Why you should care

These scientific studies helped stoke the pheromone craze that is still going strong, as people smell their way to love and friendship.

Hate to break it to you, but people judge books by their cover all the damn time, and the Book of You is no exception. Check out OZY’s series What’s in a First Impression to delve into the psychology of appearances, and how to hack it.

Can you smell how attractive someone is by sniffing that person’s sweaty T-shirt?

Well, maybe. It depends on which scientist you ask.

It has become common for the mysteries of attraction to be chalked up to pheromones. Pheromones are chemicals that we, and other mammals, all vertebrates really, secrete that affect the behavior of other members of our species — not unlike those we’re familiar with in the plant world. They are not the same as odors, although they are often used synonymously, and don’t really have a discernable scent.

That does not stop people from having pheromone parties, where participants sleep in a T-shirt for three days, then bag them up and have others smell them out to try to pair themselves up romantically. Why are we linking the science of smell with T-shirts and love anyway? One popular study in the ’90s kicked off the pheromone phrenzy.

They were instructed to avoid smelly rooms and refrain from using perfumed detergents and soaps.

Swiss scientist Claus Wedekind ran a study published in 1995 in which men wore cotton T-shirts for two consecutive nights and then placed the shirts in plastic bags. They were instructed to avoid smelly rooms and refrain from using perfumed detergents and soaps. Women were asked to smell the shirts and rate them for “intensity, pleasantness and sexiness.”

Before the smell tests, Wedekind had collected DNA samples from all of the participants in an effort to see if body odor correlated with their genes. He was looking at the major histocompatibility complex (MHC) genes specifically, as those are tied to our immune system’s markers of identity.

The results? Unless they were taking oral contraceptives, the women showed a preference for T-shirts from men with dissimilar MHC genes. A study on laboratory rats conducted in the ’70s had suggested that animals choose mates with dissimilar MHC genes, and the resulting speculation was that this could be a genetic method of preventing inbreeding or a way to diversify immune systems in offspring. Does this mean our smells stop us from being attracted to our siblings?

Not so fast.

A 2008 study showed that Wedekind’s study had overlooked nuances. Sometimes, in parts of the world, spouses have similar MHC gene profiles. Basically, MHC can influence mate choice in some human populations, but not all. Social factors are still at play.

Should everyone just stop wearing deodorant?

Shortly after Wedekind’s study, a New Mexico study used T-shirts and concluded that “women at their most fertile time of month will prefer the odor of the fittest-looking men.” Another study, also released in 1998, claimed the odor from women’s underarms can change the timing of other women’s menstrual cycles.

Smell studies and the debate about whether human pheromones exist continue to play out to this day. Marketers have latched on to this trend, and you can even buy pheromone-enhanced body wash. In fact, just this year a study was published concluding that we are likely to be genetically similar to our friends, and some of those common genes involve smell.

What does this all mean? Should single guys and gals jump over to pheromone parties and start smelling cotton shirts out of bags? Does your best friend smell things more similarly to you than your acquaintance does? Should everyone just stop wearing deodorant?

All science has shown is that human pheromones likely exist, and smells may or may not help you determine mate choice, depending on where you live. So basically, it is all up in the air. Probably though, you can skip the pheromone-enhanced body wash. But, for our sake, don’t skip the deodorant.

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