Male warrior hypothesis

Archaeologists have found mass graves dating to the late Pleistocene and early Holocene that contain primarily male skeletons showing signs of blunt force trauma, indicating the cause of death was by weapons used in combat.

Because females gestate, birth, feed, and invest more overall resources in each of their offspring, they are more selective with their mates but have greater certainty of being able to reproduce.

Consistent with the expectations of the male warrior hypothesis, several studies have shown more ethnocentric and xenophobic[9] beliefs and behaviors among men (compared to women), including the more frequent use of dehumanizing speech to describe outgroup members;[10] stronger identification with their groups;[10] greater cooperation when faced with competition from another group;[11] a greater desire to engage in war when presented with images of attractive (but not unattractive) members of the opposite sex;[12] greater overall rates of male-male competition and violence (as shown in violent crime and homicide statistics[13]); and larger body size correlating with quicker anger responses.

[15] Women also have more negative responses around peak fertility when the males belong to an outgroup that the woman associates with physical formidability, even if the group was constructed in the lab.

[16] Overall, women who feel most at risk of sexual coercion are more likely to fear outgroup males,[15][17] which aligns with the predictions of the MWH.

[17] Because the neural circuitry for fear responses are more developed towards stimuli that have posed a larger threat for most of human history (snakes and spiders, for example, which were dangers frequently encountered by foragers[18]), these findings suggest that outgroup males may have been more of a threat to physical safety than outgroup women or ingroup members, supporting the male warrior hypothesis.

This hypothesis is supported by the observation that the most popular modern male sports require the skills needed for success in male-male physical competition and primitive hunting and warfare, and that champion male athletes obtain high status and thereby reproductive opportunities in ways that parallel those gained by successful primitive hunters and warriors.

[19] There is evidence that male and female athletes generally differ in their motivation in sports, specifically their competitiveness and risk taking, in accordance with the spectator lek hypothesis.