Why Have Pubic Hair?

28 October 2007

Question

My question is about pubic hair. Some people have said its purpose is to protect your bits, or to keep your bits warm, or to make you smell more attractive to the opposite sex. I want to know why to humans have it, do other animals have it, and what is its main function?

Answer

We asked Christophe Soligo from University College London to help with this question...

I think a good indication of why we have pubic hair comes from the distribution of sweat glands that humans have. We essentially have two types of sweat glands; ones which are called eccrine glands, which are distributed across the whole of the body and they're the sweat glands which we use for keeping cool. On top of these we also have a second type of sweat glands which are called apocrine glands. The distribution of apocrine glands essentially coincides with the distribution of pubic and also axillary hair in the armpit, and the secretion from apocrine glands also contains small parts of cellular material. The cellular material gets broken down by bacteria and that's what creates to a large extent our personal body odour. So the secretion from sweat glands together with the location and the hair creates a nice damp substrate for growth for bacteria.The next step is a bit more complicated than just to smell more attractive to the opposite sex. Some research that's been done where men were made to wear the same t-shirt for several nights running, and women were made to smell the t-shirts after and to rank them according to how attractive they found the smell. The result was that women seem to be able to detect genetic differences in the men, specifically in a genetic complex we call the Major Histocompatability Complex (MHC). What's interesting there is that women were actually going for the men whose MHC composition was the most different to their own. That makes sense in the context of fighting disease because if you have offspring with a very variable MHC it increases their ability to fight off disease.

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