficult methodological problem: Can alternative models be tested? Is the historical record rich enough to impose serious evidential constraints on theories of human cognitive evolution?

We begin by contrasting human and chimp culture. Chimpanzee material culture is quite varied, but it is also quite rudimentary: there is no evidence that any chimp tools exist in their current form as the result of a cycle of discovery and improvement (Laland and Galef 2009 ). Cycles of discovery and improvement depend on reliable and high fidelity transmission between generations. If an innovative australopithecine discovers a more efficient way of flaking stone tools, without reliable social transmission, the technique will disappear at the death of its discoverer. Imitation plays little role in chimp social learning, and they lack language. So chimp social learning is not adapted to a communal data base and a communal skill base that can be ratcheted up over the generations. But for the last couple hundred thousand years the human environment has been the result of a ratchet effect in operation: a cycle in which an innovation is made, becomes standard for the group, and it then becomes a basis for further innovation. So material culture and informational culture is built by cumulative improvements. This process of cumulative improvement depends in part on cognitive adaptations for cultural learning: adaptations that make human children soak up the skills and information of the adults with whom they grow up, but it also depends upon information pooling. Information pooling makes the flow of information across generations much more reliable, as children have access to information controlled by the group as a whole. Moreover, information pooling allows an innovation made by any individual in the group to spread through the group as a whole, and that innovation is then available as a foundation for further improvement. To the extent that information pooling is crucial to the reliable and high fidelity transmission of information across generations, human cooperation and human capacities for high-load decision making are intimately linked.

High fidelity cultural transmission is effective because children are adapted to receive this information, and because information pooling ensures that it is sent reliably, with plenty of redundancy (see Csibra and Gergely 2006 , Gergely and Csibra 2005 , Gergely et al. 2007 ); for archaeological support, see Sterelny ( 2011 ) and the citations therein). But it also depends on niche construction. We have become cosmopolitan in part because we have learned to take our world with us. We have progressively modified our own physical, social, and biological environment. Tools, clothes, shelters have changed the worlds we live in. But we have modified our learning environment too: reshaping both the information available to children and the access they have to that information. Learning is scaffolded in many ways. Ecological tools have informational side effects. A fish trap can be used as a template for making more fish traps; a toolmaker can be immersed in a social world where environmentally salient tools, tool manufacture, and tool use are ubiquitous. Skills associated with manufacture are demonstrated in a form suited for learning. Completed and partially completed artifacts are used as teaching props. Practice is supervised and corrected. The decomposition of a skill into its components is made obvious; subtle elements will often be exaggerated, slowed down, or repeated. Moreover, skills are often taught in an optimal sequence so that one forms a platform for the next. This makes it possible to learn the otherwise unlearnable. Artifacts also act as props in games, rituals, and storytelling, providing opportunities for motor skill acquisition by novice users, and opportunities for an individual to understand artifact deployment within highly coordinated group activities well before their contribution is crucial to group success.

On this view, the organization of human learning environments, cultural variation in those learning environments, and human developmental plasticity interact to provide a range of human cognitive phenotypes. Humans do not have a single cognitive design; cognitive skills are a fundamental part of our cognitive systems, and these in turn are contingent on our environment. Only highly structured developmental environments make the acquisition of complex automatized skills possible. These skills are phenomenologically like modules: they are fast, automatic, and typically adaptive. Skilled drivers make life-and-death decisions without skipping a conversational beat based on quite subtle information about the physical conditions and the behavior of other drivers. But these skills are developmentally very different from modules: they develop slowly, with much practice and instruction, and with much variation both with and across cultures.

Dan Dennett has suggested a more radical version of the idea that differences in technology result in profoundly different developmental trajectories. He has proposed that our capacity to represent and reason about our own thoughts and those of others depends on prior exposure to public representations. Agents in a culture with enduring public symbols inherit an ability to make those symbols themselves objects of perception and to manipulate them voluntarily. Imagine a group of friends drawing a sketch map in the sand to coordinate a hike. Those representations are voluntary and planned. Dennett suggests that we first learn to think about thoughts by thinking about these public representations. In drafting and altering a sketch map, we are using cognitive skills that are already available—they are just being switched to a new target. Moreover, manipulation of such a public representation makes fewer demands on memory; no one has to remember where on the map the camp site is represented. Rich metarepresentational capacities are developmentally scaffolded by an initial stage in which public representations are objects of thought and action (Dennett 2000 ); Andy Clark develops a similar picture in his 2002 work.

Nativist evolutionary psychologists think we have a “folk psychology” module for we are very good at estimating what others will think and do. If an arrangement goes wrong, and a friend fails to turn up to a meeting at a café, we are quite good at working how to recoordinate on the fly. We predict others’ responses, even taking into account the fact that their response will depend on what they expect us to do. The nativist explanation of this remarkable capacity is that we have an innate module equipped with a good model of human thought and decision. There is an alternative: we interpret others as the result of having a biologically prepared, culturally amplified, automated skill. That skill is acquired very reliably, both because humans of one generation engineer the learning environment of the next generation, and because the acquisition of this skill is supported by perceptual systems tuned to relevant cues. We are sensitive to facial expression; signs of affect in voice, posture, and movement; the behavioral signatures that distinguish between intentional and accidental action, and the like. These systems make the right aspects of behavior, voice, posture, and facial expression salient to us. They make learning easier because we are apt to notice the right things in other agents. The acquisition of interpretive skills depends on perceptual preadaptation and individual exploration in a socially structured learning environment.

In addition to these perceptual preadaptations, children live in an environment soaked with agents interpreting one another. They are exposed both to third party interpretation, and to others interpreting them. Much of this interpretation is linguistic but there are also contingent interactions in which the child is treated as an agent: imitation games, joint attention, and joint play. It helps that children interact with their developing peers for they have not yet gained the abilities to mask their emotions, inhibit their desires, and suppress their beliefs. Interacting with more transparent agents simplifies the problem of inferring from an action to its psychological root. In adults, the connection between psychological state and action can be very complex and indirect. How could anyone learn that action depends on an agent's beliefs and goals, when those are so hidden? But when children interact with their peers, the connections between desire, emotion, and action will often be very direct. Children are less good at concealing overt signs of their emotion than adults, and less good at resisting the urge to act on those emotions. As three- and four-year-olds are making crucial developmental transitions, this lack of inhibition of their peers simplifies their epistemic environment.

Parents make the interpretive task easier by offering models of their own and their children's actions: they often rehearse interpretations of both their own and their children's actions. Likewise, children's narrative stories are full of simplified and explicit interpretative examples. Language itself scaffolds the acquisition of interpretative capacities by supplying a premade set of interpretative tools. Thus linguistic labels help make differences salient (Peterson and Siegal 1999 ). Finally, focusing on the concept of belief can make the task of acquiring theory of mind seem even more challenging than it really is. Belief and preference are often hidden, having no overt and distinctive behavioral signature. But many folk psychological concepts—those for sensations and emotions—do have a regular behavioral signature, and these scaffold the acquisition of less behaviorally overt concepts by making available easier examples of inner causes of outer actions (Sterelny forthcoming).

The position outlined agrees with the nativists’ scepticism about the power of general purpose learning mechanisms. Nativists think evolution has solved this problem by reducing the amount we need to learn. But the alternative model suggests that evolution has found a different and more flexible strategy: the power of general purpose learning has been augmented by optimizing the learning environment. No doubt the cognitive capacities involved in understanding others would be very hard to acquire by our own unaided efforts, but we do not have to acquire them that way. Our environments have been informationally engineered to circumvent the cognitive limits of individuals on their own. Alternatives to nativist evolutionary psychology present a model of how a fast, automatic, and sophisticated cognitive specialization can develop without it depending on specific innate structures.

Of course many hybrids are possible. Perhaps folk psychology is acquired both through a richly structured environment together with some minimal but specific prewiring: a view that might be very plausible, if the evidence for very early acquisition is further supported. In any case, it is likely that the truth will lie somewhere between the two extremes of nativism and niche construction. The alternatives will be refined and tested within the laboratories of cognitive scientists. But that is not the only evidence that is relevant, for if modules and automatized skills are phenomenologically similar, then one way of choosing between the two hypotheses is the rate of change in behaviors over time. Niche construction and other culture and learning based models predict that human behavior and social organization should be highly variable in space and time (since cultural variation is not constrained by innate modules). Moreover, our distinctive cognitive capacities are coevolutionary products of individual innovation, cultural transmission, and niche construction. This implies that they should appear gradually, as their appearance does not depend on genetic change in the human lineage. The nativist model makes contrary predictions. Change should be more stepwise, as a cognitive module comes on-line, opening up a new set of behaviors. But is there enough information in the historical record for us to tell who is right? We conclude with this pressing methodological problem, beginning with a review of the record and its data.

4. Going Beyond the Evidence? Historical Traces of Cognitive Evolution

As noted in Section 1 , there has been speculation about the evolution of human psychology for well over a century. However, within archaeology and paleoanthropology this speculation has typically been naϯve about the cognitive sciences. Psychologists’ speculations on human evolution have been equally naϯve (see for instance Foley 1996 ). This began to change in the latter decades of the last century, with a small but significant number of publications that were either joint productions of cognitive scientists and archaeologists (Noble and Davidson 1996 ), or that took cognitive theories more seriously (Wynn 1991 ; Wynn 1993 ; Renfrew 1994 ; Mithen 1996 ). This new movement within archaeology and evolutionary studies both tested the claims of evolutionary psychology and morphed into an active branch of “evolutionary psychology” in its own right. So what can this area of evolutionary psychology tell us? Can it discriminate between alternative hypotheses about the history of cognition?

Archaeology can tell us a great deal about our human ancestors. Analysis of a stone tool can show that a hominin manufactured it out of a certain rock type, and thus can also show that hominins traveled long distances, or traded, for the raw material. Biochemical analysis can show that there are residues of animal protein on the tool that indicates its use for butchery. Microscopic analysis can show wear patterns characteristic of certain functions. Fossil evidence provides information about physiological adaptations, such as a shift to bipedalism, and the evolution of precision grip. However, this information is not about cognition as such. To go beyond artifacts and fossils, we have to construct models of behavior, and from these behaviors, models of the associated cognitive skills. So we have evidence for specific cognitive capacities only if these capacities have impacts upon the physical world: impacts that are a consequence of behaviors that are preserved in the historical record. Thus, the best models of cognitive evolution tested in the historical record will take the external environment and its manipulation by actors seriously.

The key, then, to making the physical evidence of the archaeological and fossil record act as a means for testing hypotheses of evolutionary psychology is the construction of models of behavior that make predictions about the interactions of individuals and groups with their physical world. A speech act might leave no direct physical evidence, but a speech act might be necessary for a particular kind of learning, behavior, or activity that in turn leaves some kind of physical evidence. We may not be in a position to determine directly when sophisticated forward planning emerges within the human lineage, but indirectly, the capacity can be inferred from behaviors that require this capacity; behaviors that in turn leave evidential traces.

The notion that we can utilize physical by-products of behavior as tools for understanding minds should not alarm us. We as individuals do this every day when we interpret the desires and beliefs of our fellow agents through the consequences of their actions. We are quite comfortable inferring a set of beliefs and desires about an individual when arriving at a shared office to find an office mate's computer on, and a warm cup of coffee and a scatter of articles on her desk, despite her temporary absence. Forensic scientists routinely reconstruct behaviors and motives from physical evidence in ways that juries find persuasive. So for the historical record to act as a test of evolutionary psychology hypotheses, our models of cognition and behavior should derive predictions about further evidence that can then be detected in the historical record. This information is going to come in two forms: fossil evidence and archaeological evidence.

