@Mangymutt: The high exposure of sunlight along the equator has encoded melanin in black/brown skinned pheontytes, that act as a natural sunscreen. The negative effect of that however, is black folkls have a hard time getting vitamin D from the sun. The lighter skin folks lacking melanin is more proned to skin cancer but much better at making vit-D. As such I supplememt D3. I am sure you already know the melanin/Vit D case.