Critical Notice of Kim Sterelny, Thought in a Hostile World (2003)
“If it were our purpose in this chapter to say what is actually known about the evolution of human cognition, we could stop at the end of this sentence. That is not to say that a great deal has not been written on the subject. Indeed, whole books have been devoted to discussions of the evolution of human cognition and its social manifestations but these works are nothing more than a mixture of pure speculation and inventive stories. Some of these speculations and stories might even be true, but we do not know, nor is it clear, as we will discuss in this chapter, how we would go about finding out. Despite the fact that there is a vast and highly developed mathematical theory of evolutionary processes in general, despite the abundance of knowledge about living and fossil primates, despite the intimate knowledge that we have of our own species' physiology, morphology, psychology, and social organization, we know essentially nothing about the evolution of our cognitive capabilities and there is a strong possibility that we will never know much about it.”
Richard Lewontin (1990)
‘A Mixture of Pure Speculation and Inventive Stories’?
Why did high intelligence evolve in the human lineage? There is no evidence for the existence of a general evolutionary trend towards an increase in cognitive abilities. Almost all species of animals that have ever existed have been well-adapted without being highly intelligent. Nor does general evolutionary theory predict the existence of any trend in the direction of greater cognitive complexity. So why did enhanced cognitive abilities evolve, apparently uniquely, in our lineage?
The specific version of an evolution-based theory of psychology that calls itself ‘Evolutionary Psychology’ (hereafter capitalized) has an answer: human intelligence is an evolutionary adaptation (Tooby and Cosmides 1992). The basic cognitive faculties and capacities of the human mind were designed by natural selection in response to adaptive problems that faced our hominin ancestors in the Pleistocene (1.8 million years ago to 10 thousand years ago). According to this hypothesis, distinctively human intelligence is an evolved response to some range of adaptive problems that our hunter-gatherer ancestors faced in the Pleistocene.
The claim that there is an adaptationist explanation for specifically human intelligence rests on two ideas: firstly, that human intelligence is a complex adaptive trait, and secondly, that natural selection is the major source (perhaps the only non-miraculous source) of complex adaptive traits. Suppose it is accepted that there was natural selection for enhanced intellectual abilities in ancestral hominins during the Pleistocene. What were these forces, and what cognitive effects did they have? Here, Evolutionary Psychology makes a tendentious move. Distinctively human intelligence is not to be construed as General Intelligence: that is, as a general, non-domain-specific capacity for rational thought and action. Instead, the modern human mind consists, for the most part, of a very large array of domain-specific cognitive skills. That is, human intelligence does not consist (for the most part) of a general rational capacity that can be applied now to this problem, now to that problem, and now to some other, entirely different problem. Instead, it consists of an array of specialist problem-solving devices, such that one cognitive device (or ‘Darwinian Algorithm’) is applied to this problem, a different device is switched on by that problem, and an entirely different device is switched on by some entirely different problem. Human intelligence gives us the capacity to respond adaptively to a very large array of different problems, but only because it consists of a very large array of corresponding problem-solving algorithms. The general rule is: for each specific adaptive problem faced by Pleistocene hominins, natural selection designed a specific, cognitive, problem-solving device.
So human intelligence is not a general-purpose capacity for rational thought but is instead a ‘tool box’ consisting of a very large number of task-specific tools, each of which has the evolved function of producing an adaptive response to some specific adaptive problem that our hominin ancestors faced in the Pleistocene. Among the problems to which the modern human mind is specifically adapted are: foraging for food (in a Pleistocene, hunter-gatherer environment, not in a modern urban environment; which is a qualification that applies to all the items in this list), navigation, selecting a mate, parenting, engaging in social exchange, dealing with aggressive threat, avoiding pathogenic contamination, avoiding predators, avoiding naturally occurring plant toxins, identifying plant foods, avoiding incest, avoiding being bitten by venomous snakes, understanding and making tools, avoiding needlessly enraging others, interpreting social situations, helping relatives, deciding which foraging efforts have repaid the energy expenditure, inhibiting one’s mate from conceiving children by another, deterring aggression, maintaining friendships, recognizing faces, recognizing emotions in others, and so on and so forth (Tooby and Cosmides 1992, p. 110). Accordingly, human intelligence consists predominantly of a very large array of Darwinian Algorithms which give us special aptitudes for: foraging for food (in a Pleistocene, hunter-gatherer environment), navigation, selecting a mate, parenting, engaging in social exchange, dealing with aggressive threat, avoiding pathogenic contamination, and so on and so forth.