Behaviors and brains do not fossilize. However, there are endocasts of fossil hominin skulls, which are molds taken from inside a fossil cranium. These can reveal the crude anatomy, hints of surface features, and size of hominin brains. How informative endocasts are, however, remains an open question. It seems unlikely that the folding of the brain surface relates directly to function, as surface folding may well be the result of an allometric process, with increased brain size resulting in increased folding. Sulci, gyrus, and other surface features of the brain, being highly labile and dependent upon body size (Sereno and Tootell 2005 ), may not then be diagnostic of function. Perhaps the surface features of the brain are only informative where gross anatomy of hominin brains reveal changes in sensory input capacities. Endocasts can reveal differences in the relative size of, say, the frontal lobes versus the cerebellum, but again, how much this reveals about cognitive function is highly dependent upon the extent to which specific, functional aspects are localized, and whether these relations between gross structure and function are stable homologies across species. Certainly, the resolution at this level is not enough to inform us of the emergence of specific functions. However, this gross anatomy, along with overall brain size, may provide clues as to the increasing importance of cognitive strategies in human evolution, even if they are uninformative of specific cognitive adaptations per se (Deacon 1997 ).

Fossilized physiological traits directly associated with specialized behaviors may provide clues to cognitive developments. Language adaptations provide a good example here. Breathing control necessary for speech requires increased muscle and nerve control and an inevitable widening of the thoracic vertebral canal. Paleoanthropologists have detected this feature in fossils of Homo neandertalensis , and Homo sapiens , but not in earlier hominins such as Homo erectus and the Australopithecines, nor in extant primates (MacLarnon and Hewitt 1999 ). Other physiological by-products of specialized behaviors include adaptations for precision grip associated with toolmaking (See for instance Marzke 1992 ; Tocheri et al. 2003 ). So there is a clear potential for an important subset of behaviors to leave signals in the fossil record, and these are equally signals of the cognitive mechanisms that drive those behaviors.

Archaeological finds of tools, marked and cracked bones, and other manipulated objects are at once highly suggestive of cognitive developments and novel behavior, but they also require a good understanding of the relationship between the evidence, the behavior, and its cognitive basis. Modeling these relationships is not straightforward. For a start, tools and their diversification in the latter stages of human evolution may be in part a response to changing economic requirements (Stiner et al. 2000 ). So there remains the constant concern that absence of archaeological evidence for cognitive sophistication is not evidence for the absence of cognitive sophistication.

A further problem is that of determining the function of specific tool types, for function tells us about the agent's behavior, and hence the mind responsible for that behavior. Nowhere is this more obvious than in the case of the Acheulean bifaces of the Early Stone Age of Africa, and the Lower Paleolithic of Europe. This technology contravenes many of the expectations we have of a fully human culture: it shows little change over an extended period (approximately two million years ago to .6 mya) and little regional differentiation over a large area (Africa and Eurasia). Quite how hominins used Acheulean handaxes is problematic. The associated cognitive developments are also difficult to interpret. They have been associated with preferences for symmetry (Wynn 1995 , 2002 ), with sexual selection in hominins (Kohn and Mithen 1999 ; Kohn 2000 ), and even as the by-product of a sophisticated hunting strategy utilizing handaxes as “killer Frisbees” (Calvin 1983 ).

The Cambridge Archaeologist Graham Clark proposed an alternative classification based on differing manufacturing methods, which is probably more suitable for evolutionary psychologists.

Mode 1  tools are simple chopping tools and flakes; they emerge approximately 2.6 million years ago in Africa with the Homo genus and make a first appearance in Europe some time later. They are typically modified cobbles, and appear to be manufactured by Early Homo species in direct response to immediate requirements.

Mode 2  tools are associated with the classic Acheulean Handaxes. These tools are bifacially flaked tools; many seem to be manufactured to a standardized “tear drop” shape and are associated with increased transportation of raw materials. Mode 2 technology makes its first appearance approximately 1.6 to 1.5 million years ago, and it overlaps with Homo erectus’ long tenure on the planet.

Mode 3  tools are manufactured from a “prepared core.” This two-step process has an initial piece of raw material that is shaped, and from this large uniform flakes are removed. These standardized flakes are in turn shaped into different tools. Mode 3 technology is associated with Homo neandertalensis and other “Archaic” sapiens.

Mode 4  Tools (Upper Paleolithic and Later Stone Age) represent the emergence of blades and finer worked stone tools, and is generally considered to represent the emergence of a full human suite of toolmaking capacities. (Although not necessarily the emergence of Homo sapiens as a species.) Mode 4 tools show regionalization, specialization, and increased use of alternative materials. Symbolic art and other cultural traits are associated with the emergence of Mode 4 technologies. The middle to upper Paleolithic transition represents the sudden arrival of Mode 4 technology in Europe, but appears to have been a gradual transition from middle to later stone age in Africa from approximately one hundred thousand years ago or even earlier (see text).

The key to understanding the relevance of such archaeological finds lies in understanding the cognitive requirements and learning strategies of two distinctive behaviors: tool manufacture and tool deployment. Tool manufacture should provide us with information on important planning skills, folk physics (or perhaps more accurately, folk engineering and materials science), and perhaps the learning and teaching skills acquired by hominins. For instance, a crucial development in hominin evolution is decoupling of immediate stimulus from tool manufacture, something of which many primates seem incapable (See for instance Jalles-Filho et al. 2001 ). The evidence for this comes from manufacturing sites away from kill sites, the emergence of raw material transport and caching as a strategy (Marwick 2003 ), and higher time investment in tool manufacture. Such analyses suggest increased abilities in forward planning (Suddendorf and Busby 2005 ; Suddendorf 2006 ), and possibly in later hominins the evolution of increased working memory (Coolidge and Wynn 2005 ). While tool manufacture seems implicitly tied to the emergence of technical intelligence, toolmaking is also informative about social intelligence. Modern tool manufacture is frequently a highly social practice, requiring group-level decisions, social pedagogy, and group coordination (for an intriguing example, see Hiscock 2004 ). Understanding the dynamics of toolmaking, particularly the social skills required for the acquisition of toolmaking competence, is a crucial area of research.

Tool deployment, understood in the light of evidence from bones from kills, tells us about hunting strategies, coordination, exploitation of new habitats, and ability to recognize and exploit seasonal resources. See for instance the shift in game profiles from prehuman to human hunters discussed in (Avery and Cruz-Uribe 1997 ). In particular, the changes in technology from general purpose cutting devices manufactured and deployed in response to immediately perceived needs, to curated tools manufactured to anticipated needs, through to highly specialized tools with distinct local cultures, suggests changes in planning capacities, learning, and consequent developments in social transmission of environmental information (Jeffares 2010a, 2010b ). Archaeological finds thus suggest increases in the sophistication of planning and means-ends reasoning of hominins, plus an increased role for social learning, direct pedagogy, and group-level logistics requiring coordination and cooperation among individuals.

It is important to note here that we can construct from a variety of evidential sources hypotheses about when and why distinctively human cognitive traits appear. Consider Ben Marwick's suggestion that archaeological evidence of long-distance trade networks in raw materials provides evidence for the evolution of language (Marwick 2003 ). By itself, the claim is highly suggestive but not compelling. However, when combined with physiological evidence of language-related physiological traits such as an increased thoracic vertebrae channel for breathing control (MacLarnon and Hewitt 1999 ), and increased requirements for directed learning associated with more sophisticated tool types, we may get a temporal cluster of evidence pointing to the emergence of a particular cognitive skill within a particular time frame. In turn, such clusters of evidence can provide us with a chronicle that documents the emergence of a variety of cognitive features.

In short, the archaeological and fossil record can provide information about the tempo and mode of the evolution of particular capacities, and thus it gives us some ability to discriminate between the two models of evolutionary psychology outlined in prior sections. As we noted, the two alternative views of cognitive evolution make quite distinct claims about the timing of the emergence of cognitive capacities. The modular nativist account sees cognition as a set of discrete competences. Consequently, we would expect to see physical evidence for the evolution of these competences as equally discrete units in the physical record. As a new behavior comes “on-line,” it would manifest itself in the physical record. However, if human cumulative cultural evolution, niche construction of information, and environments underpin human cognitive evolution, then we should expect to see evidence of an accumulative ratchet of cultural competences in the archaeological record, with technological and behavioral developments building on prior developments.

These alternative views on the tempo of human cognitive evolution have an important echo within paleoanthropology. Much ink has been spilt over the significance of the Middle to Upper Paleolithic transition in tools in Europe approximately fifty thousand years ago. This transition shows the comparatively sudden emergence of new materials for tools. Bone and wood appear for the first time, symbolic art emerges, and we see evidence of other quintessential human cultural traits. In fact, the Middle to Upper Paleolithic transition is so profound and puzzling that some of the hypotheses offered have been wildly speculative. Thus Michael Winkelman suggests that the emergence of symbolic art was a strategy to cope with the integration of a bicarmel consciousness, guided by shamanic cultural practices (Winkelman 2002 ). Some of the more reasonable suggestions for the cognitive basis for this transition have included the emergence of fully articulate language (wee for instance Lieberman 1998 ), and (notably for the nativist evolutionary psychologists) Stephen Mithen's suggestion that it marks the final phase of a modular development of human cognition (Mithen 1996 ). Thus, the Middle to Upper Paleolithic transition could be interpreted as evidence of the emergence of nativist module, with a new set of skills coming “on-line” in the human lineage.

However, recent work suggests that this sudden European transition in tool types represents migration, with culturally developed humans displacing previous populations, and that this transition is consequently an artifact of the European record, and not a sign of a cognitive leap forward. A reevaluation of the archaeological record beyond Europe, particularly Africa, suggests that fully human behaviors are much older, emerging via the cumulative evolution of culture (Mcbrearty and Brooks 2000 ). The result has been a reevaluation of the emergence of modern humans. There are a range of proposals, some with the emergence of modern humans going back as far as three hundred thousand years ago, and associated with the emergence of Mode 3 tools. (For a brief overview of this debate, see Henshilwood and Marean 2003 ) Currently, the general picture that emerges is of Homo sapiens arising in Africa, slowly developing a sophisticated culture, and then displacing preexisting hominin populations in Europe and elsewhere. Consequently, archaeological evidence of later hominins favors a cumulative, slow cultural evolution and not a modular, discrete series of punctuated pulses in cultural developments.

5. The Future of the Evolutionary Past

This overview of evolutionary psychology has had two themes. We have underscored the variety of evolutionary approaches to human cognition. There are, of course, various hybrids between evolutionary nativism and the alternatives we have sketched; there is a spectrum of models between undiluted nativism and undiluted constructivism. For example, one might suppose that some or all of the distinctively human cognitive capacities arose and were established in human populations as automated skills (i.e., by the mechanisms discussed in Section 3 ), and were subsequently modularized by genetic entrenchment, their development becoming less reliant on rich environmental support. The second theme has been to emphasize the constraints history should place on theory. In the existing literature, most of the evidential debates have focused on proximate mechanisms. How do our cognitive capacities develop? How do they operate? These are good questions, for evolutionary psychologists of all stripes make claims about the cognitive capacities of living humans. But they also make claims about the history of those capacities. So it is important to test their models against the record of physical evidence from the past. In the debates on evolutionary psychology, this mode of testing has been underexplored. Despite the obvious limitations of the historical record, we think it is a potentially important source of evidence, as well as an important strand of research in its own right. But that potential will be quite difficult to realize. To test models of cognitive evolution, we need to isolate physical proxies for behaviors: behaviors that are in turn proxies for important cognitive capacities. Those proxies then tell us when the behavior appeared in the hominin repertoire, and the behaviors in turn tell us about the cognitive capacities that underpin those behaviors. That is important, because different models make differing predictions about the tempo and mode of cognitive evolution, so we need a chronology that charts the emergence of our cognitive capacities. As we have just seen, to some extent, and still very tentatively, we can compare different predictions about the construction of the human cognitive suite with its actual construction. The more general point though is that models of cognitive evolution are constrained by physical evidence of our past, not just evidence about current function.

Much of the literature on evolutionary psychology, pro and con, has focused almost wholly on evolutionary nativism. Much of that literature has been more polemical than informative. As we see it, the way forward is to develop and to test specific alternatives to such nativist models (many of which will be hybrids, incorporating elements of those nativist models). There is no novelty in emphasizing testing. We do, however, think that the historical record is richer in information, and hence in the potential to test and refine these alternative methods than has often been supposed. It is true that thoughts do not fossilize. But thoughts drive actions, and these leave traces which, collectively, are surprisingly informative about the lives and minds of ancient humans.

