Evolutionary explanations for behavior Pages 108-114

What you will learn The theory of evolution A range of evolutionary explanations in psychology Evolutionary explanation for disgust Criticism of evolutionary explanations in psychology

The theory of evolution Evolution is the process by which organisms change from generation to generation as a result of a change in heritable characteristics. The modern theory of evolution (a combination of Darwin’s theory with the discoveries of genetics) is based on the following premises: Biological organisms are driven by the need to survive and reproduce There is considerable variation in the traits of individual organisms from the same population. Organisms having different traits are adapted to their environment to varying degrees – some better, some worse. This is called “differential fitness”. Organisms that are well adapted to the environment have higher chances of surviving and producing offspring. Organisms that are less adapted die out or are unable to produce offspring. This is called “survival of the fittest”. Gradually as those organisms that are less adapted do not pass on their genes, those genes disappear from the population gene pool. More adapted organisms produce more offspring, so their genes in the gene pool get stronger. This is called “natural selection”.

The theory of evolution Modern research has shown that in terms of their DNA, humans are 99.5% similar to each other. As a species, we share 98% of genes with chimps, 90% with cats, 69% with rats, and 60% with chickens and fruit flies. This hints at the possibility of using animals to get an insight into human behavior and links to the principles of a biological approach to behavior.

A range of evolutionary explanations in psychology Evolutionary psychology attempts to explain psychological traits or behaviors as adaptations. Here is a brief overview of some popular explanations, some of which you will hear more about in detail later: Chiao and blizinsky (2010) proposed Gene-culture co-evolution theory to explain the higher prevalence of genetic susceptibility to depression in collectivistic societies. Hamilton (1964) proposed the kin selection theory which explains altruistic behavior observed both in animals and humans. Theory of mind, or the ability to recognize the beliefs and intentions of others, may be something that humans as a species have uniquely.

Evolutionary explanation for disgust Curtis, aunger and rabie (2004): published a study suggesting that disgust evolved as a protection from risk of disease. Researchers reasoned that if this was true, then the following conditions have to be fulfilled: Disgust should be felt more strongly when faced with disease-salient stimulus as opposed to similar stimulus with less salience. Disgust should operate in a similar way across cultures. Disgust should be more pronounced in females since they have to protect their babies in addition to themselves. Disgust should become weaker as the individual’s reproductive potential declines with age (there is less responsibility to care about offspring). Disgust should be stronger in contact with strangers than with those close relatives because strangers potentially can carry novel pathogens. Obtain AIM, METHODS, & RESULTS from pages 111-112.

Criticism of evolutionary explanations in psychology Some limitations that are commonly mentioned by critics are as follows: Speculations about the environment Evolutionary adaptation is always adaptation to a certain environment. So to suggest an evolutionary explanation of a trait, you need to have knowledge about the environment in which the trait evolved – our knowledge of the environments in which homo sapiens evolved as a species is limited. Testability Evolutionary explanations for behavior are difficult – and in many cases impossible – to test. Critics of evolutionary psychology say that these explanations rest on a logical fallacy known as ad hoc reasoning, also known as “a just-so story”.

Ted talks https://www.youtube.com/watch?v=N4wFyRGilp4 https://www.youtube.com/watch?v=CtvIX4s1bTU