Male Warrior Hypothesis
The male warrior hypothesis is an evolutionary theory that refers to the idea that men’s behaviors and cognitions are more strongly intergroup-oriented than women’s, such that men likely evolved psychological mechanisms that enable the formation of coalitions that are capable of carrying out acts of aggression and violence on members of outgroups as a means to acquire or protect reproductive resources. These mechanisms are purported to have developed as the result of an ancestral history that was largely influenced by frequent and violent intergroup conflict among males, in which success increased their reproductive fitness.
Due to reproductive and survival benefits, humans (and other species) tend to come together in groups (Baumeister and Leary 1995). Although costly, intergroup conflict is, and has been, pervasive among humans (Bowles 2009). When these conflicts involve acts of aggression and violence, research finds that, across time and cultures, men are almost exclusively the perpetrators of such acts (e.g., Goldstein 2003). This greater propensity to engage in intergroup violence and aggression is suggested to have evolved in men due to the resulting benefits to men’s reproductive fitness (e.g., Buss 1999; Van Vugt 2009; Van Vugt et al. 2007). Men’s reproductive fitness is limited by access to fertile women, whereas women’s fitness is limited by physiological, energetic, and resource constraints (e.g., Buss 1999). Thus, men, but not women, can increase their fitness by maintaining exclusive access to large numbers of mates, which can be accomplished through intergroup conflict (e.g., McDonald et al. 2012). That is, groups of successful men in intergroup conflicts may reap the benefits of increased access to mates and gains in prestige. Indeed, research conducted on traditional (i.e., tribal) human societies finds that male warriors have more mates and children and enjoy higher status than other men (Chagnon 1988) and young male street-gang members have been found to have more sexual partners than other young males (Palmer and Tilley 1995). Thus, evolutionary psychologists assert that men may have evolved psychological mechanisms for forming coalitions that are able to plan and execute aggressive attacks on members of other groups and should be more intergroup oriented in general, than women (e.g., McDonald et al. 2012; Van Vugt et al. 2007). This is known as the male warrior hypothesis (McDonald et al. 2012; Van Vugt 2009; Van Vugt et al. 2007).
Support for the Male Warrior Hypothesis
The male warrior hypothesis asserts that men are more intergroup oriented than women and have evolved psychological mechanisms that increase the potential for success in intergroup conflicts (e.g., Van Vugt et al. 2007). Evidence for the operation of these mechanisms can be found in research examining the conflict-relevant thoughts, emotions, and behaviors of men in modern societies (McDonald et al. 2012). Although inclusion of all such research is beyond the limits of this entry, examples of empirical support for some of the major predictions of the male warrior hypothesis, specifically in the areas of intergroup aggression, prejudice, preference for intergroup hierarchies, and ingroup identification and cooperation, are discussed.
The most basic prediction of the male warrior hypothesis is that men should be more likely than women to initiate and engage in aggressive intergroup behavior because success in intergroup conflicts likely increases access to mates and other resources. This prediction has also largely been supported across many studies. As stated previously, in instances of real-world violent intergroup conflicts such as warfare, genocide, and street-gang violence, groups of men are almost exclusively the perpetrators (e.g., Goldstein 2003). And warrior males have also been found to have more mates and children, as well as higher social status (e.g., Chagnon 1988) than other males. Further, on a daily basis, men tend to report a higher frequency of competitive intergroup interactions than women (Pemberton et al. 1996; Van Vugt 2009). These aggressive tendencies have also been found in laboratory manipulations. For example, in one particularly interesting study, pairs of participants played a simulated wargame in which they were asked to imagine that they were the leader of a fictitious country in conflict with another country over newly discovered resources (Johnson et al. 2006). Results revealed that men were significantly more likely than women to attack the other country without provocation and were also more confident that they would win the conflict. Interestingly, even though participants were unaware of the sex of their rival, pairs of male participants yielded the most intense warfare, whereas pairs of female participants yielded the least. In further support for the male warrior hypothesis, men’s propensity towards intergroup conflict appears to be specifically tied to mating motives. In a series of studies, Chang et al. (2011) examined whether activating mating motives would increase participants’ access to war-related cognition and perception. Men, but not women, exposed to attractive, opposed to unattractive, opposite-sex photos were more likely to endorse pro-war statements, but not trade-conflict statements. In addition, men who were primed with attractive faces or legs of women, as opposed to unattractive faces of women and national flags, responded significantly faster to war-related words and images, but not farming-related words and images or expressions of general aggression. Taken together, the preponderance of evidence suggests that men are more inclined to engage in aggressive or competitive intergroup behavior than are women, and this tendency appears to be related to mating motives.