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Evolutionary Psychology

A brief history of evolutionary psychology, from darwin to 2023..

Updated November 14, 2023 | Reviewed by Tyler Woods

• Evolutionary psychology, as a field, can be traced back to Darwin's own work.
• Several variants of evolutionary psychology have emerged on the scene over the decades.
• Here is a brief timeline of the field—with an eye toward the future.

Trying to understand human behavior (a basic feature of our species, shaped by natural selection) without understanding evolutionary principles would be like trying to understand the details of a car without realizing that its purpose is to locomote. As several scholars, including myself, have maintained over the years, understanding evolution is simply essential for a full take on the human behavioral experience (see Evolutionary Psychology 101 ).

In an effort to help document some critical junctures that have shaped this area of inquiry, here is a brief* chronology of the field.

1859: Charles Darwin publishes On the Origins of the Species —showing the process of natural selection, evolution's primary process when it comes to the nature of life, to the world.

1872: Darwin publishes The Expression of Emotion of Man and Animals . Without question, his ideas in this book fully represent an evolutionary approach to human psychology. With Darwin's publications on evolutionary processes applied to psychological states, the field of evolutionary psychology was born.

1953: Niko Tinbergen and other behavioral scientists advance the Ethology movement, applying evolutionary principles, in a broad manner, to issues of animal behavior .

1964: William Hamilton demarcates the ideas of "inclusive fitness" and "kin-selected altruism " to help explain how evolutionary principles can shed light on prosocial (other-oriented) behavior.

Early 1970s: Robert Trivers published several seminal theoretical articles on the importance of parental investment in mating systems, reciprocal altruism, and parent/offspring conflict. These articles set the stage for the large-scale application of evolutionary principles to various facets of the behavioral experience.

1975: E. O. Wilson, of Harvard, publishes the book Sociobiology , about how evolution has shaped social behaviors across various species—our own species included. Not everyone loved the idea. But wow, this book pushed the needle in a big way.

1976: Oxford biologist Richard Dawkins published the groundbreaking book The Selfish Gene , which essentially presents Darwin's ideas for a relatively modern audience. The book focuses on the evolution of behavior in particular.

1980s-1990s: The Harvard Connection

As a then-junior faculty member, evolutionary psychologist David Buss (now at the University of Texas) took a position at Harvard University, which, as history would come to tell us, served as a hotbed for the cultivation of evolutionary behavioral science.

While not there at exactly the same time, evolutionary pugilists Steve Pinker (who was still in the early stages of applying evolutionary concepts in his work at that point) and Robert Trivers held positions at Harvard at nearly the same time. And importantly, Martin Daly and Margo Wilson held one-year sabbatical positions at Harvard while Buss was there, partly shaping this burgeoning epicenter of evolutionary thinking.

Concurrently, two thinkers who would eventually become major scholars in the field, Leda Cosmides and the late-great John Tooby, called Harvard home at the time. They both obtained undergraduate and graduate degrees while there and they learned about this budding young evolutionary thinker, David Buss, along the way.

Cosmides and Tooby later went on to marry and to, collaboratively, launch the Center for Evolutionary Psychology at UC Santa Barbara, which still operates as an internationally renowned hub of evolutionary scholarship to this day. They also introduced Buss to legendary Harvard evolutionary anthropologist, Irv Devore, during this time period. The connections and ideas regarding evolution and the human experience were percolating at full-force.

As Buss (2023) stated, this work by Cosmides and Tooby set the stage for the "develop[ment of] the conceptual foundations of evolutionary psychology, merging cognitive (science)/information processing with evolutionary theory."

Buss remained close friends with both Cosmides and Tooby. The effects all these scholars had on the advancement of evolutionary psychology have been nothing short of huge over the years.

Several other major evolutionists, such as E. O. Wilson, Ernst Mayr, and Paul Bingham, also called Harvard home during this general era.

1987-1990: Building the Foundations of Evolutionary Psychology

Between 1987 and 1990, at the Center for Advanced Study in the Behavioral Sciences at Stanford, David Buss led an intellectual initiative designed to really demarcate the foundational concepts of evolutionary psychology. As part of this process, he built an all-star team of scholars, including Leda Cosmides, John Tooby, Martin Daly, and Margo Wilson. The group spent the better part of a year putting together a draft of a would-be textbook in the field of evolutionary psychology. At the end of the day, everyone went back to their full-time gigs at their respective universities, and the book never was completed. But the seeds of so many evolutionary projects that would become foundational in the field were sown.

1989: The Launching of the Human Behavior and Evolution Society (HBES)

Another landmark event for the field is found in the formation of the world's first (and currently largest) intellectual society dedicated to the study of human behavior and evolution (the Human Behavior and Evolution Society; HBES ).

With roots in the work of scholars who were stationed at Michigan at the time (including Bill Irons and Napoleon Chagnon at Northwestern and David Buss and Randy Nesse at the University of Michigan), the formal launching of HBES, with renowned evolutionary biologist, William Hamilton, as founding president and founder of the field of Darwinian Medicine, Randy Nesse playing a primary role in the formalization of the organization, was an instant hit. Among the invited speakers at this first meeting of the society were Richard Dawkins and William Hamilton. Highly revered evolutionary biologist George Williams was also a regular presence at the early meetings of HBES. To put things into perspective, in the field of evolutionary studies, these folks are nothing short of icons and the society was well on its way to making a splash right out of the gate.

1992: Jerome Barkow, Cosmides, and Tooby published The Adapted Mind , which would quickly become a classic in the field, paving the way for how the field of evolutionary psychology would proceed.

1992: Then-graduate-student Margie Profet publishes (partly in The Adapted Mind ) stunning work showing that pregnancy sickness, a basic feature of the broader human experience, can best be understood within an evolutionary framework. This piece paved the way for understanding all kinds of human phenomena from an evolutionary perspective.

1994: Buss publishes the first edition of The Evolution of Desire —an insightful treatise on how evolutionary principles shed light on all facets of the human mating experience. The influence of this book on thinking within the behavioral sciences has been profound and has proven as relevant to all kinds of human issues.

1994: Randy Nesse coins the term "Darwinian Psychiatry " and shows how powerfully evolutionary principles can be applied in the field of psychiatry specifically, as well as in medicine in general. He also coined the term "Darwinian Medicine" and has been a stalwart champion of integrating Darwinian ideas into all branches of medical science and practice.

1998: David Sloan Wilson, largely in an attempt to shed light on prosociality (the helping of others), posits the idea of multi-level selection , which underscores the fact that evolutionary forces are constantly working at multiple levels regarding the evolution of organisms—humans included.

1998: Buss publishes the first textbook titled Evolutionary Psychology . In a sense, the field (which had been brewing and steeping and churning for well over a century) was born.

2009 (or so): Scholars in all kinds of fields ( education , politics , mental health, nutrition , and more) start the large-scale application of evolution to address a number of human issues. This field sits under the umbrella of Applied Evolutionary Psychology, and it even has its own society (the Applied Evolutionary Psychology Society). Leaders of this initiative included the likes of Daniel Kruger, Nicholas Armenti, and Daniel Glass, along with several other key thinkers.

2009 (or so): A similar group of scholars works to integrate the often-disparate fields of evolutionary psychology and feminism, starting the Feminist Evolutionary Perspectives Society. Leaders of this initiative included Rosemarie Sokol, Maryanne Fisher, Justin Garcia, Rebecca Burch, Laura Johnsen, and others. Perhaps the most conspicuous product of this work is found in the book Evolution's Empress: Darwinian Perspectives on the Nature of Women .

Importantly, both AEPS and FEPS were spinoffs of the NorthEastern Evolutionary Psychology Society ( NEEPS ), which held its first conference on the campus at SUNY New Paltz in 2007 and featured David Sloan Wilson and Gordon Gallup as inaugural invited speakers.

2019 (or so): Multiple scholars (including myself and Nicole Wedberg— Positive Evolutionary Psychology: Darwin's Guide to Living a Richer Life ), Doug Kenrick and David Lundberg-Kenrick ( Solving Modern Problems with a Stone-Age Brain ), and David Sloan Wilson ( This View of Life )—among several others—work to apply evolutionary principles to the bright side of the human experience. In other words, there is currently a large international effort to use information from evolutionary psychology to help improve the broader human condition.

Bottom Line and the Future of Evolutionary Psychology

Importantly, the chronology presented here is limited at best. It is also noteworthy (as partly described prior) that several major regional, national, and international intellectual societies have formed over the years to help advance work in the field of evolutionary psychology (e.g., the Human Behavior and Evolution Society, the NorthEastern Evolutionary Psychology Society, International Society for Human Ethology, and more). Further, several major scholars whose work has been dedicated to evolutionizing certain subfields within psychology also warrant significant recognition (e.g., Gordon Gallup in terms of evolution connecting with neuroscience , David Bjorklund in terms of how evolution connects with developmental psychology, Peter Gray in terms of how evolution pertains to education, and more).

The above chronology hopefully sheds light on some of the critical historical markers of evolutionary psychology. In 2011, along with several collaborators (Garcia et al., 2011), we discussed the future of the field of evolutionary psychology in detail. On one hand, we found reason for optimism —for instance, we found that work in the field of evolutionary psychology shows all kinds of academic markers of being a truly interdisciplinary academic field. That said, our work, along with that of several others, has shown significant resistance to this way of thinking about the human behavioral condition within higher education.

In short, this powerful field of inquiry, which has demonstrated an extraordinary capacity to shed light on the human condition, has something of an uncertain future. Hopefully, articles like this one can help move the needle a bit and get people to think about how Darwin's big ideas might have the capacity to help make the world a better place. For all of us.

Note: This article was largely inspired by conversations with David Buss—and is dedicated to a pioneer in (and champion of) the field, the late Dr. John Tooby

*and hardly complete!

Barkow, J., Cosmides, L., & Tooby, J. (Eds.; 1992), The adapted mind: Evolutionary psychology and the generation` of culture. New York: Oxford University Press.

Buss, D. M. (November 10, 2023). Personal communication.

Buss, David M. (1994). The Evolution of Desire: Strategies of Human Mating. New York: Basic Books.

Buss, D. M. (1998). Evolutionary Psychology: The New Science of the Mind (1st Edition). New York: Allyn & Bacon.

Darwin, C. (1859). On the origin of species by means of natural selectionor the preservation of favoured races in the struggle for life (1st ed.). London, UK: John Murray.

Darwin, C. (1872). The expression of the emotions in man and animals. London, UK: John Murray.

Dawkins, R. (1976). The Selfish Gene. Oxford: Oxford University Press.

JR Garcia, G Geher, B Crosier, G Saad, D Gambacorta, L Johnsen & E Pranckitas. (2011). The interdisciplinary context of evolutionary approaches to human behavior: a key to survival in the ivory archipelago. Futures , 43, 749-761.

Geher, G. (2014). Evolutionary Psychology 101. New York: Springer.

Geher, G. & Wedberg, N. (2022). Positive Evolutionary Psychology: Darwin’s Guide to Living a Richer Life. New York: Oxford University Press.

Hamilton W.D. (1964). "The genetical evolution of social behaviour. I" J. Theor. Biol. 7, 1–16.

Profet, M. (1992). Pregnancy Sickness as Adaptation: A Deterrent to Maternal Ingestion of Teratogens. The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Oxford University Press. pp. 327–365.

Tinbergen, N. 1953. The Herring Gull's World . London: Collins.

Trivers, R. L. 1971. The evolution of reciprocal altruism. Quarterly Review of Biology 46:35-57.

Trivers, R. L. 1972. Parental investment and sexual selection. In B. Campbell, ed. Sexual Selection and the Descent of

Man, 1871-1971, Aldine-Atherton, Chicago, pp. 136-179.

Trivers, R. L. 1974. Parent-offspring conflict. American Zoologist 14:247-262.

Wilson, D. S. (1998). Hunting, sharing and multilevel selection: The tolerated theft model revisited. Current Anthropology , 39 , 73–97.

