Where do differences in skin color originate from?
In: Biology
Distance from the equator. The closer you are, the darker the skin; The farther you are, the lighter your skin.
Melanin.
Different places in the world evolved a different need for sunlight absorption, and that manifests in a chemical called melanin.
In Africa for millennia and don’t need to absorb as much sun? Have more melanin, dark roast.
In arctic lands with a deficit of sunlight most of the time? No melanin for you, pasty mo fo.
It seems to be a balance of vitamin D production vs. preventing skin cancer.
Dark pigmentation protects from UV, but UV is used in your skin to make vitamin D.
People in Northern latitudes tend to be lighter so they can still make enough vitamin D even in the less sunny winter months, and there’s less danger of skin cancer as well.
People along the equator are darker because they get more even, strong sun, and so they can make enough vitamin D even while blocking most UV and protecting themselves from cancer.
Also, making pigments takes some effort, so if you can get away without spending resources on them, it can be beneficial. This is why many cave-dwelling creatures lose pigmentation. If there’s no one to see you and no sun to block, you’re better off saving those pigment chemicals for other uses.
So, I’m no expert but what I remember from my college anthropology class it stems from humans migrating north from Africa many, many moons ago. As humans migrated farther away from the equator, their sun exposure was less and less the farther north they migrated generationally because of the rotation around the sun and tilt of the axis of the Earth. The sun provides vitamin D and the sun was really the only source for that. Evidently, skin pigmentation acts as SPF and the northern migrants weren’t getting enough of it so over many generations the humans adapted by losing melanin to gain the ability to absorb vitamin D. Apparently, vitamin D is important for calcium absorption and, as we all know, calcium is important for bone strength, which was important to a species that stands upright, and so on. I found it so interesting. I kinda wish I had taken more anthropology classes but in the moment I just wanted to be done with school.
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