Interestingly, Charles Darwin was born a very lightly pigmented man, in a moderately-to-darkly pigmented world. Over the course of his life, Darwin had great privilege. He lived in a fairly wealthy home. He was raised by very supportive and interested parents. And when he was in his 20s he embarked upon a remarkable voyage on the ship the Beagle. And during the course of that voyage, he saw remarkable things: tremendous diversity of plants and animals, and humans. And the observations that he made on that epic journey were to be eventually distilled into his wonderful book, "On the Origin of Species," published 150 years ago.
有趣的是,查爾斯·達爾文 是一位膚色很淺 而生在一個平均到深膚色世界的人。 在他的一生中, 達爾文享受了許多特權。 他的家境相當的富裕, 他的父母在他成長的過程給了許多的支持和關心。 而他在二十幾歲時, 他踏上了小獵犬號,開始了一趟卓越的航海歷險。 在航巡的途中, 他看到了非凡的事物。 驚人的多樣性存在於植物,動物,和人類之間。 而他在那趟壯舉般的旅程中 所做的觀察, 終究被提煉入 他150年前出版的完美著作, 「物種起源」。
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 about human evolution. "Light will be thrown on the origin of man and his history." It wasn't until much longer, much later, that Darwin actually spoke and wrote about humans.
而「物種起源」真正有趣, 和對一些人在某種程度上來說, 聲名狼藉的地方, 是書裡面一筆就帶過了 人類的演化。 光終究會照耀於人類起源 和歷史的暗谷中。 達爾文在很長 很晚的一段時間後 才終於談論 和寫作關於人類的起源。
Now in his years of traveling on the Beagle, and from listening to the accounts or explorers and naturalists, he knew that skin color was one of the most important ways in which people varied. And he was somewhat interested in the pattern of skin color. He knew that darkly pigmented peoples were found close to the equator; lightly pigmented peoples, like himself, were found closer to the poles.
在他在小獵犬號 上航行的日子裡所做的觀察, 和從其他探險家 及自然學者聽來的紀錄, 他歸納出膚色 是人類變異的 最重要的方法之一。 而他對於膚色的型態略感興趣。 他知道深膚色的人種 是居住在接近赤道的地區。 而淡膚色人種,像他自己, 則是居住於靠近南北極的地方。
So what did he make of all this? Well he didn't write anything about it in The Origin of Species. But much later, in 1871, he did have something to say about it. 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." And he went on to say, "These differences do not coincide with corresponding differences in climate." So he had traveled all around. He had seen people of different colors living in different places. And yet he rejected the idea that human skin pigmentation was related to the climate.
所以他下了什麼結論? 他在物種起源對此隻字未提, 但在許久以後,在1871年, 他確實是發表了一些意見。 而令人好奇的是,他說: 「人類所有的不同裡, 皮膚的顏色是最顯著 和最醒目的差別之一。」 而他接著說了: 「這些差異和氣候的不同 是沒有關聯的。」 他到遍了世界各地, 看過了不同膚色的人 住在不同的地方。 然而他仍然排斥 人類皮膚色素 和氣候是有關聯的可能。
If only Darwin lived today. If only Darwin had NASA. 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. And for many decades now there have been a series of TOMS satellites that have collected data about the radiation of the Earth's surface. The TOMS 7 satellite data, shown here, show the annual average ultraviolet radiation at the Earth's surface. Now the really hot pink and red areas are those parts of the world that receive the highest amounts of UV during the year. The incrementally cooler colors -- blues, greens, yellows, and finally grays -- indicate areas of much lower ultraviolet radiation.
可惜達爾文不是活在今日, 達爾文在世時也沒有美國航太總署 美國航太總署所做的美妙事情之一 就是建立各種衛星系統 來偵測各種關於我們的環境裡有趣的事情。 而幾十年以來 一系列的TOMS(完全臭氧層製圖光譜儀)衛星被發射到外太空 來收集地球表面輻射的數據。 這是看到的,是TOMS 7衛星數據, 這告訴我們地球表面 紫外線輻射的年平均值。 亮粉紅色和紅色的區域 是世界上在一年中接收最多 紫外線的地方。 逐漸變暗的顏色-- 藍色、綠色、黃色、然後最後到灰色— 代表著接受顯著少量的輻射的區域。
What's significant to the story of human skin pigmentation is just how much of the Northern Hemisphere is in these cool gray zones. This has tremendous implications for our understanding of the evolution of human skin pigmentation. And what Darwin could not appreciate, or didn't perhaps want to appreciate at the time, is that there was a fundamental relationship between the intensity of ultraviolet radiation and skin pigmentation. And that skin pigmentation itself was a product of evolution. 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, and the lightest ones toward the poles.
