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Anonymous
Anonymous asked in Science & MathematicsBiology · 2 years ago

From an evolutionary perspective, what is hair on our head designed for?

I know you don't like the word designed but I don't know another word besides maybe "EVOLUTIONARY DESIGNED"

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  • 2 years ago
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    We evolved from an ape, and apes live inside forests. Forests are shady and they have a full body of fur. Our ancestors were apes that were unable to maintain a territory inside the forest, and they were forced to eke out a living in the open African savanna, where it is hot and there is little shade. To adapt to the new environment, humans evolved a nearly hairless body since fur would not allow excess body heat to be lost as easily. We also evolved a lot of sweat glands to further cool our body. When sweat evaporates from our skin it requires energy, and that energy comes from our body. Because we lost most of our body hair, we also needed eumelanin to block cancer causing UV light from the sun. Eumelanin is black to dark brown in color, and it made our skin dark.

    Light skin only evolved later when Africans migrated out of Africa 60,000 years ago and the migrants evolved to be non-Africans. Humans still have some hair on our bodies, and they serve different purposes. The eyebrows prevent rain from getting inside our eyes. The armpit and pubic hair trap phermones released by skin glands and the phermones attract the opposite sex. The hair on top of our head shields our brain from being overheated by the hot sun. Originally all people had curly hair, with air space betwen the hair and the scalp. The air space acts to trap cool air to insulate us from the hot sun. Straight hair evolved when some people migrated to cold climates. The straight hair eliminates the air space between hair and scalp to prevent cold drafts from chilling our heads. In fact, Africans who live in cold climates wear hoodies or hats to keep cold drafts from chilling their head. In contrast, Asians who live in SE Asia often have to carry umbrellas to shield their head from the hot sun because many of them have straight hair. Those who have straight hair evolved in north Asia, and their ancestors migrated south to hotter climates after the invention of agriculture and the population ballooned up north.

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  • 2 years ago

    Hair over the entire body generally leaves the head last, it's a warming thing. Or helps with sexual selection in the species.

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  • 2 years ago

    the phrase that would most likely fit is "what benefit does head hair provide that makes it a fairly universal feature"? Not all features exist because of a beneficial positive feedback loop. Many are neutral. However, universal features tend to be linked to survival and reproduction so something like the unique distribution of human hair to the head, armpits, and genitals means that the hair does provide some benefit.

    I would suggest two likely benefits: protection against excessive sun (head hair) and excessive temperature (insulation), and a sexual desirability role. Sexual dimorphism is often explained by reproductive selection effects (mate choice). Men have beards but women don't. This suggests that manliness and facial hair have a link even if only a perceived link rather than a real one.

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  • 2 years ago

    People who had hair on their head tended to have more kids and grandkids, compared to bald people. Maybe it was because they were more attractive to mates. Maybe it was because they got less sunburn. Maybe it was because they less cold in winter, and therefore were better at getting food for the family.

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  • Bill
    Lv 7
    2 years ago

    Perhaps a better question might be, why did our ancestors lose hair on the rest of their bodies? Even in warm climates, most mammals are covered with fur.

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  • 2 years ago

    Its leftover fur.

    Its not "for anything", considering we've lost most of the hair that was on our bodies, and men lose even that bit on top.

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