Nina Jablonski breaks the illusion of skin color

譯者: Eric Chu 審譯者: Shelley Krishna Tsang

有趣的是，查爾斯·達爾文

Interestingly, Charles Darwin

was born a very lightly pigmented man,

是一位膚色很淺

in a moderately-to-darkly pigmented world.

而生在一個平均到深膚色世界的人。

Over the course of his life,

在他的一生中，

Darwin had great privilege.

達爾文享受了許多特權。

He lived in a fairly wealthy home.

他的家境相當的富裕，

He was raised by very supportive and interested parents.

他的父母在他成長的過程給了許多的支持和關心。

And when he was in his 20s

而他在二十幾歲時，

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

他踏上了小獵犬號，開始了一趟卓越的航海歷險。

And during the course of that voyage,

在航巡的途中，

he saw remarkable things:

他看到了非凡的事物。

tremendous diversity of plants and animals, and humans.

驚人的多樣性存在於植物，動物，和人類之間。

And the observations that he made

而他在那趟壯舉般的旅程中

on that epic journey

所做的觀察，

were to be eventually distilled

終究被提煉入

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

他150年前出版的完美著作，

published 150 years ago.

「物種起源」。

Now what is so interesting

而「物種起源」真正有趣，

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

和對一些人在某種程度上來說，

about "The Origin of Species,"

聲名狼藉的地方，

is that there is only one line in it

是書裡面一筆就帶過了

about human evolution.

人類的演化。

"Light will be thrown on the origin of man

光終究會照耀於人類起源

and his history."

和歷史的暗谷中。

It wasn't until much longer,

達爾文在很長

much later,

很晚的一段時間後

that Darwin actually spoke

才終於談論

and wrote about humans.

和寫作關於人類的起源。

Now in his years of

在他在小獵犬號

traveling on the Beagle,

上航行的日子裡所做的觀察，

and from listening to the accounts

和從其他探險家

or explorers and naturalists,

及自然學者聽來的紀錄，

he knew that skin color

他歸納出膚色

was one of the most important ways

是人類變異的

in which people varied.

最重要的方法之一。

And he was somewhat interested in the pattern of skin color.

而他對於膚色的型態略感興趣。

He knew that darkly pigmented peoples

他知道深膚色的人種

were found close to the equator;

是居住在接近赤道的地區。

lightly pigmented peoples, like himself,

而淡膚色人種，像他自己，

were found closer to the poles.

則是居住於靠近南北極的地方。

So what did he make of all this?

所以他下了什麼結論？

Well he didn't write anything about it in The Origin of Species.

他在物種起源對此隻字未提，

But much later, in 1871,

但在許久以後，在1871年，

he did have something to say about it.

他確實是發表了一些意見。

And it was quite curious. He said,

而令人好奇的是，他說：

"Of all the differences between the races of men,

「人類所有的不同裡，

the color of the skin is the most conspicuous

皮膚的顏色是最顯著

and one of the best marked."

和最醒目的差別之一。」

And he went on to say,

而他接著說了：

"These differences do not coincide

「這些差異和氣候的不同

with corresponding differences in climate."

是沒有關聯的。」

So he had traveled all around.

他到遍了世界各地，

He had seen people of different colors

看過了不同膚色的人

living in different places.

住在不同的地方。

And yet he rejected the idea

然而他仍然排斥

that human skin pigmentation

人類皮膚色素

was related to the climate.

和氣候是有關聯的可能。

If only Darwin lived today.

可惜達爾文不是活在今日，

If only Darwin had NASA.

達爾文在世時也沒有美國航太總署

Now, one of the wonderful things that NASA does

美國航太總署所做的美妙事情之一

is it puts up a variety of satellites

就是建立各種衛星系統

that detect all sort of interesting things about our environment.

來偵測各種關於我們的環境裡有趣的事情。

And for many decades now

而幾十年以來

there have been a series of TOMS satellites

一系列的TOMS(完全臭氧層製圖光譜儀)衛星被發射到外太空

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

來收集地球表面輻射的數據。

The TOMS 7 satellite data, shown here,

這是看到的，是TOMS 7衛星數據，

show the annual average

這告訴我們地球表面

ultraviolet radiation at the Earth's surface.

紫外線輻射的年平均值。

Now the really hot pink and red areas

亮粉紅色和紅色的區域

are those parts of the world that receive the highest amounts

是世界上在一年中接收最多

of UV during the year.

紫外線的地方。

The incrementally cooler colors --

逐漸變暗的顏色--

blues, greens, yellows, and finally grays --

藍色、綠色、黃色、然後最後到灰色—

indicate areas of much lower ultraviolet radiation.

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

人類皮膚色素的故事的重要性

is just how much of the Northern Hemisphere

是在於北半球大部分

is in these cool gray zones.