人類皮膚色素的故事的重要性 是在於北半球大部分 都處於這些涼爽的灰色地帶。 這對於我們對人類皮膚色素演化 的過程有極大的影響。 而達爾文無法體會, 或至少在他當年不想體會的, 是紫外線的輻射量 和皮膚的色素 在本質上是息息相關的。 而膚色本身 就是演化的產物。 所以當我們看著膚色分布的地圖 而預測了膚色的分布,就如同現況, 我們所看到的是一個美麗的漸層, 從位於赤道的最暗的膚色 到位於地球兩極最亮的膚色。
What's very, very important here is that the earliest humans evolved in high-UV environments, in equatorial Africa. The earliest members of our lineage, the genus Homo, were darkly pigmented. And we all share this incredible heritage of having originally been darkly pigmented, two million to one and half million years ago.
這裡非常非常重要的一點 是最早期的人類 在非洲赤道的 高紫外線輻射環境裡演化。 而人類物種最早的成員, 人屬,是有著深膚色的。 我們都繼承了 這個奇妙的現象-- 在兩百萬到一百五十萬年前 有著深色的膚色。
Now what happened in our history? Let's first look at the relationship of ultraviolet radiation to the Earth's surface. In those early days of our evolution, looking at the equator, we were bombarded by high levels of ultraviolet radiation. The UVC, the most energetic type, was occluded by the Earth's atmosphere. But UVB and UVA especially, came in unimpeded. UVB turns out to be incredibly important. It's very destructive, but it also catalyzes the production of vitamin D in the skin, 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.
我們的歷史是發生了什麼變化? 我們先來看看紫外線輻射 和地球表面的關係。 在人類演化的早期, 注意看赤道附近, 人類曝露在高量的紫外線輻射下。 其中最多能量的紫外線C(UVC) 被地球的大氣層阻擋在外, 但紫外線B(UVB)和紫外線A(UVA) 則是毫無障礙的進入地球表面。 其中UVB特別的重要。 UVB非常的有破壞性, 但是它也催化皮膚裡維生素D的生產。 維生素D是我們非常需要的一種分子, 它幫助強健骨骼、增強免疫系統、 還有在我們身體裡行使其他各式各樣的重要功能。
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 -- served as a superb natural sunscreen. This polymer is amazing because it's present in so many different organisms. Melanin, in various forms, has probably been on the Earth a billion years, and has been recruited over and over again by evolution, as often happens. Why change it if it works?
所以住在赤道附近,人類吸收了 很多很多的紫外線輻射, 而黑色素— 我們皮膚裡完美、複雜、 和古老的聚合物— 是優秀的天然防曬劑。 這個聚合物相當的神奇, 因為它在存在於很多不同的生物裡。 黑色素以不同的型態大概已經在地球上 存在了十億年, 也在演化的過程中 一次又一次的被應用。 既然它如此的有用,為什麼要改變它的作用呢?
So melanin was recruited, in our lineage, and specifically in our earliest ancestors evolving in Africa, to be a natural sunscreen. 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, which helps to fuel cell production, and reproduction in the body. So, it's wonderful. We evolved this very protective, wonderful covering of melanin.
因此黑色素在人類, 尤其是我們最早的 在非洲的祖先們, 的演化裡扮演了天然防曬劑的角色。 它保護我們的身體 免於紫外線輻射的摧殘、 避免DNA的毀滅或損傷、 和一種非常重要的分子—葉酸的分解。 葉酸提供在身體裡製造 和複製細胞的能量。 所以,這很完美。我們演化出這層 非常有保護性而美妙的黑色素。
But then we moved. And humans dispersed -- not once, but twice. Major moves, outside of our equatorial homeland, from Africa into other parts of the Old World, and most recently, into the New World. When humans dispersed into these latitudes, what did they face? Conditions were significantly colder, but they were also less intense with respect to the ultraviolet regime.
但之後我們開始了遷移, 而人類開始分散,不只一次,而是兩次。 大規模的外移出我們在赤道的家, 移出非洲到其他部分的舊大陸和, 最近發生的,新大陸。 當人類分散到其他的緯度地區時, 他們面對了什麼? 環境變得顯著的更寒冷, 但紫外線輻射量 也相對的減弱許多。
So if we're somewhere in the Northern Hemisphere, look at what's happening to the ultraviolet radiation. We're still getting a dose of UVA. But all of the UVB, or nearly all of it, is dissipated through the thickness of the atmosphere. In the winter, when you are skiing in the Alps, you may experience ultraviolet radiation. But it's all UVA, and, significantly, that UVA has no ability to make vitamin D in your skin.
