7:28AM GMT 26 Jan 2012
Monogamy has replaced polygamy because societies where men can marry more than one woman are more violent, researchers say.
A study found that in polygamous cultures, levels of rape, kidnap, murder and robbery increase as the dissatsified men left on the shelf go on the rampage.
Researchers from the University of British Columbia say that monogamous marriage has replaced polygamy because it has lower levels of inherent social problems.
Prof Joseph Henrich said: “Our goal was to understand why monogamous marriage has become standard in most developed nations in recent centuries, when most recorded cultures have practiced polygaymy.
“The emergence of monogamous marriage is also puzzling for some as the very people who most benefit from polygymy – wealthy, powerful men – were best positioned to reject it.