Comments

You must log in or register to comment.

Ansuz07 t1_j2drvfc wrote

It is a vestigial reaction back from when humans used to have much more body hair.

Goosebumps cause our body hair to stand up on end. When we were much hairier, this had two effects:

  • Trapped more air near the skin, warming us up (like a natural sweater).

  • Made us look larger and less attractive to preditors.

While the hair has evolved away, the goosebump reaction remains when we get cold or scared.

4

Pandalite t1_j2dun7z wrote

Even shorter- you know how a cat puffs out its hair when it's scared or cold? Humans do the same thing except we're not furry like that anymore.

More info:

There are little muscles in hair follicles that make them stand up. It's called piloerection. It's controlled by the sympathetic nervous system.

1

NobblyNobody t1_j2dva92 wrote

but what's the actual mechanism?

something in the follicles?, muscular, or fluid moving around? why does the skin feel tighter? where does whatever the bumps are made of go afterwards, why didn't that mechanism go when we lost the hair - does it serve another purpose most of the time?

1

Ansuz07 t1_j2dvj9o wrote

There are small muscles attached to each hair follicle. When those muscles contract, the skin tightens up and the hair stands on end. When they relax, the bump goes away.

As for why they are still there, evolution doesn't have a goal - it rewards what works. There was never a benefit in the reaction going away, so it never did.

2

NobblyNobody t1_j2dwwh3 wrote

kinda mind blowing there is a tiny muscular infrastructure there still, like almost everywhere, just doing nothing most of the time.

1

wjbc t1_j2dsfk3 wrote

Apparently goose bumps are a relic of our ape-like ancestors. Back when our ancestors were covered in fur, the goose bump reflex would make their fur rise and make them look bigger. This was useful in scaring off predators.

It was also useful when cold, because it would create a layer of air for insulation. This reflex is common in many mammals, and is most obvious in porcupines, since they have long quills.

Now that our hair is sparse it doesn't do us much good. But we still have some vestigial body parts (like the appendix) or reflexes (like goose bumps) that used to be more useful.

1

zeiandren t1_j2dttea wrote

You know that thing where a scared cat gets all puffed up to look big?

Imagine instead of cool cat hair you just had tiny little arm hairs. That’s a goosebump

1

Flair_Helper t1_j2dz6q8 wrote

Please read this entire message

Your submission has been removed for the following reason(s):

  • ELI5 requires that you search the ELI5 subreddit for your topic before posting. Users will often either find a thread that meets their needs or find that their question might qualify for an exception to rule 7. Please see this wiki entry for more details (Rule 7).

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.

1