1.Interestingly, Charles Darwin was born a very lightly pigmented man, in a moderately-to-darkly pigmented world.
有趣的是，查尔斯-达尔文 一个肤色非常浅的人 生在一个深肤色的世界。
2.Over the course of his life, Darwin had great privilege.
在他的一生中， 达尔文享受到了很大的特权。
3.He lived in a fairly wealthy home.
他的家境相当富裕，
4.He was raised by very supportive and interested parents.
他的父母给予了他大量的支持和关心。
5.And when he was in his 20s he embarked upon a remarkable voyage on the ship the Beagle.
在二十多岁的时候， 他踏上了小猎犬号，开始了一段不寻常的征程。
6.And during the course of that voyage, he saw remarkable things.
在那次航行中， 他目睹了许多不寻常的事情：
7.Tremendous diversity of plants and animals, and humans.
植物、动物还有人类中惊人的多样化。
8.And the observations that he made on that epic journey, were to be eventually distilled into his wonderful book, On the Origin of Species,
他在那史诗般的旅程中的 种种观察 最终凝结成了 他伟大的著作──《物种起源》，
9.published 150 years ago.
发表于150年前。
10.Now what is so interesting and to some, the extent, what’s a bit infamous about The Origin of Species, is that there is only one line in it
而这本书的有趣之处， 甚至有点臭名昭著之处 就在于 整本书中，只有一行字
11.about human evolution.
是关与人类的进化。
12.Light will be thrown on the origin of man and his history.
“人类的起源与历史 终将得以阐明。”
13.It wasn’t until much longer, much later, that Darwin actually spoke and wrote about humans.
直到很久以后 很久很久以后 达尔文才真正地开始在人类的话题上 撰文、讨论。
14.Now in his years of traveling on the Beagle, and from listening to the accounts or explorers and naturalists, he knew that skin color
乘坐小猎犬号 周游的经历， 和途中从探险者和博物学家那里 听到的很多故事， 使他知道
15.was one of the most important ways in which people varied.
肤色是不同种族之间 最重要的差异之一。
16.And he was somewhat interested in the pattern of skin color.
他也对肤色的分布规律产生了一点兴趣。
17.He knew that darkly pigmented peoples were found close to the equator.
他知道深色肤色的人 常常居住在赤道附近。
18.Lightly pigmented peoples, like himself, were found closer to the poles.
而和他一样的浅色人种 则是常常在居住在两极的附近。
19.So what did he make of all this?
对此，他的结论是什么呢？
20.Well he didn’t write anything about it in The Origin of Species.
其实，他在《物种起源》中对此只字未提
21.But much later, in 1871, he did have something to say about it.
不过多年以后， 在1871年 他最终对此阐述了自己的想法──
22.And it was quite curious. He said, “Of all the differences between the races of men, the color of the skin is the most conspicuous and one of the best marked.”
一个让人费解的想法。他说： “人与人之间众多的差别中， 肤色是最显著 最醒目的。”
23.And he went on to say, “These differences do not coincide with corresponding differences in climate.”
他接着又说道： “而这些肤色的差别 和气候的差别是没有关联的。”
24.So he had traveled all around.
他的确是周游过世界，
25.He had seen people of different colors living in different places.
也看到了不同地方 不同肤色的人。
26.And yet he rejected the idea that human skin pigmentation was related to the climate.
但他却不认为 人类的肤色 和气候是相关的。
27.If only Darwin lived today.
要是达尔文活在今天该多好。
28.If only Darwin had NASA.
要是达尔文那时候有NASA（美国航天局）该多好。
29.Now, one of the wonderful things that NASA does is it puts up a variety of satellites that detect all sort of interesting things about our environment.
NASA做过的美妙事情之一 就在于它建立了各种各样的卫星系统 用以侦测我们周边环境中所发生的有趣的事。
30.And for many decades now there have been a series of TOMS satellites that collected data about the radiation of the Earth’s surface.
而在过去的几十年里， 已经有一系列的TOMS卫星被发送上天 来收集地球表面辐射的数据。
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31.The TOMS 7 satellite data, shown here, show the annual average ultraviolet radiation at the Earth’s surface.
