The "male warrior" instinct means that men are programmed to be aggressive towards anyone they view as an outsider, a study claims.
In evolutionary terms an instinct for violence against others helped early men improve their status and gain more access to mates, but in modern terms this can translate into large-scale wars.
In contrast women are naturally equipped with a "tend and befriend" attitude which means they seek to resolve conflicts peacefully in order to protect their children, researchers said.
The study, published in the Philosophical Transactions of the Royal Society B, is a review of evolutionary evidence for the so-called "male warrior hypothesis".
It claims that in every culture throughout history, men have been more likely than women to use violence when confronted by people they saw as outsiders.
The "tribal" attitude of men, ultimately aimed at boosting their chances of reproducing, is similar to the territorial behaviour of chimpanzees, it was claimed.
The study also examined evidence which suggests men have a stronger sense of group identity than women, and that they will develop closer ties with others in their group if they are in competition with rivals.
Although men's hostile responses most likely evolved to combat the threat from outsiders, they "might not be functional in modern times and are often counterproductive," experts said.
Over time this has resulted in full-scale wars between countries and empires, and also in scraps and skirmishes between rival groups of football supporters and urban gangs.
Prof Mark van Vugt, who led the study, said: "A solution to conflict, which is an all too common problem in societies today, remains elusive. One reason for this might be the difficulty we have in changing our mindset, which has evolved over thousands of years.
"Our review of the academic literature suggests that the human mind is shaped in a way that tends to perpetuate conflict with ‘outsiders’."
The original article, titled Evolution and the psychology of intergroup conflict: the male warrior hypothesis, is by Melissa M. McDonald, Carlos David Navarrete1, and Mark Van Vugt, and appears in Philosophical Transactions of the Royal Society B, 367 (1589), March 5, 2012, pp. 670-679.
