Why is black skin good in hot climates?
Question
How does black skin give better survival in hot places? Black colour absorbs heat while white colour reflects it, then black colour at hot places should burn the skin, but actually it is not so. Why?
Answer
Kat - Well, basically, this all boils down to a pigment called melanin...
This is the dark pigment - if you're fair skinned, you can see it in your moles; if you're dark skinned, you have a lot of melanin all over your skin. And melanin is almost like the body's natural sunscreen, it helps to protect you against the damage that ultra-violet light can do.
This means that people from countries that have dark skin, they're actually much less likely to get skin cancer. Us people with very fair, pale skin, when we're exposed to a lot of sun, a lot of ultra-violet radiation, our chances of getting skin cancer are actually much higher because the UV light from the sun can really penetrate into the skin. Whereas if you have dark skin, the melanin helps to protect you.
There's also an interesting argument, some recent evidence, from Nina Jablonski; we heard her talking on the show recently about this, that very deep ultra-violet radiation can actually break down folic acid, folate, in your body. Obviously, you need to protect yourself against this happening, because folate is really important for healthy metabolism and also for making healthy babies.
So it's probably a natural defence mechanism that's evolved in people from countries where it's very hot to tend to have dark skin and lots of melanin to protect you.
Comments
Heat?
As a defensive mechanism against UV lighting, melanin is good. But still, there must be a downside to this, as you start to absorb more heat, which is unfavourable in warmer countries?
It is really not a question, more a thought.
melanin consequences
More resistance to heat less resistance to cold, like Light skinned people have more resistance to cold but less resistance to heat.
No scientific down sides to melanin
More specifically Eumelanin
Oh and onmi can you share some unrefute full facts as to melanin being less resistant to cold
Re: Eumelanin
If you're living farther north, where there's not as much direct sunlight in the colder months, melanin can prevent the body from using sunlight to synthesize vitamin D. Actually, it inhibits it a little bit even in equatorial Africa, but it's ok because there's enough direct sunlight there that some of it gets past the melanin and triggers vitamin D synthesis (and the body could synthesize too much Vitamin D if ALL the sunlight got through). Vitamin D can also be sourced from food and supplements, so it's not a major problem if you have a good diet, but the reduced ability to synthesize vitamin D from sunlight is one potential downside, especially if someone was living in a less developed place or time at such northerly latitudes.
black gives off heat quickly
White skin absorbs heat slowly but also loses heat slowly so it's good for cold region. When black people live in cold weather their skin begins to whiten naturally. White people have the reverse effect. Yes black skin gains heat rapidly but loses it rapidly as well. White-skinned people normally darken in hot weather. Melanin responses learned by the body and passed down.
Even though black skin (in
Even though black skin (in reality it is still brown skin), absorbs the heat and or ultraviolet radiation only at the epidermis level the sweat glands and sufficient water intake the skin radiates the heat out of the skin thus creating a sticky and cooling condensation onto the skin itself. That is all thanks to Eumelanin.
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