So in the spirit of romance, I want to talk about a study that specifically looked at female -> male attraction in humans, more scientifically known as “mate choice.” You may have heard of this particular experiment, as it was groundbreaking and applicable to everyone. Basically, they had 6 guys wear tee-shirts for a few nights without washing them, and then had a bunch of girls smell them and rate them on how good they smelled. Consistently, girls liked the smell of tee-shirts worn by guys with the most differing MHC (major histocompatability complex) from their own, and disliked those worn by guys with similar MHC’s. MHC-whaaaaat? I’ll explain.
In the most very basic sense, MHC a protein profile. All of your cells have a membrane, like the skin of a balloon. Except your cell membranes are not smooth; they have tons of proteins sticking out of the surface. A specific group of these surface proteins are involved in your immune system, and they are coded by a long sequence of genes called the major histocompatability complex. Complex is an appropriate word, since 128 genes determine the MHC. As you can imagine, everyone’s is intricate and different.
So, why would we prefer mates who had different MHC than our own? It all has to do with increasing genetic variation. For one, people with really different MHC’s are less likely to be related to you. So it decreases the chance of mating with a relative. Furthermore, if you are to mate with someone with dramatically different immunity proteins, then your kids are likely to get a wide variety of immunity. Ah lah, healthier offspring.
But the story doesn’t end there. Girls that were on the pill had reversed preferences. They preferred the scents of guys with more similar MHC, which is just completely screwy and in no way advantageous. Ladies, when it comes time to get serious and find yourself a husband, I would consider going au natural for a while so that you aren’t out at bars trying to pick up your second cousin.
I think the next step in this might be to look at gay people’s mate choice in relation to major histocompatability complex. This study only considered straight people. But if we remove the gender variable, I’m willing to bet the exact same thing is happening with gay peoples’ mate preference.
Here, one might be tempted to say that we’re all just bags of chemicals and love is just the result of hormones and pheromones. But I don’t buy that. I think it’s a large part of it, but certainly not all of it. I’m confident that there’s more going on than just chemical pathways.
So if you have a special someone, be sure to tell him or her that you care about them deeply… and that you find their MHC irresistibly different from your own. That’s sexy, right?
Notes:
MHC is super complex, so if you want to know more, I encourage you to look into it. Better yet, find a molecular nerd to tell you about it.
The study is described in the paper MHC-dependent mate preferences in humans by Claus Wedekind, Thomas Seebeck, Florence Bettens, and Alexander J. Paepke. Published in The Royal Society’s Proceedings: Biological Sciences, Vol. 260, No. 1359, June 1995.
I wonder how we detect MHC molecule composition just by the sense of smell? It's amazing what goes on without us knowing.
ReplyDeleteThere was also a study that talked about how birth control alters that response in a woman and they choose a mate with the same MHC molecules and then when they want to have a baby, she stops taking her birth control and it switches back to normal and she becomes unattracted to her mate. Very interesting, no idea if it's valid because it was published by psychologists. Ugh.