这里看到的，就是TOMS 7号卫星 所收集的地表紫外线辐射的 年平均值。
32.Now the really hot pink and red areas are those parts of the world that receive the highest amounts of UV during the year.
这些深粉色和红色的地域 就代表着世界上每年接受紫外线辐射 最大量的地区。
33.The incrementally cooler colors, blues, greens, yellows, and finally grays, indicate areas of much lower ultraviolet radiation.
而那些逐步变浅的颜色： 蓝色、绿色、黄色、一直到灰色， 则是显示了接受比较少量紫外线辐射的地区。
34.What’s significant to the story of human skin pigmentation is just how much of the Northern Hemisphere is in these cool gray zones.
而对人类肤色的研究至关紧要的一点 就在于北半球的大部分地区 都集中在这些凉爽的灰色地带。
35.This has tremendous implications for our understanding of the evolution of human skin pigmentation.
这一点，对于我们理解人类肤色的进化过程 有着极其深远的影响。
36.And what Darwin could not appreciate, or didn’t perhaps want to appreciate at the time, is that there was a fundamental relationship
而达尔文当时没有意识到的， 或者是不想意识到的， 就是紫外线的强度
37.between the intensity of ultraviolet radiation and skin pigmentation.
和人体的肤色 是在本质上息息相关的。
38.And that skin pigmentation itself was a product of evolution.
肤色本身 就是进化的产物。
39.And so when we look at a map of skin color, and predicted skin color, as we know it today, what we see is a beautiful gradient from the darkest skin pigmentations toward the equator,
所以当我们研究人类现有肤色 和根据现今情况所预测的肤色的分布图时， 我们所看到的是一条美丽的色彩渐变 从赤道附近的最深色肤色一直延伸到
40.and the lightest ones toward the poles.
两极附近的最浅色肤色。
41.What’s very very important here is that the earliest humans evolved in high UV environments, in equatorial Africa.
非常非常重要的一点就在于 最早期的人类 进化于高紫外线的环境下， 在非洲靠近赤道的地带。
42.The earliest members of our lineage, the genus Homo, were darkly pigmented.
我们的老祖宗， 所谓的“直立人”，是有着很深的肤色的。
43.And we all share this incredible heritage of having originally been darkly pigmented, two million to one and half million years ago.
我们都是这一奇妙现象的继承者， 都是在最原始的时候， 在两百万到一百五十万年前， 拥有着深色的皮肤。
44.Now what happened in our history?
但随后，我们的历史发生了怎样的变化呢？
45.Let’s first look at the relationship of ultraviolet radiation to the Earth’s surface.
让我们首先来看一看 紫外线辐射和地表的关系。
46.In those early days of our evolution, looking at the equator, we were bombarded by high levels of ultraviolet radiation.
在人类的早期进化过程中—— 注意赤道附近—— 我们面临着大量紫外线辐射的冲击。
47.The UVC, the most energetic type, was occluded by the Earth’s atmosphere.
其中最富能量的一种，UVC， 是被我们的大气层隔离在外。
48.But UVB and UVA especially, came in unimpeded.
不过UVB还有UVA， 则是毫无阻隔地横冲直入。
49.UVB turns out to be incredibly important.
其中UVB扮演着极其重要的角色。
50.It’s very destructive.
它充满了破坏性，
51.But it also catalyzes the production of vitamin D in the skin.
不过与此同时，它也催化着皮肤内维生素D的生产。
52.Vitamin D being a molecule that we very much need for our strong bones, the health of our immune system, and myriad other important functions in our bodies.
维生素D是我们非常需要的一种元素， 帮助我们强壮骨骼，增强免疫系统， 以及其他体内非常重要的各种作用。
53.So, living at the equator, we got lots and lots of ultraviolet radiation and the melanin, this wonderful, complex, ancient polymer compound in our skin,
所以居住在赤道附近， 我们接受着大量的紫外线辐射， 而黑色素—— 我们皮肤内 美妙、复杂、古老的聚合物，
54.served as a superb natural sunscreen.
