Have you ever been to a pheromone party? The idea is to find your perfect partner based on smell. That’s right, body odour, and there’s no deodorant allowed. Pheromones are very particular smells: chemical signals animals evolved to communicate with one another. We know pheromones play a key role in the animal world, but scientists are arguing about whether the same is true for us.

Bombykol, the first pheromone to be identified chemically, is used by female silkworm moths to attract mates. Image credit: Nikita via Flickr (modified).

Bombykol

The first animal pheromone was identified in silkworm moths, back in 1959. The pheromone was christened bombykol, and its discovery was the result of 20 years of painstaking work. Scientists had long suspected a chemical was responsible for the way female moths successfully lure males. But it required extractions from the scent glands of 313,000 female moths to purify just 5.3 milligrams of bombykol. So groundbreaking was the discovery that it earned the German biochemist who led the work a Nobel Prize.

Pheromones aren’t just any old smells. To qualify as a pheromone, a chemical an animal releases has to prompt a consistent reaction in a member of the same species. The reaction might be in behaviour, like male moths flocking around a female. But the reaction can also be a change in how an animal’s body functions. For example, queen bees release a pheromone that results in worker bees being unable to lay their own eggs.

We now know pheromones play a central role in the lives of most animals. The pheromones we hear most about are the ones used to lure members of the opposite sex, which have been studied in many animals, including lobsters, frogs and goldfish. But we also know aphids release alarm pheromones when they are in danger, and ants follow the same path using trail pheromones.

Want to be a sex magnet?

Pheromones play an important role in the lives of mammals. The ancient Greeks knew that female dogs on heat used an invisible signal to attract males. Scientists worked out the chemical structure of that pheromone in 1979. Every time your dog pees against a tree or fence when you’re out walking, it’s using pheromones to communicate with other dogs. Now pheromones have been identified in most mammals, including in elephants, goats, mice and lemurs.

Given that we’re also mammals, it’s reasonable to expect we might use pheromones to communicate with one another. And there’s been plenty of research looking for human pheromones. There was the famous T-shirt sniffing experiment of 1995 in which men were asked to wear a T-shirt for 48 hours, avoiding deodorants, aftershave and smelly foods. Women were then asked to rate the T-shirts according to ‘sexiness’ and ‘pleasantness’. The researchers concluded that the women were able to determine which men had genes, which, in combination with their own, would boost the immune system of potential children. More recently, researchers have reported they’ve identified pheromones that communicate masculinity and femininity.

No wonder people have been so keen to find a human pheromone. Imagine how rich you’d be if you could bottle a substance guaranteed to make a person irresistible to potential partners. A quick Google search and you’ll discover there’s no shortage of sites promising their bottled pheromone will turn you into a sex magnet.

But it’s just a con

It’s hardly surprising the promise of an ultimate aphrodisiac is appealing but the problem is, there’s no good science to back up the existence of a human sex pheromone.

There’s no question smell is a powerful form of communication. But the problem is scent contains hundreds of molecules. To conclude a particular molecule is a pheromone, you have to prove that molecule causes a response in other individuals of the same species. The T-shirt sniffing experiment wasn’t about pheromones; it was about the signature smells we all have. Similarly, pheromone parties aren’t about pheromones at all.

The best evidence for human pheromones we have so far has nothing to do with finding your perfect partner. Instead, French researchers have shown a secretion from the nipple glands of a breastfeeding mother prompts babies (not just her own) to suck and try to breastfeed. Because all of the babies tested responded in the same way, we may have our first human pheromone.

Unfortunately it isn’t going to help anyone find the love of their lives, but it may help premature babies to survive. I reckon that’s worth bottling!

Links and stuff

• TED talk: The smelly mystery of the human pheromone
• SciShow video: Do humans have pheromones?
• The Guardian: Sexing up the human pheromone story: How a corporation started a scientific myth
• Pheromone parties