Human Pheromones

Information from Wikipedia

A few well-controlled scientific studies have been published demonstrating that humans may use pheromones in some circumstances. The best-studied case involves the synchronization of menstrual cycles among women based on odor cues (by Martha McClintock, Professor of Psychology at the University of Chicago). This study states that there are two types of pheromone involved: "One, produced prior to ovulation, shortens the ovarian cycle, and the second, produced just at ovulation, lengthens the cycle". Other studies have suggested that people can use odor cues to select mates who are not closely related to themselves.

Pheromones in humans are believed to be produced by the apocrine glands. These glands become functional after reaching puberty, which could explain why most people become attracted to the opposite sex at that time. Pheromones could also be the reason why a person can sense "chemistry", or feel an instant attraction or dislike when first meeting someone.

"Using a brain imaging technique, Swedish researchers have shown that homosexual and heterosexual 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. The new research may open the way to studying human pheromones, as well as the biological basis of sexual preference. Pheromones, chemicals emitted by one individual to evoke some behavior in another of the same species, are known to govern sexual activity in animals, but experts differ as to what role, if any, they play in making humans sexually attractive to one another." New York Times