Just as evolutionary theories in the biological sciences assume that living things adapt generation-by-generation to survive in their environment, in psychology, the evolutionary approach (also referred to as "evolutionary psychology") involves the study of our cognitive processes and behavior with the view that they too have been altered over millions of years to help us to reproduce.
Evolutionary psychology assumes that tendencies towards behavior which reduces the chances of reproducing will be reduced as less offspring are produced. Meanwhile, dispositions towards behavior which is viewed positively by a potential mate will be passed on genetically to children and future generations.
Sets of behavior and responses, known as cognitive modules, which evolutionary psychology assumes have been passed on through natural selection, include humans' ability to express ourselves and interact with potential mates using language, the sense of responsibility a parent feels towards their offspring, the bizarre mating rituals that we see across the animal kingdom among many other examples. As these modules give an animal and their offspring an increased chance of survival, the latter will be more likely to produce offspring themselves than their peers who lack such modules.
In this article, we look at the origins of the evolutionary approach in psychology, from the popularisation of the theory by Charles Darwin, and explore examples which demonstrate how cognitive modules serve a purpose in helping humans and other animals to reproduce. We will also examine how maladaptations occur when evolution is led astray, and evaluate common criticisms of the evolutionary approach.
Biological Origins of Evolutionary Psychology
The term 'evolutionary psychology' was popularised by U.S. biologist Michael Ghiselin in the mid-20th Century (Ghiselin, 1973). However, the study of psychology with a view to its evolutionary, inherited origins dates back to the 1800s.
In the field of biology, Charles Darwin (1809-1882) developed the evolutionary ideas outlined in Charles Lyell's work Principles of Geology and in 1859 he published the groundbreaking book On the Origin of Species (Darwin, 1859).
Darwin's theory built on his findings from a voyage on the HMS Beagle to the archipelago of islands west of Ecuador known as the Galapagos, where he had studied a number of animals including birds and giant tortoises.
Whilst the animals on each island had been separated and unable to mate for many generations, Darwin noted that "I have not as yet noticed by far the most remarkable feature in the natural history of this archipelago; it is, that the different islands to a considerable extent are inhabited by a different set of beings." (Darwin, 1845).1
Each species had evolved different physical characteristics to survive the particular environment of each island, which had then been passed on in animals' genes to their offspring.
Biological evolution may have been more widely welcomed from its introduction had it not been also applied to humans. A natural conclusion of Darwin's theory was that in addition to other species, humans were also subject to evolution, and shared common ancestry with apes. Such an assertion initially proved to be controversial to Victorian sensibilities, but evolution eventually gained widespread support among biologists to the point where it is almost universally accepted today.
Meanwhile, however, while modern psychology as a scientific discipline was still in its infancy, Darwin chose to push forward his theory of evolution with regards to the study of the human mind with his 1872 book The Expression of the Emotions in Man and Animals (Darwin, 1872). In the work, he studied subjects' faces as expressions of their emotions with the view that the human psyche could be understood from a biological perspective.
Support for the evolutionary approach and inherited dispositions towards certain behavior increased in the 20th Century, with Walter Bradford Cannon's fight-or-flight response to stressful or dangerous situations; a reaction which aided our ancestors' chances of survival and still affects us when it is evoked today.
Adaptations and cognitive modules
In order to understand our behavior, evolutionary psychologists tend to reduce it to a set of individual responses to stimuli which together form our overall consciousness. These sets of behaviors are known as cognitive modules and include activities such as the way in which we might read and interpret text (in other words, reading) or our ability to speak and communicate with our peers using a shared language. In The Modularity of Mind, U.S. philosopher Jerry Fodor emphasised the modularity of our cognitive abilities and described a set of requisites for these modules (Fodor, 1983).2
Fodor also identified a cheat detection module, an intuitive suspicion of being deceived by another person, which may be advantageous in acting as a deterrent to a person's peers who act in a selfish manner against their own interests (Fodor, 2000).3 Many other cognitive modules have also been noted and encompass a range of specific abilities or cognitive processes. According to evolutionary psychology, these modules have survived or been eradicated through natural selection according to the degree to which they positively affect or hinder our survival chances. Such evolutions in a species' cognitive abilities are referred to as adaptations, which are passed genetically to ancestors when an animal reproduces, much as beneficial physical characteristics are inherited according to evolution's 'survival of the fittest'.
