eli5: Why does black skin almost never suffer from skin cancer ? Isn’t melanin being present mean anyone could be affected?
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>Isn’t melanin being present mean anyone could be affected?
Melanin makes you *less* likely to get skin cancer. Skin cancer happens when sunlight damages the DNA in your skin cells, messing them up so they start dividing too much. The melanin is a dark pigment that absorbs incoming light and prevents it from penetrating deeper into the skin where it could damage the DNA in living cells and cause them to become cancerous. It’s not the melanin that becomes cancer when you get skin cancer – the melanin forms a protective “natural sunscreen” layer that *protects* vs skin cancer. Dark skinned people have more melanin, so they get skin cancer much less often.
>Isn’t melanin being present mean anyone could be affected?
Melanin makes you *less* likely to get skin cancer. Skin cancer happens when sunlight damages the DNA in your skin cells, messing them up so they start dividing too much. The melanin is a dark pigment that absorbs incoming light and prevents it from penetrating deeper into the skin where it could damage the DNA in living cells and cause them to become cancerous. It’s not the melanin that becomes cancer when you get skin cancer – the melanin forms a protective “natural sunscreen” layer that *protects* vs skin cancer. Dark skinned people have more melanin, so they get skin cancer much less often.
I think you’re thinking of a melanoma as being “caused” by melanin. But it isn’t. Melanomas, like all cancers, are a result of cells multiplying out of control, usually as a result of damage to their DNA. In this case, it comes from over-multiplication of *melanocytes*, the cells that produce melanin in the skin. But the production of melanin is not, in itself, the problem.
Melanin is in the skin in the first place to absorb the ultraviolet light that would otherwise cause DNA damage. It’s the whole reason most people who live in the sunny tropics are dark-skinned in the first place (or rather, why all humans were until *light* skin evolved later in less-sunny areas).
I think you’re thinking of a melanoma as being “caused” by melanin. But it isn’t. Melanomas, like all cancers, are a result of cells multiplying out of control, usually as a result of damage to their DNA. In this case, it comes from over-multiplication of *melanocytes*, the cells that produce melanin in the skin. But the production of melanin is not, in itself, the problem.
Melanin is in the skin in the first place to absorb the ultraviolet light that would otherwise cause DNA damage. It’s the whole reason most people who live in the sunny tropics are dark-skinned in the first place (or rather, why all humans were until *light* skin evolved later in less-sunny areas).
>Isn’t melanin being present mean anyone could be affected?
Melanin makes you *less* likely to get skin cancer. Skin cancer happens when sunlight damages the DNA in your skin cells, messing them up so they start dividing too much. The melanin is a dark pigment that absorbs incoming light and prevents it from penetrating deeper into the skin where it could damage the DNA in living cells and cause them to become cancerous. It’s not the melanin that becomes cancer when you get skin cancer – the melanin forms a protective “natural sunscreen” layer that *protects* vs skin cancer. Dark skinned people have more melanin, so they get skin cancer much less often.
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