Sex, smell and the genome

| Sex Columnist

There are many attractive people in the world, but why one finds one fish more gorgeous than the cornucopia of others in the sea has long been a mystery to both the average sexual being and the scientist. Watching mammals such as dogs sniffing one another other and either engaging in aggressive (growling) or sexual (humping) behavior prompted many toward the olfactory theory of attraction: that some specific smell cast off by a being works to attract another.

Scientists made most of their headway, looking for chemical signals called pheromones that are transmitted through the vomeronasal organ (VNO), a chemoreceptor in the nasal cavity present in mammals, reptiles and insects. By first studying predictable insects, specifically silk moths, in their sexual exploits, 1950s German scientists were able to isolate a chemical compound from female moths responsible for male response mating rituals.

According to the Howard Hughes Medical Institute, “after removing certain glands at the tip of the abdomen of 500,000 female moths, they extracted a curious compound. The minutest amount of it made male moths beat their wings madly in a ‘flutter dance.’” But how do these wildly-fluttering moths tell us anything about how we find our own mates?

Well, with the clear evidence that pheromones exist at least in animals with expected behavior, the prospect that humans are influenced by a similar genetic pattern is quite likely. With research on male golden hamsters and their obvious responses through the VNO to female hamster vaginal secretions at the Monell Chemical Senses Center in Philadelphia, more evidence pointing to mammalian sexual chemistry was identified. Further, the knowledge that women in close proximity begin to synchronize their menstrual cycles points to human sexual connection through something more scientific than environmental or physical factors.

In more contemporary studies, connection of the MHC (major histocompatibility complex) genes to sexual attraction has been identified in humans. According to Discover magazine: “MHC genes are the most diverse of all genes. In fact, they differ so widely from person to person that they constitute a molecular John Hancock, one that helps an organism recognize its own healthy cells, identify pathogens and reject foreign tissue.”

In this way, MHC genes reflect their carrier’s attributes and respond during a mammal’s sexual prime (from puberty through pregnancy) to MHC genes most dissimilar from their own. The effects of synthetic hormones (steroids, birth control pills, etc.) on changing responses of MHC genes are still uncertain.

Nevertheless, the existence of such genes and their chemical and neurological responses are significant markers of the reality of sexual chemistry—that is, a genetic formula working beyond one’s physical and mental preferences defined by societal norms. In plainer terms, there is truth to a science behind our sexual inclinations. Gary Brook’s “Centerfold Syndrome” and the existence of Megan Fox are not the only explanations of our attractions. Your genome is, too.

Sign up for the email edition

Stay up to date with everything happening as Washington University returns to campus.