Evolution tells us that different environments create selection pressure for/against different traits, which causes species to differentiate into distinct haplogroups or entirely different species.
Science tells us that "species" as a term is highly overrated and grossly misunderstood. But by no definition are different kinds of humans anywhere near to being different species. You might describe them as different varieties, at most.
Most everyone agrees that modern humans left Africa and spread throughout the world between 50,000 - 100,000 years ago. Now if I were to take any other animal, say a canid, and stick a bunch of them in northern europe and a bunch of them in Africa and then ask if you if it's possible that after 100,000 years we'd get very different animals descended from the common ancestors, you'd agree.
The things about them that needed to change will have changed. The things that didn't mostly won't.
But if that animal is man instead of a dog you'd call me an evil racist to suggest that perhaps the cold climates of northern europe selected against those humans who weren't intelligent enough to make long-term plans while the year-round abundance of food in Africa selected against the weak and slow but not against the unintelligent.
That's because it's an unintelligent argument. Intelligence is good for you no matter what your situation, and strength and speed don't preclude intelligence. Also, stupid people have intelligent children, and vice versa.
For instance, in the United States the average IQ for blacks is 85, 92 for Latinos, 100 for whites, 108 for asians, and 115 for Ashkenazi Jews. This correlates very well to income levels for each group.
Correlation, he said, is not causation. That's a sophomoric error. Is this just a kiddie troll?