If these inherited Darwinian Algorithms existed alongside a capacity for general intelligence, then this evolutionary narrative would have failed to explain those general intellectual capacities themselves. Evolutionary Psychology would only have explained the origins of some of our instincts (Cosmides and Tooby 1994). If this were the case, then Evolutionary Psychology would have made only a marginal contribution to the explanation of the modern human mind. Perhaps the risk of marginalization explains the vigour with which Evolutionary Psychologists have argued against general intelligence. Yet in the face of obvious facts about the intellectual life of the mind, it is very implausible to say that what looks at first like a capacity for general intelligence is really the aggregate operation of a very large array of domain-specific cognitive skills. So one objection to Evolutionary Psychology is that it fails to take seriously the existence of general intelligence. A related difficulty concerns the evolutionary explanation for the existence of each of these specific cognitive skills. Evolutionary Psychology is committed to the view that a very large array of independent cognitive adaptations evolved through independent genetic changes to the hominin genotype in response to a very large array of independent forces of selection, all of this happening over a rather short period of time. And as if all this were not bad enough, when it comes to empirical evidence for the existence of all these Darwinian Algorithms in the modern human mind, Evolutionary Psychology is (to put it politely) evidentially challenged.
If Evolutionary Psychology is the best scientific account that we can have of human cognitive evolution, then Lewontin’s scepticism about the whole enterprise begins to look very attractive. This would be a shame, because the problem of explaining how and why human intelligence evolved is an especially beautiful problem. Happily, Australian philosopher Kim Sterelny has now given us reason to hope that some scientifically credible understanding of human cognitive evolution may be within our reach.
Sterelny’s ‘Thought in a Hostile World’ (Sterelny 2003) contains two intertwined evolutionary narratives. The first is a species-specific history of the principal factors that actually propelled cognitive evolution in the human lineage. The second is a general account of the kinds of cognitive modifications and enhancements that have to occur in any evolutionary process that begins with animals that are only minimally intelligent and that culminates in animals that are as cognitively sophisticated as modern humans.
A Species-specific Narrative
What were the principal factors that actually propelled cognitive evolution in the hominin lineage, after its separation from the lineage of modern chimpanzees? Sterelny argues that human cognitive evolution came about through the confluence of three factors: cooperation, the interaction of evolving lineages with their environments, and selection for plasticity (Sterelny 2003, p. 146). Of these, as we will see, cooperation is particularly important.
In comparison with other animals, including other group-living animals, human beings are an extraordinarily cooperative species. But cooperation is an improbable adaptation.
Competition for survival is a fundamental Darwinian fact. Different individuals typically have different biological interests. So relationships between individuals tend towards hostility rather than cooperation. We live in a hostile world. There is a point to cooperation, of course. Cooperation can yield significant benefits to each of the cooperating individuals. However, each individual stands to win an even greater benefit if he can free ride (cheat), gaining the benefits from the contributions that others make while not paying the cost of a contribution himself. In this situation, how can cooperation be initiated, or, once initiated, how can it be maintained? Differently described, how is it possible to make the difficult transition from an initial state of mutual distrust (prudent and sensible distrust) to a state of mutual trust (prudent and sensible trust)?
Biological hostility is expressed in a distinctive way in the domain of cognitive activity (or thought: hence ‘thought in a hostile world’). Biological hostility results in pollution of the epistemic environment. The epistemic environment is the environment in which knowledge-acquisition occurs. An epistemically optimal environment would be informationally transparent: adaptively relevant information would just lie around in the world, waiting to be picked up. Epistemically polluted natural environments, however, are informationally translucent: information needed for survival is often hidden from view (by the defensive activities of other organisms), and indeed is often badly contaminated by false information, deceptive signals produced by biological rivals.
In a hostile world, the adaptively important knowledge that an animal needs to survive and flourish is often not readily available, because it is often in the interests of each animal to deprive other animals of good information, or to provide other animals with deceptive information.
In the endless struggle for competitive advantage, animals often act in ways that have the function of corrupting the natural flow of information in the world. Yet each individual animal stands to benefit from improvements in the quality of information in its environment. This is a typical prisoner’s dilemma: it is beneficial for everyone if everyone cooperates to make the epistemic environment transparent; but it is even more beneficial for each individual if they can manage to enjoy the benefits of everyone else’s honest signals while also enjoying the benefits from their own dishonest signals.
