为什么蓝鲸不得癌症？——佩托悖论：英语精读讲义

Cancer is a creepy and mysterious thing.

癌症是一种令人毛骨悚然又神秘的东西。

In the process of trying to understand it, 語法

在试图理解它、

to get better at killing it, 短語搭配

以便更好地消灭它的过程中，

we discovered a biological paradox that remains unsolved to this day. 短語搭配

我们发现了一个至今尚未解开的生物学悖论。

Large animals seem to be immune to cancer,

大型动物似乎对癌症免疫，

which doesn't make any sense. 短語搭配

这完全说不通。

The bigger a being, 語法

一个生物越大，

the more cancer it should have.

它体内应该有的癌症就越多。

To understand why,

为了理解为什么，

we first need to take a look at the nature of cancer itself. 短語搭配

我们首先需要看看癌症本身的本质。

Our cells are protein robots made out of hundreds of millions of parts. 短語搭配

我们的细胞是由数亿个部件组成的蛋白质机器人。

Guided only by chemical reactions,

仅靠化学反应的引导，

they create and dismantle structures,

它们创造并拆除各种结构，

sustain a metabolism to gain energy,

维持新陈代谢以获取能量，

or make almost perfect copies of themselves.

或者复制出几乎完美的自己。

We call these complex chemical reactions pathways.

我们把这些复杂的化学反应称为通路。

They are biochemical networks upon networks,

它们是重重叠叠的生化网络，

intertwined and stacked on top of each other. 短語搭配

彼此交织并堆叠在一起。

Most of them can barely be comprehended by a single human mind,

对单个人类大脑来说，其中大部分都难以理解，

and yet they function perfectly,

然而它们却能完美运作，

until they don't. 表達脈絡

直到它们出了问题。

With billions of trillions of reactions happening in thousands of networks over many years,

在长达数年的时间里，成千上万个网络中发生着亿万兆次反应，

the question is not if something will go wrong, 表達脈絡

问题不在于是否会出错，

but when.

而在于何时出错。

Tiny mistakes add up until the grandiose machinery gets corrupted. 短語動詞

微小的错误不断累积，直到这座宏伟的机器遭到破坏。

To prevent this from getting out of hand, 習語

为了防止情况失控，

our cells have kill switches that make them commit suicide. 用詞

我们的细胞配备了让其自杀的“死亡开关”。

But these kill switches are not infallible.

但这些死亡开关并不是万无一失的。

If they fail,

如果它们失效，

a cell can turn into a cancer cell.

细胞就可能变成癌细胞。

Most of them are slain by the immune system very quickly,

其中大多数很快会被免疫系统消灭，

but this is a numbers game. 習語

但这只是个概率游戏。

Given enough time, 語法

只要有足够的时间，

a cell will accrue enough mistakes,

一个细胞就会累积足够的错误，

slip by unnoticed, 短語動詞

神不知鬼不觉地溜过防线，

and begin making more of itself.

并开始不断自我复制。

All animals have to deal with this problem. 短語動詞

所有动物都必须面对这个问题。

In general,

通常来说，

the cells of different animals are the same size.

不同动物的细胞大小是相同的。

The cells of a mouse aren't smaller than yours,

小鼠的细胞并不比你的小，

it just has fewer cells in total,

它只是细胞总数较少，

and a shorter lifespan.

寿命也较短。

Fewer cells and a short life means a lower chance of things going wrong or cells mutating,

更少的细胞和更短的寿命意味着出错或细胞突变的几率更低，

or at least it should mean that.

或者至少在理论上应该是这样。

Humans live about 50 times longer and have 1,000 times more cells than mice, 語法

人类的寿命大约是小鼠的50倍，细胞数量是其1000倍，

yet the rate of cancer is basically the same in humans and in mice.

但人类和小鼠的癌症发病率基本相同。

Even weirder,

更诡异的是，

blue whales with about 3,000 times more cells than humans

细胞数量比人类多约3000倍的蓝鲸

don't seem to get cancer at all really.

