Elizabeth Murchison: Fighting a contagious cancer

翻译人员: Chunxiang Qian 校对人员: Felix Chen

Everyone's familiar with cancer,

每个人都熟悉癌症

but we don't normally think of cancer

但我们通常认为

as being a contagious disease.

癌症不是传染病

The Tasmanian devil has shown us

袋獾（又称塔斯马尼亚恶魔）已经向我们证实

that, not only can cancer be a contagious disease,

癌症不但可能是传染病

but it can also threaten

也可能

an entire species with extinction.

导致整个一个物种灭绝

So first of all, what is a Tasmanian devil?

首先，袋獾是什么？

Many of you might be familiar with Taz, the cartoon character,

很多人可能熟悉塔斯这个卡通形象（华纳兄弟－Looney Tunes）

the one that spins around and around and around.

一直不停转圈的那个

But not many people know

但很多人并不知道

that there actually is a real animal called the Tasmanian devil,

确实有一种动物叫塔斯马尼亚恶魔（袋獾）

and it's the world's largest carnivorous marsupial.

这是世界上最大的肉食性有袋动物

A marsupial is a mammal with a pouch

有袋动物是一种身前有口袋的哺乳动物

like a kangaroo.

比如袋鼠

The Tasmanian devil got its name

袋獾被称作塔斯马尼亚恶魔

from the terrifying nocturnal scream that it makes.

是因为它们在夜间发出吓人的尖叫声

(Screaming)

（尖叫）

(Laughter)

（笑声）

The Tasmanian devil is predominantly a scavenger,

袋獾主要食腐肉

and it uses its powerful jaws

它们用有利的下颌骨

and its sharp teeth

和尖利的牙齿

to chomp on the bones of rotting dead animals.

啃食腐烂动物尸体的骨头

[The] Tasmanian devil is found only on the island of Tasmania,

袋獾只分布在塔斯马尼亚岛

which is that small island

这是一个

just to the south of the mainland of Australia.

在澳洲大陆南边的小岛

And despite their ferocious appearance,

虽然袋獾的面孔有点吓人

Tasmanian devils are actually

但它们其实

quite adorable little animals.

是很可爱的小动物

In fact, growing up in Tasmania,

我本人在塔斯马尼亚岛长大

it always was incredibly exciting

能在野外看到

when we got a chance to see

袋獾

a Tasmanian devil in the wild.

一直是件令人兴奋的事情

But the Tasmanian devil population

但袋獾数量

has been undergoing a really extremely fast decline.

呈急速下降的趋势

And in fact, there's concern

很多人担心

that the species could go extinct in the wild

这个物种可能将在二三十年内

within 20 to 30 years.

消失殆尽

And the reason for that

原因就是

is the emergence of a new disease,

一种新疾病的出现

a contagious cancer.

一种传染性癌症

The story begins in 1996

事情始于1996年

when a wildlife photographer took this photograph here

一位野外摄影师拍下了这张

of a Tasmanian devil

袋獾的照片

with a large tumor on its face.

它的脸部有个巨大的肿瘤

At the time, this was thought to be a one-off.

当时这被认为是个个例

Animals, just like humans,

动物，和人一样

sometimes get strange tumors.

有时会长出奇形怪状的肿瘤

However, we now believe

但是，如今我们发现

that this is the first sighting of a new disease,

那是这种新型疾病的初露端倪

which is now an epidemic spreading through Tasmania.

现在已经肆虐整个塔斯马尼亚岛

The disease was first sighted

这种新型疾病首先

in the northeast of Tasmania in 1996

于1996年在塔斯马尼亚岛北部发现

and has spread across Tasmania like a huge wave.

然后大规模波及到整个岛

Now there's only a small part of the population,

如今只剩下群体的小部分

which remains unaffected.

还未被感染

This disease appears first as tumors,

这种病首先表现为肿瘤

usually on the face or inside the mouth

通常出现在袋獾的

of affected Tasmanian devils.

脸部或口腔内

These tumors inevitably grow into larger tumors,

这些肿瘤最终长成大块的肿瘤

such as these ones here.

比如这样的

And the next image I'm going to show

下一张图片

is quite gruesome.

比较恶心

But inevitably, these tumors progress

最终，这些肿瘤

towards being enormous, ulcerating tumors like this one here.

不断繁殖，溃烂的肿瘤就像这样

This one in particular sticks in my mind,

这个病例我一直记忆犹新

because this is the first case of this disease

因为这是我接触的

that I saw myself.

