Yahoo News: Experts explain the wild reason we get goosebumps

Prevention reported that goosebumps are called “cutis anserine” or “piloerection.” The former literally means skin (cutis) goose (anser), and riffs off of the appearance of raw poultry skin after its feathers are plucked.

The latter title stems from the arrector pili muscles, the smooth muscles responsible for the physical response. They contract, pulling body hair that typically lays an at angle to stand upright, which creates a visible bump at the site of a hair follicle, says Mutasim. “When this happens, it involves all hair follicles in an area of the body, hence goosebumps,” he adds.

In short, goosebumps are triggered by various stimuli, including cold temperatures and emotions like fear, surprise, or other intense feelings, says Mutasim. And as a function of the sympathetic nervous system, they happen involuntarily.

But why are they triggered in the first place? That’s where things get interesting. Goosebumps are believed to be an evolutionary fight-or-flight response “left over from earlier animals,” explains Mutasim. When wild mammals are cold, goosebumps trigger their fur coats to stand taller, inviting additional insulation and warmth. In a study on mice, researchers found that they could also stimulate hair growth to provide warmth long-term. “Humans do not have enough hair for the phenomenon to be beneficial to protect against cold weather, yet the phenomenon persists,” Mutasim adds.