Social Intelligence hypotheses are hypotheses about the social causes of human intellectual evolution. These hypotheses make explanatory connections between the evolution of higher intellectual capacities in the human lineage and the special challenges that arise out of the flow of information in social environments. The best known of these hypotheses, the Machiavellian Intelligence hypothesis, identifies contests for individual advantage as the key factor in the evolution of intelligence (Byrne and Whiten 1988). Competitive individuals struggle to devise ever better methods for cheating and deceiving each other, and ever more subtle methods for detecting cheating and deception. An evolutionary arms race between cheaters (all of us, some of the time) and cheater detectors (all of us, some of the time) pushes human intelligence upwards.
This is plausible. But Sterelny argues that, in this concentration on social competition, we have neglected the role of cooperation in human cognitive evolution. Humans are an extraordinarily cooperative species (p.123). It is no accident that we are also extraordinarily intelligent. At some time in the past (at least 500 thousand years ago, perhaps much more), there was an ‘explosion’ of cooperation in the human lineage. As cooperation became deeper and richer, so too, in a coevolutionary process, did novel cognitive and emotional adaptations appear.
One such cognitive adaptation is language. Language is a sophisticated form of cooperation. Unless speaker and hearer agree on the meanings of words, on grammar, and so on, then the use of language to communicate cannot be reliably secured: language cannot even be used to deceive unless there is substantial agreement between speaker and hearer. (Similarly with biological deception. Deceptive mimicry presupposes the existence of truthful signals. An edible variety of moth cannot protect itself from predators by mimicking the colouration of a toxic variety of moth unless the warning colours of the toxic moth really do signal its toxicity.) Language is unlikely to be simply a product of prior cognitive evolution, nothing more than an external medium for the communication of thought. It is much more likely that there was a coevolutionary process in which growing complexity in the external symbolic technology both powered and was powered by growing complexity in the cognitive capacities of language users. Some of this evolution in cognition was probably genetic: genetic evolution by natural selection does not occur only in response to factors in the ‘natural’ environment but can equally be a response to features of the social environment. However, there can also be evolution, in a robust sense, in the absence of genetic change. Suppose that some higher cognitive capacities (such as the language capacity) are implemented in neural structures that are not genetically specified but which are installed in the brain through processes of learning during individual development. Suppose that the cultural environment that supports those forms of learning is reliably replicated from one generation to the next, such that the neural structures and the cognitive capacities that they implement are also robustly replicated from one generation to the next. Then nongenetic cognitive evolution has occurred.
Fundamental to this conception of cognitive evolution is a set of ideas developed by Michael Tomasello (Tomasello 1999). Tomasello thinks that the evolution of modern human forms of cognition could have been triggered by a single mutational event. Instead of the very large set of discrete genetic mutations required by the Evolutionary Psychology model, a single mutation could (in principle) have been sufficient to trigger a cascade of nongenetic cognitive changes. Suppose, says Tomasello, that this genetic mutation created in the human brain a new cognitive capacity: the capacity for ‘mind reading’, the capacity, that is, for understanding behaviour as the expression of intentional mental states such as beliefs and desires. The capacity for mind reading gives rise in turn to new and powerful forms of cooperation within human groups. In particular, says Tomasello, it creates new and powerful forms of social learning, especially what he refers to as ‘true imitation learning’, which occurs only when learners understand the teacher’s intentions. In turn, the new forms of social learning make possible the process of cultural-cognitive evolution known as ‘Tomasello’s ratchet’ (Sterelny 2003, pp. 116f). In cumulative cultural evolution, each new generation inherits through social channels of learning the collective knowledge of the group, and has the opportunity to add to this collective stock before participating in its transmission, through reliable channels, to the next generation.
Cumulative cultural evolution also results in extensive modifications to our epistemic environment. Epistemic engineering modifies the environment so as to improve its epistemic qualities, for example, by making the human habitat informationally more transparent. Sterelny regards epistemic engineering as a form of niche construction (Odling-Smee et al, 2003). The epistemic engineering that goes on in one generation can endure over several or many generations, such that later generations inherit the epistemic and cognitive benefits of living in those epistemically engineered niches. A uniquely important part of our engineered epistemic niche is, of course, the extensive array of external symbolic technologies that we have collectively devised: signs, symbols, natural languages. These are a critically important part of the culturally constructed aspects of the cognitive niche in which hominins acquired advanced cognitive powers.
