Evolution Of Human Cognition Research Paper

Following common practice in the various branches of comparative biology and psychology, it may be assumed that if all the species of a given evolutionary taxon possess a certain physical trait or behavioral propensity, then the common ancestor for that taxon also possessed that trait or propensity. In the case of humans, the taxon of direct relevance is primates, with special attention to Pan troglodytes and Pan paniscus (referred to collectively as chimpanzees), because human beings shared a common ancestor with them a mere 6 million years ago. The cognitive processes common to chimpanzees and human beings thus represent the best evidence we have for the cognitive processes of the very first hominids.

For most of the day, every day, primates forage for food, quite often for patchy resources such as fruits and new leaves and buds (which only grow on some plants at some times of the year), and sometimes for insects or other animal prey who can move freely on their own. In order to forage efficiently, therefore, primates must:

(a) remember ‘what’ is ‘where’ in their local environments, for example, which fruits are in which trees at what times;

(b) take creative detours and shortcuts to get to the food as quickly as possible;

(c) track the visible and sometimes invisible movements of prey and other objects;

(d) recognize and categorize different foods and objects on the basis of perceptual features;

(e) quantify relative amounts of foods on the basis of perceptual features; and

(f) use insight in problem solving, for example, in extracting food from substrates.

A variety of empirical studies—both observational in the wild and experimental in captivity—demonstrate that virtually all anthropoid primates have all of these cognitive skills (see Tomasello and Call 1997 for a review). Primates also must use sophisticated cognitive skills to deal effectively with their social environments. Among the most important of these (again, see Tomasello and Call 1997, for a review) are the abilities to:

(a) recognize individuals within the social group; (b) form social relationships with group mates based

on such things as kinship, friendship, and dominance rank;

(c) recognize the ‘third-party social relationships’ of other group mates based on such things as kinship, friendship, and dominance rank;

(d) predict the behavior of individuals based on such things as their emotional state and their direction of locomotion;

(e) use many types of social and communicative strategies to outcompete group mates for valued resources;

(f) cooperate with conspecifics in problem-solving situations and in forming social coalitions and alliances; and

(g) engage in various forms of social learning from conspecifics.

Indeed, the fact that the primate social environment presents such a wide array of cognitive challenges has led some theorists to posit that the truly unique features of primate cognition—involving such things as understanding and dealing with relational information—have come from their adaptations not to the physical world but to the social world (Humphrey 1976, Tomasello and Call 1997). Empirical work on primate cognition—coupled with the working assumptions of comparative biology—has thus established that by the time hominids set out on their own evolutionary pathway some 6 million years ago, they already possessed a plethora of cognitive skills, derived mainly from adaptations in the context of foraging for food and dealing effectively with group mates. In brief, they already conceptualized a sensory-motor world of permanent objects—arrayed in a representational space and categorized and quantified in some fundamental ways—and a social world of animate conspecifics with whom they could cooperate and compete in various complex ways.

However, if we compare contemporary chimpanzees and human beings there are still some cognitive skills that are unique to humans and that therefore must have arisen after the human–chimpanzee divergence 6 million years ago. Most important, in the physical world human beings, and only human beings, understand the causality of events; that is, they understand events in terms of the unobservable ‘forces’ that explain why they happen in the way they do (Visalberghi and Tomasello 1998). Understanding causality enables individuals to interact with their physical words in much more flexible ways, for example, by creating or blocking key antecedent events in order to produce a desired consequent. Analogously, in the social world human beings, and only human beings, understand the intentionality of behavior; that is, they understand behavior in terms of the unobservable mental ‘forces’ (thoughts, beliefs, desires) that explain why individuals behave the way they do (Visalberghi and Tomasello 1998). Understanding intentionality enables individuals to interact with conspecifics in much more flexible ways, for example, by attempting to manipulate their knowledge or motivational states so that they will act in desired ways. But perhaps even more importantly, understanding conspecifics as intentional agents constitutes the social–cognitive foundation for human culture, which gives human cognition its species-unique socialcollective dimension (see Sect. 3).

1. Hominid Material Artifacts

For the first 4 million of its 6 million years of existence, the human lineage consisted exclusively of one or another species of australopithecine. Australopithecines were small in stature, bipedal, with ape-sized brains, and no stone tools; many modern paleoanthropologists thus refer to them as ‘bipedal apes.’ Although we know little of the behavior of these earliest hominids, there are no clear indications that they cognized the world in anything other than the typical great ape manner.

With the birth of the genus Homo some 2.5 to 2 million years ago, the human lineage began to show signs of some unique cognitive adaptations. Most important, humans began to make stone tools in ways that required at least some degree of planning and causal understanding of the way rocks could be modified and used instrumentally (Schick and Toth 1993). Thus, early in this period Homo habilis made Oldowan ( pebble) tools, which required some understanding of how rocks break when struck in certain ways, and which were often made in one location and then carried to another for subsequent use. Later, Homo erectus made Acheulean hand axes (bifaced and symmetrical), which showed a clear ability to hold in mind a definite end product during the process of manufacture and in addition an ability to understand some of the basic causal forces at work in stone tool making. During the early parts of this period (especially from 2 to 1.5 million years ago), the brains of hominids expanded in size by about one third, perhaps because of the cognitive demands of making and using these complex technological products.

