美国科学60秒 SSS 2013-02-21

搜索关注在线英语听力室公众号：tingroom，领取免费英语资料大礼包。

　　Penn State anthropologist² Nina Jablonski on the evolution of human skin pigmentation at the annual meeting of the American Association for the Advancement³ of Science in Boston on February 16th.

　　The variation in pigmentation is one of the most conspicuous⁴ and interesting features of human skin. In fact that within one species we have a wide variation skin pigmentation from very dark to very light, and that this pattern has a sensible geographical⁵ distribution that is related to the intensity⁶ of UV radiation is highly significant.

　　Ultraviolate radiation exerts such negative effects, predominantly negative effects on the body, strong malinen pigmentation evolved to protect us from most of those negative effects.

　　Loss of pigmentation was one of the most conspicuous things that occurred in these few small populations of homosapiens that left Africa arround 17,000 years ago. So that we actually see depigmented skin evolving in the ancestors of Western Europeans and Eastern Asians independently as a a result of independent genetic⁷ mutations, because this depigmented skin was very important to people living under low UV regimes. It allowed people to make Vitamin-D more easily out of available UV radiation in sunlight and it afforded tremendous evolutionary⁸ advantages.

分享到：