Wilson, E. O., (1975). Sociobiology: The New Synthesis , Harvard University Press.

Glenn Geher, Ph.D. , is professor of psychology at the State University of New York at New Paltz. He is founding director of the campus’ Evolutionary Studies (EvoS) program.

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Evolutionary Psychology

Evolutionary psychology is one of many biologically informed approaches to the study of human behavior. Along with cognitive psychologists, evolutionary psychologists propose that much, if not all, of our behavior can be explained by appeal to internal psychological mechanisms. What distinguishes evolutionary psychologists from many cognitive psychologists is the proposal that the relevant internal mechanisms are adaptations—products of natural selection—that helped our ancestors get around the world, survive and reproduce. To understand the central claims of evolutionary psychology we require an understanding of some key concepts in evolutionary biology, cognitive psychology, philosophy of science and philosophy of mind. Philosophers are interested in evolutionary psychology for a number of reasons. For philosophers of science —mostly philosophers of biology—evolutionary psychology provides a critical target. There is a broad consensus among philosophers of science that evolutionary psychology is a deeply flawed enterprise. For philosophers of mind and cognitive science evolutionary psychology has been a source of empirical hypotheses about cognitive architecture and specific components of that architecture. Philosophers of mind are also critical of evolutionary psychology but their criticisms are not as all-encompassing as those presented by philosophers of biology. Evolutionary psychology is also invoked by philosophers interested in moral psychology both as a source of empirical hypotheses and as a critical target.

In what follows I briefly explain evolutionary psychology's relations to other work on the biology of human behavior and the cognitive sciences. Next I introduce the research tradition's key theoretical concepts. In the following section I take up discussions about evolutionary psychology in the philosophy of mind, specifically focusing on the debate about the massive modularity thesis. I go on to review some of the criticisms of evolutionary psychology presented by philosophers of biology and assess some responses to those criticisms. Finally, I introduce some of evolutionary psychology's contributions to moral psychology.

1. Evolutionary Psychology: One research tradition among the various biological approaches to explaining human behavior

2. evolutionary psychology's theory and methods, 3. the massive modularity hypothesis, 4. philosophy of biology vs. evolutionary psychology, 5. moral psychology and evolutionary psychology, 6. prospects for future work, bibliography, other internet resources, related entries, acknowledgments.

This entry focuses on the specific approach to evolutionary psychology that is conventionally named by the capitalized phrase “Evolutionary Psychology”. This naming convention is David Buller's (2000; 2005) idea. He introduces the convention to distinguish a particular research tradition (Laudan 1977) from other approaches to the biology of human behavior. [ 1 ] This research tradition is the focus here but lower case is used throughout as no other types of evolutionary psychology are discussed. Evolutionary psychology rests upon specific theoretical principles (presented in section 2 below) not all of which are shared by others working in the biology of human behavior (Laland and Brown 2002). For example, human behavioral ecologists present and defend explanatory hypotheses about human behavior that do not appeal to psychological mechanisms (e.g., Hawkes 1990; Hrdy 1999). Behavioral ecologists also believe that much of human behavior can be explained by appealing to evolution while rejecting the idea held by evolutionary psychologists that one period of our evolutionary history in the source of all our important psychological adaptations (Irons 1998). Developmental psychobiologists take yet another approach: they are anti-adaptationist (Michel and Moore 1995; but see Bateson and Martin 1999; Bjorklund and Hernandez Blasi 2005 for examples of developmentalist work in an adaptationist vein). These theorists believe that much of our behavior can be explained without appealing to a suite of specific psychological adaptations for that behavior. Instead they emphasize the role of development in the production of various human behavioral traits. From here on, “evolutionary psychology” refers to a specific research tradition among the many biological approaches to the study of human behavior.

Paul Griffiths argues that evolutionary psychology owes theoretical debt to both sociobiology and ethology (Griffiths 2006; Griffiths forthcoming). Evolutionary psychologists acknowledge their debt to sociobiology but point out that they add a dimension to sociobiology: psychological mechanisms. Human behaviors are not a direct product of natural selection but rather the product of psychological mechanisms that were selected for. The relation to ethology here is that in the nineteen fifties, ethologists proposed instincts or drives that underlie our behavior; [ 2 ] evolutionary psychology's psychological mechanisms are the correlates to instincts or drives. Evolutionary psychology is also related to cognitive psychology and the cognitive sciences. The psychological mechanisms they invoke are computational, sometimes referred to as “Darwinian algorithms” or as “computational modules”. This overt cognitivism sets evolutionary psychology apart from much work in the neurosciences and from behavioral neuroendocrinology. In these fields internal mechanisms are proposed in explanations of human behavior but they are not construed in computational terms. David Marr's (e.g., 1983) well known three part distinction is often invoked to distinguish the levels at which researchers focus their attention in the cognitive and neurosciences. Many neuroscientists and behavioral neuroendocrinologists work at the implementation level while cognitive psychologists work at the level of the computations that are implemented at the neurobiological level (cf. Griffiths 2006).

Evolutionary psychologists sometimes present their approach as potentially unifying, or providing a foundation for, all other work that purports to explain human behavior (e.g., Tooby and Cosmides 1992). This claim has been met with strong skepticism by many social scientists who see a role for a myriad of types of explanation of human behavior, some of which are not reducible to biological explanations of any sort. This discussion hangs on issues of reductionism in the social sciences. (Little 1991 has a nice introduction to these issues.) There are also reasons to believe that evolutionary psychology neither unifies nor provides foundations for closely neighboring fields such as behavioral ecology or developmental psychobiology. (See the related discussion in Downes 2005.) In other work, evolutionary psychologists present their approach as being consistent with or compatible with neighboring approaches such as behavioral ecology and developmental psychobiology. (See Buss's introduction to Buss 2005.) The truth of this claim hangs on a careful examination of the theoretical tenets of evolutionary psychology and its neighboring fields. We now turn to evolutionary psychology's theoretical tenets and revisit this discussion in section 4 below.

In a recent presentation of evolutionary psychology's theoretical tenets Tooby and Cosmides provide the following list (2005):

• The brain is a computer designed by natural selection to extract information from the environment.
• Individual human behavior is generated by this evolved computer in response to information it extracts from the environment. Understanding behavior requires articulating the cognitive programs that generate the behavior.
• The cognitive programs of the human brain are adaptations. They exist because they produced behavior in our ancestors that enabled them to survive and reproduce.
• The cognitive programs of the human brain may not be adaptive now; they were adaptive in ancestral environments.
• Natural selection ensures that the brain is composed of many different special purpose programs and not a domain general architecture.
• Describing the evolved computational architecture of our brains “allows a systematic understanding of cultural and social phenomena” (18).

Tenet 1 emphasizes the cognitivism that evolutionary psychologists are committed to. 1 in combination with 2 directs our attention as researchers not to parts of the brain but to the programs run by the brain. It is these programs—psychological mechanisms—that are products of natural selection. While they are products of natural selection, and hence adaptations, these programs need not be currently adaptive. Our behavior can be produced by underlying psychological mechanisms that arose to respond to particular circumstances in our ancestors' environments. Tenet 5 presents what is often called the “massive modularity thesis” (See e.g. Samuels 1998; Samuels 2000). There is a lot packed into this tenet and we will examine this thesis in some detail below in section 3. In brief, evolutionary psychologists maintain that there is an analogy between organs and psychological mechanisms or modules. Organs perform specific functions well and are products of natural selection. There are no general purpose organs, hearts pump blood and livers detoxify the body. The same goes for psychological mechanisms; they arise as responses to specific contingencies in the environment and are selected for to the extent that they contribute to the survival and reproduction of the organism. Just as there are no general purpose organs, there are no general purpose psychological mechanisms. Finally, tenet 6 introduces the reductionist or foundational vision of evolutionary psychology, discussed above.

There are numerous examples of the kinds of mechanisms that are hypothesized to underlie our behavior on the basis of research guided by these theoretical tenets: the cheat detection module; the waist/hip ratio detection module; the snake fear module and so on. A closer look at the waist/hip ratio detection module illustrates the above theoretical tenets at work. Singh (Singh 1993; Singh and Luis 1995) presents the waist/hip ratio detection module as one of the suite of modules that underlies mate selection in humans. This one is a specifically male psychological mechanism. Men detect variations in waist/hip ratio in women. Men's preferences are for women with waist/hip ratios closer to .7. Singh claims that the detection and preference suite are adaptations for choosing fertile mates. So our mate selection behavior is explained in part by the underlying psychological mechanism for waist/hip ratio preference that was selected for in earlier human environments.

What is important to note about the research guided by these theoretical tenets above is that all behavior is best explained in terms of underlying psychological mechanisms that are adaptations for solving a particular set of problems that humans faced at one time in our ancestry. Also, evolutionary psychologists stress that the mechanisms they focus on are universally distributed in humans and are not susceptible to much, if any, variation. They maintain that the mechanisms are a product of adaptation but are no longer under selection (Tooby and Cosmides 2005, 39–40).

The methods for testing hypotheses in evolutionary psychology come mostly from psychology. For example, in Singh's work, male subjects are presented with drawings of women with varying waist hip ratios and ask to give their preference rankings. In Buss's work supporting several hypothesized mate selection mechanisms, he performed similar experiments on subjects, asking for their responses to various questions about features of desired mates (Buss 1990). Buss, Singh and other evolutionary psychologists emphasize the cross cultural validity of their results, claiming consistency in responses across a wide variety of human populations (But see Yu and Shepard 1998; Gray et al. 2003 for different types of conflicting results to Singh's). For the most part standard psychological experimental methods are used to test hypotheses in evolutionary psychology. This has raised questions about the extent to which the evolutionary component of evolutionary psychologists' hypotheses is being tested (See e.g. Shapiro and Epstein 1998; Lloyd 1999; Lloyd and Feldman 2002). A response profile may be prevalent in a wide variety of subject populations but this says nothing about whether or not the response profile is a psychological mechanism that arose from a particular selective regimen.

Claims that the mind has a modular architecture, and even massively modular architecture, are widespread in cognitive science (See e.g. Hirshfield and Gelman 1994). The massive modularity thesis is first and foremost a thesis about cognitive architecture. As defended by evolutionary psychologists, the thesis is also about the source of our cognitive architecture: the massively modular architecture is the result of natural selection acting to produce each of the many modules. Our cognitive architecture is composed of computational devices, that are innate and are adaptations (Cf. Samuels 1998; Samuels et al. 1999a; Samuels et al. 1999b; Samuels 2000). This massively modular architecture accounts for all of our sophisticated behavior. Our successful navigation of the world results from the action of one or more of our many modules.

Jerry Fodor was the first to mount a sustained philosophical defense of modularity as a theory of cognitive architecture (Fodor 1983). His modularity thesis is distinct from the massive modularity thesis in a number of important ways. Fodor argued that our “input systems” are modular—for example, components of our visual system, our speech detection system and so on—these parts of our mind are dedicated information processors, whose internal make-up is inaccessible to other related processors. The modular detection systems feed output to a central system, which is a kind of inference engine. The central system, on Fodor's view is not modular. Fodor presents a large number of arguments against the possibility of modular central systems. For example, he argues that central systems, to the extent that they engage in something like scientific confirmation, are “Quinean” in that “the degree of confirmation assigned to any given hypothesis is sensitive to properties of the entire belief system” (Fodor 1983, 107). Fodor draws a bleak conclusion about the status of cognitive science from his examination of the character of central systems: cognitive science is impossible. So on Fodor's view, the mind is partly modular and the part of the mind that is modular provides some subject matter for cognitive science.

A distinct thesis from Fodor's, the massive modularity thesis, gets a sustained philosophical defense from Peter Carruthers (See especially Carruthers 2006). Carruthers is well aware that Fodor (See e.g. Fodor 2000) does not believe that central systems can be modular but he presents arguments from evolutionary psychologists and others that support the modularity thesis for the whole mind. Perhaps one of the reasons that there is so much philosophical interest in evolutionary psychology is that discussions about the status of the massive modularity thesis are highly theoretical. [ 3 ] Both evolutionary psychologists and philosophers present and consider arguments for and against the thesis rather than simply waiting until the empirical results come in. Richard Samuels (1998) speculated that argument rather than empirical data was being relied on (in 1998), because the various competing modularity theses about central systems were hard to pull apart empirically. This still seems to be a problem as Carruthers relies heavily on arguments for massive modularity over specific empirical results that tell in favor of the thesis.