都處於這些涼爽的灰色地帶。

This has tremendous implications for our understanding

這對於我們對人類皮膚色素演化

of the evolution of human skin pigmentation.

的過程有極大的影響。

And what Darwin could not appreciate,

而達爾文無法體會，

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

或至少在他當年不想體會的，

is that there was a fundamental relationship

是紫外線的輻射量

between the intensity of ultraviolet radiation

和皮膚的色素

and skin pigmentation.

在本質上是息息相關的。

And that skin pigmentation itself

而膚色本身

was a product of evolution.

就是演化的產物。

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

所以當我們看著膚色分布的地圖

and predicted skin color, as we know it today,

而預測了膚色的分布，就如同現況，

what we see is a beautiful gradient

我們所看到的是一個美麗的漸層，

from the darkest skin pigmentations toward the equator,

從位於赤道的最暗的膚色

and the lightest ones toward the poles.

到位於地球兩極最亮的膚色。

What's very, very important here

這裡非常非常重要的一點

is that the earliest humans

是最早期的人類

evolved in high-UV environments,

在非洲赤道的

in equatorial Africa.

高紫外線輻射環境裡演化。

The earliest members of our lineage,

而人類物種最早的成員，

the genus Homo, were darkly pigmented.

人屬，是有著深膚色的。

And we all share this incredible heritage

我們都繼承了

of having originally been

這個奇妙的現象--

darkly pigmented,

在兩百萬到一百五十萬年前

two million to one and half million years ago.

有著深色的膚色。

Now what happened in our history?

我們的歷史是發生了什麼變化?

Let's first look at the relationship

我們先來看看紫外線輻射

of ultraviolet radiation to the Earth's surface.

和地球表面的關係。

In those early days of our evolution,

在人類演化的早期，

looking at the equator,

注意看赤道附近，

we were bombarded by high levels of ultraviolet radiation.

人類曝露在高量的紫外線輻射下。

The UVC, the most energetic type,

其中最多能量的紫外線C(UVC)

was occluded by the Earth's atmosphere.

被地球的大氣層阻擋在外，

But UVB and UVA

但紫外線B(UVB)和紫外線A(UVA)

especially, came in unimpeded.

則是毫無障礙的進入地球表面。

UVB turns out to be incredibly important.

其中UVB特別的重要。

It's very destructive,

UVB非常的有破壞性，

but it also catalyzes the production of vitamin D in the skin,

但是它也催化皮膚裡維生素D的生產。

vitamin D being a molecule that we very much need

維生素D是我們非常需要的一種分子，

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

它幫助強健骨骼、增強免疫系統、

and myriad other important functions in our bodies.

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

所以住在赤道附近，人類吸收了

lots and lots of ultraviolet radiation

很多很多的紫外線輻射，

and the melanin --

而黑色素—

this wonderful, complex, ancient polymer

我們皮膚裡完美、複雜、

compound in our skin --

和古老的聚合物—

served as a superb natural sunscreen.

是優秀的天然防曬劑。

This polymer is amazing

這個聚合物相當的神奇，

because it's present in so many different organisms.

因為它在存在於很多不同的生物裡。

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

黑色素以不同的型態大概已經在地球上

a billion years,

存在了十億年，

and has been recruited over and over again

也在演化的過程中

by evolution, as often happens.

一次又一次的被應用。

Why change it if it works?

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,

因此黑色素在人類，

and specifically in our earliest ancestors

尤其是我們最早的

evolving in Africa,

在非洲的祖先們，

to be a natural sunscreen.

的演化裡扮演了天然防曬劑的角色。

Where it protected the body

它保護我們的身體

against the degradations of ultraviolet radiation,

免於紫外線輻射的摧殘、

the destruction, or damage to DNA,

避免DNA的毀滅或損傷、

and the breakdown of a very important molecule called folate,

和一種非常重要的分子—葉酸的分解。

which helps to fuel cell production,

葉酸提供在身體裡製造

and reproduction in the body.

和複製細胞的能量。

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

所以，這很完美。我們演化出這層

wonderful covering of melanin.

非常有保護性而美妙的黑色素。

But then we moved.

但之後我們開始了遷移，

And humans dispersed -- not once, but twice.

而人類開始分散，不只一次，而是兩次。

Major moves, outside of our equatorial homeland,

大規模的外移出我們在赤道的家，

from Africa into other parts of the Old World,

移出非洲到其他部分的舊大陸和，

and most recently, into the New World.

最近發生的，新大陸。

When humans dispersed into these latitudes,

當人類分散到其他的緯度地區時，

what did they face?

他們面對了什麼?

Conditions were significantly colder,

環境變得顯著的更寒冷，

but they were also less intense

但紫外線輻射量

with respect to the ultraviolet regime.

