Researcher claim sexually transmitted diseases led to monogamy. Credit: Alamy
Why did humans become monogamous, apparently rejecting the promiscuity that is natural to most animals?
Was it morality? Religion? Maybe love?
The answer is germs, researchers said on Tuesday, arguing that the havoc caused by sexually transmitted diseases (STIs) convinced our ancestors it would be better to mate for life.
A research duo from Canada and Germany observed that STIs flourished among large groups of people living in the villages, towns and cities that arose after prehistoric hunter-gatherers settled down to farm.
Left unchecked, spreading diseases can affect individual fertility and a group's overall reproduction rate.
Falling population numbers would force a rethink of sexual behaviour - which in turn gives rise to social mores.
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