似乎根本就不会得癌症。

This is Peto's paradox, 文化背景

这就是皮托悖论，

the baffling realization that large animals have much much less cancer than they should. 語法

一个令人困惑的事实：大型动物患癌的几率比预期的要低得多。

Scientists think there are two main ways of explaining the paradox,

科学家认为解释这一悖论主要有两个方向：

evolution,

进化，

and hyper tumors.

以及超级肿瘤。

Solution one,

第一种解答，

evolve or become a blob of cancer.

要么进化，要么沦为一团癌症。

As multicellular beings developed 600 million years ago,

随着多细胞生物在6亿年前发展，

animals became bigger and bigger, 語法

动物变得越来越大，

which added more and more cells,

这使得细胞数量不断增加，

and hence more and more chances that cells could be corrupted.

进而意味着细胞受损的几率也越来越大。

So the collective had to invest in better and better cancer defenses.

因此，这个集体必须投资于越来越好的癌症防御机制。

The ones that did not died out. 短語動詞

那些没有这么做的物种就灭绝了。

But cancer doesn't just happen,

但癌症并不是凭空发生的，

it's a process that involves many individual mistakes and mutations in several specific genes within the same cell.

这是一个在同一个细胞内、多个特定基因发生许多个别错误和突变的过程。

These genes are called proto-oncogenes, 用詞

这些基因被称为原癌基因，

and when they mutate,

当它们发生突变时，

it's bad news.

那就是坏消息。

For example,

例如，

with the right mutation,

伴随特定的突变，

a cell will lose its ability to kill itself.

细胞将失去自杀的能力。

Another mutation, 語法

再发生一次突变，

and it will develop the ability to hide.

它就会发展出隐藏的能力。

Another,

再来一次，

and it will send out calls for resources.

它就会发出索取资源的信号。

Another one,

又发生一次，

and it will multiply quickly.

它就会迅速繁殖。

These oncogenes have an antagonist,

这些致癌基因有一个克星，

though,

那就是，

tumor suppressor genes. 用詞

肿瘤抑制基因。

They prevent these critical mutations from happening or order the cell to kill itself if they decide it's beyond repair. 講解

它们阻止这些致命突变的发生，或者在认定细胞无法修复时命令其自杀。

It turns out that large animals have an increased number of them. 表達脈絡

事实证明，大型动物体内这种基因的数量增加了。

Because of this,

正因如此，

elephant cells require more mutations than mouse cells to develop a tumor.

大象的细胞要想发展成肿瘤，需要比小鼠细胞经历更多的突变。

They are not immune, 用詞

它们并非免疫，

but more resilient.

而是更具抵抗力。

This adaptation probably comes with a cost in some form, 短語搭配

这种适应性进化可能在某种形式上是有代价的，

but researchers still aren't sure what it is.

但研究人员还不确定代价是什么。

Maybe tumor suppressors make elephants age quicker later in life or slow down how quickly injuries heal.

也许肿瘤抑制基因会让大象在晚年衰老得更快，或者减慢伤口愈合的速度。

We don't know yet.

我们现在还不知道。

But the solution to the paradox may actually be something different,

但该悖论的解答可能实际上是另外一种东西，

hypertumors.

那就是超级肿瘤。

Solution two,

第二种解答，

hypertumors.

超级肿瘤。

Yes,

是的，

really.

真的。

Hypertumors are named after hyperparasites, 短語搭配

超级肿瘤的名字来源于超级寄生虫，

the parasites of parasites.

即寄生虫的寄生虫。

Hypertumors are the tumors of tumors. 用詞

超级肿瘤就是肿瘤的肿瘤。

Cancer can be thought of as a breakdown in cooperation. 講解

癌症可以被视为一种合作机制的崩溃。

Normally,

通常情况下，

cells work together to form structures like organs,

细胞协同工作以形成器官、

tissue,

组织，

or elements of the immune system.

或是免疫系统的一部分。

But cancer cells are selfish and only work for their own short-term benefit. 短語搭配

但癌细胞是自私的，只为自己短期的利益而工作。

If they're successful,

如果它们成功了，

they form tumors,

它们就会形成肿瘤，

huge cancer collectives that can be very hard to kill.