也相對的減弱許多。

So if we're somewhere in the Northern Hemisphere,

所以如果我們在北半球的某個地方

look at what's happening to the ultraviolet radiation.

來檢視紫外線輻射的變化，

We're still getting a dose of UVA.

我們會看到我們仍然在吸收UVA，

But all of the UVB,

但是所有的UVB，

or nearly all of it,

或幾乎所有的UVB，

is dissipated through the thickness of the atmosphere.

都被地球的厚大氣層所吸收了。

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

在冬天裡，當你再阿爾卑斯山滑雪時，

you may experience ultraviolet radiation.

你可能會感受到紫外線輻射，

But it's all UVA,

但那全部都是UVA，

and, significantly, that UVA

而顯著的，那些UVA

has no ability to make vitamin D in your skin.

沒有在你的皮膚裡製造維生素D的能力。

So people inhabiting northern hemispheric environments

所以住在北半球環境的人們

were bereft of the potential

在一年的大部分

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

都喪失了在皮膚裡製造維生素D的能力。

This had tremendous consequences

這對人類膚色的演化

for the evolution of human skin pigmentation.

有著極重大的影響。

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

為了確保身體的健康，

these lineages of people

這些分散於

dispersing into the Northern Hemisphere

北半球的人們

lost their pigmentation.

失去了他們色素的維持。

There was natural selection

自然選擇

for the evolution of lightly pigmented skin.

造就了淺膚色的演化。

Here we begin to see the evolution

在這裡我們開始看到

of the beautiful sepia rainbow

全人類的如同

that now characterizes all of humanity.

深色彩虹的膚色的演化。

Lightly pigmented skin evolved not just once,

淺色皮膚演化不只了一次、

not just twice, but probably three times.

不只兩次、但大概發生了三次。

Not just in modern humans,

這不只發生在現代人類，

but in one of our distant unrelated ancestors,

但也發生在人類遠古但連結不大的祖先之一—

the Neanderthals.

尼安德塔人。

A remarkable, remarkable testament

他們正是演化的力量

to the power of evolution.

強而有利的證明。

Humans have been on the move for a long time.

人類的遷移進行了很長的一段時間，

And just in the last 5,000 years,

而在過去五千年，

in increasing rates, over increasing distances.

人類遷移的越來越頻繁也越來越遠。

Here are just some of the biggest movements of people,

這裡所看到是人類的一些最大規模的遷移，

voluntary movements, in the last 5,000 years.

在過去五千年自主的移動。

Look at some of the major latitudinal transgressions:

注意那些橫跨緯度的大規模遷移。

people from high UV areas

人們從高紫外線照射區域

going to low UV and vice versa.

移動到低紫外線照射區域，反之亦然。

And not all these moves were voluntary.

而也不是所有的遷移都是自主的。

Between 1520 and 1867,

在1520年和1867年之間，

12 million, 500 people

一千兩百萬零五百人

were moved from high UV

因為跨大西洋的奴隸貿易被迫

to low UV areas

從高紫外線照射區

in the transatlantic slave trade.

移往低紫外線照射區。

Now this had all sorts of invidious social consequences.

這除了引發各式各樣的令人憎惡的社會後果，

But it also had deleterious

還造成了對人體

health consequences to people.

有害的健康後果。

So what? We've been on the move.

那又如何?我們一直都在遷移。

We're so clever we can overcome all of these

我們是如此的聰明我們可以克服

seeming biological impediments.

所有這些所謂的生理障礙。

Well, often we're unaware

可惜的是，我們常常不知道

of the fact that we're living

我們生存在

in environments in which our skin

我們的皮膚本身有不足

is inherently poorly adapted.

而有困難適應的環境裡。

Some of us with lightly pigmented skin

我們中一些有著淺膚色的人

live in high-UV areas.

住在高紫外線照射的區域。

Some of us with darkly pigmented skin

我們中一些有著深膚色的人

live in low-UV areas.

住在低紫外線照射的區域。

These have tremendous consequences for our health.

這一切對我們的健康都有極大的影響。

We have to, if we're lightly pigmented,

如果我們有淺膚色的話，我們必須要

be careful about the problems of skin cancer,

格外注意得到皮膚癌

and destruction of folate in our bodies,

和葉酸被

by lots of sun.

大量陽光摧毀的問題。

Epidemiologists and doctors

流行病理學家和醫生們

have been very good about telling us

都很盡職的告訴我們

about protecting our skin.

要保護我們的皮膚。

What they haven't been so good about instructing people

但他們並沒有盡力的是告訴人們的是

is the problem of darkly pigmented people

有深膚色、

living in high latitude areas,

住在高緯度地方、

or working inside all the time.

