Nina Jablonski breaks the illusion of skin color

翻译人员: Zachary Lin Zhao 校对人员: An Li

有趣的是，查尔斯-达尔文

Interestingly, Charles Darwin

was born a very lightly pigmented man,

一个肤色非常浅的人

in a moderately-to-darkly pigmented world.

生在一个深肤色的世界。

Over the course of his life,

在他的一生中，

Darwin had great privilege.

达尔文享受到了很大的特权。

He lived in a fairly wealthy home.

他的家境相当富裕，

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。

And when he was in his 20s

在二十多岁的时候，

he embarked upon a remarkable voyage on the ship the Beagle.

他踏上了小猎犬号，开始了一段不寻常的征程。

And during the course of that voyage,

在那次航行中，

he saw remarkable things:

他目睹了许多不寻常的事情：

tremendous diversity of plants and animals, and humans.

植物、动物还有人类中惊人的多样化。

And the observations that he made

他在那史诗般的旅程中的

on that epic journey

种种观察

were to be eventually distilled

最终凝结成了

into his wonderful book, "On the Origin of Species,"

他伟大的著作──《物种起源》，

published 150 years ago.

发表于150年前。

Now what is so interesting

而这本书的有趣之处，

and to some, the extent, what's a bit infamous

甚至有点臭名昭著之处

about "The Origin of Species,"

就在于

is that there is only one line in it

整本书中，只有一行字

about human evolution.

是关与人类的进化。

"Light will be thrown on the origin of man

“人类的起源与历史

and his history."

终将得以阐明。”

It wasn't until much longer,

直到很久以后

much later,

很久很久以后

that Darwin actually spoke

达尔文才真正地开始在人类的话题上

and wrote about humans.

撰文、讨论。

Now in his years of

乘坐小猎犬号

traveling on the Beagle,

周游的经历，

and from listening to the accounts

和途中从探险者和博物学家那里

or explorers and naturalists,

听到的很多故事，

he knew that skin color

使他知道

was one of the most important ways

肤色是不同种族之间

in which people varied.

最重要的差异之一。

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。

He knew that darkly pigmented peoples

他知道深色肤色的人

were found close to the equator;

常常居住在赤道附近。

lightly pigmented peoples, like himself,

而和他一样的浅色人种

were found closer to the poles.

则是常常在居住在两极的附近。

So what did he make of all this?

对此，他的结论是什么呢？

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

But much later, in 1871,

不过多年以后， 在1871年

he did have something to say about it.

他最终对此阐述了自己的想法──

And it was quite curious. He said,

一个让人费解的想法。他说：

"Of all the differences between the races of men,

“人与人之间众多的差别中，

the color of the skin is the most conspicuous

肤色是最显著

and one of the best marked."

最醒目的。”

And he went on to say,

他接着又说道：

"These differences do not coincide

“而这些肤色的差别

with corresponding differences in climate."

和气候的差别是没有关联的。”

So he had traveled all around.

他的确是周游过世界，

He had seen people of different colors

也看到了不同地方

living in different places.

不同肤色的人。

And yet he rejected the idea

但他却不认为

that human skin pigmentation

人类的肤色

was related to the climate.

和气候是相关的。

If only Darwin lived today.

要是达尔文活在今天该多好。

If only Darwin had NASA.

要是达尔文那时候有NASA（美国航天局）该多好。

Now, one of the wonderful things that NASA does

NASA做过的美妙事情之一

is it puts up a variety of satellites

就在于它建立了各种各样的卫星系统

that detect all sort of interesting things about our environment.

用以侦测我们周边环境中所发生的有趣的事。

And for many decades now

而在过去的几十年里，

there have been a series of TOMS satellites

已经有一系列的TOMS卫星被发送上天

that have collected data about the radiation of the Earth's surface.

