Love at first sight is rare, depending on who you ask, but what about love at first sniff? Most of us have been influenced into thinking a prospective mate is more appealing by their scent, both artificial and natural. Mating is one of evolution’s vital mechanisms, so any intrinsic propensities we have for figuring out who is the best match certainly has a strong evolutionary basis. This means that any and all human foibles around dating have been selected as the most useful over a few billion years. In other words, even though romance is confusing and frustrating, there is a good reason for everything we are driven to do in its name, which includes unconsciously finding certain scents appealing or repelling.
In the search for the smell of love, scientists have looked at a lot of the hormones that appear after puberty and are associated with sex traits. Some studies support the idea that our airborne hormones influence our choice of mate, but many others have failed to find any links.
It turns out there is something in the air that will impact who you think is hot, but it’s more boring than sexy hormones and closer to unsexy allergies. Let’s take a look at the science behind attraction and smell, and what our personal musks tell another person of child-bearing age.
Do humans have pheromones that influence who we think is attractive?
It has not been ruled out that certain sex-linked hormones influence human behavior, but no one has ever discovered individual chemicals that conclusively smell like an attractive person. Pheromones have been identified in other species, and some human hormones appear to have an impact on decision-making areas of the brain. However if anyone tries to sell you human spray-on pheromones in a perfume or cologne, they didn’t include any science-backed substances.
Part of the confusion comes from the marketing efforts of a perfume company called EROX. In the early 1990s they marketed “putative human pheromones,” which they called androstadienone from men and estratetraenol from women. Further experiments have failed to show these two chemicals impact attractiveness and also that not all humans even produce them. In this same bin of findings is the idea that women’s menstrual cycles sync up as a result of being able to smell each other, which has found weak to no support in experiments.
On the other hand, many studies do pick up small impacts, such as estratetraenol making intimate emotional reactions stronger in men, or that the secretion of oestradiol and progesterone by women may impact how desirable they are to men looking for female mates. These studies had mixed results and the authors considered further research to really show the effect. The results were similarly confusing among partnered women, who find single men with more testosterone to have a more attractive body odor, but also prefer their mate’s odor compared to a stranger.
Though the slang term horny might be derived from hormone, a hormone that makes us horny has not yet been found. Still, there are reasons for being attracted to someone’s scent. There are scents we all can identify that would be pleasant coming from a date, like flowers, and scents that would be unpleasant, like most kinds of food. But it turns out that what we just ate might have more of an impact than we think.
Take-home dating advice: Don’t bother with perfumes, colognes, after-shaves, or any other added scents for their so-called “human pheromones.”
What have you been eating?
Successful partnering is the goal of evolution, success being either a child or more cohesive social bonds. As a result almost all of our mating behavior is designed to find someone who is fit enough to care for a child or a home with us. Even though the stakes are very different depending on if you have to carry a child or not, how we judge the fitness of our mates needs to be useful for the whole species. For example, the progesterone hormone might signal to a man of child-bearing age when a woman is fertile during the month, but wouldn’t help her pick a mate.
Our noses are sensitive to billions of chemicals, and it turns out that hormones aren’t the only or even the best way to figure out if it’s worth spending resources on someone to build a long term relationship. All other things being equal, a well-fed partner is a good partner, because a good diet indicates a sufficient combination of personal and family resources, and this is something we can smell.
In one study, women found men with diets rich in fruits and vegetables had a pleasant floral quality to their odor, and that in general fat, eggs, meat, and tofu produced better smelling sweat. Excessive processed carbohydrates produced the most unattractive smells in men. Along the same lines, men found the scent of women who hadn’t eaten in a few days less attractive than a woman who had a full belly.
Take-home dating advice: Don’t starve yourself before a date. Eating healthy doesn’t just help you look fit, it also helps you smell fit.
And what are you allergic to?
In addition to eating nutritious food, a prospective mate must also not be allergic to our bodies or pregnancy is going to be a lot less possible. That means the specific markers that make up your body’s unique chemical signature aren’t detected as too foreign by a possible mate’s body. Immune incompatibility can lead to problems from autoimmune diseases in offspring to a rare physical allergy that causes rashes like any other.
The major histocompatibility complex (MHC), which is the lower part of Y-shaped antibodies, contains markers that help your body tell its cells from someone else’s cells. When we inhale tiny airborne bits of a date’s cells, our body will analyze them for MHCs that are different from ours in a few very specific ways. There are a few theories out there, but most revolve around being attracted to a coupling that would result in children with the best immune functions from both parents.
Take-home dating advice: Sometimes a no is a no due to the laws of chemistry and biology, which can’t be overcome with any clothing, words, or choice of venue.
There is a lot of love in your air, so use it
Further studies see romantic attraction as an interaction of visual, olfactory, social and many other factors. How we interpret our own scents also has a large impact on our choice of mate because it affects our confidence. This could be a result of our modern culture where few people smell like people, or a deeper self-consciousness that was born during times when one’s smell could impact success in hunting or hiding. In yet another study, women viewed pictures of men that had been sprayed with a positive scent and men that hadn’t. The men who thought they smelled better were judged to be more attractive solely based on facial cues and body language.
Romantic partnering and smells are both huge parts of our lives with huge overlaps. People who can smell better can engage deeper in romantic and sexual relationships in both the long term and short term as a result of their fuller experience of life. Partnered people who have lost their sense of smell reported a loss of sexual desire in addition to the depression that comes along with losing a channel to perceive the world.
Take-home dating advice: Successful romance doesn’t just involve compatible smells between people, how your nose detects your own odor can impact who is willing to date you.