是优良的天然防晒霜。
55.This polymer is amazing because it’s present in so many different organisms.
这个聚合物的奇妙之处 就在于它存在于众多的生物体内。
56.Melanin, in various forms, has probably been on the Earth a billion years.
不同形式的黑色素很有可能存在于地球上 长达十亿年。
57.And has been recruited over and over again by evolution, as often happens.
并且一次又一次地 被进化的过程所招纳。
58.Why change it if it works?
既然它如此实用，为何要对它做任何改变呢？
59.So melanin was recruited, in our lineage, and specifically in our earliest ancestors evolving in Africa, to be a natural sunscreen.
因此在人类早期的时候， 尤其是对于我们最早的在非洲进化的祖先们， 黑色素扮演着 天然防晒霜的作用。
60.Where it protected the body against the degradations of ultraviolet radiation, the destruction, or damage to DNA, and the breakdown of a very important molecule called folate,
它保护我们的身体 不受紫外线的摧毁， 避免DNA的损伤和破坏， 也防止叶酸的分解。
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61.which helps to fuel cell production, and reproduction in the body.
叶酸对于细胞的制造和再生 至关重要。
62.So, it’s wonderful. We evolved this very protective, wonderful covering of melanin.
所以黑色素其实是非常美好的。 我们也因此而进化出这层绝妙的黑色素保护层。
63.But then we moved.
但随后，我们开始了迁移。
64.And humans dispersed, not once, but twice.
人类开始分散——不止一次，而是两次。
65.Major moves, outside of our equatorial homeland, from Africa, into other parts of the old world, and most recently, into the New World.
从我们赤道附近的家乡，从非洲， 开始大规模地迁移到其他的地域， 而最近的一次迁移则是新大陆的探索。
66.When humans dispersed into these latitudes, what did they face?
当人类迁移至其他的纬度地区时， 他们所面临的是什么呢？
67.conditions were significantly colder, but they were also less intense with respect to the ultraviolet regime.
环境变得异常寒冷， 而紫外线的强度 也减弱了许多。
68.So if we’re somewhere in the Northern Hemisphere, look at what’s happening to the ultraviolet radiation.
所以观看北半球的话， 就可以看出紫外线辐射所发生的变化。
69.We’re still getting a dose of UVA.
我们还是会接受到UVA
70.But all of the UVB, or nearly all of it, is dissipated through the thickness of the atmosphere.
不过所有的UVB 差不多所有的UVB 都会被厚重的大气层所吸收。
71.In the winter, when you are skiing in the Alps, you may experience ultraviolet radiation.
在冬天，当你在阿尔贝斯山滑雪的时候， 你也许还能感觉到紫外线的辐射，
72.But it’s all UVA, and significantly, that UVA has no ability to make vitamin D in your skin.
不过那些都是UVA。 至关重要的一点就在于 UVA是无法在你的皮肤内制造维生素D的。
73.So people inhabiting northern hemispheric environments, were bereft of the potential to make vitamin D in their skin, for most of the year.
所以居住在北半球环境下的人们 在一年内大部分的时间里，都丧失了 在皮肤内生产维生素D的潜能。
74.This had tremendous consequences for the evolution of human skin pigmentation.
这对人类肤色的进化 有着极其重大的影响。
75.Because what happened, in order to ensure health and well-being, these lineages of people dispersing into the Northern Hemisphere, lost their pigmentation.
为了确保自身的健康， 这些迁移到北半球的人群 逐渐失去了 色素的堆积。
76.there was natural selection for the evolution of lightly pigmented skin.
自然选择造就了 浅色肤色的进化。
77.Here we begin to see the evolution of the beautiful sepia rainbow that now characterizes all of humanity.
我们也因此可以看到 全人类共有的 美丽的宛如深色彩虹般的肤色。
78.Lightly pigmented skin evolved not just once, not just twice, but probably three times.
浅色的肤色不仅仅进化了一次 不仅仅进化了两次，而是很有可能进化了三次。
79.Not just in modern humans, but in one of our distant unrelated ancestors, the Neanderthals.
