It is possible that being less aggressive and more cooperative was also an advantage for early humans, giving those with these traits a better chance of surviving and reproducing. Alternatively, researchers have argued that humans became less aggressive and more cooperative simply as a consequence of their large bodies and brains. Animals with these features typically show more self-control, so it is conceivable that our ancestors became less impulsive or quick to anger simply by virtue of their size. Sexual selection could also have played a role, with females finding less aggressive males more attractive, perhaps because they provided better care for their young. Wrangham and Brian Hare at Duke University in North Carolina have suggested that a similar process could explain why bonobos have evolved to be so much less violent than chimpanzees.

It is possible that being less aggressive and more cooperative was also an advantage for early humans, giving those with these traits a better chance of surviving and reproducing. Alternatively, researchers have argued that humans became less aggressive and more cooperative simply as a consequence of their large bodies and brains. Animals with these features typically show more self-control, so it is conceivable that our ancestors became less impulsive or quick to anger simply by virtue of their size. Sexual selection could also have played a role, with females finding less aggressive males more attractive, perhaps because they provided better care for their young. Wrangham and Brian Hare at Duke University in North Carolina have suggested that a similar process could explain why bonobos have evolved to be so much less violent than chimpanzees.