A second major brain expansion about 500,000 to 200,000 years ago increased hominid brain size by a factor of one third once again, basically to its modern size. This took place in a set of hominids known collectively as archaic Homo sapiens, followed soon by modern Homo sapiens. These hominids invented some new techniques for making stone tools, initially the Levallois technique in which a large stone core is specially prepared so that smaller flakes of a special type may be systematically struck off, and later the technique of making blade tools (in much the same way) whose great length to width ratio made them much more multipurpose. Following this in many populations were specialized microlith tool industries, with all kinds of highly specialized tools for highly specialized purposes (each made in a specialized way). Interestingly, some of these flakes, blades, and micoliths were hafted onto wooden or bone handles, which made them even more efficient cutting tools. Of special importance from a cognitive point of view, manufacturing these hafted tools required their makers to understand, before the manufacturing process began, that different parts of the tool had different instrumental functions. These so-called composite tools may thus indicate the ability of archaic and early modern Homo sapiens to understand and plan for the different causal roles of the different components of a tool.

Another feature of hominid tool use suggests something of how individuals learned to make and use their tools. Both Oldowan and Acheulean types of tools showed great uniformity of use at particular historical periods across all groups of hominids who used them, no matter how far apart from one another they may have lived. In the case of the Oldowan tools of Homo habilis (and relatives), this uniformity was confined to Africa and lasted for hundreds of thousands of years. In the case of the Acheulean tools of Homo erectus, this uniformity extended all over Africa, Western Europe, and the near East and India, and lasted for over one million years. But with the rise of the more modern techniques of tool making and use, especially the blade and microlith technologies uniquely associated with modern humans, different populations of human beings began to make and use their tools in population specific ways. This new pattern of distribution among social groups suggests the possibility of the cultural transmission of tool making and using techniques in the different populations, in much the manner of contemporary human populations.

We cannot know much about the social lives of the earliest modern humans because we have so few fossils and artifacts. But if indeed truly cultural organization emerged only with modern humans, then it is reasonable to suppose that there was some change in social cognition that led to this new form of social organization. The main reason to believe this is that before nine months of age human infants are ‘acultural’ creatures in the sense that they are not yet able to appropriate the cultural artifacts and practices of those around them actively. Soon a major change in their social cognition occurs and they begin to understand other persons as intentional beings like themselves, with mental states like their own. This is indicated by the emergence a whole suite of new behaviors such as:

(a) following the gaze direction and pointing gestures of adults;

(b) engaging in shared attentional interactions with adults;

(c) imitating adult actions on external objects; and

(d ) directing adult attention through pointing and other gestures, all of which indicate a new understanding that other persons have intentional relations to the world (Carpenter et al. 1998).

Because of this new understanding, infants begin to acquire in earnest the tools, linguistic symbols, and other cultural artifacts and activities of their social groups (Tomasello et al. 1993). (Note that children with severe autism never develop this social cognitive ability and they, in a sense, remain a cultural individuals; Hobson 1993.) If we assume this same relationship between social cognition and cultural learning in human evolution, we can use the artifactual evidence for the emergence of human cultures to infer that a change in social cognition occurred with modern humans.

2. Culture And Cognition

With the advent of modern humans and their cultural organization, human cognition took on a radically different character. First, with the advent of skills of cultural learning and teaching (resulting from the social-cognitive ability to understand others as intentional and mental agents), human beings began to create artifacts and social practices that accumulated modifications over time. Thus, the so-called ‘cultural explosion’—which took place in some, but not all, human populations at about 40,000 years ago—was characterized by many new technological inventions and very rapid changes and improvements in existing technologies. Tomasello et al. (1993) hypothesized that this kind of cumulative cultural evolution, in which the complexity of material and symbolic artifacts ratchets up very quickly over historical time, is only possible with the human form of cultural learning in which the learner understands the intentions of another individual in the sense that she understands what the behavior is ‘for.’ The need for this kind of understanding is clearest in the case of tools and symbols since both of these artifacts clearly point to things beyond themselves: the tool to its instrumental function in modifying the physical world and the symbol to its communicative function in modifying other people’s attention and behavior.

Once this kind of cultural learning was operative, human populations could, in effect, pool their cognitive resources in a way unique in the animal kingdom. Chimpanzees and other nonhuman primates benefit from observing the activities of their conspecifics, but because they do not understand the intentions of others, what they learn from these observations is limited (Tomasello 1996, see also Kummer and Goodall 1985). Human beings, on the other hand, are able to acquire relatively faithfully many of the tools, symbols, and social practices of others, so that inventions spread relatively rapidly and are preserved in the group effortlessly until some new and improved innovation comes along, which is then acquired faithfully, and perhaps modified further, by another generation. An important result of this ratcheting up of cultural inventions over historical time, is that human children are born into a world of artifacts and social practices that embody something resembling the accumulated wisdom of their entire social group throughout its entire cultural history (Donald 1991).

