Women who wore perfume with synthesized female pheromone were more attractive to their male partners, conclude scientists at San Francisco State University.

Pheromones are odorless chemicals excreted from the body that affect reproductive interactions among both animals and humans. They are picked up by a special organ or tissues in the nose, and then conveyed to regions higher up in the brain.

The new study, appearing in the journal Physiology and Behavior, found that women who had pheromone added to their perfume reported a more than 50 percent increase in sexual attention from men: they were involved in more sexual intercourse, kissing, heavy petting, affection, and slept closer to their partner or date.

Women wearing perfume with a placebo also experienced an increase in these activities, though not as great as the pheromone group. The authors say this increase can be explained by the effect that results from "just thinking" you are wearing a sexy pheromone.

"The most highly significant difference between the placebo and the pheromone group was actually sexual intercourse," says Norma McCoy, lead author and professor of psychology at San Francisco State University. "It is clear that there is something that is odorless and is being exuded from reproductive age women -- that affects male behavior -- that makes the women attractive."

The pheromone used in the study( click for product info) is what its maker, Athena Institute for Women's Wellness Research, believes is a generic substrate, a substance that when put on someone's skin reacts with that person's own chemistry to achieve its effect.

Adds Winnifred Cutler (click for bio), institute founder and president and a reproductive biologist and co-discoverer of pheromones in humans (click for more on pheromone discovery), "When it works for a woman, it doesn't seem to matter what perfume she wears."

Research has also shown that significantly more men who wore aftershave with a synthetic version of a male-excreted pheromone engaged in sexual intercourse and sleeping next to their partner than those who wore aftershave with placebo.

The institute is offering the pheromone for sale, using the proceeds to fund pheromone research. The company also sells a pheromone that can be worn by men.

There is more to pheromones than sexual attraction, according to Cutler.

"If you divide up the research on pheromones into what type of behaviors are shown to be affected by them, you can organize them into four different classes," says Cutler: mother-infant interaction, territorial marking, reproductive synchrony, and sexual attraction.

While most studies on the topic use animals, there have been intriguing human findings, too.

Studies have shown, for instance, that babies as young as three days old are able to distinguish the odor of their mother from that of other nursing mothers. Babies will turn their faces toward lingerie that has been worn by their own mothers -- and ignore other women's -- when the garments are waved over their heads.

Other research on reproductive synchrony has shown that women living together in dorms or working together have synchronized menstrual cycles. Interestingly, one study of women working in pairs found that women who said they disliked each other did not cycle together.

In addition to providing interesting insight into the roots of human behavior, pheromone research may have some therapeutic uses(click for more research on sexuality and pheromones).

The Athena Institute is currently exploring uses of attractant pheromones to improve social interactions of people who may experience subconscious shunning by others, such as people with cerebral palsy. In addition, infertility groups have expressed interest in doing research on women who are undergoing infertility treatments to see the effect that these chemicals have on the outcome.

Attractant pheromones may also be useful to women who have undergone hysterectomies.

"In women a loss of sexual attraction is frequently experienced after hysterectomy (click for more hysterectomy research) and there is a need for a double blind study to look at the role that pheromones play in that," explains Cutler.

These future research projects have the potential to expand the application of pheromones to humans beyond the perfume bottle.