所以如果我們在北半球的某個地方 來檢視紫外線輻射的變化, 我們會看到我們仍然在吸收UVA, 但是所有的UVB, 或幾乎所有的UVB, 都被地球的厚大氣層所吸收了。 在冬天裡,當你再阿爾卑斯山滑雪時, 你可能會感受到紫外線輻射, 但那全部都是UVA, 而顯著的,那些UVA 沒有在你的皮膚裡製造維生素D的能力。
So people inhabiting northern hemispheric environments were bereft of the potential to make vitamin D in their skin for most of the year. This had tremendous consequences for the evolution of human skin pigmentation. Because what happened, in order to ensure health and well-being, these lineages of people dispersing into the Northern Hemisphere lost their pigmentation. There was natural selection for the evolution of lightly pigmented skin.
所以住在北半球環境的人們 在一年的大部分 都喪失了在皮膚裡製造維生素D的能力。 這對人類膚色的演化 有著極重大的影響。 為了確保身體的健康, 這些分散於 北半球的人們 失去了他們色素的維持。 自然選擇 造就了淺膚色的演化。
Here we begin to see the evolution of the beautiful sepia rainbow that now characterizes all of humanity. Lightly pigmented skin evolved not just once, not just twice, but probably three times. Not just in modern humans, but in one of our distant unrelated ancestors, the Neanderthals. A remarkable, remarkable testament to the power of evolution. Humans have been on the move for a long time. And just in the last 5,000 years, in increasing rates, over increasing distances. Here are just some of the biggest movements of people, voluntary movements, in the last 5,000 years.
在這裡我們開始看到 全人類的如同 深色彩虹的膚色的演化。 淺色皮膚演化不只了一次、 不只兩次、但大概發生了三次。 這不只發生在現代人類, 但也發生在人類遠古但連結不大的祖先之一— 尼安德塔人。 他們正是演化的力量 強而有利的證明。 人類的遷移進行了很長的一段時間, 而在過去五千年, 人類遷移的越來越頻繁也越來越遠。 這裡所看到是人類的一些最大規模的遷移, 在過去五千年自主的移動。
Look at some of the major latitudinal transgressions: people from high UV areas going to low UV and vice versa. And not all these moves were voluntary. Between 1520 and 1867, 12 million, 500 people were moved from high UV to low UV areas in the transatlantic slave trade. Now this had all sorts of invidious social consequences. But it also had deleterious health consequences to people.
注意那些橫跨緯度的大規模遷移。 人們從高紫外線照射區域 移動到低紫外線照射區域,反之亦然。 而也不是所有的遷移都是自主的。 在1520年和1867年之間, 一千兩百萬零五百人 因為跨大西洋的奴隸貿易被迫 從高紫外線照射區 移往低紫外線照射區。 這除了引發各式各樣的令人憎惡的社會後果, 還造成了對人體 有害的健康後果。
So what? We've been on the move. We're so clever we can overcome all of these seeming biological impediments. Well, often we're unaware of the fact that we're living in environments in which our skin is inherently poorly adapted. Some of us with lightly pigmented skin live in high-UV areas. Some of us with darkly pigmented skin live in low-UV areas. These have tremendous consequences for our health.
那又如何?我們一直都在遷移。 我們是如此的聰明我們可以克服 所有這些所謂的生理障礙。 可惜的是,我們常常不知道 我們生存在 我們的皮膚本身有不足 而有困難適應的環境裡。 我們中一些有著淺膚色的人 住在高紫外線照射的區域。 我們中一些有著深膚色的人 住在低紫外線照射的區域。 這一切對我們的健康都有極大的影響。
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. Epidemiologists and doctors have been very good about telling us about protecting our skin. 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.
如果我們有淺膚色的話,我們必須要 格外注意得到皮膚癌 和葉酸被 大量陽光摧毀的問題。 流行病理學家和醫生們 都很盡職的告訴我們 要保護我們的皮膚。 但他們並沒有盡力的是告訴人們的是 有深膚色、 住在高緯度地方、 或常常在室內工作的人所面臨的問題。
Because the problem there is just as severe, but it is more sinister, because vitamin D deficiency, from a lack of ultraviolet B radiation, is a major problem. 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, or loss of immune function, and probably some problems with their mood and health, their mental health.