第一个病例

And I remember the horror of seeing this little female devil

我仍然记得当时看到这个嘴里长着

with this huge ulcerating, foul-smelling tumor

溃烂并发出恶臭的大肿瘤的袋獾时

inside her mouth

受到的惊吓

that had actually cracked off her entire lower jaw.

实际上它的整个下巴因为这个肿瘤已经脱开

She hadn't eaten for days.

几天没有进食

Her guts were swimming with parasitic worms.

腹中大量寄生虫繁殖

Her body was riddled with secondary tumors.

整个身体因为次发性肿瘤已经千疮百孔

And yet, she was feeding three little baby Tasmanian devils

然而它还得喂养袋里三个嗷嗷待哺的

in her pouch.

小袋獾

Of course, they died along with the mother.

毫无疑问，小袋獾和妈妈一起死掉了

They were too young to survive without their mother.

他们太幼小无法独立生存

In fact, in the area where she comes from,

事实上，在这只袋獾的生活区域

more than 90 percent of the Tasmanian devil population

那里百分之九十以上的袋獾

has already died of this disease.

都已经死于这种病

Scientists around the world

世界上的科学家

were intrigued by this cancer,

开始研究这种癌症

this infectious cancer,

这种在整个袋獾群体中

that was spreading through the Tasmanian devil population.

传播的传染性癌症

And our minds immediately turned to cervical cancer in women,

我们首先立刻想到了子宫颈癌

which is spread by a virus,

这是通过病毒传播

and to the AIDS epidemic,

还有艾滋病

which is associated with a number of different types of cancer.

感染者可能患上几种不同的癌症

All the evidence suggested that this devil cancer

所有证据都表明这种癌症

was spread by a virus.

是通过病毒传播

However, we now know -- and I'll tell you right now --

然而现在我们知道－我正要告诉你们的－

that we know that this cancer is not spread by a virus.

是这种癌症并不是通过病毒传播

In fact, the infectious agent of disease in this cancer

事实上，该癌症的传播病原体

is something altogether more sinister,

是更险恶的东西

and something that we hadn't really thought of before.

一种完全出乎意料的东西

But in order for me to explain what that is,

为了更好地解释此内容

I need to spend just a couple of minutes

先让我花上几分钟

talking more about cancer itself.

谈谈癌症本身

Cancer is a disease

每年全世界有

that affects millions of people around the world every year.

上百万人患上癌症

One in three people in this room

这个屋子里的人有三分之一

will develop cancer at some stage in their lives.

会在未来患上不同程度的癌症

I myself had a tumor removed from my large intestine

我14岁的时候就从大肠摘除了

when I was only 14.

一个肿瘤

Cancer occurs

当你体内的

when a single cell in your body

一个细胞上的重要基因

acquires a set of random mutations in important genes

发生一系列的偶发突变

that cause that cell to start to produce

这个细胞开始不断自我增殖

more and more and more copies of itself.

癌症就产生了

Paradoxically, once established,

然后，一旦上述情况发生

natural selection actually favors

自然选择的规律

the continued growth of cancer.

却使癌症不断长大

Natural selection is survival of the fittest.

自然选择是适者生存

And when you have a population of fast-dividing cancer cells,

在一群快速分裂的癌细胞中

if one of them acquires new mutations,

如果一个细胞获得新的突变

which allow them to grow more quickly,

从而更快的繁殖

acquire nutrients more successfully,

更好的吸收营养

invade the body,

侵入机体

they'll be selected for by evolution.

他们则被自然保留

That's why cancer is such a difficult disease to treat.

所以癌症是非常难以治疗的疾病

It evolves.

它会进化

Throw a drug at it,

进行药物治疗

and resistant cells will grow back.

抗药性的细胞会卷土重来

An amazing fact is that,

令人不可思议的是

given the right environment and the right nutrients,

如果给以适当的环境和营养

a cancer cell has the potential

一个癌细胞

to go on growing forever.

可以无限繁殖

However cancer is constrained

然而癌症也受制于

by living inside our bodies,

它寄生的身体

and its continued growth,

癌细胞不断生长

its spreading through our bodies

遍布整个身体

and eating away at our tissues,

吞噬掉组织

leads to the death of the cancer patient

最后导致癌细胞的寄主死亡的同时

and also to the death of the cancer itself.

也是癌细胞自己的末日

So cancer could be thought of

所以癌症可以被看作

as a strange, short-lived, self-destructive life form --

一个奇怪的，短命的，自我毁灭性的生命形式

an evolutionary dead end.

