evolution and altruism

An outline of the processes of evolution and how altruism is an adaptation resulting from the selective forces that have operated during evolution.

The impact of evolutionary theory on psychology is exemplified by the recent rise of the evolutionary psychology perspective. This essay will outline the key evolutionary processes which evolutionary psychology draws upon, to explore universal human behaviours in terms of their evolutionary history and adaptive functionality.
As an example of such behaviours, the essay will consider functional explanations on the adaptive role of altruism, focusing on hypotheses of kin selection, reciprocal altruism, indirect reciprocity and sexual selection. Evidence of altruistic behaviour in non-human species will also be considered.

The theory of evolution was first devised by Darwin as a slow, unpurposive process, by which complex organisms are derived from common simpler ancestors.
Evolution presumes that a population will exhibit random variations of physical and psychological characteristics, by which some organisms are advantaged over others to cope with their environments. Evolutionary change is achieved through selection of these characteristics (“survival of the fittest”, (Clegg, 2007, p.121)) and their accumulation over time through inheritance.

With the advances of genetics, Darwin’s ideas have been revised in terms of genetic variation and selection. Diversity occurs through sexual reproduction, genetic mutation due to environmental influences (i.e. radiations) or chance. According to Dawkins’ (1976 as cited by Clegg, 2007) ’selfish gene’ theory, if the genetic variations lead to characteristics that increase the survival and/or reproductive rate of the organisms, the genes underpinning those characteristics will be selected in virtue of their likelihood to be passed on through generations (in Clegg, 2007, p.121).

Thus, physical and psychological traits evolve as adaptations of the organisms to their environments, selected in virtue of their capacity to increase survival and/or reproductive success (’sexual’ selection). Because of the differential between evolutionary time and human progress (in Clegg,2007,p.131-32), some traits today may appear maladaptive. Also, there is debate on what influence genes and environment have and which characteristics can be considered as adaptations, by-products of adaptations or are socially constructed (Clegg, 2007, p.123-124).

Several studies support the universality of altruism in modern and early humans and the existence of a genetic basis related to altruistic behaviours, thus suggesting that altruism has an adaptive role (cited in Clegg, 2007, p.144). However, the notion of altruistic behaviour as a disinterested sacrifice performed to favour others seems in contradiction with the aim of adaptive behaviour to maximise one’s reproductive success.
The apparent paradox is partly addressed by Hamilton’s theory of kin selection (1964), according to which, as evolution operates at the level of the gene, reproductive success of an individual can be maximised either increasing the individuals’ fitness or indirectly favouring those who are more likely to share some of their genes, their relatives (in Clegg, 2007,p.144) .

The hypothesis of kin selection seems to be supported by the evidence of the correlation between high mortality rates among early humans and their tendency to live in small groups of relatives (Symons,1979,cited in Clegg,2007, p.146). Hamilton’s explanation, however, does not account for altruistic acts that are performed towards non-relatives. This is better explained by the concept of reciprocal altruism, according to which individuals act altruistically to those that they believe are more likely to reciprocate. However, as the probability of being reciprocated in the future is uncertain, an explanation is needed to understand what triggers individuals to act altruistically.

In response to this dilemma, several studies have focused on cooperation using different versions of the prisoner’s game. Here, two prisoners are asked separately to collaborate with the police: if both prisoners don’t trait each other, they will be put in prison, but the punishment will be smaller than the one given if both deceit; if only one collaborates, the traitor will be set free, thus getting the maximum gain, while the deceived prisoner will have a greater punishment than in all the other scenarios.

The evolutionary stable strategy, ‘tit-for-tat’, that emerges in the iterative version of the game, is one by which each individual starts off by co-operating and then mirrors the action previously performed by the other individual. The explanation given is that if iteration is sufficiently high the benefit for cooperation and thus for reciprocal altruistic behaviour, is greater than the benefit for selfish defection (in Clegg,2007, p.148).

There are several criticisms to these studies. Fehr and Fishbacher (2003, cited in Clegg, 2007), argue that these experiments are largely based on unrepresentative samples of the population (Western university students) and therefore their findings cannot be generalised. Also, as suggested by Barrett et al.(2002, cited in Clegg, 2007), the prisoner’s dilemma inaccurately models real-world experiences such as non-simultaneous situations where the individual’s response is informed by the other’s decision Finally, they do not account for altruistic acts being reciprocated by a third party rather than the direct benifeciary. This type of altruism, known as indirect reciprocity, seems to be better explained in terms of a gain in reputation by the altruistic person, that leads the him/her to have greater access to resources and support from others (Clegg,2007,p.149).

Altruism has also been related more closely to sexual selection. A possible explanation suggests that altruistic behaviour has evolved as a strategy by which individuals maximize their reproductive success enhancing their attractiveness through altruistic acts (Clegg,2007,p.150). Findings (Farrelly et al.,2006, in Clegg,2007,p.150) on the tendency to act altruistically towards more attractive members of the opposite sex and the positive correlation between perceived attractiveness of an individual and his/her reputation as an altruist all seem to support this hypothesis.
Finally, several studies have looked at the presence of altruistic behaviour in our ancestors. However, although evidence of altruistic behaviour has been found in other non-human species (Hauser et al.,2003;Workman and Reader,2004), interpretations on findings of altruism in other hominines such as chimpanzees are too controversial to confidently support such claim (in Clegg,2007,p.150).

After introducing the key tenets of evolutionary theory, this essay sought to explain the adaptive functionality of altruism from an evolutionary perspective. As we saw, rather than a comprehensive theory on the subject, different hypotheses have been formulated, which, by focusing on different types of altruistic behaviour and by drawing from different sources of evidence, complement one another in their explanation of the adaptive role of altruism.

References

Clegg, H. (2007). Evolutionary psychology. In D. Miell, A. Phoenix, & K. Thomas (Eds.), Mapping Psychology (2^nd ed., pp 43-95). Milton Keynes: The Open University