Conflict between males and females over reproduction is ubiquitous in nature due to fundamental differences between the sexes in reproductive rates and investment in offspring. In only a few species, however, do males strategically employ violence to control female sexuality. Why are so many of these primates? Why are females routinely abused in some species, but never in others? And can the study of such unpleasant behavior by our closest relatives help us to understand the evolution of men's violence against women?

In the first systematic attempt to assess and understand primate...