Sexual Selection in Human Evolution - Culture

Culture

Geoffrey Miller, drawing on some of Darwin's largely neglected ideas about human behaviour, has hypothesized that human culture arose through a process of sexual selection. He argues that cultural traits such as art, music, dance, verbal creativity and humour are of no survival value. Miller is critical of theories that imply that human culture arose as accidents or by-products of human evolution. He believes that human culture arose through sexual selection for creative traits. In that view, many human artifacts could be considered subject to sexual selection as part of the extended phenotype, for instance clothing that enhance sexually selected traits. During human evolution, on at least two occasions, hominid brain size increased rapidly over a short period of time followed by a period of stasis. The first period of brain expansion occurred 2.5 million years ago, when Homo habilis first began using stone tools. The second period occurred 500,000 years ago, with the emergence of archaic Homo sapiens. Miller argues that the rapid increases in brain size would have occurred by a positive feedback loop resulting in runaway selection for larger brains. Tor Nørretranders, in The Generous Man conjectures how intelligence, musicality, artistic and social skills, and language might have evolved as an example of the handicap principle, analogously with the peacock's tail, the standard example of that principle. Another hypothesis proposes that human intelligence is a courtship indicator of health and resistance against parasites and pathogens which are deleterious to human cognitive capabilities.

Anthropologists believe that "male genitalia ...represent a critical target of sexual selection for fertilization efficiency and sperm competition" and so have developed theories as to why about 25% of societies practice some form of male genital mutilation. Recently, Charles Wilson of Cornell University suggests that in societies where competition among males is acute, male genital mutilation reduces the threat of conflict for female mates, and so a young man who accepts male genital mutilation "gains immediate access to social and sexual privileges that are suggested to outweigh the cost of the male genital mutilation itself."

The same author indicates that female genital mutilation (FGM) may play a similar paradoxical role:

"Under this ‘sexual conflict’ hypothesis, male genital mutilation functions in a parallel context to female genital mutilation (FGM). Women who undergo vaginal infibulation or clitoridectomy experience sexual sequelae that would tend to limit EPCs (extra-pair copulations), including restriction of intromission and a reduced capacity to experience sexual pleasure. This reduces the paternity uncertainty of a husband, increasing the trust and investment he is selected to offer. These benefits to a woman and her children seem to outweigh the heavy cost of the mutilation itself in societies with high paternity uncertainty".