為什麼藍鯨不會得癌症？——佩托悖論：英語精讀講義

Cancer is a creepy and mysterious thing.

癌症是一種令人毛骨悚然又神祕的東西。

In the process of trying to understand it, 文法

在試圖理解它、

to get better at killing it, 片語搭配

以便更好地消滅它的過程中，

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

我們發現了一個至今尚未解開的生物學悖論。

Large animals seem to be immune to cancer,

大型動物似乎對癌症免疫，

which doesn't make any sense. 片語搭配

這完全說不通。

The bigger a being, 文法

一個生物越大，

the more cancer it should have.

它體內應該有的癌症就越多。

To understand why,

為了理解為什麼，

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

我們首先需要看看癌症本身的本質。

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

我們的細胞是由數億個部件組成的蛋白質機器人。

Guided only by chemical reactions,

僅靠化學反應的引導，

they create and dismantle structures,

它們創造並拆除各種結構，

sustain a metabolism to gain energy,

維持新陳代謝以獲取能量，

or make almost perfect copies of themselves.

或者複製出幾乎完美的自己。

We call these complex chemical reactions pathways.

我們把這些複雜的化學反應稱為途徑。

They are biochemical networks upon networks,

它們是重重疊疊的生化網絡，

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

彼此交織並堆疊在一起。

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

對單個人類大腦來說，其中大部分都難以理解，

and yet they function perfectly,

然而它們卻能完美運作，

until they don't. 表達脈絡

直到它們出了問題。

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

在長達數年的時間裡，成千上萬個網絡中發生著億萬兆次反應，

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

問題不在於是否會出錯，

but when.

而在於何時出錯。

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

微小的錯誤不斷累積，直到這座宏偉的機器遭到破壞。

To prevent this from getting out of hand, 慣用語

為了防止情況失控，

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

我們的細胞配備了讓其細胞凋亡的「死亡開關」。

But these kill switches are not infallible.

但這些死亡開關並不是萬無一失的。

If they fail,

如果它們失效，

a cell can turn into a cancer cell.

細胞就可能變成癌細胞。

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

其中大多數很快會被免疫系統消滅，

but this is a numbers game. 慣用語

但這只是個機率遊戲。

Given enough time, 文法

只要有足夠的時間，

a cell will accrue enough mistakes,

一個細胞就會累積足夠的錯誤，

slip by unnoticed, 片語動詞

神不知鬼不覺地溜過防線，

and begin making more of itself.

並開始不斷自我複製。

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

所有動物都必須面對這個問題。

In general,

通常來說，

the cells of different animals are the same size.

不同動物的細胞大小是相同的。

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

小鼠的細胞並不比你的小，

it just has fewer cells in total,

它只是細胞總數較少，

and a shorter lifespan.

壽命也較短。

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

更少的細胞和更短的壽命意味著出錯或細胞突變的機率更低，

or at least it should mean that.

或者至少在理論上應該是這樣。

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

人類的壽命大約是小鼠的50倍，細胞數量是其1000倍，

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

但人類和小鼠的癌症發病率基本相同。

Even weirder,

更詭異的是，

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

細胞數量比人類多約3000倍的藍鯨

don't seem to get cancer at all really.

似乎根本就不會得癌症。

This is Peto's paradox, 文化背景

這就是皮托悖論，

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

一個令人困惑的事實：大型動物罹癌的機率比預期的要低得多。

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

科學家認為解釋這一悖論主要有兩個方向：

evolution,

演化，

and hyper tumors.

以及超級腫瘤。

Solution one,

第一種解答，

evolve or become a blob of cancer.

要麼演化，要麼淪為一團癌症。

As multicellular beings developed 600 million years ago,

隨著多細胞生物在6億年前發展，

animals became bigger and bigger, 文法

動物變得越來越大，

which added more and more cells,

這使得細胞數量不斷增加，

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

進而意味著細胞受損的機率也越來越大。

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

因此，這個集體必須投資於越來越好的癌症防禦機制。

The ones that did not died out. 片語動詞

那些沒有這麼做的物種就滅絕了。

But cancer doesn't just happen,

但癌症並不是憑空發生的，

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

這是一個在同一個細胞內、多個特定基因發生許多個別錯誤和突變的過程。

These genes are called proto-oncogenes, 用詞

這些基因被稱為原癌基因，

and when they mutate,

當它們發生突變時，

it's bad news.

