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Thread: Selection pressures for long hair and beards in humans?

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    Veteran Member excreationist's Avatar
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    Selection pressures for long hair and beards in humans?

    Maybe there is a good answer...

    but anyway let's say there was an ape-man with very short head hair.... then after a long time basically every single human had long hair (and long beards for the men). For all humans to have it then there must have been selection pressures to have hair that grows to a few feet in length...

    Here are some humans that lived in a primitive way:



    So why would there be selection pressures for the hair to consistently grow long if most humans are just going to cut it - like in the photo where it is cut very short.... in this picture their beards have been shaved off....

    The fact that basically every single human can grow long hair and beards suggests that there must be a very important reason for it.

    I get the impression that it is for self-expression - there is a huge amount of variety of hair styles and beards, etc.... though I'm not sure if that is a strong enough selection pressure to affect our ancestors in a way that affected basically all humans....

    For me this is an example of guided evolution....

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    Veteran Member excreationist's Avatar
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    Well apparently humans are able to chase after most animals until the victim collapses because humans are able to sweat. I think horses are similar - they also have good endurance and can sweat. And horses have long head hair... maybe it lets them keep the sweat for cooling... maybe the head hair can also help keep the sweat cool us in humans

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    Contributor DrZoidberg's Avatar
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    Quote Originally Posted by excreationist View Post
    Maybe there is a good answer...

    but anyway let's say there was an ape-man with very short head hair.... then after a long time basically every single human had long hair (and long beards for the men). For all humans to have it then there must have been selection pressures to have hair that grows to a few feet in length...

    Here are some humans that lived in a primitive way:



    So why would there be selection pressures for the hair to consistently grow long if most humans are just going to cut it - like in the photo where it is cut very short.... in this picture their beards have been shaved off....

    The fact that basically every single human can grow long hair and beards suggests that there must be a very important reason for it.

    I get the impression that it is for self-expression - there is a huge amount of variety of hair styles and beards, etc.... though I'm not sure if that is a strong enough selection pressure to affect our ancestors in a way that affected basically all humans....

    For me this is an example of guided evolution....
    What do you mean by guided evolution? Evolution is just a mechanic. Evolution guides itself. What's an unguided evolution? I'm just trying to understand what you mean by using the word "guided"?

    Not every single human. Only men can grow beards. Since humans travelled together, and basically kept pace with one another, it doesn't make sense that beards are only beneficial to men or necessary in any way.

    Anything that's selected for and weird is usually sexual selection. Giraffs for example. Male giraffes make massive swings with their heads into eachother. Whoever makes the most spectacular bash gets the ladies. Which makes long necks selected for, in a grazing animal that mostly eats grass from the ground, needs to bend over awkwardly just to eat, and who would benefit being able to outrun beasts of pray, which it can't. It's an example of sexual selection going nuts.

    Peacock feather patterns are very sensitive to genetic defects. It allows female peacocks to quickly see which males are healthy. I suspect long human hair has a similar function. Humans who aren't eating properly or are seriously ill, it shows up in hair super fast. Thick shiny hair is associated with youth and health. So having long, thick and shiny hair will be sexually selected for. Any trait that is associated with the other gender, uniquely, will only be selected for in that gender. Which can explain why only beards in men. Even though it might on some level be functional, the fact that it's missing from women tells us that it's not only functional. It signals masculinity. Just like boobs (functionally useless) signals femininity.

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    Contributor DrZoidberg's Avatar
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    Quote Originally Posted by excreationist View Post
    Well apparently humans are able to chase after most animals until the victim collapses because humans are able to sweat. I think horses are similar - they also have good endurance and can sweat. And horses have long head hair... maybe it lets them keep the sweat for cooling... maybe the head hair can also help keep the sweat cool us in humans
    You can't really compare them. Remember that for most of human evolution humans had curly hair. Yes, the afro. It's main function seems to be to protect the head from the sun when we started walking upright. But since humans lived in wide open plains they should have been hair all over any surface exposed to the sun all day. So it's not a rock solid theory.

    Straight hair is a pretty recent human evolution. And that seems to be purely sexually selected for. Since it's in no way more practical. Remember that combs is something that only came later in human evolution.