也就是极难被杀死的巨大癌症聚集体。

Making a tumor is hard work,

然而，制造一个肿瘤是项艰难的工作，

though.

不过确实如此。

Millions or billions of cancer cells multiply rapidly,

数百万甚至数十亿个癌细胞迅速繁殖，

which requires a lot of resources and energy.

这需要大量的资源和能量。

The amount of nutrients they can steal from the body becomes the limiting factor for growth. 短語搭配

它们能从身体里窃取的营养物质数量成为了生长的限制因素。

So the tumor cells trick the body to build new blood vessels directly to the tumor to feed the thing killing it.

于是肿瘤细胞欺骗身体，直接向肿瘤构建新血管，以此来喂养这个正在杀死身体的怪物。

And here,

而在这里，

the nature of cancer cells may become their own undoing. 習語

癌细胞的本性可能会成为它们自取灭亡的原因。

Cancer cells are inherently unstable, 短語搭配

癌细胞天生不稳定，

and so they can continue to mutate.

因此它们会不断变异。

Some of them faster than their buddies.

其中一些比它们的同伴变异得更快。

If they do this for a while,

如果它们持续一段时间，

at some point one of the copies of the copies of the original cancer cell might suddenly think of itself as an individual again and stop cooperating, 短語搭配

在某一时刻，最初那个癌细胞的复制品的复制品可能会突然又把自己当作一个独立的个体，并停止合作，

which means,

这意味着，

just like the body,

就像宿主身体一样，

the original tumor suddenly becomes an enemy fighting for the same scarce nutrients and resources.

最初的肿瘤突然变成了一个争夺同样稀缺营养和资源的敌人。

So the newly mutated cells can create a hypertumor.

所以这些新突变的细胞可以制造一个超级肿瘤。

Instead of helping, 語法

它们非但不帮忙，

they cut off the blood supply to their former buddies, 短語動詞

反而切断了以前同伴的血液供应，

which will starve and kill the original cancer cells.

这会使原来的癌细胞饿死并被消灭。

Cancer is killing cancer.

这就是癌症在杀死癌症。

This process can repeat over and over, 短語搭配

这个过程可以一遍又一遍地重复，

and this may prevent cancer from becoming a problem for a large organism.

这或许能阻止癌症成为大型生物的致命问题。

It is possible that large animals have more of these hyper tumors than we realize. 語法

大型动物体内的超级肿瘤可能比我们意识到的还要多。

They might just not become big enough to notice, 語法

它们可能只是没有长到能被注意到的程度，

which makes sense.

这是合理的。

A 2-g tumor is 10% of a mouse's body weight,

一个2克的肿瘤占小鼠体重的10%，

while it's less than 0.002% of a human,

但它不到人类体重的0.002%，

and 0.000002% of a blue whale.

对蓝鲸来说则是0.000002%。

All three tumors require the same number of cell divisions and have the same number of cells.

这三种肿瘤需要相同次数的细胞分裂并拥有相同数量的细胞。

So an old blue whale might be filled with tiny cancers and just not care.

所以一头老蓝鲸体内可能满是微小的癌症，但它根本不在乎。

There are other proposed solutions to Peto's paradox,

对于皮托悖论还有其他的解答提出，

such as different metabolic rates or different cellular architecture.

比如不同的代谢率或不同的细胞结构。

But right now,

但现在，

we just don't know.

我们仍然一无所知。

Scientists are working on the problem.

科学家们正在研究这个问题。

Figuring out how large animals are so resilient to one of the most deadly diseases we know

弄清楚大型动物如何能对我们所知最致命的疾病之一拥有如此强大的抵抗力，

could open the path to new therapies and treatments. 習語

可能会为新疗法和新治疗手段开辟道路。

Cancer has always been a challenge.

癌症一直是一项挑战。

Today,

今天，

we are finally beginning to understand it,

我们终于开始理解它了，

and by doing so, 表達脈絡

通过这一过程，

one day we might finally overcome it. 語法

也许有一天我们终能战胜它。