The Science of Love

Everything you want to know about love, sex, and marriage

Human Pheromones – Fact or Fantasy?

When it comes to sex appeal, does how we smell matter?

Late one night, I was flipping through television stations in a somewhat futile effort to find something interesting (for that, read “non-reality”) to watch, when I came across a police drama and decided to check it out. I missed the beginning, but the basic story involved a scientist who had invented some kind of pheromonal drug that, when inhaled, caused men to be overcome with insatiable and urgent sexual desires. This mind-control drug was released in the air vent system during a fashion show in which beautiful models wearing skimpy clothing pranced about on a runway. Immediately, all of the men in the audience began to leap onto the stage and grab at the helpless models, pushing and shoving and fighting each other, and essentially reverting to an animalistic, primal state of being. Of course, the heroes saved the day and all ended well – no models were harmed and most of the men escaped with no more than a few bruises. I wish I could remember the name of this show, because it was certainly entertaining. It’s always entertaining – and frustrating – when television gets science so wrong.

And that science was really, really wrong. Pheromones – chemical secretions that elicit unlearned behavioral or developmental responses from others of the same species – act to regulate sexual and reproductive behavior in many nonhuman mammals. [So the TV show at least got something right – pheromones produce unlearned responses.] We can see examples of this throughout the animal kingdom. My dog Phoebe becomes a canine sex symbol, the Marilyn Monroe of shepherds, lusted after by boy dogs far and wide, when she is going through her heat cycle and is giving off scent markers that signal her reproductive readiness. But whether pheromones exist in humans and, more importantly, whether human sexual behavior is regulated by pheromones is doubtful.

Let’s consider the evidence. To establish that a human pheromone exists, we would need to demonstrate first, that the human body produces chemical secretions that have pheromonal properties; second, that we have the ability to detect these secretions when exposed to them; and third, that we respond to their presence in a consistent way (for example, by feeling increased levels of sexual desire or passion).

What does science tell us? Do we produce pheromonal secretions? Men and women do have odor-producing apocrine glands in their underarm, nipple, and genital areas. Also, biochemists have isolated compounds that have pheromonal properties in pigs from the urine and sweat of men and, to a lesser extent, women. So, we give off body odor and our bodies excrete substances that pigs find sexually stimulating. Hmmm. Jury is out on this one – it seems possible, but scientists have not yet identified the specific secretions that might serve as pheromones in our species.

Assuming the human body can secrete pheromonal substances, are we capable of detecting them? Here, the evidence is a bit more solid. Scientists have found that human infants, children, and adults are able to discriminate between other individuals on the basis of olfactory cues – we can tell each other apart using our noses. It seems possible that we have the capacity to detect pheromones, should they exist.

The question that interests most of us, of course, is whether pheromones actually influence our sexual responses. Certainly many perfumes and colognes contain pheromones (or their synthetic equivalents) from a variety of mammals, including the musk deer, civet cat, beaver, and pig. Studies find that exposure to these substances either has no effect at all or decreases sexual feelings among adults. So exposure to pheromones produced by other mammals doesn’t seem to do much to or for us, sexually speaking.

But pheromones are species-specific. Thus, it really isn’t surprising that exposure to nonhuman pheromones does not directly influence sexual attraction in humans. However, it is possible that these substances have an indirect effect on desire – a scent or odor may elicit a pleasant emotional response which, in turn, may increase sexual feelings. In addition, it is likely that a particular scent or odor that has been paired repeatedly with a sex partner or with sexual activity (for example, a specific brand of cologne or perfume) may come to produce a learned desire response. Of course, these types of elicited or learned responses do not constitute a true pheromone reaction.

Science will continue to advance, and the quest to identify a human pheromone will undoubtedly go on. Maybe in a year or two, I’ll be able to post a new, updated entry that presents more conclusive evidence with respect to pheromones. For now, though, the TV show got it wrong. Human sexuality is multiply-determined, and much more complex than the writers portrayed it to be. Our sexual responses are much less biochemically-dependent than those of other mammals – unlike my dog Phoebe, men and women don’t require the presence of a particular hormone or chemical secretion to feel desire, want sex, or become attracted to another member of the species. And no single substance would have the power to produce those animalistic, primal sexual and aggressive behaviors the writers showcased. Had the mad scientist truly identified a pheromone, we’d expect this substance to have produced, at most, something akin to “Wow, she’s kind of hot” from the men in the audience. That probably wouldn’t make for good ratings, though.

Pamela Regan, Ph.D., is a professor of psychology at Cal State Los Angeles. She is the author of Close Relationships (Routledge).

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