By Lauren Donley

    Pssst… I don’t mean to alarm you, but I think your piloerection is showing.

    If your mind found its way into the gutter, let’s set the record straight – we’re talking about goosebumps. Straight outta Latin, with ‘pilo’ meaning hair, and ‘erectus’ meaning upright.

    Alternatively, if you were momentarily transported back to reading teen horror novels by R.L Stine in the 1990s, you may be tickled to learn that another technical term for goosebumps is ‘horripilation’.

    Goosebumps are caused by contraction of tiny muscle in the skin, known as the arrector pili. These muscles are attached to the base of each hair follicle. Contraction pushes individual hairs into an upright position, creating little skin bumps reminiscent of plucked poultry. 

    Scientists have understood this biological response since the time of Charles Darwin. In 1872, Sir Charles described this phenomenon in dogs, baboons, and parrots, in his book titled: The Expressions of the Emotions of Man and Animals.

    A hairy situation

    Goosebumps are a vestigial feature, meaning that they were once useful to our primate ancestors, but no longer serve a clear purpose in modern-day humans. Other examples of vestigial features include your appendix, and the coccyx bone at the base of your spine.

    In our ancestors, goosebumps most likely served two main purposes: one relating to the cold, and the other relating to fear. Basically, the two situations most commonly associated with goosebumps. When considering these situations, you may find it helpful to conjure up a mental image of Homo habilis – our fuzzier relatives who walked the earth two million years ago. 

    Firstly, in cold conditions, goosebumps would have helped our ancestors to conserve heat in a few different ways: 1) by trapping an insulating layer of air around the raised hair follicles; 2) by contracting the arrector pili muscles to create heat; and 3) by closing skin pores to retain heat. 

    Secondly, in the presence of a predator, goosebumps would have created a puffed-up appearance to intimidate and threaten rivals. If you’re currently picturing H. habilis, as recommended, I now invite you to switch this mental image to a more sparsely covered modern-day human, such as a family member or neighbour. In theory, less intimidating… right?

    Trigger happy

    On the surface, these triggers of cold and fear may seem somewhat unrelated. However, in both instances, goosebumps are an involuntary response to adrenaline – a stress hormone involved in the ‘fight or flight’ response. Circling back to the piloerection response, it’s this spike in adrenaline that stimulates those tiny arrector pili muscles to contract, literally giving rise to goosebumps.

    Adrenaline is not only released in response to cold and fear; we also get a hit of adrenaline when experiencing stress or strong emotions such as anger or excitement. This helps to explain why some people break out in goosebumps during powerful moments, such as while listening to uplifting words or music, or when feeling inspired by impressive scenery or artwork.

    However, it should be noted that a study into ‘emotional piloerection’ found that chills and goosebumps are not the same thing. Half of the study participants reported feeling chills while listening to My Heart Will Go On by Celine Dion, but only 14 percent experienced goosebumps. Of those who listened to The Sound of Silence by Simon and Garfunkel, all felt chills, but none experienced goosebumps. Make of that what you will.

    Now if you’ll excuse me I’m heading out for a winter walk. Let it be known that I’ll be wearing my puffiest jacket to ward off rivals. And I might even listen to some Celine Dion for that extra chill factor. 

    Human Interest
    Human Interest
    Welcome to your regular column on the science of human beings…and being human. Brought to you by Lauren Donley, an unashamed science nerd who never misses an opportunity to share a story about bodily functions. Please note that this article is for general interest and is not a replacement for medical care. If you have any questions or concerns about your health, please contact your doctor.

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