因為這些問題也是同樣嚴重的。 不過卻更難察覺, 因為由於紫外線B不足 所造成的維生素D短缺 是一個重大的問題。 維生素D短缺不知不覺找上人們 而造成各式各樣的健康問題於骨骼、 到免疫系統逐漸的衰退、 或免疫功能的失去, 和有可能對心情 和精神健康 造成影響。
So we have, in skin pigmentation, one of these wonderful products of evolution that still has consequences for us today. And the social consequences, as we know, are incredibly profound. We live in a world where we have lightly and darkly pigmented people living next to one another, but often brought into proximity initially as a result of very invidious social interactions. So how can we overcome this? How can we begin to understand it? Evolution helps us.
所以皮膚色素 是今日仍然影響我們 的完美的演化產物之一。 而它對社會所造成的影響, 如同我們知道的,非常的深遠。 我們住在一個 淺膚色和深膚色人種 居住在一起的世界。 但這個現象常常是因為 一些非常可增的社會互動所造成的。 所以我們如何來克服這一點呢? 我們怎麼能夠開始去了解這一點? 演化的過程可以幫助我們。
200 years after Darwin's birthday, we have the first moderately pigmented President of the United States. (Applause) How wonderful is that? (Applause) This man is significant for a whole host of reasons. But we need to think about how he compares, in terms of his pigmentation, to other people on Earth. He, as one of many urban admixed populations, is very emblematic of a mixed parentage, of a mixed pigmentation. And he resembles, very closely, people with moderate levels of pigmentation who live in southern Africa, or Southeast Asia.
達爾文誕辰兩百年之際, 我們有了第一位有著稍微深色皮膚的美國總統。 (掌聲) 這是多麼完美阿? (掌聲) 他在很多方面都代表著重大意義, 但我們需要思考他的膚色 和地球上其他人比較起來是如何。 他,身為都市和混合的人口族群之一, 很恰當的象徵了 一支混合父母的血統、混合的膚色。 而他那不深不淺的膚色 和住在南非洲或東南亞 的人非常相近。
These people have a tremendous potential to tan, to develop more pigment in their skin, as a result of exposure to sun. They also run the risk of vitamin D deficiency, if they have desk jobs, like that guy. So lets all wish for his great health, and his awareness of his own skin pigmentation.
這些人有很高的可能 在太陽下被曬嘿, 更近接的產生更多色素。 如果他們有坐辦公桌的工作, 他們同時也有著維生素D短缺的風險,就像他一樣。 所以讓我們全部都祝他身體健康, 也希望他了解他自己的膚色。
Now what is wonderful about the evolution of human skin pigmentation, and the phenomenon of pigmentation, is that it is the demonstration, the evidence, of evolution by natural selection, right on your body. When people ask you, "What is the evidence for evolution?" You don't have to think about some exotic examples, or fossils. You just have to look at your skin.
人類膚色的演化 和膚色這個現象 真正完美的地方 就是他是天擇演化 在你身體上 的展示、 的證據。 當別人問你:「演化的證據是什麼?」 你不需要去想出一些奇特的例子,或化石。 你只需要看看你自己的皮膚。
Darwin, I think, would have appreciated this, even though he eschewed the importance of climate on the evolution of pigmentation during his own life. I think, were he able to look at the evidence we have today, he would understand it. He would appreciate it. And most of all, he would teach it.
達爾文,我想,會很欣賞這種做法, 雖然他自己在他的年代 避開了氣候在膚色演化中的重要性。 我想,如果他能夠看到 我們今天有的證據,他就能夠理解。 他就能夠欣賞。 而最重要的是,他就能夠教導這一點。
You, you can teach it. You can touch it. You can understand it. Take it out of this room. Take your skin color, and celebrate it. Spread the word. You have the evolution of the history of our species, part of it, written in your skin. Understand it. Appreciate it. Celebrate it. Go out. Isn't it beautiful? Isn't it wonderful? You are the products of evolution. Thank you. (Applause)
你,你可以去教導這一點。 你可以觸碰它。 你可以了解它。 把這點帶出這個房間。 帶著你的膚色, 然後好好的慶祝。 散布這個訊息。 我們物種 演化的歷史 的一部分就寫在你的皮膚上。 了解它、欣賞它、慶祝它。 去外面吧!你的皮膚不是很美麗很完美嗎? 你們是演化下的產物。 謝謝你們。 (掌聲)