Why incest among animals cuts male sexual aggression

摘要

In the animal world. Incest helps put an end to sexual violence. That's the conclusion of a modelling study of species in which males harm their mating partners. In some species, competition between males can mean that females are harmed during copulation. Male cowpea weevils, for instance, have spiky penises (pictured) that puncture the female's insides and are thought to help anchor the male inside her, ensuring that he delivers his sperm and outcompetes other males.