The document discusses several evolutionary explanations for human aggression. It describes Lorenz's view that aggression serves three functions - increasing reproductive success, defending sexual partners from cuckoldry through mate retention strategies, and competing with other males over territory and resources. It also discusses research finding links between mate retention behaviors and violence, age/resources/status and male-male homicide rates, and how female aggression tends to be verbal rather than physical. The document outlines that aggression may have evolved from drives to ensure in-group survival through xenophobia.