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Comment on What's the evolutionary advantage of very long hair on human heads?

mech@feddit.org ⁨3⁩ ⁨weeks⁩ ago

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.

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jumperalex@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

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.

Perhaps the hair change was the result of some other gene expression that was beneficial while the hair change itself was neutral-ish.

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Klear@piefed.world ⁨3⁩ ⁨weeks⁩ ago
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!!!!”

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- myrmidex@belgae.social ⁨3⁩ ⁨weeks⁩ ago
  You had it: people whose hair didn’t smell when burning died more often, skewing the chances of survival towards smelly-when-on-fire hair.
  
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  - TheLunatickle@lemmy.zip ⁨3⁩ ⁨weeks⁩ ago
    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.
    
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  - ParlimentOfDoom@piefed.zip ⁨3⁩ ⁨weeks⁩ ago
    How often were people catching on fire and not noticing that this would cause any kind of selection criteria?
    
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    Aeao@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
    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.
    
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    myrmidex@belgae.social ⁨3⁩ ⁨weeks⁩ ago
    Does the subject’s awareness of the selection matter?
    
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  - SpacetimeMachine@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
    People would not have been catching their hair on fire when the only fire they would encounter was natural wildfires or bonfires.
    
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  - Klear@piefed.world ⁨3⁩ ⁨weeks⁩ ago
    Not what I was wondering about, but thanks.
    
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Swaus01@piefed.social ⁨3⁩ ⁨weeks⁩ ago

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

It feels cool to have curly hair despite being from a long line of cold climaters.

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ShellMonkey@piefed.socdojo.com ⁨3⁩ ⁨weeks⁩ ago
Way I figure, the common traits for any given part of the world where as much influenced by the isolation of groups as environmental factors. Back in primitive times it could take months wandering before you happened across another group, and even then there may be ‘untrusted tribe’ type conflicts.

It still shows up today in how rural isolated communities tend to foster more prejudiced attitudes towards people different from them. But now we can move all over quickly and communicate instantly, so there’s a less concentrated effect by location. Plus the whole advent of ordered society and the host of factors that brings into play.

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Mothra@mander.xyz ⁨2⁩ ⁨weeks⁩ ago
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.

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