STUDY: GAYS MAKE SCENTS

It is all in the nose. That is what Dr. Ivanka Savic and colleagues at the Karolinska Institute in Stockholm say in some phenomenal new research being showcased in The New York Times and numerous other media outlets this week. Their findings—most notably that gay and straight men respond differently to two odors that may be involved in sexual arousal, and that the gay men respond in the same way as women— may open the way to studying human pheromones, as well as the biological basis of sexual orientation, according to the Times story. “This is just one more piece of information that proves what gay and lesbians have known all along—that sexual orientation is not a choice, but has a true biological basis,” said Dr. Stephen Goldstone, FACS, Medical Director of gayhealth.com. “The conservative right’s insistence in preaching that sexual orientation is a choice is not based on scientific proof and is demeaning to gays and lesbians.” Although previous studies were done to investigate the role odor plays in making straight men or women attractive to members of the opposite sex, this is the first study that has looked into its role in sexual orientation. The finding is similar to a report in 1991 by Dr. Simon LeVay that a small region of the hypothalamus is twice as large in straight men as in women or gay men. The brain scanning technique used by the Swedish researchers lacks the resolution to see the region studied by Dr. LeVay, which is a mere millimeter or so across. Nevertheless, both findings suggest that the hypothalamus is organized in a way related to sexual orientation. Most odors cause specific smell-related regions of the human brain to light up when visualized by a form of brain imaging that tracks blood flow in the brain and therefore, by inference, sites where neurons are active. Several years ago, Dr. Savic and colleagues showed that the two chemicals activated the brain in a quite different way from ordinary scents. The estrogen-like compound, though it activated the usual smell-related regions in women, lighted up the hypothalamus in men. This is a region in the central base of the brain that governs sexual behavior and, through its control of the pituitary gland lying just beneath it, the hormonal state of the body. The male sweat chemical, on the other hand, did just the opposite; it activated mostly the hypothalamus in women and the smell-related regions in men. The two chemicals seemed to be leading a double life, playing the role of odor with one sex and of pheromone with another. The new research was recently published in The Proceedings of the National Academy of Sciences.