Attraction and the Contraceptive Pill
20 March 2008
You may never have heard of the Major Histocompatibility Complex (MHC) genes but if you have ever found yourself in a passionate embrace, the chances are you owe it to your MHC.
The genes that appear in the MHC area of your DNA are related to your immune system and they are one of the most highly diverse regions of DNA in human beings. Generally the more diverse your genes are in this region the stronger your immune system will be.
Perhaps more interestingly for those of us interested in attracting a mate, several studies show that women are attracted to men with MHC genes very different to their own and psychologists believe that scent plays a very significant role in the subconscious processes of mate selection.
In 1995 the Swiss Biologist Claus Wedekind asked a group of male college students to sleep in a t-shirt for two nights without using deodorant or scent of any kind. He then asked a group of female students to smell the t-shirts and rate the scents for attractiveness.
By a large margin, the women preferred the scents of men who had MHC dissimilar to their own.
So why would a woman prefer a man with a dissimilar immune system from her own?
Evolutionary biologists believe that it's an adaptation designed to secure the best possible health for their children. That makes sense, the more diverse your genes in this area then the better your chances of survival against disease.
But what is really interesting is that women who were taking the contraceptive pill overwhelmingly preferred men with similar MHC to their own. Exactly the opposite of what nature intended!
This suggests that women using the contraceptive pill might be subconsciously attracted to men that they wouldn't normally select. Any children produced might not have the optimum immune system genes but no big deal. The problem might come when those women stop using the contraceptive pill. Will they find that they are suddenly less attracted to their partners?
We need more studies to find out. In the meantime, keep making the responsible choices. Never make decisions about contraception on one research finding.