A similar occurrence can be observed with cultures that are traditionally used to dairy products (cheese, milk etc) vs cultures where dairy product producing animals aren't the norm. (Cows, goats et al)
ie There was once a study done of French cholesterol levels. Despite a traditionally very high cholesterol intake of dairy products, their cholesterol levels were on average lower
than other contemporary non-traditional dairy consumers. Evolution has not only allowed a higher lactose tolerance, but a natural resistance to it's adverse affects.
The same can also be applied to skin colour pigmentation. Peoples from traditionally warm, sunny climates have a darker pigmentation as opposed to peoples who came from colder and less sunny climates. ie Africa vs Europe
Disease resistance is another. Native Americans/Aboriginals were hit very hard by introduced foreign diseases that traditionally did not occur in their isolated sphere of existence.
The list is quite large really. Evolution is a continual work in progress of adaptation.
(Theoretical Tangent Time)
There is currently no 'supreme' race. White supremacy, Black supremacy, Asian supremacy etc - it's all BS.
If there is ever to be a 'supreme' race, it will will be the humans that are the culmination of inter-racial human breeding over the continuing thousands of years that take the 'strongest' facets from each 'race' while discarding the 'weakest' genetic traits along the way.
Superior intellect, physical ability, disease resistance, environmental tolerance and so and so forth garnered from continual inter-racial breeding is the key to an ultimately stronger species. Segregated inter-breeding amongst ones own kind is actually detrimental to the well being of homosapiens in the long run.
Think in-breeding on a world wide scale. We've seen the flaws that occurs from in-breeding amongst a small sub-set of genetic material. "Kissing cousins" that pass inherent weakness and flaws to their offspring. Add non related genetics to the mix and the result is an improvement. Extrapolate and add further genetic improvements and the flaws start to wane as the addition of improved genetic material creates a healthier and hardier human.
Fast forward a few thousand years of continued genetic mixing and the best traits derived from each 'race' manifest themselves as a vastly superior homosapien vs continued segregated inter-bred genetics.
I know it's a pretty roughly delivered outline, but it's just a post on forum after all and not a dissertation