Longer apparently is better when it comes to a brain hormone which determines whether a man is likely to steadfastly commit to monogamy or is more likely to play around.

It all comes down to length of receptors on vasopressin, the so-called White Knight hormone that determines how strongly a male will guard his mate and turf.

“Long version” genes indicate a male who is likely to be committed to monogamy; “short version” receptors suggest a likelihood towards promiscuity.

Furry Creatures Gave the Lead

Scientists were first alerted to the possibility of a genetic connection while observing the sexual behaviour of two types of voles.  The prairie voles are dedicated one-female critters, coupling tirelessly with a selected mate over 24 hours and then bonding with her for life.

Meantime their cousins the promiscuous montane voles specialise in one night stands that last less than a minute.

Changed Forever

Studies showed when the prairie vole mates with his chosen female the sexual activity changes his brain forever.  An area of his brain memorises his female’s smell and touch and from then on he aggressively rejects every other female.

It seems during mating the type of vasopressin released had receptors which made him monogamous.  When these receptors were blocked, the prairie male was no longer monogamous.

Although men’s brains may turn out to be more complicated, a Swedish study found that men with the long version of the vasopressin receptor gene were twice as likely to commit to one woman for life.

Throats Tell Story

Similar genetically determined indicators of monogamy have been found amongst side blotched lizards where males with three different coloured throats are matched with three different mating styles…

The orange throats are the alpha males, corralling a group of females, guarding them from other males and and mating with them all; the yellow throats sneak about coupling where ever they can steal  females from other males, and the blue throats, are strictly monogamous, selecting one female and guarding her 24/7 from other competitors.

Scientists warn that human behaviour is determined by many factors, and the gene’s influence is likely to be small.  According to Wired magazine, it is also linked to a tendency towards autism, raising speculation it could be poor social and communication skills that created marriage problems for the “short receptor” men.

But it does raise the interesting question… Is the day far away when you could tell whether a man is husband material just by peering at his genes?  And if we could would we take any notice anyway?

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073pnas.0803081105

Image taken from: infoniac.com

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About the author

Jenny W