Infanticide drives female promiscuity and big ballsThe NY Times is less sensationalist about the same study:
Great balls of furriness! Among mammals, large testicles are a sign of a species with a history of males that have no qualms about killing the babies of their competitors.
A study of more than 200 mammals from mice to lions reveals that in species where infanticide is frequent, females make it hard for males to know which baby to kill by mating with lots of different males during the same season. The study also finds that the ancestor to all great apes - including humans - probably committed infanticide.
Infanticide is widespread among mammals. Lions do it, chimps do it, many adorable-looking lemurs do it. Why? A leading theory is that males kill infants sired by other males because it frees up females to have their own offspring, perpetuating their own genes rather than those of their competitors.
There had been earlier reports of infanticide by adult male mammals, but scientists mostly dismissed the behavior as an unimportant pathology. But in 1974, Dr. Hrdy made a provocative counter proposal: infanticide, she said, is the product of mammalian evolution. By killing off babies of other fathers, a male improves his chances of having more of his own offspring. ...I don't want to read too much into animal studies, but whenever you hear about a father abusing a kid, it is usually a step-father or a foster father. Efforts to remove a kid from a real dad usually make things worse.
The authors of the new study, Dieter Lukas and Elise Huchard, started by plowing through the scientific literature, looking for evidence of infanticide in a variety of mammalian species. The researchers ended up with data on 260 species, and in 119 of them — over 45 percent — males had been observed killing unrelated young animals.
The pacifist anti-violence feminist types might argue that all male aggression is harmful, and should be bred out of the population by separating such men from kids. Research indicates that men are naturally aggressive, and women are more attracted to the more violent and aggressive men.