There is a cross-culturally universal sex difference in homicide perpetration, and motives of male sexual proprietariness and rivalry are implicated in some substantial proportion of all homicides everywhere. With the exception of some forensic psychiatrists, however, criminologists have paid these motives little explicit attention. Human motives and emotions have evolved by selection, and the theoretical framework of evolutionary psychology can be used to develop hypotheses about the psychological links between violence and sexually rivalrous and possessive motives in men. Violent inclinations are not simply pathological, but self-interested, although their expression is often counterproductive where social and material circumstances differ greatly from those in which the human social psyche evolved. Evolutionary psychology is also a rich source of hypotheses about how situational, economic, demographic and other factors are likely to affect men's uses of violence against wives and rivals, and hence about the sources of cross-cultural and historical variations in rates of homicide and assault.