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    Veteran Member excreationist's Avatar
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    Quote Originally Posted by DrZoidberg View Post
    What do you mean by guided evolution?....
    This is the Religions vs. Science forum.... I was playing around with the idea of an intelligent force guided evolution with goals in mind...

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    Veteran Member excreationist's Avatar
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    Quote Originally Posted by DrZoidberg View Post
    ....Remember that for most of human evolution humans had curly hair. Yes, the afro....
    https://en.wikipedia.org/wiki/Human
    "....Homo sapiens also appearing around 300,000 years ago in Africa...."

    If it is so useful (in order to have been selected for) why do most people, like the Bushmen, trim it so much? Maybe you're right it just doesn't make as much sense as I'd hope. Also I've never seen a picture of a primitive person (from 100,000s of years ago) with an untrimmed afro

    Also apparently people could create fire for more than 300,000 years.... so they are capable of making a hat.... though Bushmen don't seem to need a hat...

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    Quote Originally Posted by DrZoidberg View Post
    Just like boobs (functionally useless) signals femininity.
    I'm hoping you mean boobs on men are functionally useless...because breasts for females are probably one of the most important genetic advantages we have as a species (ability to feed young)...

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    Contributor DrZoidberg's Avatar
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    Quote Originally Posted by excreationist View Post
    Quote Originally Posted by DrZoidberg View Post
    What do you mean by guided evolution?....
    This is the Religions vs. Science forum.... I was playing around with the idea of an intelligent force guided evolution with goals in mind...
    Well.. an intelligent force didn't guide evolution. Or we'd have some evidence of it. Not the result of randomly combining things in a godawful mess of complexity... which we have now. There's as much stupid design in our bodies as clever design. More. There's so much in our bodies that's just plain dumb.

    Unless you are claiming that God is an idiot. But that rules out the "intelligent" part of intelligent design.

    What trips up creationists is the time aspect. If you have enough time on your hands just randomly combining things can result in amazing complexity and beauty. And stuff that works. What we have now is the result of 4 billion years of evolution. That's a very long time. No intelligence is needed for this.

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    Contributor DrZoidberg's Avatar
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    Quote Originally Posted by Sajara View Post
    Quote Originally Posted by DrZoidberg View Post
    Just like boobs (functionally useless) signals femininity.
    I'm hoping you mean boobs on men are functionally useless...because breasts for females are probably one of the most important genetic advantages we have as a species (ability to feed young)...
    Nope. There is no relation between breast size and ability to produce milk. Functionally big boobs just give women a back-ache. In lean times the fat that goes to milk can be taken from the belly and thighs, just as well from the breasts. So there's no reason the fat should be stored high up on the chest. A terrible place to store fat in a species with a weak midriff and that walks upright.

    It's just sexually selected for. It has no function other than to attract men sexually.

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    Contributor DrZoidberg's Avatar
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    Quote Originally Posted by excreationist View Post
    Quote Originally Posted by DrZoidberg View Post
    ....Remember that for most of human evolution humans had curly hair. Yes, the afro....
    https://en.wikipedia.org/wiki/Human
    "....Homo sapiens also appearing around 300,000 years ago in Africa...."

    If it is so useful (in order to have been selected for) why do most people, like the Bushmen, trim it so much? Maybe you're right it just doesn't make as much sense as I'd hope. Also I've never seen a picture of a primitive person (from 100,000s of years ago) with an untrimmed afro

    Also apparently people could create fire for more than 300,000 years.... so they are capable of making a hat.... though Bushmen don't seem to need a hat...

    Sure, homo sapiens arrived on the scene 300 000 years ago. But Australopithecus also walked upright. And they've been around for 6 million years.

    A big problem with hats and other soft materials is that they don't survive fossilisation. So we have no idea when people started wearing hats. But it's a safe bet that humans didn't start wearing clothes until after we left Africa. We evolved to live in Kenya. In that environment we will never need clothes. So there's no reason to think we started covering up while still in our native lands.

    It's deceptive to use modern Bushmen as a straight up analogue of our hunter/gatherers ancestors. The communities of modern Bushmen are living in extremely inhospitable environments, pushed there by farmers who displaced them. The only regions Bushmen have survived is in regions unsuitable for farming. That means that it's hard to survive in general. Selections of clothing and diet might be simply down to necessity rather than choice. They live a much harsher lifestyle than our ancestors would have had. Their ancestors might have had big afroes and hats.

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