进化的死胡同

But that is where the Tasmanian devil cancer

但是袋獾的癌细胞

has acquired an absolutely amazing

具备一种令人无比惊奇的

evolutionary adaptation.

进化适应能力

And the answer came from studying

通过研究袋獾癌症的DNA

the Tasmanian devil cancer's DNA.

我们找到了答案

This was work from many people,

这是很多人工作的结果

but I'm going to explain it through a confirmatory experiment

但是将通过几年前我做的一个验证试验

that I did a few years ago.

来向各位解释

The next slide is going to be gruesome.

下张幻灯片会比较恶心

This is Jonas.

这是乔纳斯

He's a Tasmanian devil that we found

我们发现它的脸上

with a large tumor on his face.

有一个大肿瘤

And being a geneticist,

作为遗传学家

I'm always interested to look at DNA and mutations.

我一直对DNA及其突变感兴趣

So I took this opportunity

所以我借此机会

to collect some samples from Jonas' tumor

收集了一样乔纳斯肿瘤的样本

and also some samples from other parts of his body.

和他身体其他部位的样本

I took these back to the lab.

带回实验室

I extracted DNA from them.

我从样本上提取了DNA

And when I looked at the sequence of the DNA,

当我完成DNA测序

and compared the sequence of Jonas' tumor

并将肿瘤的测序结果和

to that of the rest of his body,

身体其他部分的测序结果对比时

I discovered that they had a completely different genetic profile.

我发现两者的基因图谱完全不同

In fact, Jonas and his tumor

实际上，乔纳斯和它的肿瘤

were as different from each other

就像你和你旁边的人一样

as you and the person sitting next to you.

完全不同

What this told us was that Jonas' tumor

这就告诉我们乔纳斯的肿瘤

did not arise from cells of his own body.

并不是来自它的身体

In fact, more genetic profiling

更多的基因图谱

told us that this tumor in Jonas

告诉我们乔纳斯的肿瘤

actually probably first arose

可能最先来自于

from the cells of a female Tasmanian devil --

一个雌袋獾

and Jonas was clearly a male.

而乔纳斯是雄性

So how come

所以

a tumor that arose from the cells of another individual

一个来自另一个体的细胞是如何

is growing on Jonas' face?

长到乔纳斯脸上去的？

Well the next breakthrough

下一个研究突破来自于

came from studying hundreds of Tasmanian devil cancers

塔斯马尼亚岛上

from all around Tasmania.

成千只袋獾的癌细胞研究

We found that all of these cancers

我们发现所有的癌细胞

shared the same DNA.

具有一样的DNA

Think about that for a minute.

这意味着什么？

That means that all of these cancers

意味着所有的癌细胞

actually are the same cancer

实际上是同一个癌细胞

that arose once from one individual devil,

从第一个袋獾个体上产生的癌症

that have broken free of that first devil's body

突破了单个个体的限制

and spread through the entire Tasmanian devil population.

传播到了整个袋獾群体

But how can a cancer spread in a population?

那一个癌症是怎么在群体中扩散的？

Well the final piece of the puzzle came

揭开谜题最后答案的是

when we remember how devils behave when they meet each other in the wild.

袋獾在野外相遇时的行为方式

They tend to bite each other,

它们会咬对方

often quite ferociously and usually on the face.

通常会很激烈，并且常常是咬脸部

We think that cancer cells

我们认为癌细胞

actually come off the tumor, get into the saliva.

从肿瘤进入唾液

When the devil bites another devil,

当袋獾相互撕咬时

it actually physically implants living cancer cells into the next devil,

癌细胞就被植入另一个袋獾体内

so the tumor continues to grow.

从而肿瘤得以继续生存

So this Tasmanian devil cancer

所以袋獾癌症

is perhaps the ultimate cancer.

可能是终极版癌症

It's not constrained by living within the body that gave rise to it.

它不受产生个体的限制

It spreads through the population,

可以在群体中传播

has mutations that allow it to evade the immune system,

并通过突变侵入免疫系统

and it's the only cancer that we know of

这是唯一一个我们目前知道的

that's threatening an entire species with extinction.

能导致一个物种整体灭绝的癌症

But if this can happen in Tasmanian devils,

但是如果这种癌症见于袋獾

why hasn't it happened in other animals

为什么没有发生在其他动物身上

or even humans?

甚至是人类？

Well the answer is, it has.

答案是，确实有过。

This is Kimbo.

这是金波

He's a dog that belongs to a family in Mombasa in Kenya.

