Evolutionary psychology and human behaviour

Understanding the ultimate and proximate causes of social behaviour in various animals provides a compelling case that evolutionary history, natural selection, development, endocrine and neural mechanisms, and the social environment all might well affect the expression of social behaviour in human beings. The process of explaining human behaviour, however, is a daunting exercise. If songbird social and sexual behaviour is the complex outcome of a large number of developmental and physiological processes, then it is unlikely that simplistic approaches to understanding human behaviour will be accurate.

For example, American psychologist John Money considered the social environment to be of overriding importance in gender identity. In treating children whose sex was ambiguous at birth, such as those with underdeveloped genitalia, he recommended that they be raised according to the parents’ initial perceptions of the child’s gender rather than the actual genetic sex of the child. This resulted in parents raising genetic boys as girls and vice versa, often requiring surgery and hormonal treatments later on in life. The complex nature of sexual behaviour observed in various animal studies and studies of human adults and adolescents suggests that Money’s social approach to sexual identity has a weak scientific foundation. These studies also suggest that decisions regarding how to treat cases of ambiguous gender should instead be based on a comprehensive knowledge of the neural, hormonal, physiological, genetic, and social bases of sexuality.

Similarly, the relatively new discipline of evolutionary psychology can easily go too far in extending evolutionary principles to human behaviour. Extant behavioral traits in humans were not shaped by the current environment. Rather, the environmental context in which humans evolved was probably quite different from that of the modern world. People in ancestral societies lived in smaller groups, had more-cohesive cultures, and had more stable and rich contexts for identity and meaning. As a result, it is important to be cautious when using present circumstances to discern the selective bases of human behaviour. Despite this difficulty, there have been many careful and informative studies of human social behaviour from an evolutionary perspective. Infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price, altruism, and the allocation of parental care have all been explored by testing predictions derived from the idea that conscious and unconscious behaviours have evolved to maximize inclusive fitness. The findings have been impressive. As with other species, however, it is important to critically evaluate and avoid overextending the evidence.

One of the key criticisms of human sociobiology is borne of fear that the findings will be used to effect unfair or immoral policies. Examples include use of social Darwinism to justify discriminatory practices, economic policies that benefit relatively few at the expense of many, genocide, eugenics, and legal systems that fail to protect the vulnerable segments within populations. These potential problems suggest the need for deep ethical consideration of the implications of evolutionary psychology. Such an approach would investigate how results might be used ethically, to benefit society, or unethically, to cause harm.

For example, consider the finding that stepfathers are more likely than biological fathers to abuse and kill nonbiological children in the household. This finding could be used to justify an increase in the social services available to blended families, particularly those in which the mother has biological children from a previous marriage. In developing countries, an understanding of the evolutionary context of bride-price (monetary or other resources given to the family of a potential bride) could be used to predict and ameliorate the detrimental impacts of rapid social change that accompanies an influx of Western culture and technology.

The real danger lies not in the scientific findings of evolutionary psychology but in the failure to recognize that scientific findings should never dictate ethics and morality. Policies that affect the rights, opportunities, and dignity of human beings occur within the moral rather than the scientific realm of human endeavour.