How do we know?
↻ One of the pages with a moving picture
A powerful microscope showed nerves wrapped around hair cells.
- When you get cold, a nerve in your skin sends a signal.
- A tiny muscle attached to each hair squeezes and pulls the hair up. The skin around it makes a little bump: a goosebump!
- Animals with thick fur fluff up, which may help them stay warm. Humans have thin body hair, so we don’t seem to benefit much.
- In mice, scientists found the same nerve also helps new hair grow when the cold lasts a long time.
Using a powerful electron microscope, the team saw nerve fibers wrapped around hair stem cells like a ribbon. They reported their findings in mice in 2020.
In mice, scientists found the same nerve also helps new hair grow when the cold lasts a long time.
Scientists at National Taiwan University teamed up with a Harvard lab to study goosebumps in mice.
Wow number
2 jobs In mice, one nerve does 2 jobs: it makes goosebumps right away, and later it helps grow new hair!
Myth or fact?
Goosebumps keep people much warmer. Myth. Furry animals may get some warmth, but humans don’t seem to benefit much.
A muscle makes each goosebump. Fact. A tiny muscle pulls the hair up and makes the bump.
Think about it
Humans have very little body hair. Why do you think we still get goosebumps?
Where in the world?
Taipei, Taiwan where scientists at National Taiwan University teamed up with a Harvard lab to study goosebumps in mice — 25.033° N, 121.5654° E.
Where these facts come from
Every number on page 74, and who measured it
This page tells us about the tiny muscle and nerve that make goosebumps.
The real reason behind goosebumps — Harvard's Department of Stem Cell and Regenerative Biology
hscrb.harvard.edu/news/the-real-reason-behind-goosebumps
We checked it on 31 October 2026
This page tells us how goosebump nerves also help hair grow, in mice.
The hair-raising reason for goosebumps is revealed — The Harvard Gazette, Harvard University's news site
news.harvard.edu/gazette/story/2020/07/the-hair-raising-reason-for-goosebumps-is-revealed
We checked it on 31 October 2026
This is the goosebumps study itself, which shows the nerve wrapping around the hair's stem cells.
Cell types promoting goosebumps form a niche to regulate hair follicle stem cells — The goosebumps science paper from the journal Cell, shared by the U.S. National Library of Medicine
pmc.ncbi.nlm.nih.gov/articles/PMC7540726
We checked it on 31 October 2026
This page also tells us how tiny muscles pull hairs straight up.
Goose bumps — Wikipedia, a free online encyclopedia
en.wikipedia.org/wiki/Goose_bumps
We checked it on 31 October 2026
Has this changed?
Why we get goosebumps is not going to change.
This was found out in mice, so scientists are still checking what it means for people.
Words from this page
- nerve
- A thin cord that carries signals between your body and your brain.
- goosebump
- A little bump on your skin that appears when a tiny muscle pulls a hair up.
- stem cell
- A cell that can grow into other kinds of cells, like new hair.
Try it!
Watch for goosebumps.
1. Look closely at the hairs on your arm with a magnifying glass. 2. Ask a grown-up to point a fan (on low) at your arm for a minute. 3. Look again. Do the hairs stand up? Can you see little bumps?
What happens: cool air can make tiny muscles pull your arm hairs up into goosebumps.
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