eli5: If more melanin is advantageous in warm climates, why is less of it advantageous in colder climates? Wouldn’t darker skin still be most advantageous in cold climates where it might occasionally be hot?
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As others have already said it is not about heat but sunshine and getting enough vitamin D
Dark skin was an evolutionary adaption to losing most of our body hair and having our skin constantly exposed to the sun.
Millions of years later some of us went out of Africa and started to have problems, then some of those people gave birth to some mutant with less dark skin, who didn’t have the same problems.
The human body is very good at conserving energy. If something is not needed, it will be produced in smaller quantities.
This is why building muscle is not a one-and-done thing, but requires constant training to maintain. Unused muscle is broken back down again.
Humans in colder climates DO produce more melanin when exposed to bright sunlight, this is what a tan is, but when the melanin is no longer needed it is no longer produced and lost along with regular shedding of dead skin cells.
The human body is very good at conserving energy. If something is not needed, it will be produced in smaller quantities.
This is why building muscle is not a one-and-done thing, but requires constant training to maintain. Unused muscle is broken back down again.
Humans in colder climates DO produce more melanin when exposed to bright sunlight, this is what a tan is, but when the melanin is no longer needed it is no longer produced and lost along with regular shedding of dead skin cells.
I always assumed evolution eliminates what’s disadvantageous, as opposed to encouraging what’s advantageous 🤷🏻♂️
As others have already said it is not about heat but sunshine and getting enough vitamin D
Dark skin was an evolutionary adaption to losing most of our body hair and having our skin constantly exposed to the sun.
Millions of years later some of us went out of Africa and started to have problems, then some of those people gave birth to some mutant with less dark skin, who didn’t have the same problems.
I always assumed evolution eliminates what’s disadvantageous, as opposed to encouraging what’s advantageous 🤷🏻♂️
The human body is very good at conserving energy. If something is not needed, it will be produced in smaller quantities.
This is why building muscle is not a one-and-done thing, but requires constant training to maintain. Unused muscle is broken back down again.
Humans in colder climates DO produce more melanin when exposed to bright sunlight, this is what a tan is, but when the melanin is no longer needed it is no longer produced and lost along with regular shedding of dead skin cells.
Your question has pretty much been answered but as a general addition: Evolution doesn’t really care much for redundancy, and an orgasim won’t develop traits just because they *might* need it, they develop traits that are essential to survival.
There are vestigial traits, but those are only observed *after* evolution has done it’s job and the organism’s need for that trait has become unnecessary. At that point, if removing the trait isn’t necessary to the organisms survival, evolution won’t touch it and the trait is considered vestigial.
Your question has pretty much been answered but as a general addition: Evolution doesn’t really care much for redundancy, and an orgasim won’t develop traits just because they *might* need it, they develop traits that are essential to survival.
There are vestigial traits, but those are only observed *after* evolution has done it’s job and the organism’s need for that trait has become unnecessary. At that point, if removing the trait isn’t necessary to the organisms survival, evolution won’t touch it and the trait is considered vestigial.
Your question has pretty much been answered but as a general addition: Evolution doesn’t really care much for redundancy, and an orgasim won’t develop traits just because they *might* need it, they develop traits that are essential to survival.
There are vestigial traits, but those are only observed *after* evolution has done it’s job and the organism’s need for that trait has become unnecessary. At that point, if removing the trait isn’t necessary to the organisms survival, evolution won’t touch it and the trait is considered vestigial.
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