How Did We Get Here?

I'm not going to go into great detail on this one. This week's Anthro issue dealt with whether early peoples came to North America via a land/ice bridge from Asia through Alaska about 9000 B.C. (or so), or whether they showed up along the Southern Pacific rim. Suffice to say, there is evidence of pre-Clovis cultures (more than 11000 years old), and there was even a skeleton found in North Carolina that is thought to be some 50000 years old.
I also got to learn about determination of melanin content in skin and how skin color is affected by UV radiation. It's pretty basic by now, and evolution kicks in on a more long-term basis, but I learned a lot about how the UV can destroy folic acid in a body, and how a body synthesizes Vitamin D3 (both of which I think affect pregnant women and can affect the baby's color as well). The credibility of the paper I read was in question, though, because one of the things besides small group studies that may have skewed the results was that they ran tests on neonatal foreskins. Weird, isn't it?