As a young lad, a visiting uncle bestowed a small bottle of cologne upon me. I don't remember if it was he or I that initially named the potion, but it became known as "foo foo juice". The idea was that this strong-smelling concoction would prove irresistible to women. It turns out that your natural scent may prove a better attractor than your favorite bottled perfume, cologne, or foo foo juice. Some researchers believe that a person's pheromones-natural scent molecules found in sweat-may provoke a favorable response in someone genetically predisposed to be receptive to them.

Research that appeared in a February, 2002 issue of Nature Genetics showed that people's odor preferences appeared to be "based upon a set of genes inherited from their fathers…women prefer the odor of men to whom they are genetically similar, but not identical, to the odor of men whose genes are nearly identical or wholly unfamiliar". Martha McClintock, who co-authored the study with Suma Jacob, believes that women can smell genetic differences, although they may not be aware of it.

The researchers began their study by identifying the human leukocyte antigen (HLA) gene sequence-the genetic inheritance for your odor and scent preferences-of 49 females, their parents, and six men selected for diverse HLA types and ethnicity. Women were found to prefer the scent of men who had HLA types similar to their fathers. According to Jacob, "Smell will have a subtle influence in the way we select mates but mate selection is much more complicated".

There has been a lot of debate over whether humans possess something called a vomeronasal organ (also known as Jacobson's organ)-a secondary olfactory system thought to sense chemical signals called pheromones. In a study published in the October 22, 1999, issue of Science, Eric Keverne and colleagues reported that the organ appeared to be vestigial in humans; they found evidence of its existence in developing babies in the womb, but it was absent in the majority of adults. Keverne found that in a study of 564 adults, 70% did not have the structure, 8% had the vestibule bilaterally in relation to the nasal septum, and 22% unilaterally.

Pheromones, nevertheless, appear to have an effect on other human beings-even on individuals of the same sex. In an article published in Nature in 1998, McClintock described a study in which she brought together 29 female volunteers between the ages of 20 and 35 for an experiment. Nine of the volunteers kept a gauze pad in each armpit for eight hours a day. Researchers then mixed the sweat from the pads with isopropyl alcohol to cover odor, and placed a sample of the mixture under each of the remaining 20 volunteer's noses. McClintock was able to document that women exposed to other females' pheromones altered the timing of their ovulation. The nine volunteers that donated their sweat functioned as the control group, receiving a dab of plain alcohol under their noses. None of their cycles were affected. McClintock documented similar research in 1971.

Noam Sobel and Windy Brown reported that men and women's brains respond to two putative pheromones-related to testosterone and estrogen, male and female hormones-in an August, 2001 issue of the journal Neuron. When men smelled a compound similar to estrogen, increased blood flow to the hypothalamus was documented. In turn, female participants experienced increased blood flow to the hypothalamus when exposed to the testosterone-like compound. Researchers found that the testosterone-like compound existed in men's sweat at levels 20 times that of women's, evidence of pheromones, according to Sobel and Brown. The researchers monitored the results using sophisticated brain imaging techniques.

Several factors, including genetics, hormones, diet, metabolism, and environment influence the odor that emanates from our sweat. For the sense of smell, odors are processed in an area of the brain called the olfactory bulb. If humans process pheromones from the vomeronasal organ, it is thought that they would be processed in an accessory olfactory bulb, which has yet to be identified in humans.

There is no doubt that that our primary olfactory system, or sense of smell, is pretty adept at picking up the multitude of odors that a we run into on a daily basis. Each of us is born with about 1,000 different odor receptors capable of detecting anywhere from a few thousand scents to billions, based on the potential combinations of our receptors.

I know why you really read all the way to the end of this article. You are wondering where you might be able to get some foo foo juice. If I knew, I couldn't tell you-family secret. I'm sure if my uncle shared his wisdom with all of us today, he'd suggest being ourselves and letting nature take its course. Most importantly though-take a shower!