Blacks also have physiological differences that make them, on average, better runners and jumpers. And it's not dryness but heat or lack thereof that affects nose shape. These differences are built into our DNA that distinguish one ethnic group from another within a race, and races from each other. It's not a bad thing, it's just reality. To say that other than skin color we're all the same is to deny our diversity. There was a super volcano in Indonesia that exploded about 70,000 years ago and it's estimated only about 10,000 humans worldwide survived it. Researchers have been able to determine that a bottleneck in mutations in our mitochondrial DNA, which is passed from mother to child, occurred about then. And believe humanity was even more diverse before then.