There are many arguments for the massive modularity thesis. Some are based upon considerations about how evolution must have acted; some are based on considerations about the nature of computation and some are versions of the poverty of the stimulus argument first presented by Chomsky in support of the existence of an innate universal grammar (See Cowie 1999 for a nice presentation of the structure of poverty of the stimulus arguments). Myriad versions of each of these arguments appear in the literature and many arguments for massive modularity mix and match components of each of the main strands of argumentation. Here we review a version of each type of argument.

Carruthers presents a clear outline of the first type of argument “the biological argument for massive modularity”: “(1) Biological systems are designed systems, constructed incrementally. (2) Such systems, when complex, need to have massively modular organization. (3) The human mind is a biological system and is complex. (4) So the human mind will be massively modularly in its organization” (Carruthers 2006, 25). An example of this argument is to appeal to the functional decomposition of organisms into organs “designed” for specific tasks, e.g. hearts, livers, kidneys. Each of these organs arises as a result of natural selection and the organs, acting together, contribute to the fitness of the organism. The functional decomposition is driven by the response to specific environmental stimuli. Rather than natural selection acting to produce general purpose organs, each specific environmental challenge is dealt with by a separate mechanism. All versions of this argument are arguments from analogy, relying on the key transitional premise that minds are a kind of biological system upon which natural selection acts.

The second type of argument makes no appeal to biological considerations whatsoever (although many evolutionary psychologists give these arguments a biological twist). The computational argument is as follows: minds are computational problem solving devices; there are specific types of solutions to specific types of problems; and so for minds to be (successful) general problem solving devices, they must consist of collections of specific problem solving devices, i.e. many computational modules. This type of argument is structurally similar to the biological argument (as Carruthers points out). The key idea is that there is no sense to the idea of a general problem solver and that no headway can be made in cognitive science without breaking down problems into their component parts.

The third type of argument involves a generalization of Chomsky's poverty of the stimulus argument for universal grammar. Many evolutionary psychologists (See e.g. Tooby and Cosmides 1992) appeal to the idea that there is neither enough time, or enough available information, for any given human to learn from scratch to successfully solve all of the problems that we face in the world. This first consideration supports the conclusion that the underlying mechanisms we use to solve the relevant problems are innate (for evolutionary psychologists “innate” is usually interchangeable with “product of natural selection” [ 4 ] ). If we invoke this argument across the whole range of problem sets that humans face and solve, we arrive at a huge set of innate mechanisms that subserve our problem solving abilities, which is another way of saying that we have a massively modular mind.

There are numerous responses to the many versions of each of these types of arguments and many take on the massive modularity thesis head on without considering a specific argument for it. I will defer consideration of responses to the first argument type until section 4 below, which focuses on issues of the nature of evolution and natural selection – topics in philosophy of biology.

The second type of argument is one side of a perennial debate in the philosophy of cognitive science. Fodor (2000, 68) takes this argument to rest on the unwarranted assumption that there is no domain-independent criterion of cognitive success, which he thinks requires an argument that evolutionary psychologists do not provide. Samuels (See esp. Samuels 1998) responds to evolutionary psychologists that arguments of this type do not sufficiently discriminate between a conclusion about domain specific processing mechanisms and domain specific knowledge or information. Samuels articulates what he calls the “library model of cognition” in which there is domain specific information or knowledge but domain general processing. The library model of cognition is not massively modular in the relevant sense but type two arguments support it. According to Samuels, evolutionary psychologists need something more than this type of argument to warrant their specific kind of conclusion about massive modularity. Buller (2005) introduces further worries for this type of argument by tackling the assumption that there can be no such thing as a domain general problem solving mechanism. Buller worries that in their attempt to support this claim, evolutionary psychologists fail to adequately characterize a domain general problem solver. For example, they fail to distinguish between a domain general problem solver and a domain specific problem solver that is over generalized. He offers the example of social learning as a domain general mechanism that would produce domain specific solutions to problems. He uses a nice biological analogy to drive this point home: the immune system is a domain general system in that it allows the body to respond to a wide variety of pathogens. While it is true that the immune system produces domain specific responses to pathogens in the form of specific antibodies, the antibodies are produced by one domain general system. These and many other respondents conclude that type two arguments do not adequately support the massive modularity thesis.

Fodor (2000) and Kim Sterelny (2003) provide different responses to type three arguments. Fodor's response is that poverty of the stimulus type arguments support conclusions about innateness but not modularity and so these arguments can not be used to support the massive modularity thesis. He argues that the domain specificity and encapsulation of a mechanism and its innateness pull apart quite clearly, allowing for “perfectly general learning mechanisms” that are innate and “fully encapsulated mechanisms” that are single stimulus specific and everything in between. Sterelny responds to the generalizing move in type three arguments. He takes language to be the exception rather than the rule in the sense that while the postulation of an innate, domain specific module may be warranted to account for our language abilities, much of our other problem solving behavior can be accounted for without postulating such modules (Sterelny 2003, 200). [ 5 ] Sterelny's counter requires invoking alternate explanations for our behavioral repertoire. For example, he accounts for folk psychology and folk biology by appealing to environmental factors, some of which are constructed by our forebears, that allow us to perform sophisticated cognitive tasks. If we can account for our success at various complex problem solving tasks, without appealing to modules, then the massive modularity thesis is false.

Even critics of the massive modularity thesis allow for the possibility of some modularity of mind. Critics of evolutionary psychology do not reject the possibility of any kind of modularity, they reject the massive modularity thesis. There is considerable debate about the status of the massive modularity thesis and some of this debate centers around the characterization of modules. If modules have all the characteristics that Fodor (1983) first presented, then he may be right that central systems are not modular. Both Carruthers (2006) and Barrett and Kurzban (2006) present modified characterizations of modules, which they argue better serve the massive modularity thesis. There is no agreement on a workable characterization of modules for evolutionary psychology but there is agreement on the somewhat benign thesis that “the language of modularity affords useful conceptual groundwork in which productive debates surrounding cognitive systems can be framed” (Barrett and Kurzban 2006, 644).

Many philosophers have criticized evolutionary psychology. Most of these critics are philosophers of biology who argue that the research tradition suffers from an overly zealous form of adaptationism (Griffiths 1996; Richardson 1996; Grantham and Nichols 1999; Lloyd 1999; Richardson 2007), an untenable reductionism (Dupre 1999; Dupre 2001), a “bad empirical bet” about modules (Sterelny 1995; Sterelny and Griffiths 1999; Sterelny 2003), a fast and loose conception of fitness (Lloyd 1999; Lloyd and Feldman 2002); and most of the above and much more (Buller 2005) (Cf. Downes 2005). [ 6 ] All of these philosophers share one version or other of Buller's view: “I am unabashedly enthusiastic about efforts to apply evolutionary theory to human psychology” (2005, x). [ 7 ] But if philosophers of biology are not skeptical of the fundamental idea behind the project, as Buller's quote indicates, what are they so critical of? What is at stake are differing views about how to best characterize evolution and hence how to generate evolutionary hypotheses and how to test evolutionary hypotheses. For evolutionary psychologists, the most interesting contribution that evolutionary theory makes is the explanation of apparent design in nature or the explanation of the production of complex organs by appeal to natural selection. Evolutionary psychologists generate evolutionary hypotheses by first finding apparent design in the world, say in our psychological make up, and then presenting a selective scenario that would have led to the production of the trait that exhibits apparent design. The hypotheses evolutionary psychologists generate, given that they are usually hypotheses about our psychological capacities, are tested by standard psychological methods. Philosophers of biology challenge evolutionary psychologists on both of these points. I introduce a few examples of criticisms in each of these two areas below and then look at some responses to philosophical criticisms of evolutionary psychology.

Adaptation is the one biological concept that is central to most debates over evolutionary psychology. Every theoretical work on evolutionary psychology presents the research tradition as being primarily focused on psychological adaptations and goes on to give an account of what adaptations are (See e.g. Tooby and Cosmides 1992; Buss et al. 1998; Simpson and Campbell 2005; Tooby and Cosmides 2005). Much of the philosophical criticism of evolutionary psychology addresses its approach to adaptation or its form of adaptationism. Let us quickly review the basics from the perspective of philosophy of biology.

Here is how Elliott Sober defines an adaptation: “characteristic c is an adaptation for doing task t in a population if and only if members of the population now have c because, ancestrally, there was selection for having c and c conferred a fitness advantage because it performed task t ” (Sober 2000, 85). Sober makes a few further clarifications of the notion of adaptation that are helpful. First, we should distinguish between a trait that is adaptive and a trait that is an adaptation . Any number of traits can be adaptive without those traits being adaptations. A sea turtles forelegs are useful for digging in the sand to bury eggs but they are not adaptations for nest building (Sober 2000, 85). Also, traits can be adaptations without being currently adaptive for a given organism. Vestigial organs such as our appendix or vestigial eyes in cave dwelling organisms are examples of such traits (Sterelny and Griffiths 1999). Second, we should distinguish between ontogenic and phylogenetic adaptations (Sober 2000, 86). The adaptations of interest to evolutionary biologists are phylogenetic adaptations, which arise over evolutionary time and impact the fitness of the organism. Ontogenetic adaptations, including any behavior we learn in our lifetimes, can be adaptive to the extent that an organism benefits from them but they are not adaptations in the relevant sense. Finally, adaptation and function are closely related terms. On one of the prominent views of function—the etiological view of functions—adaptation and function are more or less coextensive; to ask for the function of an organ is to ask why it is present. On the Cummins view of functions adaptation and function are not coextensive, as on the Cummins view, to ask what an organ's function is, is to ask what it does (Sober 2000, 86–87) (cf. Sterelny and Griffiths 1999, 220–224).

Evolutionary psychologists focus on psychological adaptations. One consistent theme in the theoretical work of evolutionary psychologists is that “adaptations, the functional components of organisms, are identified […] by […] evidence of their design: the exquisite match between organism structure and environment” (Hagen 2005, 148). The way in which psychological adaptations are identified is by evolutionary functional analysis, which is a type of reverse engineering. [ 8 ] “Reverse engineering is a process of figuring out the design of a mechanism on the basis of an analysis of the tasks it performs. Evolutionary functional analysis is a form of reverse engineering in that it attempts to reconstruct the mind's design from an analysis of the problems the mind must have evolved to solve” (Buller 2005, 92). Many philosophers object to evolutionary psychologists' over attribution of adaptations on the basis of apparent design. Here some are following Gould and Lewontin's (1979) lead when they worry that accounting for apparent design in nature in terms of adaptation amounts to telling just-so stories but they could just as easily cite Williams (1966), who also cautioned against the over attribution of adaptation as an explanation for biological traits. While it is true that evolutionary functional analysis can lend itself to just-so story telling, this is not the most interesting problem that confronts evolutionary psychology. What lies behind Buller's criticisms of evolutionary psychologist's adaptationism is a different view than theirs about what is important in evolutionary thinking. Buller thinks that evolutionary psychologists overemphasize design and that they make the contentious assumption that with respect to the traits they are interested in, evolution is finished, rather than ongoing.