When children acquire the use of a material or symbolic artifact, or learn to engage in a conventional social practice in their culture, they internalize the intentional states of the adult inventors and users of the artifact or social practice (Vygotsky 1978). This internalization process is of special importance when children acquire linguistic symbols, because a human language embodies all of the myriad ways that the people of a social group have found it useful to categorize and construe their worlds for purposes of communicating with one another. Because the same entity may be construed in many different ways linguistically—this object is a dog, an animal, a pet, or a pest—in acquiring a natural language children are induced to take multiple simultaneous perspectives on entities in the world, with some of these perspectives being common to all languages and some of them being unique to particular languages. When internalized by the child, then, the process of linguistic communication creates in each individual a species-unique form of perspectivally based cognitive representation, commonly known as symbolic representation (Tomasello in press).

As a way of highlighting the cognitive importance of processes of cumulative cultural evolution over historical time and their interaction with processes of cultural learning and internalization over ontogenetic time, we may imagine a human child raised on a desert island in isolation from all other human beings, with a normal brain, body, and sense organs, but with no access to tools, other material artifacts, language, graphic symbols, writing, Arabic numerals, pictures, people who could teach her things, people whose behavior she could observe and imitate, or people with whom she could collaborate. It is likely that as an adult this child’s cognitive skills would look very little like those of contemporary human beings (Tomasello in press). The point is thus that modern human beings have the cognitive skills they do because they inherit things from their progenitors both biologically and culturally (cf. the Dual Inheritance Model of Boyd and Richerson 1985, Durham 1991). They inherit biologically the ability to understand conspecifics as intentional agents—and the cultural learning processes that this enables—and these abilities then in turn open the way to the cultural line of inheritance and children’s internalization of the ways of understanding the world embodied in their culture’s accumulated artifacts and social practices.

3. Conclusion

Much of this account, in common with other accounts of human evolution, is necessarily speculative. But it is based on a solid body of research demonstrating precisely how human cognition is similar to and different from that of nonhuman primates, and on a relatively straightforward search for the two most important species-unique aspects of human cognition in the human artifactual record. First, the earliest humans some 2 million years ago began to demonstrate some new skills of causal understanding in the context of complex tool manufacture and use. Second, and even more important, the earliest modern humans some 150,000 years ago began to demonstrate some new skills of social cognition—understanding conspecifics as intentional and mental agents—that fundamentally changed the process of human cognitive evolution because they enabled uniquely powerful processes of cultural learning and cumulative cultural evolution. These cultural processes, in turn, transformed the ontogenetic niche in which human cognition developed ontogenetically from a social into a truly cultural niche including artifacts, symbols, and social practices with accumulated histories. The ability to pool cognitive resources in these ways may even have been the competitive advantage that modern humans had over other contemporaneous hominids. The ultimate outcome of these evolutionary and cultural processes in humans today is a form of cognition that is culturally and symbolically constituted in ways unprecedented in the animal kingdom.

Bibliography:

1. Boyd R, Richerson P 1985 Culture and the Evolutionary Process. The University of Chicago Press, Chicago
2. Carpenter M, Nagell K, Tomasello M 1998 Social cognition, joint attention, and communicative competence from 9 to 15 months of age. Monographs of the Society for Research in Child Development 255
3. Donald M 1991 Origins of the modern mind. Harvard University Press, Cambridge, MA
4. Durham W 1991 Coevolution: Genes, Culture, and Human Diversity. Stanford University Press, Stanford, CA
5. Hobson P 1993 Autism and the Development of Mind. Erlbaum, Hillsdale, NJ
6. Humphrey N K 1976 The social function of intellect. In: Bateson P, Hinde R A (eds.) Growing Points in Ethology. Cambridge University Press, Cambridge, UK, pp. 303–21
7. Kummer H, Goodall J 1985 Conditions of innovative behaviour in primates. Philosophical Transactions of the Royal Society of London Series B 308: 203–14
8. Schick K, Toth N 1993 Making Silent Stones Speak. Simon and Schuster, New York
9. Tomasello M 1996 Do apes ape? In: Galef J, Heyes C (eds.) Social Learning in Animals: The Roots of Culture. Academic Press, New York
10. Tomasello M in press The Cultural Origins of Human Cognition. Harvard University Press, Cambridge, MA
11. Tomasello M, Call J 1997 Primate cognition. Oxford University Press, Oxford, UK
12. Tomasello M, Kruger A, Ratner H 1993 Cultural learning. Behavioral and Brain Sciences 16: 495–552
13. Visalberghi E, Tomasello M 1998 Primates causal understanding in the physical and psychological domains. Behavioural Processes 42: 189–203
14. Vygotsky L 1978 Mind in society. In: Cole M (ed.) The Development of Higher Psychological Processes. Harvard University Press, Cambridge, MA