3 ms·

It is not just photography, even in real life under low light conditions it can be hard to read the facial expressions of dark skinned people.

mirimir 8y ago
True. So maybe skin darkening would be more practical than CV Dazzle, because it wouldn't be so unusual. Horrible legacy and PR, though. Anyway, I suspect that was an evolutionary advantage. For hunting in forest and savannah, to hide in shadows. The human rootstock was black, I gather. And lighter skin evolved where soft UV was limiting for vitamin D synthesis. But that's solvable with the right technology. Maybe something like getting overall color value, and then tweaking color contrast. If we can do it in astronomy, we can do it with people.
- an_ko 8y ago
  I would guess that the evolutionary advantage of black skin was not primarily camouflage. Tool-using humans of any colour can do that with mud and grass. My bet is on UV tolerance. Black people have lower rates of skin cancer in the US compared to whites. https://www.jaad.org/article/S0190-9622(05)02730-1/fulltext https://www.jaad.org/article/S0190-9622(05)02730-1/fulltext (Mortality is higher in blacks, but that's because it's diagnosed at later more severe stages.) The effect would have been far bigger when foraging and hunting all day every day under the equatorial sun.
  - todd8 8y ago
    Or perhaps light skin was an evolutionary development as humans moved to higher latitudes in order to obtain high enough levels of vitamin D. See [1]: The evolutionary significance of vitamin D, skin pigment, and ultraviolet light. 1. https://www.ncbi.nlm.nih.gov/m/pubmed/1211435/ https://www.ncbi.nlm.nih.gov/m/pubmed/1211435/
  - mirimir 8y ago
    Good points. And maybe there's linked stuff that got selected for.
- danieltillett 8y ago
  The genetic history of human skin colour is really amazing. All our ancestor had fair skin because of body hair (Chimps have fairish skin under all their body hair), we then became dark skinned as we lost most of our body hair, and then those of us who had ancestors that lived far from the equator became fair again. As someone who has the ancestry of people who lived far from the equator and now lives in a country that is much closer to the equator I wish we hadn't lost our body hair.
  - mirimir 8y ago
    Huh. I guess that I've never seen a shaved chimp. But now that I think of it, hairless mice have light-colored skin. Some hairless dogs too.
    - danieltillett 8y ago
      Yes if you are covered with hair you not only don’t need dark skin for UV protection, but it will likely interfere with your ability to synthesise vitamin D. Also why waste energy synthesising something you don’t need (melanin).

mirimir 8y ago

True. So maybe skin darkening would be more practical than CV Dazzle, because it wouldn't be so unusual. Horrible legacy and PR, though. Anyway, I suspect that was an evolutionary advantage. For hunting in forest and savannah, to hide in shadows. The human rootstock was black, I gather. And lighter skin evolved where soft UV was limiting for vitamin D synthesis. But that's solvable with the right technology. Maybe something like getting overall color value, and then tweaking color contrast. If we can do it in astronomy, we can do it with people.

an_ko 8y ago
I would guess that the evolutionary advantage of black skin was not primarily camouflage. Tool-using humans of any colour can do that with mud and grass. My bet is on UV tolerance. Black people have lower rates of skin cancer in the US compared to whites. https://www.jaad.org/article/S0190-9622(05)02730-1/fulltext https://www.jaad.org/article/S0190-9622(05)02730-1/fulltext (Mortality is higher in blacks, but that's because it's diagnosed at later more severe stages.) The effect would have been far bigger when foraging and hunting all day every day under the equatorial sun.
- todd8 8y ago
  Or perhaps light skin was an evolutionary development as humans moved to higher latitudes in order to obtain high enough levels of vitamin D. See [1]: The evolutionary significance of vitamin D, skin pigment, and ultraviolet light. 1. https://www.ncbi.nlm.nih.gov/m/pubmed/1211435/ https://www.ncbi.nlm.nih.gov/m/pubmed/1211435/
- mirimir 8y ago
  Good points. And maybe there's linked stuff that got selected for.
danieltillett 8y ago
The genetic history of human skin colour is really amazing. All our ancestor had fair skin because of body hair (Chimps have fairish skin under all their body hair), we then became dark skinned as we lost most of our body hair, and then those of us who had ancestors that lived far from the equator became fair again. As someone who has the ancestry of people who lived far from the equator and now lives in a country that is much closer to the equator I wish we hadn't lost our body hair.
- mirimir 8y ago
  Huh. I guess that I've never seen a shaved chimp. But now that I think of it, hairless mice have light-colored skin. Some hairless dogs too.
  - danieltillett 8y ago
    Yes if you are covered with hair you not only don’t need dark skin for UV protection, but it will likely interfere with your ability to synthesise vitamin D. Also why waste energy synthesising something you don’t need (melanin).