In what I’m sure will be bad news for – well, let’s be honest – people everywhere, researchers at the University of New Mexico, Albuquerque have found that a cluster of genes known as the major histocompatibility loci, or MHC, may contribute to the probability that women will cheat on their spouses. These genes are primarily related to immune response. In fact, they’re the reason you can’t take just anybody’s liver. The above-linked study shows that may also contribute to sexual response as well. The interesting part is that these aren’t “infidelity genes”, and they don’t directly determine behavior – the study hinges on the difference between the woman’s genotype and that of her spouse. Simply put, women are more likely to cheat on men to whom they are genetically similar, while in men, there is no relationship between genotype and propensity to cheat. If you want a snarky comment, you can put it in yourself. I’m taking the high road on this one.
The ultimate explanation for this result is that more genetically different mates will produce offspring with more variable MHC genes, and therefore, stronger immune systems. Why do I bring this up? Well, one of the studies that contributed to this work just happens to be my favorite scientific study ever. It’s almost universally known in the science biz as the “sweaty tee-shirt study”. In this experiment, men and women were selected to represent a variety of MHC genotypes. The men were given clean t-shirt to wear for two nights, as which point they returned them to the scientists. The female participants then had to smell the grody t-shirts, and rate the odor in terms of – and to quote Dave Barry, I’m not making this up- “intensity, pleasantness, and sexiness”. In spite of the undeniable seductive power of underarm funk, the women in the study actually preferred the scent of t-shirts worn by men with MHC genotypes different from their own. Something to bear in mind when you head out to the bars – or to your local Drinking Liberally chapter this week.