A very cute, music-loving cartoon I found from here
It happened just a few days ago. I was listening to music, the grand crescendo swelling louder and louder in my ears - then suddenly I felt a crawling sensation all over my body. I looked down, and realized I had goosebumps on my arms. I wondered why it happened in the moment, then promptly forgot about it. The next day, when thinking about what to write for this blog post, I remembered the interesting occurrence and realized it would be a fun topic to discuss for this project. Thus, my journey searching for the source of those mysterious goosebumps began.
What are goosebumps?
Goosebumps, or goose-pimples, get their funny-sounding name from their appearance, as they resemble the little bumps left on a goose's skin when its feathers are plucked. Goosebumps are the bumps on a person's skin at the base of body hairs, and are often caused by cold, or strong emotions.
Goosebumps on a person from Wikimedia
How do we get them?
Cold and strong emotions are physiological states that trigger an autonomic nervous system in your body called the sympathetic nervous system. The sympathetic nervous system is responsible for several fight - or flight responses, which are your body's physiological reactions that occur in response to a perceived threat to survival. As part of this response, your hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands, which leads to the rapid secretion of adrenaline by your adrenal glands, which are located above the kidneys.
What is adrenaline?
Adrenaline, (also known as epinephrine) is a hormone that plays a key role in your body's flight-or-fight response by increasing the output of the heart, blood flow to the muscles, blood sugar, and pupil dilation. Adrenaline can also cause sweaty palms, tears, trembling hands, increased blood pressure, and a rapid heartbeat. Adrenaline is a catecholamine hormone, and is responsible for causing goosebumps by inducing a contraction of the arrector pili muscle (a process called piloerection) at the base of your hair follicles. It does this by binding to adrenergic receptors and activating them. (You can read more about adrenergic receptors here) When activated, the α1 receptor triggers smooth muscle contraction in blood vessels in the skin, as well as in the gastrointestinal tract, kidney, and brain, among other areas. This makes your skin pull tight and forms an indentation in the area around the follicle, making the goosebumps pronounced. Professor William Griffith, head of the Department of Neuroscience and Experimental Therapeutics at the Texas A&M College of Medicine, explains that intense emotions can trigger the same release of adrenaline via the hypothalamus as a fight-or-flight response. It also explains why goosebumps make your hairs stand on end, and why we don't ever get goosebumps on our faces, because the hair follicles on your face are too close together.
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Scientists consider goosebumps to be a vestigial trait. Vestigial traits are traits that have no apparent function and appear to be residual parts from an ancestor. Examples of vestigial structures include the human appendix, the pelvic bone of a snake, and the wings of flightless birds. Learning this, I realized that goosebumps had to have had a function to our early ancestors. But after doing some more research, I was surprised to learn just how helpful goosebumps actually were in aiding our ancestors to survive in a variety of ways. Since goosebumps make your hairs stand up, they made the early humans (who had a furry coat) seem larger to predators, scaring the predators off and increasing human chances of survival. A perfect example of this still happening today is when all of the hairs stand up on a cat when it's startled. The early humans that got goosebumps were more likely to survive predation and thus pass their genes for goosebumps on, which is selection for the goosebumps trait. The upright hairs also served as insulation and an indicator of low body temperature, as well as let the early humans know that they needed to find warmth. More than a million years ago, our ancestors began shedding their thick coat of hair, and goosebumps’ usefulness plummeted. Today, we humans have about 5 million body hairs, roughly the same as a chimp. But our hairs are much finer, rendering goosebumps a useless relic- although all humans still get them. We still get goosebumps because vestigial structures (especially non-harmful ones) take a long time to be phased out, since eliminating them would require major alterations that could result in negative side effects.
Getting goosebumps might still be strange to you, but the next time you get them listening to your favorite song, just know they were once an trait that helped your early ancestor to survive long ago.
Wow Caitlin!! This is so informative and fun to read! I had no idea how goosebumps worked, and they're much more complicated than I expected! I always wondered what their purpose was, so it's interesting to learn that they're vestigial. The image of a super hairy human puffing out their fur with goosebumps is making me laugh, but it totally makes sense! Great job!
ReplyDeleteWoah Caitie! This is so cool. I had no idea that goosebumps actual purpose was to make us seem bigger by raising hairs. I had never thought about it before. It's so cool too how music can affect you so much that it triggers adrenaline and a physical reaction. Very interesting article!
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