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?
In: 1641
Think of melanin as a “shield”.
Melanin protects against UV radiation from the sun, and also determines how much vitamin D we produce, as a result of the sun that does reach us.
On the equator, this is good – there is so much sun so often that we need the melanin to shield us from the UV, and we get just enough sun to make the vitamin D we need.
But in the North, having that level of melanin blocks out all possibility of vitamin D reaching us – it shields too well, to the point we produce no vitamin D.
Therefore, when we live in the North, we reduce our shield against UV, adjusting it according the UV levels we encounter – less UV, less shield needed. That way, we can still make the right amount of vitamin D.
Think of melanin as a “shield”.
Melanin protects against UV radiation from the sun, and also determines how much vitamin D we produce, as a result of the sun that does reach us.
On the equator, this is good – there is so much sun so often that we need the melanin to shield us from the UV, and we get just enough sun to make the vitamin D we need.
But in the North, having that level of melanin blocks out all possibility of vitamin D reaching us – it shields too well, to the point we produce no vitamin D.
Therefore, when we live in the North, we reduce our shield against UV, adjusting it according the UV levels we encounter – less UV, less shield needed. That way, we can still make the right amount of vitamin D.
No because in regions with less sunlight there is also less vitamin D. I’m a biology major and actually we recently talked about this in one of our assignments. Having less melanin in areas with less sunlight allows you to get more vitamin D.
There are acceptions to the rule, as there are darker skin natives in some cold climates. I can’t remember the reasoning behind that. But generally, having less melanin allows for more vitamin D.
No because in regions with less sunlight there is also less vitamin D. I’m a biology major and actually we recently talked about this in one of our assignments. Having less melanin in areas with less sunlight allows you to get more vitamin D.
There are acceptions to the rule, as there are darker skin natives in some cold climates. I can’t remember the reasoning behind that. But generally, having less melanin allows for more vitamin D.
No because in regions with less sunlight there is also less vitamin D. I’m a biology major and actually we recently talked about this in one of our assignments. Having less melanin in areas with less sunlight allows you to get more vitamin D.
There are acceptions to the rule, as there are darker skin natives in some cold climates. I can’t remember the reasoning behind that. But generally, having less melanin allows for more vitamin D.
No! Because lighter skin has its own advantage for places that get less sunlight than around the equator-you can absorb vitamin D easier with lighter skin.
(here’s your note that, if you’re darker skinned in a colder climate, and you’re tired all the time, get checked for vitamin D deficiency! It’s very normal to be deficient when it’s harder to absorb and there’s less sun in general)
No! Because lighter skin has its own advantage for places that get less sunlight than around the equator-you can absorb vitamin D easier with lighter skin.
(here’s your note that, if you’re darker skinned in a colder climate, and you’re tired all the time, get checked for vitamin D deficiency! It’s very normal to be deficient when it’s harder to absorb and there’s less sun in general)
No! Because lighter skin has its own advantage for places that get less sunlight than around the equator-you can absorb vitamin D easier with lighter skin.
(here’s your note that, if you’re darker skinned in a colder climate, and you’re tired all the time, get checked for vitamin D deficiency! It’s very normal to be deficient when it’s harder to absorb and there’s less sun in general)
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 🤷🏻♂️
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