Sober's definition of adaptation is not constrained only to apply to organs or other traits that exhibit apparent design. Rather, clutch size (in birds), schooling (in fish), leaf arrangement, foraging strategies and all manner of traits can be adaptations (Cf. Seger and Stubblefield 1996). Buller argues the more general point that phenotypic plasticity of various types can be an adaptation, because it arises in various organisms as a result of natural selection. [ 9 ] The difference here between Buller (and other philosophers and biologists) and evolutionary psychologists is a difference in the explanatory scope that they attribute to natural selection. For evolutionary psychologists, the hallmark of natural selection is a well functioning organ and for their critics, the results of natural selection can be seen in an enormous range of traits ranging from the specific apparent design features of organs to the most general response profiles in behavior. According to Buller, this opens up the range of possible evolutionary hypotheses that can account for human behavior. Rather than being restricted to accounting for our behavior in terms of the joint output of many specific modular mechanisms, we can account for our behavior by appealing to selection acting upon many different levels of traits. This difference in emphasis on what is important in evolutionary theory also is at the center of debates between evolutionary psychologists and behavioral ecologists, who argue that behaviors, rather than just the mechanisms that underlie them, can be adaptations (Cf. Downes 2001). Further, this difference in emphasis is what leads to the wide range of alternate evolutionary hypotheses that Sterelny (Sterelny 2003) presents to explain human behavior. Given that philosophers like Buller and Sterelny are adaptationists, they are not critical of Evolutionary Psychologists' adaptationism. Rather, they are critical of the narrow explanatory scope of the type of adaptationism evolutionary psychologists adopt.

Buller's criticism that evolutionary psychologists assume that evolution is finished for the traits that they are interested in connects worries about the understanding of evolutionary theory with worries about the testing of evolutionary hypotheses. Here is Tooby and Cosmides clear statement of the assumption that Buller is worried about: “evolutionary psychologists primarily explore the design of the universal, evolved psychological and neural architecture that we all share by virtue of being human. Evolutionary psychologists are usually less interested in human characteristics that vary due to genetic differences because they recognize that these differences are unlikely to be evolved adaptations central to human nature. Of the three kinds of characteristics that are found in the design of organisms – adaptations, by-products, and noise – traits caused by genetic variants are predominantly evolutionary noise, with little adaptive significance, while complex adaptations are likely to be universal in the species” (Tooby and Cosmides 2005, 39). This line of thinking also captures evolutionary psychologists' view of human nature: human nature is our collection of universally shared adaptations. The problem here is that it is false to assume that adaptations cannot be under variation. The underlying problem is the constrained notion of adaptation. Adaptations are traits that arise as a result of natural selection and not traits that exhibit design and are universal in a given species. As a result, it is quite consistent to argue, as Buller does, that many human traits may still be under selection and yet reasonably be called adaptations. So far this is a disagreement that is located in differing views about the nature and scope of evolutionary explanation but it has ramifications in the discussion about hypothesis testing.

If the traits of interest to evolutionary psychologists are universally distributed, then we should expect to find them in all humans. This partly explains the stock that evolutionary psychologists put in cross cultural psychological tests (See e.g. Buss 1990). If we find evidence for the trait in a huge cross section of humans, then this supports our view that the trait is an adaptation —on the assumption that adaptations are organ-like traits that are products of natural selection but not subject to variation. But given the wider scope view of evolution defended by philosophers of biology, this method of testing seems wrong-headed as a test of an evolutionary hypothesis. Certainly such testing can result in the very interesting results that certain preference profiles are widely shared cross culturally but the test does not speak to the evolutionary hypothesis that the preferences are adaptations (Cf. Lloyd 1999; Buller 2005).

Another worry that critics have about evolutionary psychologists' approach to hypothesis testing is that they give insufficient weight to serious alternate hypotheses that fit the relevant data. Buller dedicates several chapters of his book on evolutionary psychology to an examination of hypothesis testing and many of his criticisms center around the introduction of alternate hypotheses that do as good a job, or a better job, of accounting for the data. For example, he argues that the hypothesis of assortative mating by status does a better job of accounting for some of evolutionary psychologists' mate selection data than their preferred high status preference hypothesis. This debate hangs on how the empirical tests come out. The previous debate is more closely connected to theoretical issues in philosophy of biology.

I said in my introduction that there is a broad consensus among philosophers of science that evolutionary psychology is a deeply flawed enterprise but there are proponents of evolutionary psychology among philosophers of science. One way of defending evolutionary psychology is to rebut criticism. In a recent article Edouard Machery and Clark Barrett (2007) do just that in their sharply critical review of Buller's book. Another way to defend evolutionary psychology is to practice it (at least to the extent that philosophers can, i.e. theoretically). This is what Robert Arp (2006) does in a recent article. I briefly review both responses below.

Machery and Barrett (2007) argue that Buller has no clear critical target as there is nothing to the idea that there is a research tradition of evolutionary psychology that is distinct from the broader enterprise of the evolutionary understanding of human behavior. They argue that theoretical tenets and methods are shared by many in the biology of human behavior. For example, many are adaptationists. But as we saw above, evolutionary psychologists and behavioral ecologists can both call themselves adaptationist but their particular approach to adaptationism dictates the range of hypotheses that they can generate, the range of traits that can be counted as adaptations and impacts upon the way in which hypotheses are tested. Research traditions can share some broad theoretical commitments and yet still be distinct research traditions. Secondly, they argue against Buller's view that past environments are not stable enough to produce the kind of psychological adaptations that evolutionary psychologists propose. They take this to be a claim that no adaptations can arise from an evolutionary arms race situation, for example, between predators and prey. But again, I think that the disagreement here is over what counts as an adaptation. Buller does not deny that adaptations— traits that arise as a product of natural selection—arise from all kinds of unstable environments. What he denies is that organ-like, special purpose adaptations are the likely result of such evolutionary scenarios. This discussion is ongoing.

Arp (2006) defends a hypothesis about a kind of module—scenario visualization—a psychological adaptation that arose in our hominid history in response to the demands of tool making, such as constructing spear throwing devices for hunting. Arp presents his hypothesis in the context of demonstrating the superiority of his approach to evolutionary psychology, which he calls “Narrow Evolutionary Psychology,” over “Broad Evolutionary Psychology,” with respect to accounting for archaeological evidence and facts about our psychology. While Arp's hypothesis is innovative and interesting, he by no means defends it conclusively. This is partly because his strategy is to compare his hypothesis with archaeologist Steven Mithen's (See e.g. 1996) non-modular “cognitive fluidity” hypothesis that is proposed to account for the same data. The problem here is that Mithen's view is only one of the many alternative, evolutionary explanations of human tool making behavior. While Arp's modular thesis may be superior to Mithen's, he has not compared it to Sterelny's (2003) account of tool making and tool use or to Boyd and Richerson's (See e.g. 2005) account and hence not ruled these accounts out as plausible alternatives. As neither of these alternative accounts rely on the postulation of psychological modules, evolutionary psychology is not adequately defended.

Philosophers who work on moral psychology understand that their topic is empirically constrained. Philosophers take two main approaches to using empirical results in moral psychology. One is to use empirical results (and empirically based theories from psychology) to criticize philosophical accounts of moral psychology (See e.g. Doris 2002) and one is to generate (and, in the experimental philosophy tradition, to test) hypotheses about our moral psychology (See e.g. Nichols 2004). For those who think that some (or all) of our moral psychology is based in innate capacities, evolutionary psychology is a good source of empirical results and empirically based theory. One account of the make-up of our moral psychology follows from the massive modularity account of the architecture of the mind. Our moral judgments are a product of domain specific psychological modules that are adaptations and arose in our hominid forebears in response to contingencies in our (mostly) social environments. This position is currently widely discussed by philosophers working in moral psychology. An example of this discussion follows.

Leda Cosmides (See e.g. 1989) defends a hypothesis in evolutionary psychology that we have a cheater-detection module. [ 10 ] This module is hypothesized to underlie important components of our behavior in moral domains and fits with the massively modular view of our psychology in general. Cosmides (along with Tooby) argues that cheating is a violation of a particular kind of conditional rule that goes along with a social contract. Social exchange is a system of cooperation for mutual benefit and cheaters violate the social contract that governs social exchange (Cosmides and Tooby 2005). The selection pressure for a dedicated cheat detection module is the presence of cheaters in the social world. The cheater detection module is an adaptation that arose in response to cheaters. The cheater detection hypothesis has been the focus of a huge amount of critical discussion. Cosmides and Tooby (2008) defend the idea that cheat detection is modular over hypotheses that more general rules of inference are involved in the kind of reasoning behind cheater detection against critics Ron Mallon (2008) and Fodor (2008). Some criticism of the cheater detection hypothesis involves rehashing criticisms of massive modularity in general and some treats the hypothesis as a contribution to moral psychology and invokes different considerations. For example, Mallon (2008) worries about the coherence of abandoning a domain general conception of ought in our conception of our moral psychology. This discussion is also ongoing.

There are a number of areas in which philosophical work on evolutionary psychology will be fruitful. The example given above of work in moral psychology barely scratches the surface of this rapidly developing field. There are huge numbers of empirical hypotheses that bear on our conception of our moral psychology that demand philosophical scrutiny (Hauser 2006 includes a survey of a wide range of such hypotheses). Also, work on moral psychology and the emotions can be drawn together via work on evolutionary psychology and related fields. Griffiths (1997) directed philosophical attention to evolution and the emotions and this kind of work has been brought into closer contact with moral psychology by Nichols (See e.g. his 2004). In philosophy of mind there is still much that can be done on the topic of modules. Work on integrating biological and psychological concepts of modules is one avenue that is being pursued and could be fruitfully pursued further (See e.g. Barrett and Kurzban 2006; Carruthers 2006) and work on connecting biology to psychology via genetics is another promising area (See e.g. Marcus 2004). In philosophy of science, I have no doubt that many more criticisms of evolutionary psychology will be presented but a relatively underdeveloped area of philosophical research is on the relations among all of the various, theoretically different, approaches to the biology of human behavior (Cf. Downes 2005; Griffiths Forthcoming). Evolutionary psychologists present their work alongside the work of behavioral ecologists, developmental psychobiologists and others (See e.g. Buss 2005; Buss 2007) but do not adequately confront the theoretical difficulties that face an integrated enterprise in the biology of human behavior. Finally, while debate rages between biologically influenced and other social scientists, philosophers have not paid much attention to potential integration of evolutionary psychology into the broader interdisciplinary study of society and culture (but see Mallon and Stich 2000).

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• Center for Evolutionary Psychology, UC Santa Barbara
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Cited Resources

• Buller, D., 2000, “ Evolutionary Psychology ” (a guided tour), in M. Nani and M. Marraffa (eds.), A Field Guide to the Philosophy of Mind .

-->adaptation and adaptationism --> | biology: philosophy of | cognitive science | -->culture: and cognitive science --> | emotion | -->function --> | game theory: evolutionary | innate/acquired distinction | innateness: and language | language of thought hypothesis | mind: modularity of | moral psychology: empirical approaches | prisoner's dilemma

Thanks to Austin Booth, David Buller, Mark Ereshevsky, Matt Haber, Ron Mallon, Shaun Nichols and the Stanford Encyclopedia referees for helpful comments on drafts of this entry.

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2.5: Humanist, Cognitive, and Evolutionary Psychology

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• Jorden A. Cummings
• University of Saskatchewan

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Jennifer Walinga

Learning Objectives

• Understand the key principles of humanistic psychology.
• Differentiate humanistic psychology from biological, psychodynamic, and behaviourist psychology.
• Critically discuss and differentiate between key humanistic concepts such as motivation, need, adaptation, and perception.
• Identify how humanistic psychology, and its related streams of cognitive and evolutionary psychology, have influenced aspects of daily life and work.

Humanistic psychology emerged as the third force in psychology after psychodynamic and behaviourist psychology. Humanistic psychology holds a hopeful, constructive view of human beings and of their substantial capacity to be self-determining . This wave of psychology is guided by a conviction that intentionality and ethical values are the key psychological forces determining human behaviour. Humanistic psychologists strive to enhance the human qualities of choice, creativity, the interaction of the body, mind, and spirit, and the capacity to become more aware, free, responsible, life-affirming, and trustworthy.

Emerging in the late 1950s, humanistic psychology began as a reaction against the two schools of thought then dominating American psychology. Behaviourism’s insistence on applying the methods of physical science to human behaviour caused adherents to neglect crucial subjective data, humanists believed. Similarly, psychoanalysis’s emphasis on unconscious drives relegated the conscious mind to relative unimportance.

