Goosebumps are a weird reaction that everyone has experienced. They can be triggered by the cold, by excitement, by music, or by a gentle touch. For some people, it is possible to create goosebumps on demand.

While everyone has had them at one point or another, most people don’t know what they really are or why we get them.

Today, they are a vestigial reflex, meaning that it is not necessary today but for our ancestors it served a purpose. If you’ve ever watched Animal Planet, you know that lots of animals will puff themselves up to make them appear larger to scare away predators.

Well, that is exactly what goosebumps were years ago when our ancestors had a whole lot more hair than we do today. When trying to intimidate another creature, the piloerection (a fancy word for goosebumps) would engage, causing the hair to stick out straighter, making us appear larger.

This is a surprisingly effective way to scare off predators in the wild, which is why it developed so well in humans. Today, we have evolved to a point where we have relatively little hair on our bodies, and having it stick out is not at all intimidating. Since goosebumps don’t really have any negative aspect to them when it comes to survival, however, we haven’t evolved to get rid of them, and it is possible that we never will.

Interestingly, however, a 2020 study found that goosebumps are still a part of the system that grows hair in humans. The sympathetic nerve fibers wrap around hair follicles like a ribbon. These hair follicles are what produce the hair. When that follicle is stimulated by these fibers for prolonged periods of time (such as in colder months), it becomes more active and grows more hair.

Yulia Shwartz is a co-author of the study, said:

“It’s a two-layer response: goosebumps are a quick way to provide some sort of relief in the short term. But when the cold lasts, this becomes a nice mechanism for the stem cells to know it’s maybe time to regenerate new hair coat. We discovered that the signal comes from the developing hair follicle itself. It secretes a protein that regulates the formation of the smooth muscle, which then attracts the sympathetic nerve. Then in the adult, the interaction turns around, with the nerve and muscle together regulating the hair follicle stem cells to regenerate the new hair follicle. It’s closing the whole circle.”

So, while goosebumps aren’t required for hair growth, they do have an influence on it. This knowledge could help to come up with future treatments for hair loss. If the same responses can be expected from other types of stem cells, this could lead to treatments for things like burn healing, some types of cancer, and more.

If you’re interested, check out this brief but fun video showing someone who can ‘engage’ their goosebumps on demand:

While goosebumps can be annoying and sometimes embarrassing, they have played an important role in our past, so let’s cut them a break.

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