它的主人住在肯尼亚的蒙巴萨

Last year, his owner noticed some blood

去年，它的主人发现

trickling from his genital region.

它的生殖器官区域开始滴血

She took him to the vet

她带着金波去看兽医

and the vet discovered something quite disgusting.

兽医发现些很恶心的东西

And if you're squeamish, please look away now.

如果你比较敏感，请转头看别处

He discovered this,

兽医发现了这个

a huge bleeding tumor

一个很大的滴血的肿瘤

at the base of Kimbo's penis.

长在金波的阴茎上

The vet diagnosed this as transmissible venereal tumor,

兽医诊断为一种传染性生殖道肿瘤

a sexually transmitted cancer

一种犬类间传染的

that affects dogs.

性病

And just as the Tasmanian devil cancer is contagious

正如同袋獾的癌症

through the spread of living cancer cells,

通过癌细胞活体传播

so is this dog cancer.

这只狗的癌症也是

But this dog cancer is quite remarkable,

但这只狗的更厉害

because it spread all around the world.

因为它已经传播到全世界

And in fact, these same cells

事实上，金波感染的

that are affecting Kimbo here

这种癌细胞

are also found affecting dogs

也出现于

in New York City,

纽约的狗身上

in mountain villages in the Himalayas

喜马拉雅山区村子里狗的身上

and in Outback Australia.

还有澳大利亚的内陆

We also believe this cancer might be very old.

我们认为这种癌症很久历史了

In fact, genetic profiling tells

基因图谱告诉我们

that it may be tens of thousands of years old,

它有几万年之久

which means that this cancer

这意味着它可能

may have first arisen

最初来自

from the cells of a wolf

一个生活在

that lived alongside the Neanderthals.

尼安德特人年代的狼身上

This cancer is remarkable.

这个癌症十分厉害

It's the oldest mammalian-derived life form that we know of.

这是我们目前所之的最古老的哺乳动物源性生命体

It's a living relic

这是从遥远上古

of the distant past.

活下来的遗迹

So we've seen that this can happen in animals.

我们了解到动物感染的情况

Could cancers be contagious between people?

那在人类间传播的癌症呢？

Well this is a question

这个问题

which fascinated Chester Southam,

引起切斯特･索伦医生的极大兴趣

a cancer doctor in the 1950s.

他是50年代的一个癌症医生

Ad he decided to put this to the test

他决定通过对人体

by actually deliberately inoculating people

进行实际注射癌细胞

with cancer from somebody else.

来进行试验

And this is a photograph of Dr. Southam in 1957

这是索伦医生于1957的照片

injecting cancer into a volunteer,

他正给一个志愿者注射癌细胞

who in this case was an inmate

这个志愿者是俄亥俄州管教所的

in Ohio State Penitentiary.

一个犯人

Most of the people that Dr. Southam injected

索伦医生注射过的大部分人

did not go on to develop cancer

并没有因为注射的癌细胞

from the injected cells.

患上癌症

But a small number of them did,

但是一小部分得了

and they were mostly people who were otherwise ill --

患癌这些人大部分也会生病

whose immune systems were probably compromised.

因为他们的免疫系统估计早败下阵来

What this tells us,

这告诉我们

ethical issues aside,

不追究道德问题的话

is that ...

就是

(Laughter)

（笑声）

it's probably extremely rare

是人之间传播的癌症

for cancers to be transferred between people.

是非常罕见的

However, under some circumstances,

但是，在某些情况下

it can happen.

仍然可能发生

And I think that this is something

我认为这是

that oncologists and epidemiologists

肿瘤学家和流行病学家

should be aware of in the future.

将来要关注的问题

So just finally,

最后

cancer is an inevitable outcome

癌症是

of the ability of our cells

细胞分化

to divide

并适应环境的

and to adapt to their environments.

必然结果

But that does not mean that we should give up hope

但是这不意味着我们在与癌症的斗争中

in the fight against cancer.

毫无希望

In fact, I believe, given more knowledge

我相信，在掌握更多的

of the complex evolutionary processes that drive cancer's growth,

关于癌细胞生长的复杂进化过程的知识后

we can defeat cancer.

我们可以打败癌症

My personal aim

我的个人目标是

is to defeat the Tasmanian devil cancer.

打败袋獾癌症

Let's prevent the Tasmanian devil

让我们共同努力

from being the first animal

不让袋獾成为第一个

to go extinct from cancer.

因癌症灭绝的物种

Thank you.

谢谢

(Applause)

（掌声）