研究生科技英语阅读答案(2)

3. Jablonski and her husband have formulated the first comprehensive theory of skin color, and what did their new findings on skin color show?

Their findings, published in a recent issue of the Journal of Human Evolution, show a strong, somewhat predictable correlation between skin color and the strength of sunlight across the globe. But they also show a deeper, more surprising process at work: Skin color, they say, is largely a matter of vitamins.

4. Why did our ancestors have to develop a better cooling system? And what was the answer?

Once on the savanna, the early humans not only had to cope with more exposure to the sun, but they also had to work harder to gather food. Mammalian brains are particularly vulnerable to overheating: A change of only five or six degrees can cause