Most mammals seem fine with shorter hair (usually denser though). The only other case that comes to mind of very long hair restricted to a specific body area is that of horses manes, which to be fair I’m also not totally sure what purpose it serves. Many equines seem fine with shorter manes and tails that don’t have such long hair, like zebras. They swish flies away all the same.
Some animals have long hair but it covers most of their bodies (like llamas or yaks maybe), it’s not restricted to a small area. Other animals have denser or longer hair in some areas, like lions, but this serves a purpose (protection of the neck and head) and even then the length ratio between these longer hairs and the rest of the fur isn’t as skewed as that of humans.
So, why? I get that hair on the head helps protect it from the elements and sun, but why so long? Some humans can grow hair longer than their own body length, which is remarkable, and without doing any fact check I’d say we are probably among the top 5 species with longest hairs ever. Is it just a showoff feature like a peacock’s tail feathers, an indicator of overall health? Or does it serve another function as well?
I didn’t mean to type this wall of text…, thanks for coming to my TED talk
Evolution doesn’t produce perfect adaptations, just “good enough”.
Humans lost their body hair and got more on their head when they developed walking upright in Africa.
Lets sweat cool the body down and protects the head from the sun.
At some point, something lead to a mutation that turned curly hair into straight hair, and that seems to have been selected for in populations living in colder climates.
But that doesn’t mean it increased chances of survival. Maybe it was just preferred by sexual partners for some reason, which may even have been cultural at that point.
Yes I understand “good enough” and that it could just be out of whimsical preference by sexual partners. But what if not? The best answer I found here was that greasy long hair, in those cold climates, was somewhat water repellant. Nobody wants to get wet in the cold.
Perhaps the hair change was the result of some other gene expression that was beneficial while the hair change itself was neutral-ish.
This reminds me of something I’ve been wondering about for a while now - burning hair has a distinct and very strong smell. That makes sense - if your hair is on fire, you want to know ASAP. My question is whether our hair evolved to have something in it that produces this smell, or if we just evolved to be particularly receptive to the smell of burning keratin.
That is of course ignoring the boring answers: “A little bit of both” and “It just worked out like that randomly”, as well as the best answer “Wait, that’s what that smell is?! Oh shit, you’re right, I’m burning! AAAAAAAA!!!”
You had it: people whose hair didn’t smell when burning probably died more often, skewing the chances of survival towards smelly-when-on-fire hair.
All hair smells bad to us when burnt, not just human, ergo it’s unlikely that it’s some human specific adaptation. It seems more likely that it’s related to avoiding wild fires than anything else.
How often were people catching on fire and not noticing that this would cause any kind of selection criteria?
People catch on fire a lot actually. I’ve caught my hair on fire dozens of times. It didn’t cover my whole head on fire because I noticed and put it out. Having long hair and cooking over a fire …. You’re occasionally going to catch on fire.
But did you notice because of the smell? Or because your head was on fire?
Smell. I noticed it before it reached my skin.
Yea in our modern society sure. But not for the last 250,000 years of human evolution.
“Having long hair and cooking over a fire” - me
Yeah I’m sure it happened alot
Does the subject’s awareness of the selection matter?
The premise here was that they noticed in time to not die… So, yes?
Ah I misread it.
I reckon it’s not so much about noticing in absolute terms (to notice vs not to notice), but rather about the smallest difference that smelly hair would make. Amplify that over millions of years and smelly hair has a good chance of being everywhere eventually.
I dunno. I’m just having trouble conceptualizing any kind of scenario that could happen with enough frequency to cause this trait to be selected for.
I think it’s more likely that the chemicals in hair just happen to smell bad when burnt. Those chemicals may have been filtered for other reasons.
Yea that could also very well be, that it was pre-existing and had no impact during evolution. I could see there being an evolutionary advantage to hair smelling bad. That’s as far as my confidence and knowledge reaches on the matter. Very interesting nonetheless! :)
People would not have been catching their hair on fire when the only fire they would encounter was natural wildfires or bonfires.
Not what I was wondering about, but thanks.
It feels cool to have curly hair despite being from a long line of cold climaters.