Sept. 5, 2002 -- Pheromones, those mysterious, scentless chemicals that some say drive human sexual behavior, have been studied for decades. But now researchers say they've finally found proof that mammals -- such as humans and mice -- are actually programmed to detect and use them.
A new study, published in the Sept. 5 issue of the journal Nature, shows the first real evidence that the nervous system of mice is wired to detect pheromones. And when that wiring is tampered with, their mating behavior is disrupted.
Researchers say mice contain pheromone receptors in a specialized organ in the smelling system of the body.
In their study, researchers at The Rockefeller University and the University of Maryland found that when these pheromone receptors were turned off through genetic mutation, the mice developed normally but were different in terms of aggression and sexual activity. The study authors say these differences might yield clues about pheromones' role in influencing sexual behavior and species development.
For example, nursing female mice are normally aggressive toward other mice that invade their nest. But nursing mice without the pheromone receptors were less aggressive and slower to attack invaders.
Among male mice, researchers found several differences between the normal and genetically altered mice.
Sometimes, young, socially inexperienced mice exhibit sexual behavior toward other males until they learn to distinguish males from females. But the mutant males made fewer sexual advances toward males. Researchers say this could indicate that either the mutants are better at distinguishing between the sexes at an early age, or their overall sexual drive is reduced without the ability to detect pheromones.
In addition, mutant male mice tended to mount female mice fewer times than would otherwise be expected.
According to the authors, the existence of a functioning specialized pheromone organ in humans has been widely debated, and the role of pheromones in human behavior has yet to be clearly understood.
But since a functional role for this organ has now been shown in mice through genetic manipulation, they say the findings should stimulate more research into the counterparts of these genes in humans.