When it comes to choosing a partner, monkeys pick a mate with genes dissimilar to their own, according to a new study.
That choice helps them to have healthy babies with strong immune systems, anthropologists say.
And they believe that the animals select mates with a different genetic make-up by using their acute sense of smell.
The findings add support to the controversial theory that people are also drawn to partners with different genes to their own.
Scientists often study mandrills, the world’s largest monkey, because of the animals’ similarity to humans.
The latest study, by anthropologists from the University of Durham, found that female mandrills were more likely to choose mates whose genes were complementary to theirs.
The team followed around 200 mandrills living in the tropical rainforest in Gabon in central Africa.
They believe that the monkeys picked genetically dissimilar mates through smelling their bodies, the aroma of which is partly determined through genes.
Dr Jo Setchell, who led the study, which is published in the Journal of Evolutionary Biology, said: "Mandrills are quite closely related to humans – we're both anthropoid primates – so our results support the idea that humans might choose genetically compatible mates.
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