The human body produces chemical cues that communicate gender¹ to members of the opposite sex, according to researchers who report their findings in the Cell Press journal Current Biology on May 1. Whiffs of the active steroid ingredients (androstadienone in males and estratetraenol in females) influence our perceptions of movement as being either more masculine（男性的） or more feminine（女性的）. The effect, which occurs completely without awareness², depends on both our biological sex and our sexual orientations³. "Our findings argue for the existence of human sex pheromones," says Wen Zhou of the Chinese Academy of Sciences. "They show that the nose can sniff⁴ out gender from body secretions⁵ even when we don't think we smell anything on the conscious level."

 

Earlier studies showed that androstadienone, found in male semen and armpits（腋窝）, can promote positive mood in females as opposed to males. Estratetraenol, first identified in female urine, has similar effects on males. But it wasn't clear whether those chemicals were truly acting⁶ as sexual cues.

 

In the new study, Zhou and her colleagues asked males and females, both heterosexual and homosexual, 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 joints⁷ in the human body, plus the pelvis, thorax, and head. The task was to decide whether those digitally morphed gaits were more masculine or feminine.

 

Individuals completed that task over a series of days while being exposed to androstadienone, estratetraenol, or a control solution, all of which smelled like cloves⁸. The results revealed that smelling androstadienone systematically⁹ biased¹⁰ heterosexual females, but not males, toward perceiving walkers as more masculine. By contrast, the researchers report, smelling estratetraenol systematically biased heterosexual males, but not females, toward perceiving walkers as more feminine.

 

Interestingly, the researchers found that homosexual males responded to gender pheromones more like heterosexual females did. Bisexual or homosexual female responses to the same scents¹¹ fell somewhere in between those of heterosexual males and females.

 

"When the visual gender cues were extremely ambiguous, smelling androstadienone versus¹² estratetraenol produced about an eight percent change in gender perception," Zhou says, a statistically¹³ very significant effect.

 

"The results provide the first direct evidence that the two human steroids communicate opposite gender information that is differentially effective to the two sex groups based on their sexual orientation," the researchers write. "Moreover, they demonstrate that human visual gender perception draws on subconscious¹⁴ chemosensory biological cues, an effect that has been hitherto（迄今） unsuspected."

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