来收集地球表面辐射的数据。

The TOMS 7 satellite data, shown here,

这里看到的，就是TOMS 7号卫星

show the annual average

所收集的地表紫外线辐射的

ultraviolet radiation at the Earth's surface.

年平均值。

Now the really hot pink and red areas

这些深粉色和红色的地域

are those parts of the world that receive the highest amounts

就代表着世界上每年接受紫外线辐射

of UV during the year.

最大量的地区。

The incrementally cooler colors --

而那些逐步变浅的颜色：

blues, greens, yellows, and finally grays --

蓝色、绿色、黄色、一直到灰色，

indicate areas of much lower ultraviolet radiation.

则是显示了接受比较少量紫外线辐射的地区。

What's significant to the story of human skin pigmentation

而对人类肤色的研究至关紧要的一点

is just how much of the Northern Hemisphere

就在于北半球的大部分地区

is in these cool gray zones.

都集中在这些凉爽的灰色地带。

This has tremendous implications for our understanding

这一点，对于我们理解人类肤色的进化过程

of the evolution of human skin pigmentation.

有着极其深远的影响。

And what Darwin could not appreciate,

而达尔文当时没有意识到的，

or didn't perhaps want to appreciate at the time,

或者是不想意识到的，

is that there was a fundamental relationship

就是紫外线的强度

between the intensity of ultraviolet radiation

和人体的肤色

and skin pigmentation.

是在本质上息息相关的。

And that skin pigmentation itself

肤色本身

was a product of evolution.

就是进化的产物。

And so when we look at a map of skin color,

所以当我们研究人类现有肤色

and predicted skin color, as we know it today,

和根据现今情况所预测的肤色的分布图时，

what we see is a beautiful gradient

我们所看到的是一条美丽的色彩渐变

from the darkest skin pigmentations toward the equator,

从赤道附近的最深色肤色一直延伸到

and the lightest ones toward the poles.

两极附近的最浅色肤色。

What's very, very important here

非常非常重要的一点就在于

is that the earliest humans

最早期的人类

evolved in high-UV environments,

进化于高紫外线的环境下，

in equatorial Africa.

在非洲靠近赤道的地带。

The earliest members of our lineage,

我们的老祖宗，

the genus Homo, were darkly pigmented.

所谓的“直立人”，是有着很深的肤色的。

And we all share this incredible heritage

我们都是这一奇妙现象的继承者，

of having originally been

都是在最原始的时候，

darkly pigmented,

在两百万到一百五十万年前，

two million to one and half million years ago.

拥有着深色的皮肤。

Now what happened in our history?

但随后，我们的历史发生了怎样的变化呢？

Let's first look at the relationship

让我们首先来看一看

of ultraviolet radiation to the Earth's surface.

紫外线辐射和地表的关系。

In those early days of our evolution,

在人类的早期进化过程中——

looking at the equator,

注意赤道附近——

we were bombarded by high levels of ultraviolet radiation.

我们面临着大量紫外线辐射的冲击。

The UVC, the most energetic type,

其中最富能量的一种，UVC，

was occluded by the Earth's atmosphere.

是被我们的大气层隔离在外。

But UVB and UVA

不过UVB还有UVA，

especially, came in unimpeded.

则是毫无阻隔地横冲直入。

UVB turns out to be incredibly important.

其中UVB扮演着极其重要的角色。

It's very destructive,

它充满了破坏性，

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。

vitamin D being a molecule that we very much need

维生素D是我们非常需要的一种元素，

for our strong bones, the health of our immune system,

帮助我们强壮骨骼，增强免疫系统，

and myriad other important functions in our bodies.

以及其他体内非常重要的各种作用。

So, living at the equator, we got

所以居住在赤道附近，

lots and lots of ultraviolet radiation

我们接受着大量的紫外线辐射，

and the melanin --

而黑色素——

this wonderful, complex, ancient polymer

我们皮肤内

compound in our skin --

美妙、复杂、古老的聚合物，

served as a superb natural sunscreen.

