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Edited for spelling. I have a lengthy beard and learned from a barber that hair has a ‘terminal length,’ that is, a length that it will grow out to and stop. I imagine hairs from different regions of the body have different terminal lengths but I’m speculating.

This conversation arose when I remarked that beard competitions are silly because they are merely “I avoided shaving the longest” contests. That’s when I learned not everyone could grow really long hair if they just stopped cutting it.

This is weird, right? Like the hair knows when to stop and to re-grow when cut back. 🤯

all cells are differentiated from the same genetic information. Your hair follicles are differentiated in the same way that your eyeballs are different from skin cells. Same genetic information, different expression.

As to why public hair is coarse, I beleive its because it reduces friction better and is more resilient to tangling. Pretty important to avoid infections and injuries.

The hairs on your eyebrows don't stop growing. They're always growing. It's just that the tips of them eventually wear out and break off so they never get longer than a certain length.

The different hairs on your body grow at different speed and have different durability. How long they can get before the tips to break off varies by location

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>learned from a barber that hair has a ‘terminal length'

Dont know how much of this is accurate but when l misspelled harebrained (foolish) to "hair brained" I found this interesting talk:

Your hair when it grows at full length gets phosphorus, calcium and vitamin D, making memory more efficient and gives you physical strength and better stamina.

They are coded genetically, simple as that.

Eyebrow hair has a different string of proteins in its DNA coding for its design, meaning when they form they are constructed differently.

Like the blueprints for them contain different instructions.

the normal showerstuff, no shampoo or soap

course, when i have

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this is absolute 100% bullshit...

All the hair on your body has a life cycle. It grows, falls out , lays dormant a little while then grows again. That is why people lose hair every day but don't go bald. It is also why you have hairs of different lengths all the time. The hair on your head, your eyebrows and the hair on your arms are all programed to grow for different lengths of time before they fall out.

Nutrients enter the body through two tubes at the top of your head.

That should have been your first red flag.

Coiling your hair up energizes the brain.

Come on. You can't be serious right now.

I knew something was up. My chest hair has always been the same length. I had surgery a few months ago and had it nearly all shaved. It grew back so quickly and I thought to myself "if my hair grew back to normal length in a month, why isn't it 10" long in a year?". It seems certain hair must have a "terminal length" like you suggested.

My understanding on this was that it's more about durability so your terminal hair length is when on average your hair will fall., not their maximum growth because the hair follicle know when to stop.. as far as i'm aware it's not an intelligent feature, just look like it

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This is not really true; your hairs don’t know how long they are, they grow for a while and then slow down and fall out. (Iirc they do this by growing a thinner section of hair that easily breaks off). Each follicle repeats this cycle over and over.

After a while this will result in an even hair length that depends on the length each hair grows in each cycle.

>and to re-grow when cut back.

it doesn't actually do that, you are just experiencing hair life-cycle.

hair grows out to x length, and then stays that long for however long (head hair is ~2 years, body hair can be as short as two weeks), then the follicle "dies", the hair falls off the follicle, and then the follicle regrows itself and does it all again. If you cut a hair in half it will be half as long for the rest of the life cycle - this is why regrowing cut head hair takes 2+ years to get to full length (although head hair is a bit special because it doesn't have a cap length), but e.g. chest or leg hair can recover in a month or two, and will APPEAR to recover even faster, because half your hair was at the end of the its cycle when it got shaved.

Hair is not circular in cross section, unless it's perfectly straight. Hair with oval or orregular cross section will be various forms of wavy, curly or tight curls.

As for why pubes are so curly, it's theoretically hygienic/ protection for the public region against certain things (but then promotes other things like crabs, so win some lose some on an evolutionary balance)

Depending on the place, its about style and beard quality also

I sort of worked this out from watching my dogs hair grow back. Either it falls out at a certain length (and regrows) or just stops growing.

I can't even remember the last time I had a haircut. My hair just stops growing at a certain length.

I don't really have to shave, either. My facial hair also has terminal length. I just trim it to keep it neat.

That fact would only make beard competitions more silly. It is not an action (or lack thereof) that has you succeed, but genetics.

Hair has 3 different phases in its life cycle. First the growing stage, followed by the resting stage, and lastly the final step in which it sheds and waits to regrow.

The hair on our head has a very long growing stage (several years) and then a shorter resting stage. So the body knows that hair will grow for x amount of time before tapering off.

Body hair, however, has a very short growing stage time (days) and a longer resting stage. That's why it grows in quickly but never gets long