Stanford DNA survey finds all humans are 99.9% the same.

[Takaavar]

One thing I don't understand, maybe someone can elaborate.

The Arabian Peninsula/Iran is the hottest place on the Earth. So how come Arab/Persians are lighter skinned than Indians or Africans?

That doesn't directly depend on where people are currently living, but their ancestors, so ancestors of Indians spent more time near the Earth's equator relative to ancestors of say Persians who actually spent more time in Central Asia and areas above that.

 

[p(-)0ENiX]

Weather conditions do not explain the different phenotypes among races, at the most, all they explain is the reason for varying skin tones even among members of the same race. Skin color does aid in identifying races, but it has never been the sole factor for identifying a particular race. Other factors like the variation in human skulls' shapes & sizes among different races have to be taken in to consideration. Had race been all about skin color, an albino would look no different from a Caucasian, but that's obviously not the case. The point is, people shouldn't confuse race with skin color. Humans are a species, just as every other species contains variations, human beings do so as well.