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.
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.
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
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.
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.
I learned that from The Cowsills, LOL