是优良的天然防晒霜。

This polymer is amazing

这个聚合物的奇妙之处

because it's present in so many different organisms.

就在于它存在于众多的生物体内。

Melanin, in various forms, has probably been on the Earth

不同形式的黑色素很有可能存在于地球上

a billion years,

长达十亿年。

and has been recruited over and over again

并且一次又一次地

by evolution, as often happens.

被进化的过程所招纳。

Why change it if it works?

既然它如此实用，为何要对它做任何改变呢？

So melanin was recruited, in our lineage,

因此在人类早期的时候，

and specifically in our earliest ancestors

尤其是对于我们最早的在非洲进化的祖先们，

evolving in Africa,

黑色素扮演着

to be a natural sunscreen.

天然防晒霜的作用。

Where it protected the body

它保护我们的身体

against the degradations of ultraviolet radiation,

不受紫外线的摧毁，

the destruction, or damage to DNA,

避免DNA的损伤和破坏，

and the breakdown of a very important molecule called folate,

也防止叶酸的分解。

which helps to fuel cell production,

叶酸对于细胞的制造和再生

and reproduction in the body.

至关重要。

So, it's wonderful. We evolved this very protective,

所以黑色素其实是非常美好的。

wonderful covering of melanin.

我们也因此而进化出这层绝妙的黑色素保护层。

But then we moved.

但随后，我们开始了迁移。

And humans dispersed -- not once, but twice.

人类开始分散——不止一次，而是两次。

Major moves, outside of our equatorial homeland,

从我们赤道附近的家乡，从非洲，

from Africa into other parts of the Old World,

开始大规模地迁移到其他的地域，

and most recently, into the New World.

而最近的一次迁移则是新大陆的探索。

When humans dispersed into these latitudes,

当人类迁移至其他的纬度地区时，

what did they face?

他们所面临的是什么呢？

Conditions were significantly colder,

环境变得异常寒冷，

but they were also less intense

而紫外线的强度

with respect to the ultraviolet regime.

也减弱了许多。

So if we're somewhere in the Northern Hemisphere,

所以观看北半球的话，

look at what's happening to the ultraviolet radiation.

就可以看出紫外线辐射所发生的变化。

We're still getting a dose of UVA.

我们还是会接受到UVA

But all of the UVB,

不过所有的UVB

or nearly all of it,

差不多所有的UVB

is dissipated through the thickness of the atmosphere.

都会被厚重的大气层所吸收。

In the winter, when you are skiing in the Alps,

在冬天，当你在阿尔贝斯山滑雪的时候，

you may experience ultraviolet radiation.

你也许还能感觉到紫外线的辐射，

But it's all UVA,

不过那些都是UVA。

and, significantly, that UVA

至关重要的一点就在于

has no ability to make vitamin D in your skin.

UVA是无法在你的皮肤内制造维生素D的。

So people inhabiting northern hemispheric environments

所以居住在北半球环境下的人们

were bereft of the potential

在一年内大部分的时间里，都丧失了

to make vitamin D in their skin for most of the year.

在皮肤内生产维生素D的潜能。

This had tremendous consequences

这对人类肤色的进化

for the evolution of human skin pigmentation.

有着极其重大的影响。

Because what happened, in order to ensure health and well-being,

为了确保自身的健康，

these lineages of people

这些迁移到北半球的人群

dispersing into the Northern Hemisphere

逐渐失去了

lost their pigmentation.

色素的堆积。

There was natural selection

自然选择造就了

for the evolution of lightly pigmented skin.

浅色肤色的进化。

Here we begin to see the evolution

我们也因此可以看到

of the beautiful sepia rainbow

全人类共有的

that now characterizes all of humanity.

美丽的宛如深色彩虹般的肤色。

Lightly pigmented skin evolved not just once,

浅色的肤色不仅仅进化了一次

not just twice, but probably three times.