Evolutionary Psychology sees human cognitive evolution as a product of natural selection acting through serendipitous genetic mutations to produce a very large array of innate cognitive capacities that together constitute what is distinctive in human cognition. The alternative model described by Sterelny, Tomasello, and others, places less emphasis on internal, innate changes to the structure of the mind and more emphasis on external factors in cognitive evolution. This is not to say that human babies are born as blank slates on which experience inscribes the whole of their human psychology. But it is to say that large chunks of human psychology are constructed during individual ontogeny, through processes in which a minimalist set of innate pre-wirings interact with an environment that has been extensively modified through cumulative cultural and epistemic engineering.
Another evolutionary factor that plays a central role in Sterelny’s model is selection for plasticity. Humans are generalists, both ecologically and cognitively. The capacity of our species to adapt to a very large range of environments provides suggestive evidence for the existence of significant plasticity, or flexibility, in human thought processes. This capacity – which seems to many to be the most significant distinguishing aspect of human cognitive psychology – is at the core of some of the central debates about the Evolutionary Psychology model. Cosmides and Tooby argue that the human mind evolved as an adaptation to a specific type of environment, the savannah environment of East Africa in the Pleistocene (or, as they sometimes say, the human mind is adapted, not to a specific environment but to a statistical average of Pleistocene environments, which rather begs the question as to whether average anythings can have causal powers: Sterelny 2003, p. 162, and references therein). There is an obvious problem here: is the apparent plasticity of the modern human mind consistent with its evolutionary adaptation to a specific ecological niche? After all, niche-specific adaptations are notoriously inflexible, prone to error or to other forms of maladaptive response in novel environments. Sterelny argues, in contrast, that the human mind is not adapted to any specific kind of environment. Instead, the human mind is adapted to the spread of variation in the environments in which hominins evolved. Whereas Evolutionary Psychology supposes that hominins are adapted to the peak (the average) in the distribution of hominin evolutionary environments, Sterelny argues instead that they are adapted to the spread of variation in those evolutionary environments. But how can any organ (including mental organs) be adapted to variation in the environments in which evolutionary adaptation occurred? Says Sterelny, our evolutionary response to variation is phenotypic plasticity (Sterelny 2003, p.162). The adapted response of the human brain to variability in the environment of selection was to evolve mental capacities that allowed behaviour to be fine-tuned to a very wide range of particular environments, circumstances and challenges.
Plasticity is just what one would expect, given the role of epistemic engineering in human cognitive evolution. Hominin cognitive niches were and are variable across time and space and are capable of rates of change far in excess of rates of biological evolution. Only a developmentally plastic mind could successfully track evolving cognitive and cultural niches that are changing at rates too fast to be tracked by adaptive genetic change.
A General Evolutionary Narrative
Earlier I distinguished two evolutionary narratives in ‘Thought in a Hostile World’. The first of these is the species-specific history of the principal factors that actually propelled cognitive evolution in the human lineage. The various factors that Sterelny identifies are contingent causes of human cognitive evolution. There is no claim that the evolution of advanced cognition in any lineage would have to proceed in this way. If cetaceans were to evolve higher cognitive abilities, they might do so along a different trajectory from that followed by the hominin lineage. Sterelny’s second evolutionary narrative steps back from the details of hominin cognitive evolution, to consider in a much more general way the kinds of cognitive modifications and enhancements that have to occur in any evolutionary process that begins with animals that are only minimally intelligent and that culminates in animals that are as cognitively sophisticated as modern humans. This general narrative also goes some way to explaining how a capacity for general intelligence (cognitive plasticity) is possible.
Classical cognitive science makes use of a distinction between rules and representations: the algorithms or computational procedures that do the information processing, and the data or information-bearing states or representations on which these processes operate. Cognition consists in rule-governed transformations of information-bearing states. Given this distinction, one part of a theory of general intelligence would be a theory about the processing rules that distinguish cognitive processes in smart minds from cognitive processes in simple minds. Another part of a theory of general intelligence would be a theory about the representational resources that distinguish cognitive processes in smart minds from cognitive processes in simple minds.
Sterelny has a theory about the representational resources that contribute to general intelligence. It is an abstract evolutionary narrative which describes how simple forms of representation evolve into more powerful forms of representation. The story begins with simple detection systems.
