Male sex drive causes hostility

Male sex drive is at the root of most conflict in the world, from football violence to world wars, scientists have claimed.

A review of psychological evidence concludes that men are shaped by evolution to be aggressive towards "outsiders". The tendency emerged through natural selection as a result of competition for mates.

Women are said to have evolved to resolve conflicts peacefully. Natural selection has programmed them to "tend and befriend" to protect their offspring.

The findings are published today in the journal Philosophical Transactions of the Royal Society.