A Very PharPoint Halloween: The Science Behind Goosebumps

Day One of #SpookyScience: Why do we get goosebumps?


Scary Story Time: Let’s Make Your Hair Stand On End

Imagine this: It’s been a long day at work and you can’t wait to get home. It’s dark out, and a storm has swept up suddenly, leaving you drenched. You unlock the front door in a hurry and throw it open to an empty, pitch-black apartment. Exhausted, you toss your keys on the counter, take off your shoes, and pad along to your bedroom, walking on those cold hardwood floors that always send creaks resounding through the thick silence. You change out of your work clothes, put on your PJs, and walk down a dark hallway to the kitchen to make a cup of tea… When a chill is sent up your spine and makes your hair stand on end.

Immediately, you bristle and look around for any source of disturbance – but there’s nothing. No big deal, right? Your apartment isn’t exactly brand-new, and has been known to be drafty. You grab your tea and collapse onto the couch with a blanket (so as to ward off any more “drafts”). After a few minutes, you begin to relax and the tension melts out of your shoulders. The silence that was so unsettling earlier is now comforting, broken only by the occasional sound of thunder in the distance. You’ve been rushing around like crazy all day, and now you’re warm, comfortable, and very, very sleepy. You lean your head back and your eyes start to droop closed… BANG! A sharp crack resonates throughout the apartment like a gunshot, and you jump out of your skin. For the next few minutes, you’re covered head-to-toe in goosebumps, on red alert for any nearby danger. It takes a while for you to relax enough to realize that it’s probably just a tree branch from that storm.

Does any of this sound familiar to you? Chances are that you’ve experienced a similar situation, where a cold draft or something unsettling makes the hair on your arms stand up, or gives you “goosebumps”, as they are more colloquially known. Goosebumps are commonly referenced in horror films and scary novels, and are well-known to be a reaction to all things spooky. But why do humans get goosebumps?

“Goosebumps”: A Gift From Our Animal Ancestors 

It turns out that goosebumps are an evolutionary reaction to danger that animals have had for many thousands of years, and humans have inherited this physiological phenomenon. It is a part of our “fight-or-flight response” – in other words, whenever danger is perceived, a stress response is triggered in our nervous systems. This response, fueled by fear, causes a rush of adrenaline that floods throughout our body and causes things like an accelerated heartrate, sweating palms, and dilated pupils. “Goosebumps”, or horripilation, is a result of this reflex. It causes contraction in the arrector pili muscles at the base of hair follicles, resulting in the hair standing up.

Goosebumps are an evolutionary reaction to danger - our fight-or-flight response, fueled by fear. Click To Tweet

Fear causes these reactions, but why? They make more sense when looking at our animal ancestors. In animals, these responses prepare them to either attack a potential threat or to flee. Dilated pupils allow more light to enter the eyes, an increased breathing and heart rate gets more oxygen to organs and muscles, and contracted follicle muscles make hair and feathers stand up, making animals appear bigger and more intimidating in the face of a threat. For example, think of a hissing cat, with back arched and elevated fur – those goosebumps come in handy when facing a pesky dog!


But while goosebumps were certainly an evolutionary advantage for most animals, they’re pretty useless in humans. Our hair isn’t conspicuous enough to be threatening, and in most cases, we won’t be in a situation where this reaction is necessary. We call this a vestigial trait – something that has hung around throughout the evolutionary process, but isn’t relevant to our everyday lives.

However, as you’ve probably noticed, fear isn’t the only thing that triggers goosebumps. Being cold can make your hair stand up as well – in animals, this results in a thicker fur layer and, therefore, more insulation (again, something that is ineffective in humans). Strong emotion can also trigger goosebumps, like a moment of nostalgia or feeling sentimental. This is because the region of our brain, the hypothalamus, is stimulated by emotion – like when we listen to music, watch an inspiring movie, or read a sad book – and also controls our primal urges. In fact, researchers at UNC Greensboro have found that people who experience goosebumps more frequently tend to be more creative and imaginative!

So the next time you are alone at night and hear a strange noise, you’ll now know that those goosebumps are simply preparing you to take charge at whatever creepy thing is knocking at your window. Just make sure to keep an eye out for things that go bump in the night to avoid using that fight-or-flight!

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