或常常在室內工作的人所面臨的問題。

Because the problem there is just as severe,

因為這些問題也是同樣嚴重的。

but it is more sinister,

不過卻更難察覺，

because vitamin D deficiency,

因為由於紫外線B不足

from a lack of ultraviolet B radiation,

所造成的維生素D短缺

is a major problem.

是一個重大的問題。

Vitamin D deficiency creeps up on people,

維生素D短缺不知不覺找上人們

and causes all sorts of health problems to their bones,

而造成各式各樣的健康問題於骨骼、

to their gradual decay of their immune systems,

到免疫系統逐漸的衰退、

or loss of immune function,

或免疫功能的失去，

and probably some problems

和有可能對心情

with their mood and health,

和精神健康

their mental health.

造成影響。

So we have, in skin pigmentation,

所以皮膚色素

one of these wonderful products of evolution

是今日仍然影響我們

that still has consequences for us today.

的完美的演化產物之一。

And the social consequences,

而它對社會所造成的影響，

as we know, are incredibly profound.

如同我們知道的，非常的深遠。

We live in a world where we

我們住在一個

have lightly and darkly pigmented people

淺膚色和深膚色人種

living next to one another,

居住在一起的世界。

but often brought into proximity initially

但這個現象常常是因為

as a result of very invidious social interactions.

一些非常可增的社會互動所造成的。

So how can we overcome this?

所以我們如何來克服這一點呢?

How can we begin to understand it?

我們怎麼能夠開始去了解這一點?

Evolution helps us.

演化的過程可以幫助我們。

200 years after Darwin's birthday,

達爾文誕辰兩百年之際，

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

我們有了第一位有著稍微深色皮膚的美國總統。

(Applause)

(掌聲)

How wonderful is that?

這是多麼完美阿?

(Applause)

(掌聲)

This man is significant for a whole host of reasons.

他在很多方面都代表著重大意義，

But we need to think about how he compares,

但我們需要思考他的膚色

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

和地球上其他人比較起來是如何。

He, as one of many urban admixed populations,

他，身為都市和混合的人口族群之一，

is very emblematic

很恰當的象徵了

of a mixed parentage, of a mixed pigmentation.

一支混合父母的血統、混合的膚色。

And he resembles, very closely,

而他那不深不淺的膚色

people with moderate levels of pigmentation

和住在南非洲或東南亞

who live in southern Africa, or Southeast Asia.

的人非常相近。

These people have a tremendous potential

這些人有很高的可能

to tan, to develop more pigment in their skin,

在太陽下被曬嘿，

as a result of exposure to sun.

更近接的產生更多色素。

They also run the risk of vitamin D deficiency,

如果他們有坐辦公桌的工作，

if they have desk jobs, like that guy.

他們同時也有著維生素D短缺的風險，就像他一樣。

So lets all wish for his great health,

所以讓我們全部都祝他身體健康，

and his awareness of his own skin pigmentation.

也希望他了解他自己的膚色。

Now what is wonderful

人類膚色的演化

about the evolution of human skin pigmentation,

和膚色這個現象

and the phenomenon of pigmentation,

真正完美的地方

is that it is the demonstration,

就是他是天擇演化

the evidence, of evolution

在你身體上

by natural selection,

的展示、

right on your body.

的證據。

When people ask you, "What is the evidence for evolution?"

當別人問你：「演化的證據是什麼?」

You don't have to think about some exotic examples, or fossils.

你不需要去想出一些奇特的例子，或化石。

You just have to look at your skin.

你只需要看看你自己的皮膚。

Darwin, I think, would have appreciated this,

達爾文，我想，會很欣賞這種做法，

even though he eschewed the importance

雖然他自己在他的年代

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

避開了氣候在膚色演化中的重要性。

I think, were he able to look

我想，如果他能夠看到

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

我們今天有的證據，他就能夠理解。

He would appreciate it.

他就能夠欣賞。

And most of all, he would teach it.

而最重要的是，他就能夠教導這一點。

You, you can teach it.

你，你可以去教導這一點。

You can touch it.

你可以觸碰它。

You can understand it.

你可以了解它。

Take it out of this room.

把這點帶出這個房間。

Take your skin color,

帶著你的膚色，

and celebrate it.

然後好好的慶祝。

Spread the word.

散布這個訊息。

You have the evolution

我們物種

of the history of our species,

演化的歷史

part of it, written in your skin.

的一部分就寫在你的皮膚上。

Understand it. Appreciate it. Celebrate it.

了解它、欣賞它、慶祝它。

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

去外面吧！你的皮膚不是很美麗很完美嗎?

You are the products of evolution.

你們是演化下的產物。

Thank you.

謝謝你們。

(Applause)

(掌聲)