Making scents of the gene pool

Is this your man?

Here's an interesting theory on how we choose our mates, and how birth control pills may be messing with our offspring's chances of survival. Well, obviously, if we don't have children at all based on the use of BCPs, this is a moot point. Assuming, however, that we choose the father of our future kids during a phase in our life when we're not quite ready to make them, here's the scoop.

Scientists believe there are advantages to dipping into a gene pool far different from our own when constructing the DNA of the next generation. Not only will this strategy decrease the likelihood of passing along two copies of a gene mutation for an inherited disorder, research suggests that the children produced from a thoroughly mixed-up match of chromosomes will also be resistant to a wider range of diseases. Those genes in charge of the composition of a person's immune system are called the major histocompatibility complex (MHC), and MHC heterozygosity (meaning mom's MHC contribution is quite a bit different than dad's) gives the kids a survival advantage in future battles against a wider array of disease-causing pathogens.

Interestingly, MHC is a major determinant of body odor in mice and men and women too. The olfactory neurons of mice in charge of odor recognition respond to fragments of MHC molecules even when these peptide pieces are present in extremely small quantities. Many rodent studies confirm that mice prefer nonself MHC-types as mates.

So what's this got to do with BCPs? A 1997 study found that all male subjects and those female participants not taking contraceptives preferred the smell of used T-shirts from persons with MHCs different than their own. The more the subject liked a T-shirt's odor, the less similar their MHC profile to that of the T-shirt's owner. No such correlation was found between Pill-users and their favorite unwashed T-shirt smells.

So if you want to party hearty with respect to producing hardy children with top-notch immune systems, sniff out potential mates in a Pill-free mode before you mate.