Sexy son hypothesis

The sexy son hypothesis is a concept from evolutionary biology, proposed by P. J. Weatherhead and R. J. Robertson in 1979.^[1] It posits that a female animal's optimal choice among potential mates is a male whose genes will produce male offspring with the best chance of reproductive success. In particular, the sexy son hypothesis implies that a potential mate's capacity as a caregiver or any other direct benefits the male can offer the female (eg. nuptial gifts, good territory) are irrelevant to his value as potential father of the female's offspring.

In his book: The Selfish Gene, Richard Dawkins wrote:

"In a society where males compete with each other to be chosen as he-men by females, one of the best things a mother can do for her genes is to make a son who will turn out in his turn to be an attractive he-man. If she can ensure that her son is one of the fortunate few males who wins most of the copulations in the society when he grows up, she will have an enormous number of grandchildren. The result of this is that one of the most desirable qualities a male can have in the eyes of a female is, quite simply, sexual attractiveness itself" ^[2]

The idea is that if females choose "attractive" males, they will get "attractive" sons, and thus more grandchildren, because choosy females will prefer the "attractive" sons. Interesting is the fact that the theory will work with any trait that females choose, as long as it is heritable, as choosing the trait makes males attractive, and not the trait in itself. It also follows that traits culturally perceived as negative can still be seen as desirable, for example why females stay with or are attracted to males they know to be disloyal in a monogamous relationship: If this trait is passed to any male children, they are more likely to themselves be non-monogamous, have several mates and spread the female's genes to multiple grandchildren. The sexy son hypothesis is one of several possible explanations for the highly diverse and often astonishing ornaments of animals.

The sexy son hypothesis has been suggested as the origin of some aspects of human sexual behavior. In particular, it has been shown that human females are more attracted to traditionally masculine men ("cads") during the most fertile times of their menstrual cycles, and more attracted to relatively feminine men ("dads") during the remainder of the cycle. However, the methodology of these claims is disputed. ^[3] These observations have led to the conclusion that infidelity is a natural occurrence in women, and evolutionarily advantageous, on the grounds that it will enable them to secure both the best genes and the best caregiver for their offspring.^[4][5]

References

See also

Fisherian runaway

References