不仅仅进化了两次，而是很有可能进化了三次。

Not just in modern humans,

不仅仅在现代人类中，

but in one of our distant unrelated ancestors,

也发生在我们远古的关联不大的祖先——

the Neanderthals.

尼安德特人之中。

A remarkable, remarkable testament

这也正是对进化的力量

to the power of evolution.

强而有力的证明。

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。

And just in the last 5,000 years,

就在过去的五千年里，

in increasing rates, over increasing distances.

迁移的速率越来越快，迁移的距离越来越远。

Here are just some of the biggest movements of people,

这里所看到就是过去五千年里，

voluntary movements, in the last 5,000 years.

比较重大的人类自主迁移活动。

Look at some of the major latitudinal transgressions:

注意那些横跨大量纬度的移动。

people from high UV areas

人们从高紫外线辐射的地区

going to low UV and vice versa.

前往低紫外线辐射的地区，反之亦然。

And not all these moves were voluntary.

但并不是所有的迁移活动都是自主的。

Between 1520 and 1867,

在1520年和1867年之间，

12 million, 500 people

一千两百万的人口

were moved from high UV

因为横渡大西洋的奴隶贸易

to low UV areas

被迫从高紫外线的地区

in the transatlantic slave trade.

转移到了低紫外线的地区。

Now this had all sorts of invidious social consequences.

这引发了许多令人憎恶的社会现象，

But it also had deleterious

但同时它也对人体的健康

health consequences to people.

产生了恶劣的影响。

So what? We've been on the move.

那又怎么样呢？我们一直都在迁移着。

We're so clever we can overcome all of these

我们是如此聪明，完全可以逾越

seeming biological impediments.

这些看似是生理上的障碍。

Well, often we're unaware

可惜我们通常并不知道

of the fact that we're living

我们的皮肤往往存在内在的不足

in environments in which our skin

无法适应

is inherently poorly adapted.

我们所生存的环境。

Some of us with lightly pigmented skin

我们中的一些浅肤色的人

live in high-UV areas.

生活在高紫外线的地区。

Some of us with darkly pigmented skin

而我们中一些深肤色的人

live in low-UV areas.

生活在低紫外线的地区。

These have tremendous consequences for our health.

这一切对我们的健康都有着深远的影响。

We have to, if we're lightly pigmented,

对于浅肤色的人来说，我们不得不

be careful about the problems of skin cancer,

格外小心皮肤癌的问题，

and destruction of folate in our bodies,

还有过度日照所引发的

by lots of sun.

体内叶酸的损伤。

Epidemiologists and doctors

皮肤学家和医生

have been very good about telling us

都很尽职地告诉我们

about protecting our skin.

要保护我们的皮肤。

What they haven't been so good about instructing people

可是他们并没有很好传达给人们的是

is the problem of darkly pigmented people

那些居住在高纬度地域

living in high latitude areas,

或者是长期在室内工作的深肤色人口

or working inside all the time.

所面临的问题。

Because the problem there is just as severe,

他们所面临的问题是同等严重的。

but it is more sinister,

不过却更加不宜察觉。

because vitamin D deficiency,

因为紫外线B辐射不足

from a lack of ultraviolet B radiation,

所引发的维生素D短缺

is a major problem.

是一个重大的问题。

Vitamin D deficiency creeps up on people,

维生素D的缺乏会在不知不觉中

and causes all sorts of health problems to their bones,

对人体的骨骼造成各种各样的问题，

to their gradual decay of their immune systems,

导致免疫系统的逐步衰退

or loss of immune function,

或者免疫机能的丧失

and probably some problems

也有可能对心情

with their mood and health,

还有精神的健康

their mental health.

造成影响。

So we have, in skin pigmentation,

所以肌肤色素中所隐藏的

one of these wonderful products of evolution

是进化过程的美妙的产物之一

that still has consequences for us today.

