Racy outfits, marijuana paraphernalia, that tongue—Miley Cyrus has featured it all on her Instagram account. On Sunday, she found a way to shock her followers all over again by posting a photo of herself with…armpit hair.
Never mind that Miley was wearing only a topless jumpsuit and pasties. People immediately zeroed in on her armpit hair and promptly freaked out. Miley’s armpit Instagram post received more than 12,700 comments in less than 24 hours, and Twitter was flooded with remarks about it.
Of course, it’s just hair. Why do we have such a strong reaction to it?
“We learn reactions based on the era and time that we’re growing up in, and we’ve been taught that body hair on women isn’t attractive,” says psychologist Simon Rego, PsyD, director of psychology training at New York’s Montefiore Medical Center.
Even though body hair is completely normal in other cultures, when we see something that we’ve been taught is unattractive, it can provoke a strong, instinctive response in us, he tells Yahoo Health. He compares our reaction to armpit hair to our response to the idea of eating cow’s tongue or chicken hearts—it’s considered a good thing in other cultures, but completely disgusts the majority of Americans. (It’s worth noting that Madonna went through the same thing last year when she posted a similar picture on Instagram.)
Our overall feelings of disgust toward body hair may also be linked to evolution, Rego says. Evolutionary psychologists have thought that we once had more hair on our bodies than we do now, and that body hair could potentially carry various parasites, bacteria, or impurities that could spread disease and impact our overall health. Therefore, our disgust toward hair near the genitals and armpits could be rooted in something deeper.
But while armpit hair is something that we’re born with, does it actually serve a purpose?
Surprisingly, yes. Among other things, armpit hair can help regulate our body temperature. “The hair facilitates a sweat and cooling response,” women’s health expert Jennifer Wider, MD, explains to Yahoo Health. When you sweat, your armpit hair can help wick away the moisture from your body, helping you to cool down faster.
The sweat wicking action performed by armpit hair may also prevent body odor, she says. When moisture is pulled away from your body, it takes bacteria with it that can colonize on your skin and create a smelly odor.
While underarm hair can keep B.O. at bay, it can also amplify a musty smell created by the aprocrine sweat glands of the armpits, Wider says. That pheromone-laden smell can attract a member of the opposite gender on a more subconscious, instinctual level.
So, while armpit hair may shock us as a culture, there’s no reason why someone shouldn’t have it.