Let us now take a look at some key examples of cognitive modules and the way in which such adaptations might positively (or even negatively) affect our survival chances as a species.
Fight-or-Flight and Maladaptations
The fight-or-flight response may be considered a cognitive module as it readies our bodies to react with a view to surviving during stressful situations.
The response was first described by the US physiologist Walter Bradford Cannon (1871-1945) with reference to the way in which animals' bodies adopt one of two binary responses in threatening environment, such as when a wild animal is approached by a predator.
The first response that their body may adopt is to stay put and to fight off the threat. Alternatively, an animal might view the risk to their live as being too significant and may flee the situation in order to survive. In either situation, the sensing of a dangerous situation can lead to a chain of physical reactions in the body. The adrenal medulla secrete adrenaline and noradrenaline which may contribute to a number of changes, including:
- The heartbeat increasing
- Blood pressure increasing
- Eye pupils dilating
- Muscles tensing
These changes enable an animal to be ready to respond to the threat more quickly. The pupils, allowing more light into the eye, enable us to be more sensitive to visual stimuli (such as the movements of the threat), whilst the tensing of the muscles prepare us to take flight or other responsive actions.
Throughout species' evolution over millions of years, those animals who experienced the fight-or-flight response would have been better prepared for threats than those who did not. Therefore, those with it would stand a better chance of surviving the threat and living to reproduce, passing on their genes and the fight-or-flight response, too.
The fight-or-flight response is of less use to humans than our distant ancestors - animals in the wild, where fighting and being hunted by predators would have been commonplace. However, the fact that this adaptation still exists in humans seems to suggest that it has remained as a result of evolutionary changes.
Although adaptations should give us an increased chance of surviving in our environment, not all of them may be pleasant. Our experience of pain, for example, may be unpleasant but it can act as a deterrent to dangerous situations and lead to safer, more risk-averse behavior.
Some adaptations may also remain from our ancestors which no longer serve any useful purpose in helping us to survive, but which still affect us today. Such adaptations are referred to in evolutionary psychology as vestigial adaptations.
One such vestigial adaptation, suggested by John Eagles, is Seasonal Affective Disorder (SAD). This leads to sufferers to feel low in autumn and winter months, when less sunlight is available, but normal in the sunnier months of Summer. A heightened mood during Summer may encourage reproduction timed to give offspring an increased chance of survival in the Spring (Eagles, 2004).5 Whilst SAD may have served a purpose when humans had less control of their environment, it appears to be redundant in the developed world where heating is abundant. The negative impact that the disorder has on sufferers means that SAD has become a maladaptation in evolutionary psychology.
Another example of a vestigial adaptation often cited in support of evolution is goosebumps. The contraction of muscles during the fight-or-flight response causes the hairs on our skin to stand on end - something which gives humans no obvious advantage in surviving challenging situations.
The evolutionary approach introduces elements of biology into the field of psychology and offers compelling explanations for how capabilities in the form of cognitive modules came into being.
Whilst Darwin's theory of evolution is now widely accepted among scientists, the evolutionary approach in psychology, as with other approaches, has been subject to criticism.
From a humanistic perspective, evolutionary psychology appears to be a highly reductionist approach which suggests that our behavior is inherited from our ancestors and predetermined by our genes. Whilst our individual differences may be explained by evolutionary psychology as adaptations or maladaptations, more generally, the approach anticipates survival and reproduction as being the sole motivations behind our behavior, ignoring the complexities of the human mind and the reasoning behind our actions.
Another problem for evolutionary psychology is that it fails to account for behavior which is self-destructive, such as self harm, or which does not give a person an evolutionary advantage. Altruism - helping another person for no obvious reward - involves a person expending their own time and energy, which, whilst giving them a sense of satisfactions, is at the expense of any advantage that they may have had. Such behavior seems to contradict the self-serving approach of evolutionary psychology.
One explanation for altruism which has been offered is that altruism acts are often carried out with the expectation that they will at some point in the future be reciprocated (Trivers, 1971).6
Gerald Wilkinson from the University of Maryland found that vampire bats, for example, will feed their relatives blood in the expectation that, when hungry, another bat will return the favor in a case of reciprocal altruism. (Wilkinson, 1988).7 This resource sharing can assist in the survival of the bats as a colony rather than just on an individual level.