The early humanistic psychologists sought to restore the importance of consciousness and offer a more holistic view of human life. Humanistic psychology acknowledges that the mind is strongly influenced by determining forces in society and the unconscious, and emphasizes the conscious capacity of individuals to develop personal competence and self-respect. The humanistic orientation has led to the development of therapies to facilitate personal and interpersonal skills and to enhance the quality of life. During the 1950s and 1960s, Carl Rogers, for instance, introduced what he called person or client-centred therapy , which relies on clients’ capacity for self-direction, empathy, and acceptance to promote clients’ development . Abraham Maslow (1908-1970) developed a hierarchy of motivation  or hierarchy of needs culminating in self-actualization . Rollo May (1909 – 1994) brought European existential psychotherapy and phenomenology into the field by acknowledging human choice and the tragic aspects of human existence, and Fritz Perls developed gestalt therapy in his workshops and training programs at the Esalan Institute and elsewhere.

During the 1970s and 1980s, the ideas and values of humanistic psychology spread into many areas of society. As a result, humanistic psychology has many branches and extensions, as outlined in Table 2.2.

Client-centred therapy provides a supportive environment in which clients can re-establish their true identity . Central to this thinking is the idea that the world is judgmental, and many people fear that if they share with the world their true identity, it would judge them relentlessly. People tend to suppress their beliefs, values, or opinions because they are not supported, not socially acceptable, or negatively judged. To re-establish a client’s true identity, the therapist relies on the techniques of unconditional positive regard and empathy. These two techniques are central to client-centred therapy because they build trust between the client and therapist by creating a nonjudgmental and supportive environment for the client.

Existential therapy contrasts the psychoanalysts’ focus on the self and focuses instead on “man in the world.” The counsellor and the client may reflect on how the client has answered life’s questions in the past, but attention ultimately emphasizes the choices to be made in the present and future and enabling a new freedom and responsibility to act. By accepting limitations and mortality, a client can overcome anxieties and instead view life as moments in which he or she is fundamentally free.

Gestalt therapy focuses on the skills and techniques that permit an individual to be more aware of their feelings . According to this approach, it is much more important to understand what patients are feeling and how they are feeling rather than to identify what is causing their feelings. Supporters of gestalt therapy argued that earlier theories spent an unnecessary amount of time making assumptions about what causes behaviour. Instead, gestalt therapy focuses on the here and now.

Research Focus

In his seminal work “Significant Aspects of Client-Centered Therapy,” Rogers described the discovery of the “capacity of the client” (1946):

Naturally the question is raised, what is the reason for this predictability in a type of therapeutic procedure in which the therapist serves only a catalytic function? Basically the reason for the predictability [page 418] of the therapeutic process lies in the discovery — and I use that word intentionally — that within the client reside constructive forces whose strength and uniformity have been either entirely unrecognized or grossly underestimated. It is the clearcut and disciplined reliance by the therapist upon those forces within the client, which seems to account for the orderliness of the therapeutic process, and its consistency from one client to the next.

I mentioned that I regarded this as a discovery. I would like to amplify that statement. We have known for centuries that catharsis and emotional release were helpful. Many new methods have been and are being developed to bring about release, but the principle is not new. Likewise, we have known since Freud’s time that insight, if it is accepted and assimilated by the client, is therapeutic. The principle is not new. Likewise we have realized that revised action patterns, new ways of behaving, may come about as a result of insight. The principle is not new.

But we have not known or recognized that in most if not all individuals there exist growth forces, tendencies toward self-actualization, which may act as the sole motivation for therapy. We have not realized that under suitable psychological conditions these forces bring about emotional release in those areas and at those rates which are most beneficial to the individual. These forces drive the individual to explore his own attitudes and his relationship to reality, and to explore these areas effectively.

We have not realized that the individual is capable of exploring his attitudes and feelings, including those which have been denied to consciousness, at a rate which does not cause panic, and to the depth required for comfortable adjustment. The individual is capable of discovering and perceiving, truly and spontaneously, the interrelationships between his own attitudes, and the relationship of himself to reality. The individual has the capacity and the strength to devise, quite unguided, the steps which will lead him to a more mature and more comfortable relationship to his reality. It is the gradual and increasing recognition of these capacities within the individual by the client-centered therapist that rates, I believe, the term discovery. All of these capacities I have described are released in the individual if a suitable psychological atmosphere is provided.

Rogers identified five characteristics of the fully functioning person:

• Open to experience: Both positive and negative emotions are accepted. Negative feelings are not denied, but worked through (rather than resort to ego defence mechanisms).
• Existential living: Being in touch with different experiences as they occur in life, avoiding prejudging and preconceptions. Being able to live in and fully appreciate the present, not always looking back to the past or forward to the future (i.e., living for the moment).
• Trust feelings: Feelings, instincts, and gut-reactions are paid attention to and trusted. A person’s own decisions are the right ones and we should trust ourselves to make the right choices.
• Creativity: Creative thinking and risk taking are features of a person’s life. A person does not play it safe all the time. This involves the ability to adjust and change and seek new experiences.
• Fulfilled life: A person is happy and satisfied with life, and always looking for new challenges and experiences.

Humanistic psychology recognizes that human existence consists of multiple layers of reality: the physical, the organic, and the symbolic. It contests the idea — traditionally held by the behavioural sciences — that the only legitimate research method is an experimental test using quantitative data. It argues for the use of additional methods specifically designed to study qualitative factors such as subjective experience, emotion, perception, memory, values, and beliefs. Whereas other approaches take an objective view of people — in essence asking, What is this person like? — humanistic psychologists give priority to understanding people’s subjectivity, asking, What is it like to be this person? (Clay, 2002).

Humanistic psychology has, of course, quietly influenced North American psychology and culture over many decades by informing the civil rights debate and the women’s rights movement, for example. In the academic world, however, humanistic psychology’s rejection of quantitative research in favour of qualitative methods caused its reputation to suffer and its adherents to be marginalized. But in recent years, there’s mounting evidence of renewal in the field itself.

Abraham Maslow’s view of human needs was more complex than Rogers’s. While Rogers believed that people needed unconditional positive regard, Maslow acknowledged that people have a variety of needs that differ in timing and priority (Figure 2.15).

Figure 2.15 Maslow’s Hierarchy of Needs. [Long Description]

Maslow called the bottom four levels of the pyramid deficiency needs because a person does not feel anything if they are met, but becomes anxious if they are not . Thus, physiological needs such as eating, drinking, and sleeping are deficiency needs, as are safety needs, social needs such as friendship and sexual intimacy, and ego needs such as self-esteem and recognition. In contrast, Maslow called the fifth level of the pyramid a growth need [2] because it enables a person to self-actualize or reach his or her fullest potential as a human being . Once a person has met the deficiency needs, he or she can attend to self-actualization; however, only a small minority of people are able to self-actualize because self-actualization requires uncommon qualities such as honesty, independence, awareness, objectivity, creativity, and originality.

Frederick Taylor’s scientific management principles of the early 1900s,  born of  the industrial revolution and focused on scientific study of productivity in the workplace, fostered the development of  motivation theory , which held that all work consisted largely of simple, uninteresting tasks, and that the only viable method to get people to undertake these tasks was to provide incentives and monitor them carefully . In order to get as much productivity out of workers as possible, it was believed that a person must reward the desired behaviour and punish the rejected behaviour — otherwise known as the “carrot-and-stick” approach.

During this time, scientists believed in two main drives powering human behaviour: the biological drive , including hunger, thirst, and intimacy; and the reward-punishment drive . However, scientists began to encounter situations during their experiments where the reward-punishment drive wasn’t producing the expected performance results. In 1949, Harry F. Harlow, professor of psychology at the University of Wisconsin, began to argue for a third drive:  intrinsic motivation — the joy of the task itself .

Harlow’s theory (1950) was based on studies of primate behaviour when solving puzzles. He found that when presented with a puzzle, monkeys seemed to enjoy solving the puzzles without the presence or expectation of rewards. He found these monkeys, driven by intrinsic motivation, solved the puzzles quicker and more accurately than monkeys that received food rewards.

Edward Deci and Richard Ryan (1985) went on to explore and replicate these findings with humans many times over in their studies of families, classrooms, teams, organizations, clinics, and cultures. They concluded that conditions supporting the individual’s experience of autonomy, competence, and relatedness foster the greatest motivation for and engagement in activities while enhancing performance, persistence, and creativity.

Dan Pink (2010) provides ample evidence to support the notion that a traditional carrot-and-stick approach can result in:

• Diminished intrinsic motivation (the third drive)
• Lower performance
• Less creativity
• Crowding out   of good behaviour
• Unethical behaviour
• Short-term thinking

Research Focus: When the Lights Went on

The term “Hawthorne Effect” was coined in 1950 by Henry A. Landsberger when analyzing earlier experiments from 1924 to 1932 at the Hawthorne Works (a Western Electric factory outside Chicago). The Hawthorne Works had commissioned a study to see if their workers would become more productive in higher or lower levels of light. (Most industrial/occupational psychology and organizational behaviour textbooks refer to these illumination studies.) In these lighting studies, light intensity was altered to examine its effect on worker productivity. The workers’ productivity seemed to improve when changes were made, and slumped when the study ended. It was suggested that the productivity gain occurred as a result of the motivational effect on the workers of the interest being shown in them. George Elton Mayo (1945) described the Hawthorne Effect in terms of a positive emotional effect due to the perception of a sympathetic or interested observer. Although illumination research of workplace lighting formed the basis of the Hawthorne Effect, other changes such as maintaining clean work stations, clearing floors of obstacles, and even relocating work stations resulted in increased productivity for short periods. Today the term is used to identify any type of short-lived increase in productivity based on attention to human needs.

Humanistic psychology gave birth to the self-help movement, with concepts grounded in emotion and intuition. The recent positive psychology movement is one form of neo-humanistic psychology that combines emotion and intuition with reason and research . Similarly, modern crisis counselling’s emphasis on empathetic listening finds its roots in Rogers’s humanistic psychology work. In the wider culture, the growing popularity of personal and executive coaching also points to humanistic psychology’s success. Humanistic psychology’s principles may become increasingly relevant as the nation ages, creating a culture preoccupied with facing death and finding meaning in life.

In 1998, a paradigm shift in thinking occurred when University of Pennsylvania psychologist Martin Seligman, in his presidential address to the American Psychological Association (APA), urged psychology to “turn toward understanding and building the human strengths to complement our emphasis on healing damage” (1998b). Though not denying humanity’s flaws, the new approach suggested by positive psychologists recommends focusing on people’s strengths and virtues as a point of departure. Rather than analyze the psychopathology underlying alcoholism, for example, positive psychologists might study the resilience of those who have managed a successful recovery through Alcoholics Anonymous. Instead of viewing religion as a delusion and a crutch, as did Freud, they might identify the mechanisms through which a spiritual practice like meditation enhances mental and physical health. Their lab experiments might seek to define not the conditions that induce depraved behaviour, but those that foster generosity, courage, creativity, and laughter.

Seligman developed the concepts of learned optimism (1998a) and authentic happiness (2002). Learned optimism follows an ABCDE model:

• A=Adversity
• C=Consequence
• D=Disputation
• E=Energization

In this model, when faced with adversity (A) such as a criticism or failure, a person might form the belief (B) that he or she is underperforming or incapable, and consider the consequence (C) of quitting. However, disputation (D) would challenge the underlying assumptions or beliefs that have formed. The person would then form a new belief in his or her capacity to grow from the critique or learn from the failure. From there, the person would become energized (E) as he or she pursues a new performance path.

In collaboration with Seligman, and within the positive psychology framework, Dr. Mihalyi Csikszentmihályi from Claremont University developed the theory of flow (1988; 1990). Flow is a state of optimal performance . A flow state can be entered while performing any activity, although it is most likely to occur when a person is wholeheartedly performing a task or activity for intrinsic purposes. Csikszentmihályi identified the following six factors as encompassing an experience of flow:

• Intense and focused concentration on the present moment
• Merging of action and awareness
• Loss of reflective self-consciousness
• Sense of personal control or agency over the situation or activity
• Distortion of temporal experience (i.e., a person’s subjective experience of time being altered)
• Experience of the activity being intrinsically rewarding (also referred to as an autotelic experience )

Flow theory suggests that three conditions have to be met to achieve a flow state. First, a person must be involved in an activity with a clear set of goals and progress. This adds direction and structure to the task. Second, the task at hand must have clear and immediate feedback. This helps the person negotiate any changing demands and allows him or her to adjust performance to maintain the flow state. And last, a person must have a good balance between the perceived challenges of the task at hand and his or her own perceived skills. The person must have confidence in his or her ability to complete the task at hand (Figure 2.16).

