Why do we get goose pimples (or goose bumps) when we are cold?

MaggieG 5

It seems that this reaction is a leftover from the time when our ancestors were hairier than we are now. Cold air causes the muscles at the base of our skin to stiffen and this makes the small hairs in our body stand up. If we were hairier this would allow us to trap more air between them and it would insulate our bodies against the cold. Other animals with hair and birds still use this mechanism to protect themselves from cold weather. Nov 07 03, 3:30 PM

sequoianoir

Going back to the days when we didn't wear clothes but were covered with hair, this would have made them stand on end, "trapping" more air close to the skin (stopping convection more than anything else) and providing a more effective insulating layer against the cold. Nov 07 03, 3:30 PM

Brainyblonde

Goose bumps are a temporary local change in the skin. The chain of events leading to this skin change starts with a stimulus such as cold or fear. That stimulus causes a nerve discharge from an involuntary portion of the nervous system called the sympathetic nervous system. The nerve discharge causes contraction of little muscles called the arrectores pilorum (the hair erector muscles). Contraction of these muscles elevates the hair follicles above the rest of the skin. And it is these tiny elevations we perceive as goose bumps. http://www.medicinenet.com/script/main/art.asp?articlekey=6842 Nov 08 03, 10:49 AM