Secondary shower thought, an image of Captain Caveman should be the image representing humans on the Wikipedia page.

Tertiary shower thought, we probably started wearing clothes because our own hair used to be our clothes, and we wanted to replace the hair we cut off when we started grooming.

Not so. Your hair and nails have a built-in, genetically predetermined, maximum length. Once they reach that length, they'll stop growing.

For most people, they'll never get anywhere near the limit. But it's there; your hair won't continue to grow and grow like Rapunzel.

IIRC some hairs have maximum length limit and some will keep growing, generally based on position on body. Eye-lashes and most body hair being of the former, while skull and beard hair being of the latter.

You can see pictures online of people who've let their head or beard hair grow for years, and the results can be pretty amazing. Ditto finger nails.

Examples:
https://www.google.com/search?q=person+who+let+their+fingernails+grow+for+years+and+years&udm=2

Technically, it goes down roughly to your thighs. I was being hyperbolic for humorous effect. But Captain Caveman is probably closer than most depictions of prehistoric man. David Letterman has a longer beard than any of the artistic depictions I've seen of a human in their natural state.

What is Captain Caveman?

1970's cartoon character, all hair, big wooden club.

... I haven't cut* my hair in over a decade, and it's been more or less the same length for the past 3-4 years. After a certain point your hair falls out regardless of cutting, and for most people that's around 7 years.

• The sides of my head are shaved, but the top and back have not been cut, or trimmed since late 2015

EDIT: Forgot to include the actual length, which is core to the point. It's about waist-length for me, but some people's hair does get longer.

I learned that from The Cowsills, LOL

What makes you think that people haven't been cutting their hair since forever? Our ancestors who came before homo-sapien had cutting tools. Hair can also be burned by the fire they could also make. I'd imagine hairstyles are older than humanity.

I get "angry" (I don't know, some emotion forces me to take action) when there is a hair in my field of view.

I'm guessing if vision is so important for modeling the world that they'd die without it, they'd do something about it (bind / cut / burn)?

Although peoples hair has a max length that is dependent on the person and the situation. That is why people growing out hair need to have dead ends cut off so that it will grow more. I would not be surprised if like the zz top guys had to so something similar to get that length.

oh man, your one of todays lucky 10000. https://hanna-barbera.fandom.com/wiki/Captain_Caveman https://youtu.be/wVuvnWd9X3k

Yeah. If prehistoric humanity is anything like current humanity, lots of people have been cutting their hair since time immemorial for vision and annoyance reasons alone.

This isn't entirely accurate. The length limit doesn't check if they reached it. Hairs are dead tissue. Instead it is the amount it grows by before falling out.

Nails tend to not fall out but experience Abrasion from use.

Irritated, annoyed.

Cutting dead ends doesn’t promote growth, but it prevents the hair from getting shorter. Split ends (being finer) are weaker and more liable to break, tangle, get caught in a brush, etc. Cutting them off stops the split from getting longer.

It's not that hair knows it's length and stops growing until you cut it, there is no mechanism for it to register its own length. Rather, there is a natural rate at which hairs will break or fall out and begin to grow again, and so a person's hair can only get so long before the longest hairs are due to be culled.

Re: tertiary shower thought: I think that was a theory for intelligence development, but also because less grooming.

Hair is a nice place for parasites to live in. That's why monkeys spend so much time grooming. If we're too lazy to groom, we evolve to not have hair, so the parasites don't have a hairy nest to snuggle up in. Then we evolve the big smart because it's cold out and now you need a jacket.