No … This is not a review of the movie “Goose bumps”, though we may possibly discuss about your response to watching it…
Ever shuddered in fear during any scary movie (even “Goosebumps”.. Psst: I did not find it scary)? Felt the skin raise in goose bumps?
Ever shivered when stepping out of a pool and felt the breeze brush your body? Felt the skin raise in goose bumps?
Or a distant memory pleasant or unpleasant that makes your skin raise in goose bumps?
So what exactly are these goosebumps?
Why are they called so…? The term ‘goose bumps’ refer to the raised portion of the skin of a bird (be it geese or chicken), after its feathers are plucked. And that is exactly how it looks like when we get it too.
But what are those and why do they occur during specific stimulation?
Goose bumps occur during a rush of the ‘fright or flight’ hormone – adrenaline in the body. This hormone is secreted by two glands present on top of each kidney which help in the rush needed to tackle emergency situations giving one that extra boost of energy needed to ‘rise up’ (pun intended) to the situation.
The skin has many hair follicles with muscles called arrector pili, attached to it. When the muscle contracts as a response to adrenaline, it pushes the nearby skin up and the hair stands up as a consequence. This resembles the protrusions seen on a plucked goose skin, hence the term ‘goosebumps’. Scientifically they are also called cutis ansterina, piloerection or horripilation (pilo: hair; horerre: horrified; cutis: skin).
Well, that seems fine… but why is this needed?
While, it is a mystery still as to the exact advantage of getting one’s hair raised thus in humans, goosebumps have many functions in the animal kingdom. Try observing an angry cat..Back arched, tail erect, hairs upright as it snarls … T
he goose bumps (though not visible then) are responsible for the cat donning such a scary look as it appears bigger and more intimidating to its opponent as it is threatened. The same phenomenon is responsible for the erect quills of a porcupine when it is gearing up for a fight.
Animals including our ancestors, the cave men had more body hair. During the cold when the hair raises as during goosebumps, it traps another layer of air between them thereby insulating the body from the chill weather. With evolution, as humans lost most of their body hair, this is not very evident though we can visually observe the goose bumps as it happens, reminders of an ancient animal-like existence.
There are amazing conditions where a very few people may voluntarily initiate a goosebump in their body.
To sum it up, goose bumps are a response to fear, awe, distant memories, when the body receives a surge of adrenaline. 
They are vestigial (no longer useful but once was of use like the appendix, tail bone etc) to human beings in our current understanding.
So the next time you experience these bumps on your skin, remember the reason why it happens and let the pleasant sensation of knowledge wash over you as well.
Some links for those who want to Read more:
https://www.healthline.com/health/goosebumps-on-skin#other-conditions
https://www.medicinenet.com/script/main/art.asp?articlekey=6842
