Body hair mystery (to me)

[SueSheeMee]

Could I Google this? Absolutely. But I don't want to.

How does your body hair, other than your head hair, know to stop growing when it reaches a certain length? You can shave it or trim it and it grows back, but when it reaches that certain point, it doesn't get any longer. What's the science?

Saturday nights don't get much more exciting than this.

I need to know the answer to this! 😂

Neither of us will be able to sleep now until the clever people enlighten us. I will not Google.

😂 This has bothered me for years!

As an aside, I lost all my body hair during chemo. Including my nasal hair which I thought was great until I started getting a snotty nose. Never knew how important those hairs are for filtration 😅

Except a few times I have had a very fine hair on my back grow several inches long so sometimes the programming goes wrong!

It’s mad isn’t it. Similar to the mystery of teeth, why do we not have a third set or continuously shed them every decade? I feel like that would be quite efficient for us as predators, but also horrific.

I don’t know either but at a guess, it’s a different type of hair so it’s just ‘programmed’ to stop at a certain length.

Just Googled- yes, the follicles are different to head hair follicles. Or the ‘phases’ that the follicles go through are different.

Cheat.

😂

Teeth aren't a mystery, we are born with two sets in our skulls. Freaky.

I think with hair there is a little person inside us in charge of each follicle with a tape measure. I'm not a scientist but I think they would agree.

No idea but....once you are in menopause the leg hairs stop growing.....mine have been the same length for years 😂

Same with animal fur. Gets to the ‘correct’ length and then stops.

But how does 'it' know the length? It's just a hair? Or do follicles have brains?!
I think the PP who alluded to teeny tiny hair police with tape measures may be on to something?

My mix breed dog has two completely different types of fur which grow at different speeds and are different lengths 🤯

I've had instances of an ingrowing hair, when it is finally 'released'being far longer than any surrounding hair. This makes me think 1/ what happens if it never comes out, does it just grow and grow inside you? And 2/ it must be something to do with light.

Teeth are ridiculous when you think about it. Wisdom teeth and braces, aren't we supposed to be superior mammals?

And oestrogen is ridiculous also. It's supposed to keep you healthy but too much causes breast cancer. WTF is that all about?

Yes, I’ve changed my mind- I like the tape measure theory.

Many years ago I did my undergraduate dissertation on hair growth in pregnancy. I can bore for England on demand.
The thing about how your hair on different parts of the body grows to different lengths is boringly that it just stays in the ‘growing’ phase for different periods of time. Hair grows, stops growing then falls out.
The control of different follicles is mostly hormonal hence male pattern balding and menopausal changes.
I moved into another area of biomedical science after graduation. A few weeks of hair related research was enough…

You sound like someone I'd love to chat with. Genuinely! Although more so if you'd stuck with your hair studies...

I get what you're saying but it still doesn't make sense to me. How does a hair that was no longer in its growing phase, know that it's been cut and go back into the growing phase again until it gets back to the magical 'full length' point where it stops again? HOW?

I have a poodle. Interestingly, her fur keeps growing and growing so she needs it cutting every six weeks.

@freelancescientist, so is it the case that some people can grow their (head) hair longer than others can? Can the growth phase vary between individuals? I can’t say I’ve ever wanted to have waist-length hair like some women and girls have, but I also don’t think my hair would grow that long, the longest mine has ever been was probably bra band length when I was much younger- I think it stopped there.

My Bedlington would disagree.
He currently looks like a pile of unravelled grey knitting

All body hair like underarms and ..ahem...other area has also stopped growing . I never had leg hair anyway so dont know about that.

I knew someone who never had to get his hair cut as it never grew beyond a certain fairly short length

For most people even hair on their head only gets so long, only a few people can grow it right down to the thighs or lower. How long it can all grow is down to genetics, some people have quite long pubic hair if not trimmed.