He writes that "Buss and Shackelford (1997a) proposed seven adaptive problems our ancestors recurrently faced that might have been solved by aggression: co-opting the resources of others, defending against attack, inflicting costs on same-sex rivals, negotiating status and hierarchies, deterring rivals from future aggression, deterring mate from infidelity, and reducing resources expended on genetically unrelated children. "Goetz writes that most homicides seem to start from relatively trivial disputes between unrelated men who then escalate to violence and death. He argues that such conflicts occur when there is a status dispute between men of relatively similar status. If there is a great initial status difference, then the lower status individual usually offers no challenge and if challenged the higher status individual usually ignores the lower status individual. At the same an environment of great inequalities between people may cause those at the bottom to use more violence in attempts to gain status. Media
Research into the media and violence examines whether links between consuming media violence and subsequent aggressive and violent behaviour exists. Although some scholars had claimed media violence may increase aggression, this view is coming increasingly in doubt both in the scholarly community and was rejected by the US Supreme Court in the Brown v EMA case, as well as in a review of video game violence by the Australian Government (2010) which concluded evidence for harmful effects were inconclusive at best and the rhetoric of some scholars was not matched by good data.
For example, between 1976 and 2008, African Americans were victims of 329,825 homicides. Although there is a widespread perception that war is the most dangerous form of armed violence in the world, the average person living in a conflict-affected country had a risk of dying violently in the conflict of about 2.0 per 100,000 population between 2004 and 2007. This can be compared to the average world homicide rate of 7.6 per 100,000 people. This illustration highlights the value of accounting for all forms of armed violence rather than an exclusive focus on conflict related violence. Certainly, there are huge variations in the risk of dying from armed conflict at the national and subnational level, and the risk of dying violently in a conflict in specific countries remains extremely high. In Iraq, for example, the direct conflict death rate for 2004–07 was 65 per 100,000 people per year and, in Somalia, 24 per 100,000 people. This rate even reached peaks of 91 per 100,000 in Iraq in 2006 and 74 per 100,000 in Somalia in 2007. History
Scientific evidence for warfare has come from settled, sedentary communities. Some scholars argue humans may have a predisposition for violence (chimpanzees, also great apes, have been known to kill members of competing groups for resources like food), placing the origins of organized violence prior to modern settled societies.