Detection systems are information processing systems in animals in which a specific environmental signal triggers a specific response. Simple detection systems rely on single environmental cues to trigger behaviour: for example, some ants carry the corpses of dead conspecifics from the nest, as a direct, hardwired response to the detection of oleic acid, which is a product of decay in ant corpses. Detection systems of this kind are remarkably effective at producing adaptive behaviour at minimal cost in stable, predictable, epistemically transparent environments. However, single-cued detection systems are also very brittle, easily disrupted by epistemic pollutants in biologically hostile environments. How might a simple detection system be improved, to enhance its capacity for adaptive behaviour in environments that are less epistemically benign?
One way to enhance the powers of a simple detection system is to enhance its abilities on the input side. Input-side enhancement involves the evolution of multiple-cued ways of tracking objects. An animal that uses multiple-cued tracking can respond to damage or subversion in one information channel by basing its response on other information channels, or on some suitable statistical inference from the spread of information that it receives through multiple channels. In effect, this organism is demanding better evidence for the presence of an object before initiating a response. The epistemically sophisticated ability to use multiple cues in registering states of the environment gives rise to a capacity for robust tracking of adaptively relevant objects in and states of the environment.
Robust tracking – which is an enhancement of the input side of a detection system - is one of the two basic dimensions of cognitive sophistication. The other basic dimension of cognitive sophistication is response breadth. Response breadth is an enhancement of the output side of a detection system. Response breadth arises when a representation of an environmental object is no longer tied to a single behavioural response. Instead, registration of the object is detached or decoupled from a specific response pattern. As a consequence, the representation of the object is potentially available for the use of any of a variety of response systems. We are on the way to the evolution of forms of representation – concepts - that are not tied to specific cognitive routines (or Darwinian algorithms) but which are available for use in multiple ways by our thinking and reasoning capacities. We are on the way to to phenotypic cognitive plasticity.
Ways of Thinking About Human Cognitive Evolution
The idea that it is a hostile world out there is hardly novel. But there is novelty in Sterelny’s idea that cooperation is not only our fundamental adaptation to hostility, but that cooperation is also the foundation of our advanced intellectual capacities. Hostility pollutes the epistemic environment, and reductions in hostility consequently improve the epistemic properties of human environments. As Sterelny says, cooperation changed the mixture of selection forces acting on the human lineage, and so pushed our lineage in an evolutionarily novel direction.
Perhaps one might think that social and cultural innovations are primarily external to the mind, and that we also need an internal story about psychological evolution. On the Evolutionary Psychology model, external facts about culture presuppose internal facts about psychological capacities for culture, and those internal facts are explained by reference to reproductive fitness in the Pleistocene. Sterelny’s view, in contrast, draws the external/internal distinction rather differently. Whereas the classical view is that cognition occurs primarily inside the head, there is a lot of recent work that explores the nature of extended cognition (Clark 1997), wherein our human cognitive achievements are attributed not to the naked brain, but to the brain as coupled to various external structure and processes (especially artefacts). Andy Clark himself tends to develop this thesis of brain-world coupling in an individualist way, describing, for example, the way in which our in-board memory is enhanced by off-loading records onto readily-accessible external storage devices. Sterelny gives a cooperative spin to this brand of externalism (see also Hutchins 1995). Not only are our cognitive talents a product of novel forms of close-coupling between brain and world (especially, to repeat, artefacts), but our cognitive talents are also enhanced in novel and powerful ways by being distributed among individual agents (offloaded, as it were, onto other brains). Cognitive divisions of labour and complex forms of cognitive cooperation are now so ubiquitous that we are sometimes inclined to overlook the extent to which they actually, literally, constitute advanced cognition, as distinct from being simply external effects of internal cognitive powers. Cognition ain’t just in the individual head.
There is a stark contrast here with the Evolutionary Psychology model, which is resolutely individualist and nativist. Nativism is typical of first generation cognitive science, which drew its inspiration from Chomsky’s nativism about our linguistic capacities. Sterelny’s alternative picture is very much in the mould of the renascent empiricism of second generation cognitive science. Nativism and empiricism represent two contrasting ways of thinking about basic problems of mind design. The nativist places his money on the strategy of installing lots of survival information in the mind so that the individual is sent into the world already knowing lots of important things. The empiricist, by contrast, places his money on the strategy of leaving the information in the world and giving to the mind capacities for extracting relevant information from the world as and when it is needed. The plausibility of empiricism depends on the account given of the extraction capacities. Classical empiricism struggled with this problem: how can individual agents learn enough about the contingent structure of their environment to survive, if they come into the world knowing nothing about the specific, contingent challenges that will face them? But the empiricist learning problem is misrepresented if we think only of the difficulties that face a lone individual as he struggles to understand a recalcitrant world. Two facts in particular tell against this individualist assumption. Firstly, the shape of the human lifespan is unique among all animal species in the hugely extended proportion of a life that is spent in a state of juvenile dependency. What is the evolved function of childhood? Once the question is posed, the answer appears obvious: childhood is for learning, and extended juvenility is a biological adaptation for massive learning. Secondly, children develop in species-specific niches which are massively epistemically engineered to support learning.
