What Scientists Actually Know About Nipples

Truths so hard, they could cut glass.

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Research shows that men have a complex relationship with breasts, but that is nothing compared to their relationship with nipples, which they have but also desire. Scientists think men have nipples and can’t really use them because males and females develop in the womb the same way. At a certain point, male nips stopped having a purpose, yet, because growing them has little metabolic cost, natural selection never really phased them out. So here men are with these sensitive, unnecessary appendages that they cannot use to nurse children. It’s a weird situation made stranger by the extraordinary importance of women’s nipples to the developmental and bonding processes. No wonder it took scientists hundreds of years to learn next to anything about nipples.

Here are five weird things we actually know about nipples.

Nipples Are Kind of Like Genitals

Functional magnetic resonance imaging (fMRI) research shows that nipple stimulation in women lights up the same parts of the brain as vaginal, clitoral, and cervix stimulation. However, that doesn’t necessarily mean that contact is always read as erotic — though it seems like it often is. To know that for sure, scientists would have to ask women subjective questions as well as screen their brains. In all likelihood, they’d receive a diversity of responses. That said, it does seem to be irrefutable that nipples are a sensitive part of most women’s bodies.

They Have a Lot in Common With Goosebumps

Nipple erections and goosebumps are actually caused by the same neurons, a study of the sympathetic nervous system reveals. These neurons control the erectile muscles in body tissues that cause them both to perk up, which is why nipples can sometimes feel like giant goosebumps. Just don’t try to refer to your goosebumps as nipples. That will get you kicked out of an R.L. Stine reading.

Size Doesn’t Really Matter

The mere existence of areola reduction surgery suggests that nipple size is a source of insecurity for both men and women. However, a study of Asian men indicates that nipple size mostly has to do with body shape, and while your weight could affect nipple location, it does not impact size. More importantly, there’s little evidence nipple size holds any bearing on your health. “The size of your nipple has no relevance to cancer risk, for example,” Maggie DiNome, physician and director of the Margie Peterson Breast Center told SELF.

Nipples Are Warmer So Babies Can Find Them

Newborn babies can’t do much of anything, but they can track a nipple like a private investigator paid to expose a cheating spouse. Italian researchers suspect this is because a mother’s nipple temperature increases after giving birth, while baby’s lips are colder than the rest of their face, in order to up the likelihood of these opposites attracting. So if your spouse’s nipples seem literally hotter since having a baby, it may not be in your head. Unfortunately, it’s not for you.

Why Nipples Are Darker Than the Rest of Your Body

In the past, experts have thought that a darker nipple color helps infants locate them as well. Though it’s true that women’s nipples do get darker during pregnancy, this does not explain why everyone else’s nipples are also darker than the rest of their bodies. Eye-tracking studies raise the more plausible theory that your nipples are darker than the rest of your body to draw attention to them — perhaps for the potential sexual pleasure previously noted. Or maybe this added focus is nature’s cruel way of keeping your shirt on.

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