This ancient secret makes men irresistible to women.
Just kidding. Pheromones might smell good, but they ain’t mind control. Tell people you wrote a book about smells and they’re bound to ask if pheromones really work. The quick answer is “no”. But that isn’t the good answer.
There’s got to be a reason why men (and women) since time immemorial have spent their money on this “secret weapon” of scent. There’s more to this story; the answer isn’t a definitive “no”, but a “very nearly almost ‘no’”. Let’s probe the subject a bit.
Animals do use pheromones, and they do function as mind-control. If you’ve ever crossed the path of a buck in rut, you’ve seen pheromones at work. They aren’t thinking about a damn thing except ‘that a**’. The most popular of pheromones is androstenone. It’s produced by male boar, and it makes the females stand in a “mounting position”, literally controlling the bodies in its presence. There are other pheromones besides those for sex, such as "the smell of fear", an alarm pheromone. One thing to note straight away is that animals sense pheromones in a different way than humans, for they have an extra component in their olfactory system, called the vomeronasal organ. Humans have the physical organ, but it doesn’t seem to work for us as it does for them.
Pheromones will not force humans into a mating stance, but they can most certainly influence our bodies and our behavior with more potency than the smell of fresh bread or brewed coffee. In fact, the most potent smells in this regard are usually bad smells. When looking for physiological evidence of odor-effects, bad smells produce a stronger effect. They can raise the breath-rate, heart-rate, and skin conductance. Across a broad spectrum of subjects, “good” smells will produce neither the same effect nor the opposite. (Sorry, Aromatherapists.) This makes pheromones all the more interesting, because they vacillate between "good" and "bad", as determined by a variety of factors.
Next, pheromones do inform humans on compatibility. Doing the sweaty t-shirt experiment, women tend to have a preference for the smell of bodies with complementary immune systems. In this case, the “pheromone” is a combination of chemicals that, although very similar, is unique to every person. And it doesn’t make women fall on their knees, drooling a puddle of pure estrogen. It’s just a preference, kind of like a strong suggestion, but it’s not mind control.
Now for the nitty-gritty. Pheromones are s special class of smells called semiochemicals. They carry a very strong meaning with them, and for humans meaning is powerful. For humans, and this is primarily where we differ from animals, smell is a learned phenomenon. Nothing is hardwired into our olfactory system. There is no universal template. In theory, we could be taught to find fecal matter as sexually-stimulating as armpit sweat.* The thing is, we are constantly being “taught” about smells, and virtually 100% of the time this is happening unconsciously. (Especially in utero, or during the early years of life, when the majority of our odor education takes place.)
Like all learning, repetition reinforces associations and streamlines response. The more times a smell is sensed in a specific context, multiplied by the “limbic intensity” of that context, the more it appears hardwired.
Coffee in the morning. You aren’t born with that response; it’s reinforced over countless mornings, matched with that exhilaration triggered by the bodyclock upon awakening. Sex. Both males and females produce pheromones, and they are similar, at least in that they both produce androstenone. When you get sexually aroused, you smell yourself, unconsciously, of course. This trigger is reinforced every time you get aroused. This is a blatant example of the relentless lessons of olfaction, but there are other situations where the “smell of sex” is perceived within a sexually-aroused context, matching aroma chemicals with physiological body states. This is what makes a semiochemical. The message is loud and clear, it says “get ready for sex”. But it is not a command.
Humans are cognition wizards. We are so good at using our mental powers, that we can override even the most irresistible physical instincts. We can even change our own genetics. Over generations, some groups of people transformed a gene that allowed them to digest milk into adulthood. Over generations, people differed in the gene that codes the receptor for androstenone (the most popular of pheromones) so that some sense it as sweaty and urinous, some as sweet and floral, and some as nothing at all.
We are in constant co-evolution with our environment, but in ways that go beyond physical interactions. Because our culture can evolve at a rate less constrained by physical limits, the messages it brings can rearrange our instinctual responses. We are not slaves to our bodies. As individuals and especially as groups, we can rearrange the “meaning” of physical information as it is understood by the body (or at least the olfactory system). If you don’t want to smell sex with your pheromones, you can turn it off.**
If you feel like you’ve been looking for love in all the wrong places, you’re better off putting your paychecks somewhere else (like towards a good fragrance, which, by the way, also use pheromones).
On a final note then, there is something to be said for the person wearing the contested mind-control scent. Placebo effect. The very act of wearing a scent, any scent, can raise the confidence of the wearer. And chances are confidence will smell better than synthetic sweat..
*This is not a stretch, when considering male homosexuality, for example.
** Perhaps something can be said here of the lack of body odor secretions from certain Asian populations.