The male warrior hypothesis also predicts that men should harbor more derogatory and prejudiced attitudes about outgroup members because this may reduce the psychological discomfort that might result from harming these individuals during violent conflicts (e.g., McDonald et al. 2012). Research has generally supported this contention. Men tend to be more xenophobic and ethnocentric than women (e.g., Ekehammar and Sidanius 1982) and are also more likely to dehumanize outgroup members (i.e., describe them using animal-like words) than are women (e.g., Van Vugt 2009). Further, men are more likely than women to describe outgroup members using danger-related stereotypes when in conditions of ambiguous threat (i.e., when primed with ambient darkness; Schaller et al. 2003). Thus, men do appear to harbor more prejudiced and derogatory attitudes about members of outgroups than women.
Intergroup conflicts inevitably result in intergroup hierarchies because some groups will be more successful than others. As a result, the male warrior hypothesis predicts that men should exhibit a stronger preference for intergroup dominance hierarchies than women (Van Vugt 2009). Consistent with this prediction, in samples taken from a variety of countries and cultures men consistently score higher in social dominance orientation (SDO; i.e., general preference for hierarchical, dominant-subordinate intergroup relations as opposed to more equal intergroup relations; Pratto et al. 1994) than do women (e.g., Lee et al. 2011; Van Vugt 2009). Of particular importance, higher scores in SDO are associated with a variety of beliefs and attitudes that serve to maintain and justify group-based hierarchies such as political-economic conservatism, meritocracy ideology, nationalism, patriotism, and cultural elitism (e.g., Lee et al. 2011). These results suggest that men do prefer intergroup hierarchies more than women and are perhaps also more likely to harbor beliefs that are involved in maintaining and supporting existing intergroup hierarchies.
Finally, the male warrior hypothesis predicts that men should be more motivated to protect and support the ingroup, especially when threatened by or in competition with another group, because success in intergroup competitions depends, to some extent, on one’s ingroup being cohesive, strong, and coordinated (Van Vugt 2009; Van Vugt et al. 2007). In accordance with this prediction, across three studies using a public goods game Van Vugt et al. (2007) found that men increased cooperative donations to their ingroup when in competition with other rival groups, as opposed to a condition in which participants were in competition with other individuals, whereas women’s cooperative donations to their group were seemingly unaffected by competition condition. In the same study, men, but not women, also reported stronger identification with the group in an intergroup competition condition than in an interindividual competition condition. Interestingly, men’s identification with the group fully mediated the association between their increased cooperative donations and competition condition. Relatedly, research also suggests that men may generally identify more strongly with groups than women. For example, Van Vugt (2009) asked 100 college students to state their favorite color and explain why this particular color was their favorite. Results indicated that 30% of men chose a color because it was associated with an ingroup (e.g., a favorite sports team), whereas no women gave this sort of explanation. Further, Gabriel and Gardner (1999) asked participants to complete the statement “I am…” and found that men were twice as likely as women to make a statement about a group membership (e.g., being a member of a fraternity or being an American). Taken together, these studies suggest that, when intergroup competition is salient, men are more likely than women to increase cooperation with their group and are also more likely to personally identify with membership groups than women.
The male warrior hypotheses is an evolutionary theory that states men have evolved psychological mechanisms that enable the formation of coalitions that are capable of carrying out acts of aggression and violence on members of outgroups as a means to acquire or protect reproductive resources. The major predictions of the male warrior hypothesis have been largely supported in both examinations of trends in real-world intergroup conflict and laboratory examinations. It is hopeful that future investigations of the predictions of the male warrior hypothesis, and other related theories, will continue to shed light on intergroup behavior and the evolved psychological mechanisms that play a role in such behavior.
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