不仅仅在现代人类中， 也发生在我们远古的关联不大的祖先—— 尼安德特人之中。
80.A remarkable, remarkable testiment to the power of evolution.
这也正是对进化的力量 强而有力的证明。
81.Humans have been on the move for a long time.
人类的迁移已经进行了很长一段时间。
82.And just in the last 5,000 years, in increasing rates, over increasing distances.
就在过去的五千年里， 迁移的速率越来越快，迁移的距离越来越远。
83.Here are just some of the biggest movements of people, voluntary movements, in the last 5,000 years.
这里所看到就是过去五千年里， 比较重大的人类自主迁移活动。
84.Look at some of the major latitudinal transgressions.
注意那些横跨大量纬度的移动。
85.People from high UV areas going to low UV and vice versa.
人们从高紫外线辐射的地区 前往低紫外线辐射的地区，反之亦然。
86.And not all these moves were voluntary.
但并不是所有的迁移活动都是自主的。
87.Between 1520 and 1867, 12 million, 500 people were moved from high UV to low UV areas, in the transatlantic slave trade.
在1520年和1867年之间， 一千两百万的人口 因为横渡大西洋的奴隶贸易 被迫从高紫外线的地区 转移到了低紫外线的地区。
88.Now this had all sorts of invidious social consequences.
这引发了许多令人憎恶的社会现象，
89.But it also had deleterious health consequences to people.
但同时它也对人体的健康 产生了恶劣的影响。
90.So what? We’ve been on the move.
那又怎么样呢？我们一直都在迁移着。
91.We’re so clever we can overcome all of these seeming biological impediments.
我们是如此聪明，完全可以逾越 这些看似是生理上的障碍。
92.Well, often we’re unaware of the fact that we’re living in environments in which our skin is inherently poorly adapted.
可惜我们通常并不知道 我们的皮肤往往存在内在的不足 无法适应 我们所生存的环境。
93.Some of us with lightly pigmented skin live in high UV areas.
我们中的一些浅肤色的人 生活在高紫外线的地区。
94.Some of us with darkly pigmented skin live in low UV areas.
而我们中一些深肤色的人 生活在低紫外线的地区。
95.These have tremendous consequences for our health.
这一切对我们的健康都有着深远的影响。
96.We have to, if we’re lightly pigmented, be careful about the problems of skin cancer, and destruction of folate in our bodies, by lots of sun.
对于浅肤色的人来说，我们不得不 格外小心皮肤癌的问题， 还有过度日照所引发的 体内叶酸的损伤。
97.Epidemiologists and doctors have been very good about telling us about protecting our skin.
皮肤学家和医生 都很尽职地告诉我们 要保护我们的皮肤。
98.What they haven’t been so good about instructing people, is the problem of darkly pigmented people living in high latitude areas, or working inside all the time.
可是他们并没有很好传达给人们的是 那些居住在高纬度地域 或者是长期在室内工作的深肤色人口 所面临的问题。
99.Because the problem there is just as severe.
他们所面临的问题是同等严重的。
100.But it is more sinister.
不过却更加不宜察觉。
101.Because vitamin D deficiency, from a lack of ultraviolet B radiation, is a major problem.
因为紫外线B辐射不足 所引发的维生素D短缺 是一个重大的问题。
102.Vitamin D deficiency creeps up on people, and causes all sorts of health problems to their bones, to their gradual decay of their immune systems,
维生素D的缺乏会在不知不觉中 对人体的骨骼造成各种各样的问题， 导致免疫系统的逐步衰退
103.or loss of immune function, and probably some problems with their mood and health, their mental health.
或者免疫机能的丧失 也有可能对心情 还有精神的健康 造成影响。
104.So we have, in skin pigmentation, one of these wonderful products of evolution, that still has consequences for us today.
所以肌肤色素中所隐藏的 是进化过程的美妙的产物之一 并且对现今的我们依旧有着影响。
105.And the social consequences, as we know, are incredibly profound.