并且对现今的我们依旧有着影响。

And the social consequences,

其中对社会产生的后果，

as we know, are incredibly profound.

我们众所周知，是非常深远的。

We live in a world where we

我们所生活的世界里

have lightly and darkly pigmented people

深肤色的人口和浅肤色的人口

living next to one another,

居住在一起。

but often brought into proximity initially

不过这种临近往往在最初

as a result of very invidious social interactions.

是由于可憎的社会作用所造成的。

So how can we overcome this?

所以我们应当如何来克服这一点呢？

How can we begin to understand it?

我们应当如何开始理解这一点呢？

Evolution helps us.

进化过程可以帮助我们。

200 years after Darwin's birthday,

达尔文诞辰200年之际，

we have the first moderately pigmented President of the United States.

我们有了第一位有色人种，被当选为美国总统。

(Applause)

（掌声）

How wonderful is that?

这是多么美好的事情呀！

(Applause)

（掌声）

This man is significant for a whole host of reasons.

他所代表着的重大意义是各方面的。

But we need to think about how he compares,

但我们仍需要仔细思考，看看他的肤色

in terms of his pigmentation, to other people on Earth.

和地球上的其他人种有怎样的区别。

He, as one of many urban admixed populations,

他作为城市中的混血人口之一，

is very emblematic

很好地象征了

of a mixed parentage, of a mixed pigmentation.

一个混合的父母血统，一个混合的肤色。

And he resembles, very closely,

他和有着中度色素堆积的人

people with moderate levels of pigmentation

非常相像

who live in southern Africa, or Southeast Asia.

比如居住在非洲南部或是东南亚的人口。

These people have a tremendous potential

这些人很容易被晒黑，

to tan, to develop more pigment in their skin,

一旦暴露在日光下，他们的皮肤就能

as a result of exposure to sun.

产生更多的色素。

They also run the risk of vitamin D deficiency,

他们也面临着维生素D短缺的危险

if they have desk jobs, like that guy.

尤其是当他们是白领阶层，就好比他一样。

So lets all wish for his great health,

所以让我们一同祝他身体健康，

and his awareness of his own skin pigmentation.

也希望他对自己的肤色有着充分的了解。

Now what is wonderful

人类肤色的进化

about the evolution of human skin pigmentation,

还有人类色素的这现象中

and the phenomenon of pigmentation,

最美妙的一点就在于

is that it is the demonstration,

这是我们自身上

the evidence, of evolution

关于自然选择和进化

by natural selection,

有力的演示

right on your body.

和证明。

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？”

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。

You just have to look at your skin.

你只需看看你的皮肤。

Darwin, I think, would have appreciated this,

我想，达尔文是可以欣赏你这样做的。

even though he eschewed the importance

尽管说在他的时代，

of climate on the evolution of pigmentation during his own life.

他曾误解了气候对人类肤色进化的影响。

I think, were he able to look

但我觉得，如果他当时

at the evidence we have today, he would understand it.

可以看到我们今天所有的证据的话，他是可以理解的。

He would appreciate it.

他是可以欣赏这一点的。

And most of all, he would teach it.

最重要的是，他会教导这一点。

You, you can teach it.

你也可以教导这一点。

You can touch it.

你可以感受到它

You can understand it.

可以理解它。

Take it out of this room.

将它带出这个房间。

Take your skin color,

带着你的肤色

and celebrate it.

尽情地为其庆祝。

Spread the word.

传扬这一信息。

You have the evolution

我们种族的进化历史

of the history of our species,

其中的一部分

part of it, written in your skin.

就撰写在你的肌肤里。

Understand it. Appreciate it. Celebrate it.

理解它。欣赏它。庆祝它。

Go out. Isn't it beautiful? Isn't it wonderful?

出外欢庆吧。它是对么美妙呀！多么美好呀！

You are the products of evolution.

你是进化的产物。

Thank you.

谢谢。

(Applause)

（掌声）