Chapter 19: Human Mate Choice and Parenting

Human Mate Preferences

Mate preference is something which is often considered a very individual choice. People have all manner of preference for hair color, body shape, height, etc., and many times the preferred types are idiosyncratic in nature. Evolutionary theory offers a number of predictions for humans based on what is known about mate selection and sociobiology in other mammalian species. Some of the major themes which include:

  • Women will prefer men who are willing and able to provide resources.
  • Men will prefer fertile women.
  • Both sexes will value fidelity, but men will value it more highly than women.

These predictions draw upon parallel situations among the primates (see Chapter 8), relating to differences in parental investment, reproductive potential, paternity certainty, and visible indicators of "good genes" (often culturally constructed categories in humans). Additionally, aspects of evolutionary psychology also suggest that social organization and selection in early hominid environments strongly influenced these sex-specific mate preferences. Unlike in primate societies (and to be expected), human mate preference appear to be heavily influenced by cultural and economic norms.

Childrearing

Raising a child provides another instance in which evolutionary predictions can be tested. Patterns of infanticide, child abuse, and adoption follow consistent trends. In the case of infanticide, Martin Daly and Margo Wilson (McMaster University) found three contexts in which parents are likely to commit infanticide:

  • child is ill or deformed
  • parental circumstances prohibit raising the child
  • child was not sired by the mother's husband

Moral judgments aside, the successful evolutionary basis for these behaviors can be determined. Ill or deformed children present a hardship to parents, one with greater investment and seemingly lower returns. In a hunter-gatherer environment, investing time and effort into these children would impede investment in other, more fit children. Though as far back as the Neandertals, there is evidence for the existence of individuals who required a great deal of care. Similarly, in cases where maintaining a child is beyond the capabilities of the parents (e.g., single parent; twins or triplets), parents are best served by first concentrating on stabilizing their situation, and only afterwards investing in children. Lastly, many cases (human and non-human) of infanticide by males who did not sire the offspring of their mates occur. Investment in the progeny of another male does little to further the prosperity of one's own lineage, biologically speaking.

This could also illustrate the relationship between child abuse cases and step-parenting. In reported cases of child abuse in North America, the frequency of child abuse increases over five times in adolescent and teenage children in households with one step-parent. In similar households, children under the age of four have a greater than twentyfold increase in their incidents of abuse. The potentially abusive relationship between some non-adoptive step-parents and biologically unrelated children could be due to many factors, such as: unfamiliarity between child and step-parent, as well as the reluctant investment in a genetic stranger. None of this should be seen as endorsements for abusive behavior however. Though these types of trends have been observed, it must be remembered that the experiences of a human individual are made up of not only the biological template, but of their cultural and social interactions. We are not literally "programmed" in a way that denies us of a myriad of behavioral choices.

Is human evolution over?

Biological evolution proceeds at a rate far slower than the slowest incident of cultural change. For this reason, the idea that biological evolution of the human species has come to an end has been posited in the popular press as well as in more academic literature. Because of the disparity in change, perhaps it is valid to say that evolution - in the sense of how humans can to be the way they are today - has ended. The forces of selection acting upon the human species have changed tremendously; however, they have changed because the environment has shifted tremendously. Instead of a predominantly ecological basis for change, the focus has moved to human culture and society. To suggest that evolution has ended completely is a rash statement however, especially in light of the subtle ways in which selection has acted (and undoubtedly, will continue to act) on all types of populations.

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