Hi,
This intriguing video explains why dark skinned people originate from equatorial countries such as Africa, India and South East Asia.
Melanin is a pigment molecule that give the dark colour to skin. It evolved by natural selection to cut out harmful UV radiation from the sun. It is a natural sunscreen.
However there has been much migration of light skinned people from low UV places to high UV places and vice versa. UVB light is important to make vitamin D in our skins. However, dark skinned people in the countries nearer to the poles are not getting enough of it and this will lead to serious health consequences such as bone and teeth problems, reduced immune system, mood and mental health problems.
Also dark skinned people who work at desk jobs should be aware of these health risks.
Light skinned people have less melanin and so they run the risk of skin cancer due to excessive UVB damaging their DNA. Lighter skin colour is a product of evolution by natural selection in a latitude that gets very little UVB light.
Cheers
Sunday, December 27, 2009
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