This association appears to mirror the winner effect, also observed in the animal literature, whereby victories in competition for mates or food have been associated with elevated testosterone levels, and increased aggression18, 19. (nature.com)
In virtually all higher primates, males have large, sharp canine teeth that they often use to threaten and attack other males during competition for mates, says Lovejoy. (discovermagazine.com)
The increased competition for mates, coinciding with the arrival of the birth control pill, helps to explain a number of things, such as the collapse of sexual taboos as young women began to offer free samples and to pursue men previously considered off limits (such as other women's husbands). (firstthings.com)