Figure 2.16 Factors of Flow State. [Long Description]

Cognitive Psychology

Cognitive psychology is the study of mental processes such as attention, memory, perception, language use, problem solving, creativity, and thinking . Much of the work derived from cognitive psychology has been integrated into various other modern disciplines of psychological study including social psychology, personality psychology, abnormal psychology, developmental psychology, educational psychology, and economics.

Ulric Neisser (1928-2012) is credited with formally coining the term cognitive psychology and defining it as “all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered, and used” (1967, page 4). Cognition came to be seen as involved in everything a human being might possibly do: every psychological phenomenon is a cognitive phenomenon. Theories of cognition include developmental, cultural, neural, computational, and moral perspectives.

While behaviourism and cognitive schools of psychological thought may not agree theoretically, they have complemented each other in practical therapeutic applications, such as in cognitive-behavioural therapy (CBT) that has demonstrable utility in treating certain pathologies, such as simple phobias, post-traumatic stress disorder (PTSD), and addiction. CBT replaces maladaptive strategies with more adaptive ones by challenging ways of thinking and reacting. CBT techniques focus on helping individuals challenge their patterns and beliefs and replace erroneous thinking, such as overgeneralizing, magnifying negatives, or catastrophizing, with more realistic and effective thoughts, thus decreasing self-defeating emotions and behaviour and breaking what can otherwise become a negative cycle. These errors in thinking are known as “cognitive distortions.” CBT helps individuals take a more open, mindful, and aware posture toward their distorted thoughts and feelings so as to diminish their impact (Hayes, Villatte, Levin, & Hildebrandt, 2011).

The psychological definition of attention is a state of focused awareness on a subset of the available perceptual information . The key function of attention is to filter out irrelevant data, enabling the desired data to be distributed to the other mental processes. The human brain may, at times, simultaneously receive inputs in the form of auditory, visual, olfactory, taste, and tactile information. Without the ability to filter out some or most of that simultaneous information and focus on one or typically two inputs at most, the brain would become overloaded as a person attempted to process all the information.

Modern conceptions of memory typically break it down into three main subclasses:

• Procedural memory:   memory for the performance of particular types of action , is often activated on a subconscious level, or at most requires a minimal amount of conscious effort (e.g., driving to work along the same route).
• Semantic memory: the encyclopedic knowledge that a person possesses, such as what the Eiffel Tower looks like, or the name of a friend from Grade 6.
• Episodic memory:  memory of autobiographical events that can be explicitly stated , contains all memories that are temporal in nature, such as when you last brushed your teeth, or where you were when you heard about a major news event.

Perception involves both the physical senses (sight, smell, hearing, taste, touch, and proprioception) as well as the cognitive processes involved in selecting and interpreting those senses. It is how people come to understand the world around them through interpretation of stimuli.

Language use

Cognitive psychologists began exploring the cognitive processes involved with language in the 1870s when Carl Wernicke (1848-1905) proposed a model for the mental processing of language (1875/1995). Significant work has been done recently on understanding the timing of language acquisition and how it can be used to determine if a child has, or is at risk of developing, a learning disability.

Problem solving

Metacognition involves conscious thought about thought processes and might include monitoring a person’s performance on a given task, understanding a person’s capabilities on particular mental tasks, or observing a person’s ability to apply cognitive strategies. Much of the current study regarding metacognition within the field of cognitive psychology deals with its application within the area of education. Educators strive to increase students’ metacognitive abilities in order to enhance their learning, study habits, goal setting, and self-regulation.

Research Focus: Divided Attention

Relating to the field of cognitive psychology is the concept of divided attention , which refers to a person’s ability to focus on two or more things at one time.  A number of early studies dealt with the ability of a person wearing headphones to discern meaningful conversation when presented with different messages in each ear. Key findings demonstrated the mind’s ability to focus on one message, while still being somewhat aware of information taken in by the ear that was not consciously attended to. Participants who were wearing earphones were told that they would be hearing separate messages in each ear and that they were expected to attend only to information related to basketball. When the experiment started, the message about basketball was presented to the left ear, and non-relevant information was presented to the right ear. At some point the message related to basketball was switched to the right ear, and the non-relevant information to the left ear. When this happened, the listener was usually able to repeat the entire message at the end, having attended to the left or right ear only when it was appropriate (Glucksberg & Cowan, 1970).

Evolutionary Psychology

Evolutionary psychology has emerged as a major perspective in psychology. It seeks to develop and understand ways of expanding the emotional connection between individuals and the natural world, thereby assisting individuals with developing sustainable lifestyles and remedying alienation from nature. The main premise of evolutionary   psychology is that while today the human mind is shaped by the modern social world, it is adapted to the natural environment in which it evolved. According to the hypothesis of biologist E.O. Wilson, human beings have an innate instinct to connect emotionally with nature. What distinguishes evolutionary psychologists from many cognitive psychologists is the proposal that the relevant internal mechanisms are adaptations — products of natural selection — that helped our ancestors get around the world, survive, and reproduce. Evolutionary psychology is founded on several core premises:

• The brain is an information-processing device, and it produces behaviour in response to external and internal inputs.
• The brain’s adaptive mechanisms were shaped by natural selection.
• Different neural mechanisms are specialized for solving problems in humanity’s evolutionary past.
• The brain has evolved specialized neural mechanisms that were designed for solving problems that recurred over deep evolutionary time, giving modern humans stone-age minds.
• Most contents and processes of the brain are unconscious; and most mental problems that seem easy to solve are actually extremely difficult problems that are solved unconsciously by complicated neural mechanisms.
• Human psychology consists of many specialized mechanisms, each sensitive to different classes of information or inputs. These mechanisms combine to produce manifest behaviour.

Evolutionary psychologists sometimes present their approach as potentially unifying, or providing a foundation for, all other work that aims to explain human behaviour (Tooby & Cosmides, 1992). This claim has been met with skepticism by many social scientists who see a role for multiple types of explanation of human behaviour, some of which are not reducible to biological explanations of any sort.

Key Takeaways

• Humanistic psychology emerged as the “third force” in psychology after psychodynamic and behaviourist psychologies.
• The key principles of humanistic psychology include human capacity for self-actualization, self-direction, and choice.
• Carl Rogers identified five principles of a fully functioning person as open, present, trusting, creative, and fulfilled.
• Humanistic psychology relies on subjective factors and utilizes qualitative methods of study.
• Abraham Maslow introduced a hierarchy of human needs including physiological, safety, belonging, esteem, and self-actualization.
• With the advance of humanistic psychology, human motivation theory shifted from a purely external or extrinsic focus to the acknowledgment of an intrinsic focus.
• Positive psychology recommends focusing on people’s strengths and virtues as a point of departure rather than analyzing the underlying psychopathology.
• Flow is a state of optimal performance that can be entered when a person is wholeheartedly performing a task or activity for intrinsic purposes.
• Cognitive psychology is the study of mental processes such as attention, memory, perception, language use, problem solving, creativity, and thinking.
• The main premise of evolutionary psychology is that while today the human mind is shaped by the modern social world, it is adapted to the natural environment in which it evolved.

Exercises and Critical Thinking

• What model do you believe the current educational system follows? Are students trained according to the behavioural model or do educators also address the subjective beliefs, thoughts, and feelings of the student?
• What are some of the psychological traits you possess that might contribute to your survival or “fitness”? Can you provide an example of when this trait contributed to your success?
• Can you see applications for the principles of evolutionary psychology in the workplace or community (e.g., certain psychological qualities will ensure that you perform more effectively in a job interview)?
• Conduct a cultural analysis of your family, cohort, or social group. What are some of the values and beliefs communicated in your family or group? In what shape or form are these values manifested or expressed? Through what ways of doing, artifacts, activities, and/or traditions are these values communicated or expressed?

Image Attributions

Figure 2.15: Diagram of Maslow’s hierarchy of needs . by J. Finkelstein ( http://commons.wikimedia.org/wiki/File:Maslow ’s_hierarchy_of_needs.png) used under CC BY SA 3.0 license ( http://creativecommons.org/licenses/by-sa/3.0/deed.en ).

Figure 2.16: Challenge vs skill Commons by Dr. enh ( http://commons.wikimedia.org/wiki/Fi...ll_Commons.jpg ) is in the public domain.

Clay, Rebecca A. (2002). A renaissance for humanistic psychology. American Psychological Association Monitor , 33 (8), 42.

Csikszentmihályi, M. (1988). The flow experience and its significance for human psychology, in Csikszentmihályi, M., (Ed.) Optimal experience: psychological studies of flow in consciousness , Cambridge, UK: Cambridge University Press, page. 15–35.

Csikszentmihályi, M. (1990). Flow: The psychology of optimal experience . New York: Harper & Row.

Deci, E. L., & Ryan, R. M. (1985).  Intrinsic motivation and self-determination in human behavior . New York: Plenum.

Glucksberg, S., & Cowen, C. N., Jr. (1970). Memory for nonattended auditory material. Cognitive Psychology , I , 149-156.

Harlow, H.F. (1950). Early social deprivation and later behavior in the monkey. page. 154-173. In A.Abrams, H.H. Gurner & J.E.P. Tomal, (Eds.),  Unfinished tasks in the behavioral sciences  (1964). Baltimore: Williams & Wilkins.

Hayes, Steven C., Villatte, Matthieu, Levin, Michael, & Hildebrandt, Mikaela. (2011). Open, aware, and active: Contextual approaches as an emerging trend in the behavioral and cognitive therapies. Annual Review of Clinical Psychology , 7, 141–168.

Mayo, Elton (1945). Social problems of an industrial civilization . Boston: Division of Research, Graduate School of Business Administration, Harvard University, page 64.

Neisser, U. (1967). Cognitive psychology . Englewood Cliffs, NJ: Prentice Hall.

Pink, Daniel H. (2010). Drive – The surprising truth about what motivates us . Edinburgh, UK: Canongate Books.

Rogers, C. R. (1946). Significant aspects of client-centered therapy. American Psychologist , 1, 415-422.

Seligman, M. E. P. (1998a). Building human strength: Psychology’s forgotten mission. APA Monitor , 29 (1).

Seligman, M.E.P. (1998b). Learned optimism: How to change your mind and your life . Second edition. New York: Pocket Books (Simon and Schuster).

Seligman, M. E. P. (2002). Authentic happiness: Using the new positive psychology to realize your potential for lasting fulfillment. New York: Free Press.

Tooby, J., & Cosmides, L. (1992). The psychological foundations of culture. In H. Barkow, L. Cosmides & J. Tooby (Eds.), The adapted mind , New York: Oxford University Press, page 19–136.

Wernicke, K. (1875/1995). The aphasia symptom-complex: A psychological study on an anatomical basis. In Paul Eling (Ed.) Reader in the history of aphasia . Amsterdam: John Benjamins Pub Co. page 69–89.

Long Descriptions

Figure 2.15 long description: In Maslow’s hierarchy of needs, there are five levels.

• Physiological needs: Breathing, food, water, sex, sleep, homeostasis, excretion.
• Safety needs: Security of body, of employment, of resources, of morality, of the family, of health, of property.
• Long and belonging needs: Friendship, family, sexual intimacy.
• Esteem needs: Self-esteem, confidence, chievement, respect of others, respect by others.
• Self-Actualization: Morality, creativity, spontaneity, problem solving, lack of prejudice, acceptance of facts.
• Adapted by J. Walinga. 
• A growth need allows one to reach full potential as a human being. 

Contributors and Attributions

• Introduction to Psychology  by Jorden A. Cummings & Lee Sanders is licensed under a  Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted. 
• Refer to  Source Chapter Attributions  for more details