Brain scans reveal human pheromones. (Biology).

More and more scientists believe that people, like insects and other animals, give off pheromones. Such scents covertly influence the behavior and physiology of other members of a species, particularly of the opposite sex (SN: 3/14/98, p. 164). A research team reports in the Aug. 30 NEURON that the brains of men and women respond differently to two putative pheromones, compounds related to the hormones testosterone and estrogen.

When smelled, an estrogenlike compound triggers blood flow to the hypothalamus in men's brains but not women's, report Ivanka Savic of the Karolinska Institute in Stockholm and her colleagues. Using brain-imaging techniques, the researchers also found that the testosteronelike compound stimulates blood flow to the same brain region, but only in women. One reason that researchers already suspected this compound of being a pheromone is that its concentration in male sweat is 20 times as high as in the sweat of women.

On top of other findings, the new study should remove any doubt about the existence of human pheromones, say Noam Sobel and Windy M. Brown, both of the University of California, Berkeley, in a NEURON commentary. "It is now time to move on and ask how pheromones take effect in humans," they add, "and how human pheromonal response may be involved in both healthy human behavior and ... in processes of disease." --J.T.