This picture contains an interesting variation on the traditional, Kantian form of nativism, represented most influentially in the later work of Konrad Lorenz (Lorenz 1965; Browne 2005). Lorenz argued for a form of minimal nativism, in which the innate structure of the mind consists primarily of learning dispositions and biases. These innate prompts ensure that the developing mind learns the correct lessons from experience. Externalism leads to a different view about at least some of the constraints, biases and channels that guide learning in adaptive directions. Instead of installing these biases in the mind through genetic evolution, why not construct them in the world, in the form of social practices, technologies, cultural objects and processes, that function to guide the child’s learning in adaptive directions? For a simple illustration, compare the accounts that these competing models give of some simple survival skills, taken from one of Evolutionary Psychology’s canonical lists: avoiding predators, avoiding naturally occurring plant toxins, avoiding being bitten by venomous snakes, making tools, and so on. How odd to think that this kind of contingent knowledge is innate! What did Pleistocene children learn, in their socially secured environment, if it was not survival knowledge of this very kind? How wasteful to install all that contingent knowledge in the brain, given that the information was also present, in stable and accessible forms, in the species-specific, socially and culturally constructed, developmental niche.
Furthermore, if one takes seriously the human capacity for flexible thought and reasoning, then Evolutionary Psychology’s commitment to the view that the modern human mind consists largely of an array of specific cognitive adaptations to a specific ancestral environment is a liability. Suppose instead, with Sterelny, that much that is distinctive of human cognition is constituted not only by brain structures but also by structures and processes in our socially and culturally constructed niche. Then flexibility and adaptability is less surprising, because the individual mind is much less constrained by a vast array of innate biases and liabilities. The individual mind instead has the freedom to take up whatever cognitive scaffolding is represented in its local environment.
We do not yet have a really good understanding of the human capacity for cognitive flexibility. But whereas Evolutionary Psychology places obstacles in the pathway to such knowledge, Sterelny’s work makes a significant contribution towards our understanding the unique cognitive powers of human species. While there are worthy targets for Lewontin’s scepticism about theories of human cognition, general scepticism about such theories is, in the light of Sterelny’s work, too pessimistic.
Browne, Derek (2005), ‘Instincts and Phylogenetic Information’, The Rutherford Journal
Byrne, Richard and Andrew Whiten (eds) (1988), Machiavellian Intelligence. Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans. Oxford: Oxford University Press.
Clark, Andy (1997), Being There. Putting Brain, Body, and World Together Again. Cambridge, MASS: MIT Press. A Bradford Book.
Cosmides, Leda and John Tooby (1994), ‘Beyond intuition and instinct blindness: toward an evolutionarily rigorous cognitive science’, Cognition, 50, 41-77.
Hutchins, Edwin (1995), Cognition in the Wild. Cambridge, MASS: MIT Press.
Lewontin, R. C. (1990), ‘The evolution of cognition’, in Thinking. An Invitation to Cognitive Science, Volume 3. Edited by Daniel N. Osherson and Edward E. Smith. Cambridge, MASS: MIT Press.
Lorenz, Konrad (1965), Evolution and Modification of Behavior. Chicago: University of Chicago Press.
Odling-Smee, F. John, Kevin N. Laland, and Marcus W. Feldman (2003), Niche Construction. The Neglected Process in Evolution. Princeton NJ: Princeton University Press.
Sterelny, Kim (2003), Thought in a Hostile World. The Evolution of Human Cognition. Oxford: Blackwell Publishing.
Tomasello, Michael (1999), The Cultural Origins of Human Cognition. Cambridge, MASS: Harvard University Press.
Tooby, John and Leda Cosmides (1992), ‘The psychological foundations of culture’, in The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Edited by J. H. Barkow, L. Cosmides and J. Tooby. New York: Oxford University Press.