User talk:Memegui

Design in sexual competition
As described in Sex at Dawn the human penis has one of the most advanced designs through eons of natural selection for high sperm competition. Comparing to our closest ancestor, the bonobo, the human penis is longer and sexual activity is much longer lasting (the bonobo reaching orgasm after merely a minute of intercourse). The repeated thrusts of human intercourse are designed to create a vaccuum effect in an attempt to remove a previous male's semen from the entrance to the cervix before depositing his own while part of the semen functions as spermicide rather than fecundative material. These traits, along with relatively large testes size compared to other primates suggest that primitive humans were predominantly polygamous before the advent of agriculture.

See also Monogamy