Chapter Seventeen: Human Mate Choice and Parenting

Chapter Review

The Psychology and Cultural Forms of Human Mate Preferences

Mate preference is something often considered a completely individual choice. People have a variety of preferences for hair color, body shape, height, and so on, and many times the preferred types are idiosyncratic in nature. Evolutionary theory offers a number of predictions for humans in a heterosexual context based on what is known about mate selection and sociobiology in other mammalian species. Some of the major themes are these:

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

These predictions draw on parallel situations among the primates (introduced in Chapter 8), relating to differences in parental investment, reproductive potential, paternity certainty, and visible indicators of good genes (often culturally constructed categories in humans).

In addition, aspects of evolutionary psychology also suggest that social organization and selection in early hominin environments strongly influenced these sex-specific mate preferences. Unlike members of nonhuman primate societies (and to be expected), human mate preferences appear to be heavily influenced by cultural and economic norms, especially considering examples such as bridewealth and other social practices that have arisen as the result of long cultural traditions.

Cultural patterns, though, intersect with adaptations in many aspects of human mate preferences. In some East African pastoralists, for example, larger bridewealth is paid for girls who have their first menstruation at a younger age (suggesting they will have a longer period of fertility). Also, plumper women garnered larger bridewealth payments than skinny women, a possible index of good health and long life. Furthermore, while most human societies prefer polygyny over other marriage patterns (consistent with the rest of the primate order and the psychology of male reproductive strategies), certain circumstances will give monogamy and interestingly, polyandry, greater social support. The Nyinba of Nepal, for example, prefer polyandrous situations because, they reason, more men in a household will result in more efficient completion of household labor. Polyandrous marriage situations also tend to break down in ways consistent with evolutionary theory: Men often decide to leave their marriages when they have not fathered many children.

Child Rearing

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, a part of practicing what they call discriminative parental solicitude:

The child is ill or deformed.
Parental circumstances prohibit raising the child.
The 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 foraging environment, investing time and effort into these children impedes investment in other, more fit children. However, as far back as the Neanderthals, there is evidence for the existence of individuals who required a great deal of care. Similarly, in cases in which maintaining a child is beyond the capabilities of the parents, parents are best served by first concentrating on stabilizing their situation and only afterward on investing in children. Last, many cases occur (human and nonhuman) of infanticide by males who did not sire the offspring of their mates. Investment in the progeny of another male does little to further the prosperity of one's own lineage, biologically speaking. None of this should be seen as biologically based endorsement for abusive behavior, however. Though these types of trends have been observed, remember that the experiences of a human individual are made up not only of the biological template but also of the person’s cultural and social interactions. We are not literally programmed in a way that denies us of a myriad of behavioral choices.

Natural selection, then, has unwittingly created a conflict by favoring offspring who demand more investment (and use the most effective tactics in manipulating their parents) as well as those mothers who provide an equitable distribution of investment (invariably less than each individual offspring would want for himself or herself). In a sense, this conflict manifests itself even in utero, where the fetus and mother engage in a battle of hormones. The fetus uses a barrage of hormones to increase placental blood flow, but the mother counteracts those hormones with some of her own.

Diametrically opposed to infanticide and neglect, though, is the phenomenon of adoption. One might think, at first, that adoption could have nothing to do with evolutionary theory, or biologically based parenting strategies, since in the United States and in other Western contexts, adoption is a formal arrangement that often severs ties between biological parents and their children. However, in many societies children are adopted by close kin who have no dependent children of their own. Biological parents in nonindustrialized societal contexts are also often very reluctant to give up their children, and they often maintain contact with them. Biological parents also prefer that their children go to families that can adequately support them.

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 discussed in the popular press as well as in more academic literature. Because of the disparity in change between social and biological processes, perhaps it is valid to say that evolution—in the sense of how humans came to be the way they are today—has ended. The forces of selection acting on 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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