About one percent of human genes (and that is a lot!) encode our ability to detect approximately 10,000 scents. Smell accounts for the largest gene family yet discovered in mammals. Aroma cues are taken very seriously by the brain. Odors guide one to eating, mating and avoiding danger.
Pheromones are chemical molecules produced by insects, animals and humans. These molecules are so strong they affect the behavior of those who inhale or ingest them. For the most part, these chemical pheromones are used to stimulate sexual interest in the opposite sex mate. Some insects and animals will not mate without first getting a whiff of their prospective partner. After a good sniff of the right chemicals signaling good health and a more than receptive attitude, there is nothing stopping the insects and animals from mating. For example, pheromones produced by male cockroaches attract female cockroaches. Not only that, it causes them to get into the correct mating position!
Some commercially-available substances claim that they contain sex pheromones and can act as an aphrodisiac. These claims generally are greatly exaggerated and have not been demonstrated scientifically. A few well-controlled scientific studies have been published demonstrating that humans may be affected by pheromones in some circumstances. One study involves the synchronization of menstrual cycles among women living together. The evidence indicates the synchronization is done unconsciously by their pheromones.
Other studies have suggested that women can use odor cues to select men who will increase chances for a healthy offspring. In 1995, Claus Wedekind of the University of Bern in Switzerland asked a group of women to smell some unwashed t-shirts worn by different men. The women were able to sniff the shirts and reject (said they were "offensive") those shirts worn by men closely related to themselves. The women were attracted to clothing that was worn by men with a very different immune system than their own. Presumably, this difference in immune systems allows the men and women to combine their defenses and give their offspring the best chances for survival. This research was repeated in the U.S. and Brazil with similar results.
More recently this same research was expanded with gene testing by evolutionary psychologist Steven Gangestad at University of New Mexico. He identified the genes involved in selecting a mate with a different immune system for best offspring. He found that women could detect the difference in men's genes and select her best choice of sexual mate for healthiest offspring. However, men could not detect any differences in women's genes concerning similar or dissimilar immune system. (My conclusion is that men are not choosy about who they will have sex with!) Gangestad also found that women who had ignored their "instincts" to not select a mate with a similar immune system (as indicated by the gene similarity in partners) were less satisfied with their relationship and the women had greater interest in outside sex (at least during their fertile days).
Pheromone production in humans becomes functional after reaching puberty. This could explain why most people become attracted to the opposite sex at puberty. Pheromones could also be the reason why we feel an instant attraction, or dislike, when we first meet someone. It may be their smell that turns us 'on' or 'off' to them.
Human pheromones are highly individualized and not always noticeable. In 1986 Dr. Winifred Cutler, a biologist and behavioral endocrinologist, discovered pheromones in humans' underarms. She found that once any overbearing underarm sweat was removed, what remained were the odorless materials containing the pheromones.
The dominant chemical scent secreted by humans is a pungent, musky scent, with men's odor stronger than women's. Much of the chemical scent is produced by dense concentrations of apocrine glands in the underarms, and by lesser concentrations in the face, scalp, ears, navel and genital area. This is not just one chemical but apparently is made up of hundreds of compounds in individualized combinations so each person has a distinct odor. People of eastern origin (China, Japan, Korea) have far fewer apocrine glands (and armpit odor) than Europeans and Africans.
Overall, the human sweat smell is a natural, animal-like, musky aroma which can be emotionally stimulating and sexually attractive. To many men and women the smell of clean skin and a little fresh sweat is the most powerful turn-on. In crowded places this is a subtle odor that gets hidden under the other odors such as food, smoke and any polluting chemicals in the air. Therefore, some men and women have resorted to their own chemical warfare with manufactured fragrances in scented products for skin and hair. These fragrances are often from flowers or herbs, or they imitate them.
There is historical evidence for the use of sweat to attract a mate. Once when Napoleon Bonaparte was returning home from a long period of warring he sent a message ahead to Josephine: "Home in three days. Don't wash." Old English folk tales passed down over many generations told young men how to seduce a young woman with his own sweat. The 'secret' was to place a clean linen handkerchief under his clean arm pit while he danced and twirled the young lady making her dizzy. After the dance, as she recovered, he was to fan her and dab her perspiring forehead with his pheromone saturated handkerchief. The results reportedly were guaranteed to be rewarding.
Desperate women from the Austrian and Swiss Alps also had their own secret weapon to capture men. They would place a part, or even a whole, peeled apple under their arm before the dancing started. After a series of dances they would discreetly remove their apple (and its secret chemical load) to give to the man to smell and eat. It was called a 'love apple' and came with an unwritten guarantee to produce its own rewards for both the woman and man.
In one research project, men preferred women's clean sweat odor over the most expensive perfumes, even when the sweat odor was imperceptible. Over 200 chemical compounds are secreted by the human body in sweat, saliva and genitals. Recent research identified that the arm pit and crotch secretions of men and women differ significantly. Not surprisingly, men and women each prefer the odor of the opposite sex. Very important factors that have great influence on the effectiveness of the sweat as an attractant are a person's cleanliness, diet and overall health.
Interestingly, some research unexpectedly found that women who live closely with a man (sleep with him and have frequent sex) have better balanced physiology. Menstrual cycles are more regular and overall health is better than women who live more isolated from men. The main factor appeared to be how much olfactory exposure (i.e smells) each woman had with the man and his body odors.
The pheromone 'androstenone' (a musky odor) has been identified in the sweat and urine of men and is presumed to be a sexual stimulant to women, especially when a day or two from, and during, their monthly ovulation. However, the same androstenone smell has an adverse effect on other men and induces anger in them! Androstenone reportedly has been synthetically manufactured and is being sold in various solutions on the Internet for men to use to hopefully attract women.
Recent research has identified a number of chemical compounds in women's vaginas that greatly affect how men rate women as a desirable partner. The compounds were named copulins. In an experiment where men were rating the attractiveness and desirability of numerous women in photos, with and without an undetectable amount of copulins present in the air the men breathed, they rated the women very differently. When copulins were present in the air the men were breathing, they rated all women as desirable! Without the copulins, they were more choosy and rejected some of the women and did not rate the others as highly. Incidentally, copulins smells a bit like butter that has gone bad in warm weather. To our ancient ancestors who never bathed, that copulins smell probably was more appealing than it is today.
According to Chicago neurologist Alan Hirsch Ph.D., men's cologne usually causes a decrease in women's vaginal blood flow unless it is a natural fresh scent. What makes a man appealing to most women are light sprays and deodorants on him, such as ocean breeze, kiwi, or a combination of baby powder and chocolate. The smell of his own clean skin with a little fresh sweat, combined with fresh fruity scents, is the strongest stimulant for a woman, especially during her ovulation. Hirsch discovered that men's penile blood flow increased up to 40% from the smell of cinnamon buns, roast meat, cheese pizza, chocolate, vanilla or peppermint.
So what can we make of all this? Maybe it is all very simple. Perhaps a 'turn-on' for men is either a pheromone from a woman or vanilla and chocolate ice cream on fresh baked apple pie with lots of cinnamon. For women it may be the right soiled T-shirt. Oh well, whatever turns you on, go for it!
