Evolutionary psychology, as christened by anthropologist John Tooby and psychologist Leda Cosmides, is a relatively new psychological perspective (Pinker, 1999). Steven Pinker argues that evolutionary psychology brings together cognitive science and evolutionary biology. Cognitive scientists are interested in the human mind and how it works. Evolutionary biology can help us to understand why humans have the minds we do. Evolutionary psychologists are interested in humans as a species, what makes us unique and how we differ from other animals. They are interested in the universal features of the human mind, trying to explain most of our contemporary behaviour using the principles of evolution. Why, despite the fact that humans and chimpanzees share a very large number of genes, are we different? Only human civilizations have been able to build complicated structures using advanced technologies. What were the evolutionary pressures that led to quite a different development of the human mind (e.g., language development) to that of the chimpanzee?
Ideally, to answer the questions proposed, evolutionary psychologists should study our ancestors. As our ancestors are not around any more, it is necessary to visit different scientific and psychological areas to gather their evidence and data to develop their theories. The theory of evolution is an important area to start with, as it helps us to understand the basic principles of natural selection.
The theory of evolution has developed primarily from the work of Charles Darwin. Following his travels to Galapagos Islands and his naturalistic observations of the animal species living on different islands, Darwin developed a theory about the origins of species, via a process known as a natural selection. He proposed that only features that are of adaptive value would be naturally selected for, in order to promote successful survival and reproduction. The genes that code for such features would therefore be more likely to be copied into the next generation. This theory is fundamental for evolutionary psychology, as it helps us to understand how and why we came about.
To also understand how the contemporary human mind came about, it is important to comprehend the pressures our ancestors had to face. As Tooby and Cosmides put it: ‘The distinctive aspects of human minds and brains probably owe their origins to the lengthy period of adaptation to the hunter-gatherer way of life’ (Tooby and Cosmides, 1989; 1992, reported in Smith et al., 2002). This notion is supported by evidence from the study of human pre-history. Paleontologists and archaeologists have concluded (based on fossils and archaeological sites found/available) that contemporary civilization is very recent, since about 10,000 years ago (as the first cities only emerged around that time). This compares to the much longer period of the existence of hunter-gatherer societies, dating back some 500,000 years. Many aspects of modern human behaviour are therefore more likely to be explained by reference to the demands of hunter-gatherer societies than by modern life.
It is not surprising then that evolutionary psychologists draw upon comparative anthropological evidence of modern hunter-gatherer societies. They believe that the development of human cognitive abilities are directly linked to environmental pressures and that cognitive skills unique to humans developed alongside social skills (Whiten, 1999, reported in Smith et al., 2002). Evidence to support these claims comes from extensive studies of the !Kung San people of the Kalahari desert in Africa, who until very recently lived in hunter-gatherer societies (Lee, 1979 reported in Smith et al., 2002). Lee observed, that successful hunting required planning, understanding of technology (how to construct arrows used for hunting), reasoning and lessons learnt for the future (from discussions after the hunt). These abilities are absent from chimpanzee hunting behaviour. Whiten argues that what differentiates human from chimpanzee society is the level of sophistication at which social integration operates (Smith and Stevens, 2002).
Observations of other primates are also relevant. Evolutionary psychologists believe that by understanding the behaviour of primates related to humans, like chimpanzees (with whom we share our ancestors), we can better understand our own evolution. The evidence they draw upon comes from ethology (study of animals in the wild). Jane Goodall’s naturalistic observation of chimpanzee societies in the Gombe Stream area of Tanzania (Goodall, 1971, reported in Smith et al., 2002) offered an invaluable insight into complexity of their cognitive and social skills. Chimpanzees observed displayed a vivid personalities and human-like emotions.
They were seen, for example, kissing, embracing, holding hands, tickling, kicking and fighting (www.evoyage.com/Whatis.html, 2002). Moreover, she observed that they not only used but made simple tools. Such behaviours are very fundamental. They are not a product of modern life. It is clear, therefore, that there are many factors working together contributing to the development of the clever human from the clever ape.
Only humans exhibit high-level intelligence. One aspect of this kind of intelligence is ‘theory of mind’. It is normal for people to have a ‘theory of mind’, i.e. the capability to understand and ‘read’ the mind of another individual and make inferences of their possible behaviour based on this understanding. Some non-human apes, such as chimpanzees, possess simple features of ‘theory of mind’, as demonstrated in controlled experimental study of a chimpanzee called Sarah (Premack, 1998, reported in Smith et al., 2002). Although these abilities are very limited, it seems reasonable to suggest that early hominids possessed basic elements of ‘theory of mind’.
Another kind of evidence used by evolutionary psychologists to support the above suggestion comes from archaeological artefacts. For example, the lion-man statuette, which is approximately 30,000 years old, found in Southern Germany (Mithen, 1996, reported in Smith et al., 2002). This statuette is indirect evidence that our ancestors possessed the ‘theory of mind’ as the creator of this statuette had to use his/her ability to pretend (one of the features of ‘theory of mind’) and be able to use symbolic representations of their mind to produce a non-existent, fictional figure, as we know that such creature did not exist.
Evolutionary psychologists believe, that as complex as our behaviour is, the evidence to support our evolutionary development cannot be any less complicated. Therefore, as shown above, evolutionary psychologists draw upon many different kinds of evidence from a variety of scientific disciplines, including, evolutionary biology, archaeology, paleoanthropology, comparative anthropology, primatology, ethology and cognitive science. Evolutionary psychology is now well established within psychological tradition and promises to continue to shed new light on modern human behaviour.