Humans Have a Nose for Gender: Sense of Smell Identifies What is Masculine and Feminine

Can humans "smell" gender? Apparently they can. Scientists have discovered that the human body produces chemical cues that communicate gender to members of the opposite sex. The findings could reveal a bit more about how and why we perceive movement as being either more masculine or more feminine.

"Our findings argue for the existence of human sex pheromones," said Wen Zhou, one of the researchers, in a news release. "They show that the nose can sniff out gender from body secretions even when we don't think we smell anything on the conscious level."

In previous studies, researchers found that androstadienone, which can be found in male semen and armpits, can actually promote positive mood in females as opposed to males. In contrast, estratetraenol, which was first found in female urine, has similar effects on males. Until now, though, researchers have been unsure whether these chemicals were actually acting as sexual cues.

In order to find out, the scientists asked heterosexual and homosexual men and women to watch what are known as point-light walkers (PLWs) move in place on a screen. PLWs consist of 15 dots representing the 12 major joints in the human body, plus the pelvis, thorax and head. These men and women then had to decide whether the PLWs moved in a more feminine or masculine manner. The scientists then exposed the volunteers to either androstadienone, estratetraenol, or a control solution to see how they viewed these movements.

So what did the scientists find? Men and women classified something as more "feminine" or "masculine" depending on what chemical cues they were exposed to. It turns out that homosexual males responded to gender pheromones like heterosexual females. Bisexual or homosexual female responses to the same scents fell somewhere in between those of heterosexual males and females.

"When the visual gender cues were extremely ambiguous, smelling androstadienone versus estratetraenol produced about an eight percent change in gender perception," said Zhou in a news release.

The findings reveal, for the first time, that two human steroids can communicate opposite gender information. Not only that, but these cues are perceived differently depending on a person's sexual orientation.

The findings are published in the journal Current Biology.