其中对社会产生的后果， 我们众所周知，是非常深远的。
106.We live in a world where we have lightly and darkly pigmented people living next to one another.
我们所生活的世界里 深肤色的人口和浅肤色的人口 居住在一起。
107.But often brought into proximity initially as a result of very invidious social interactions So how can we overcome this?
不过这种临近往往在最初 是由于可憎的社会作用所造成的。 所以我们应当如何来克服这一点呢？
108.How can we begin to understand it?
我们应当如何开始理解这一点呢？
109.Evolution helps us.
进化过程可以帮助我们。
110.200 years after Darwin’s birthday, we have the first moderately pigmented President of the United States.
达尔文诞辰200年之际， 我们有了第一位有色人种，被当选为美国总统。
111.(Applause) How wonderful is that?
（掌声） 这是多么美好的事情呀！
112.(Applause) This man is significant for a whole host of reasons.
（掌声） 他所代表着的重大意义是各方面的。
113.But we need to think about how he compares, in terms of his pigmentation, to other people on Earth.
但我们仍需要仔细思考，看看他的肤色 和地球上的其他人种有怎样的区别。
114.He, as one of many urban and mixed populations, is very emblematic of a mixed parentage, of a mixed pigmentation.
他作为城市中的混血人口之一， 很好地象征了 一个混合的父母血统，一个混合的肤色。
115.And he resembles, very closely, people with moderate levels of pigmentation who live in southern Africa, or Southeast Asia.
他和有着中度色素堆积的人 非常相像 比如居住在非洲南部或是东南亚的人口。
116.These people have a tremendous potential to tan, to develop more pigment in their skin, as a result of exposure to sun.
这些人很容易被晒黑， 一旦暴露在日光下，他们的皮肤就能 产生更多的色素。
117.They also run the risk of vitamin D deficiency, if they have desk jobs, like that guy.
他们也面临着维生素D短缺的危险 尤其是当他们是白领阶层，就好比他一样。
118.So lets all wish for his great health, and his awareness of his own skin pigmentation.
所以让我们一同祝他身体健康， 也希望他对自己的肤色有着充分的了解。
119.Now what is wonderful about the evolution of human skin pigmentation, and the phenomenon of pigmentation, is that it is the demonstration,
人类肤色的进化 还有人类色素的这现象中 最美妙的一点就在于 这是我们自身上
120.the evidence, of evolution by natural selection, right on your body.
关于自然选择和进化 有力的演示 和证明。
121.When people ask you, “What is the evidence for evolution?”
所以当人们问你：“进化论的证据是什么？”
122.You don’t have to think about some exotic examples, or fossils.
你无需去列举那些奇珍异葩或是化石的例子。
123.You just have to look at your skin.
你只需看看你的皮肤。
124.Darwin, I think, would have appreciated this, even though he eschewed the importance of climate on the evolution of pigmentation, during his own life.
我想，达尔文是可以欣赏你这样做的。 尽管说在他的时代， 他曾误解了气候对人类肤色进化的影响。
125.I think, were he able to look at the evidence we have today, he would understand it.
但我觉得，如果他当时 可以看到我们今天所有的证据的话，他是可以理解的。
126.He would appreciate it.
他是可以欣赏这一点的。
127.And most of all, he would teach it.
最重要的是，他会教导这一点。
128.You, you can teach it.
你也可以教导这一点。
129.You can touch it.
你可以感受到它
130.You can understand it.
可以理解它。
131.Take it out of this room.
将它带出这个房间。
132.Take your skin color, and celebrate it.
带着你的肤色 尽情地为其庆祝。
133.Spread the word.
传扬这一信息。
134.You have the evolution of the history of our species, part of it, written in your skin.
我们种族的进化历史 其中的一部分 就撰写在你的肌肤里。
135.Understand it. Appreciate it. Celebrate it.
理解它。欣赏它。庆祝它。
136.Go out. Isn’t is beautiful? Isn’t it wonderful?
出外欢庆吧。它是对么美妙呀！多么美好呀！
137.You are the products of evolution.
你是进化的产物。
138.Thank you.
谢谢。
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