DSE212 Exploring Psychology

Chapter 2, on Evolutionary Psychology, runs to 46 pages and is quite a change in content from the identity chapter. It’s split into four basic sections with two essentially biological and two more psychological in nature. One of the options in the second TMA is based around the final section on altruism so the notes on that will probably be better than those on the other sections initially.

I’ve highlighted the key exam topics.

The chapter begins by looking at the different types of evidence which evolutionary psychologists use. Archaeological evidence includes the relative sizes of males and females, pelvis size, tools, cave paintings and evidence of social groupings from excavations. Genetic evidence looks over a longer time-scale considering the evolutionary split between apes and our human ancestors and any breeding that may have taken place between the various human species in the past. Studies on present day non-human primates and hunter-gathers looks at the social structures but recognising that these populations are not the same as our distant ancestors and that the presence of modern humans may distort the findings. Studies looking at the universality of behaviours and what modern humans actually do consider that if a behaviour is universal these days then it has derived from a common behaviour amongst our ancestors e.g. the male preference for features that indicate fertility in females.

The chapter moves on to consider the various evolutionary processes which generated all the differences that we see in the present day in what feels very much a whistle-stop tour of evolutionary biology. The genes which collectively form the DNA are at the core of this with the mixing of the chromosomes during sex forming a unique individual from the contribution of the genetic content of the egg and sperm. Selection is at the core of this with natural selection relying on 1) variation in individuals 2) part of this variation being due to genetics and 3) there being some competition in terms of resources. This selection process leads to adaptations with the fittest for the particular circumstances out-breeding the less fit. Sexual selection is the process though which reproductive success is improved by passing on physical and behavioural characteristics to one’s descendants; males by having a lower investment in their offspring would generally tend towards having more of them whereas females tend to invest more in each so look for long term mates. This section finishes with a brief overview of the hominine family touching on the super-family of apes from 30 million years ago, to hominoids (apes and humans) 22 million years ago and our human ancestors around 5 to 7 million years ago, noting that up to around 30,000 years ago there were multiple human species around at the same time.

From the biology, we have a bit of a lurch into psychology with the theory of mind, which is the ability to think from the perspective of another and to thereby predict what someone else is likely to do. That it is not fully present in chimpanzees indicates that it evolved after the split some 5-7 million years ago. The Maxi (Sally-Anne) [Wimmer and Perner, 1983] test indicates that we develop a theory of mind by around 6 years old although the false-belief that it tests is not all that encompasses theory of mind and alternatives (e.g. Chandler’s 1989 hide and seek test) have indicated that it is present from around 2 years of age. Although children generally follow the same developmental trajectory, the age at which it arises differs across cultures. As one might expect, it is much less developed in those with autism. Apes exhibit the deception aspect of this. It is illustrated in archaeology in terms of art from 30,000-40,000 years ago but the lack of human evolution for some 200,000 years indicates that it has been around for quite a while despite the lack of concrete evidence for it earlier than the cave paintings.

Finally, the related issues of altruism and reciprocity are covered. Since natural selection is all about reproductive success, you might think that altruism would play no part in the selection process. However, the reproductive success is not about the success of a particular individual but rather about the reproductive success of the genes involved. Therefore, through the process of kin selection one can see that it is advantageous to help individuals with whom we have a lot of genes in common i.e. our relatives and that we would tend to help those with whom we had a greater number of genes in common i.e. the closer the relative, the more the help that would be offered. Outside our relatives we also help complete strangers which is generally on the basis that a helpful act will be repaid later (reciprocal altruism) which brings into play a certain amount of game theory. This is illustrated in psychology by the prisoner’s dilemma where the best strategy is usually to defect (i.e. not to make the initial altruistic act) although in an ongoing relationship, it’s better to be altruistic first then do whatever the other guy did on you; it also has cultural biases and the students that it’s generally tried out on would be expected to be somewhat more clued in than actual criminals. Indirect reciprocity covers the situation where others benefit but there is no direct benefit to the altruist, the assumption here being that the altruist will gain brownie points as their benefit which in turn helps them. Evidence for altruism in animals is mixed with initial studies looking at food sharing indicating that it didn’t happen (but they tend not to share food at all) whereas later studies looking at general helpfulness showed that they were altruistic; there are issues with all of these studies as they were using animals raised in captivity.

For the exam, the key topics for this chapter are highlighted above and are:

Theory of mind
Natural selection
Sexual selection
Reciprocal altruism

The next chapter is on learning which is an exam rather than a TMA topic but I’ll be covering it over the next week anyway.

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