Why do men possess such a strong preference for female youth and beauty? Why is monogamy central to human mating, when it is so rare in other mammals? Why is male infidelity relatively common? Why do men respond to female infidelity with an intense jealousy that sometimes drives them to commit physical abuse or murder? In this video, we explore these questions through the lens of evolutionary psychology.
In his book The Evolution of Desire, David Buss writes:
“…men face an adaptive problem not faced by women, at least not as poignantly—choosing a fertile partner. To be reproductively successful, the most obvious criterion would be a woman’s ability to bear children. A woman with high reproductive capacity would be extremely valuable in evolutionary currencies. Men need some basis, however, on which to judge a woman’s reproductive capacity.”
David Buss, The Evolution of Desire
The most reliable signals of a woman’s reproductive capacity are youth and beauty. A woman’s fertility peaks in her late teens to early twenties, and then steadily declines until it reaches zero around the age of 50. Facial and bodily symmetry along with youthful features such as clear and glowing skin, full lips, and wide eyes, disclose a woman’s general health, minimal genetic mutations, minimal pathogens and parasites, as well as a robustly functioning immune system. A waist-to-hip ratio of around 0.7, which men universally find most attractive, “is linked to a myriad of fitness-related-variables” (David Lewis, The Logic Of Physical Attractiveness), one of which is an optimal fat distribution for a healthy pregnancy. Male ancestors who mated with young and attractive women had more and healthier offspring than men who mated with older women, or with women whose appearance signaled infertility, poor genetic expression, and ill-health. Hence, over the course of evolution, this male desire to mate with young and beautiful women spread throughout our species via the process of sexual selection. Or as Buss explains:
“Telling men not to become aroused by signs of youth and health is like telling them not to experience sugar on their tongues as sweet….standards of attractiveness are not arbitrary—they reflect cues to youth and health, and hence to reproductive value. Beauty is not merely skin-deep. It reflects internal reproductive capabilities.”
David Buss, The Evolution of Desire
Another factor that has shaped the mating psychology of men is the problem of paternal certainty. Throughout human evolution, every woman who has ever given birth has known beyond all shadow of doubt that the child is genetically hers. A man, in contrast, cannot be so sure of his paternity. An old African proverb conveys this uniquely male problem: “Mama’s baby, papa’s maybe.” Or as the ancient Roman jurist Baius observed: “Maternity is a fact, paternity is a matter of opinion.” In the book A Mind of Her Own: The Evolutionary Psychology of Women, Anne Campbell references a blood typing study of newborns conducted in 1990 which revealed that “anywhere between 5 and 30 per cent of babies could not have been sired by the putative father.” Or as the psychologist Anthony Stevens wrote:
“Paternal uncertainty is not an irrational anxiety: it has always been a sexual reality. As numerous DNA studies have confirmed, about 10 per cent of married men’s children are genetically not their own.”
Anthony Stevens, Archetype Revisited: An Updated Natural History of the Self
A man who raises a child he mistakenly thinks is his own succumbs to what is called cuckoldry. This term is derived from the behavior of the cuckoo bird, who lays its eggs in the nests of the birds of other species so as to trick them into raising the cuckoo’s offspring. From an evolutionary perspective, cuckoldry is one of the worst of fates as the cuckolded man unknowingly devotes time, energy, and resources to a genetically unrelated child which he otherwise could have channeled to his own biological offspring.
The problem of paternal certainty and the risk of cuckoldry is one of the principal reasons why paternal investment occurs in only 3-5% of mammalian species.
