They go by different names: goosebumps, goose pimples, goose flesh, and my personal favorite, goose bumples. They resemble goose skin after the feathers are plucked.
The medical terms for goosebumps include cutis anserine (cutis means skin and anser means goose) horripilation, piloerection, or the pilomotor reflex. These terms describe a temporary change in the skin from smooth to bumpy that most commonly occurs after exposure to cold.
But many people associate goosebumps with fear. Or, perhaps more accurately, with horror. Maybe that's why R.L. Stine named his popular series of children's horror stories, published in the 1990s, Goosebumps.
Ever wonder why you get goosebumps? Do they serve a purpose? Why do they develop when we're frightened?
Goosebumps occur when tiny muscles flex in the skin and cause hair follicles to rise up a bit and hairs to stand up. Goosebumps are an automatic response. Nerves from the sympathetic nervous system — the ones that control the "fight-or-flight" response — also control these skin muscles.
In the animal kingdom, a threatened animal has a similar reaction. Its fur will puff out a bit. This makes the animal appear bigger and more dangerous. Perhaps the most dramatic example is the porcupine. Its quills puff out when they sense danger. This can make a menacing enemy think twice before attacking.
Goosebumps may help to conserve heat when you're exposed to cold. They may do this in several ways:
Each of these might be more important for furry animals than for humans. In fact, it's not clear how important goosebumps are in humans. For example, if you couldn't form goosebumps at all, it's not clear that you'd have problems with temperature control.
Goosebumps may be one of those "leftovers" from our evolutionary ancestors (like the coccyx, or tailbone) that serves no important purpose.
Most people associate goosebumps with unpleasantness such as feeling particularly cold or feeling afraid. Yet, there is more to it than that.
Because the arrectores pilorum are hooked up to the sympathetic nervous system, which has input from many parts of the brain — including those involved with motivation, arousal and emotion — other stimuli may cause goosebumps, including:
Though rare, goosebumps can be a sign of a seizure disorder (called temporal lobe epilepsy), a disorder of the sympathetic nervous system, or a brain tumor. They are also common during heroin or other opiate withdrawal. In fact, the term "quitting cold turkey" refers to the presence of goose bumps (that mimic cold turkey flesh) during withdrawal from heroin. (The term could also have come from the expression, "talk turkey," meaning to speak bluntly or directly, without preparation.)
Goosebumps are universal, but poorly understood. As a remnant of evolution, perhaps they'll fade away over the coming centuries. Or, they may serve a more important role than is currently appreciated. You'll see them most often when you're cold. But don't be surprised (or afraid or awed) if they may appear at other times.
Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.