Wednesday, 25 September 2013

Ooh I love a good testicle story.....

Recent story from the beeb says men with small testicles make better parents -  "the idea being that larger testicles would suggest greater commitment to creating more children over raising them."

I first fell in love with testicle stories when Robert Wright told me about the correlation between testicle size and monogamy in apes. In The Moral Animal he explains that gorillas, despite being the largest apes, have teeny tiny balls. Bonabo chimpanzees, on the other hand, have whopping great knackers (nb Wright didn't put it exactly like this), despite their much punier bodies. The testicle:body size ratio matches up nicely to levels of sexual promiscuity in these and other ape species. The small balls-big body Gorillas form strong pair bonds, while the king-of-nads bonabos are notoriously loose and will have it off with anyone, any time. The delightful sociobiological explanation is that the bonabo males are under selection to maximise sperm production in order to 'flood out' their competitors, while gorillas are able to economise by making only as much as is needed. And the final intrigue? A human male's testicle:body size ratio falls around halfway along the continuum, suggesting that humans have tended to have only intermediate levels of monogamy during their recent selective history.

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