I looked out the airplane window and then at my 20-month-old, who had no idea that after enjoying the warmth of Florida for two weeks, we were about to enter the frozen tundra of Montreal. “Get ready, Zoe. It’s going to be cold when we go outside!” And as if instinctively, I started chattering my teeth, as one normally does when they’re shivering from the cold, and she looked at me in bewilderment. She’s too young to string together full sentences, but her furrowed brows said it blatantly – “Mommy, what are you doing with your teeth??” Good question, I thought…
Shivering is our body’s way of raising its core temperature to bring it back to a state of homeostasis. We do it to keep us warm. So, if body temperature dips below the normal 98.6° F (37° Celsius), we will start shivering, which will then cause muscles to contract and then relax very rapidly, thereby expending energy to warm up the whole body. These muscle contractions cause limbs to shake and also teeth to chatter. Shivering, similar to blood pressure and heart rate, is an automatic and totally involuntary function that the body performs to regulate itself.
A study done on rats (yes rats, because while they aren’t humans there are many parallels as to how rats and humans sense and regulate heat) traced the shivering sensory pathway from the rat’s skin cells to specialized brain cells. These cells can then transmit this information to another part of the brain that decides when the body should start the shivering response. These two systems are triggered both at once – one causes the brain to say “I’m cold!” while the other, at the same time, is what causes the shivering to occur.
And then there’s that one-second feeling of chills going up the spine that quickly comes and goes. These shivers occur during moments of excitement or distress and are triggered by the release of certain chemicals. In a frightful situation, a shiver is caused by the release of adrenaline and noradrenaline which produce the fight-or-flight response. In mythical literature, this type of shiver has been referred to as “somebody walking over your grave”, suggesting that experiencing this sudden sensation is caused by walking over the place of one’s eventual grave. The phrase was apparently coined hundreds of years ago to refer to British prisoners who were marched out of their cells to be hanged, walking across their own burial site. Yikes. I have shivers just thinking about that one.
On a happier note, in an excitable moment, one may experience a shiver due to the release of dopamine, the pleasure hormone.
And then there are goosebumps, or “goose pimples,” as some people call them. Like shivers, goosebumps are another way that the body responds to emotion or stress. Think about it – you’re cleaning the house, vacuuming away while listening to music – and all of a sudden, your favourite song comes on, and just as it’s ramping up to the chorus, you start to get goosebumps up your arms. This feeling of intense emotion, brought on by Lizzo no doubt, causes the hypothalamus to send a signal to our bodies to release adrenaline in our blood, which then triggers the arrector pili muscles on our skin to contract, causing our hairs to stand on end. This is also why we literally get chills up and down our spine. We are just such emotional beings! [Sidenote: this is when, of course, one would naturally put down the vacuum for a dance break].
From an evolutionary perspective, we get goosebumps from our animal ancestors. When they were cold, the hair on their bodies would stand up, adding an extra layer of insulation. Goosebumps also played a role in how animals react toward one another. When feeling threatened, one wants to look as large as possible. And so, hair and skin expanding and standing on end was one way of doing so. [some food for thought: 80’s hairstyles = threatening?]
But back to reality, as we step out of the airport into the taxi line, I see that thanks to global warming, Montreal is actually rather mild and the snow has melted. In fact, I’m not shivering at all and my body temperature is right where it should be. Even Zoe is too warm in her bulky Patagonia that I made sure to get her in before stepping outside. We get into the taxi, (still sans shivers, I can’t believe it), and our girl Lizzo is belting on the radio. And just as the music swells with her rousing “I do my hair toss, check my nails, baby how you feeling?”, there they are - those goosebumps running along my arms. I’ll take a good shiver thanks to a surge of dopamine over a drop in body temperature any day. Thank you, Lizzo.