那就是壞消息。

For example,

例如，

with the right mutation,

伴隨特定的突變，

a cell will lose its ability to kill itself.

細胞將失去自殺的能力。

Another mutation, 文法

再發生一次突變，

and it will develop the ability to hide.

它就會發展出隱藏的能力。

Another,

再來一次，

and it will send out calls for resources.

它就會發出索取資源的訊號。

Another one,

又發生一次，

and it will multiply quickly.

它就會迅速繁殖。

These oncogenes have an antagonist,

這些致癌基因有一個剋星，

though,

那就是，

tumor suppressor genes. 用詞

腫瘤抑制基因。

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

它們阻止這些致命突變的發生，或者在認定細胞無法修復時命令其自殺。

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

事實證明，大型動物體內這種基因的數量增加了。

Because of this,

正因如此，

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

大象的細胞要想發展成腫瘤，需要比小鼠細胞經歷更多的突變。

They are not immune, 用詞

它們並非免疫，

but more resilient.

而是更具抵抗力。

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

這種適應性演化可能在某種形式上是有代價的，

but researchers still aren't sure what it is.

但研究人員還不確定代價是什麼。

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

也許腫瘤抑制基因會讓大象在晚年衰老得更快，或者減慢傷口癒合的速度。

We don't know yet.

我們現在還不知道。

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

但該悖論的解答可能實際上是另外一種東西，

hypertumors.

那就是超級腫瘤。

Solution two,

第二種解答，

hypertumors.

超級腫瘤。

Yes,

是的，

really.

真的。

Hypertumors are named after hyperparasites, 片語搭配

超級腫瘤的名字來源於超級寄生蟲，

the parasites of parasites.

即寄生蟲的寄生蟲。

Hypertumors are the tumors of tumors. 用詞

超級腫瘤就是腫瘤的腫瘤。

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

癌症可以被視為一種合作機制的崩潰。

Normally,

通常情況下，

cells work together to form structures like organs,

細胞協同工作以形成器官、

tissue,

組織，

or elements of the immune system.

或是免疫系統的一部分。

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

但癌細胞是自私的，只為自己短期的利益而工作。

If they're successful,

如果它們成功了，

they form tumors,

它們就會形成腫瘤，

huge cancer collectives that can be very hard to kill.

也就是極難被殺死的巨大癌症聚集體。

Making a tumor is hard work,

然而，製造一個腫瘤是項艱難的工作，

though.

不過確實如此。

Millions or billions of cancer cells multiply rapidly,

數百萬甚至數十億個癌細胞迅速繁殖，

which requires a lot of resources and energy.

這需要大量的資源和能量。

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

它們能從身體裡竊取的營養物質數量成為了生長的限制因素。

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

於是腫瘤細胞欺騙身體，直接向腫瘤建構新血管，以此來餵養這個正在殺死身體的怪物。

And here,

而在這裡，

the nature of cancer cells may become their own undoing. 慣用語

癌細胞的本性可能會成為它們自取滅亡的原因。

Cancer cells are inherently unstable, 片語搭配

癌細胞天生不穩定，

and so they can continue to mutate.

因此它們會不斷變異。

Some of them faster than their buddies.

其中一些比它們的同伴變異得更快。

If they do this for a while,

如果它們持續一段時間，

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, 片語搭配

在某一時刻，最初那個癌細胞的複製品的複製品可能會突然又把自己當作一個獨立的個體，並停止合作，

which means,

這意味著，

just like the body,

就像宿主身體一樣，

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

最初的腫瘤突然變成了一個爭奪同樣稀缺營養和資源的敵人。

So the newly mutated cells can create a hypertumor.

所以這些新突變的細胞可以製造一個超級腫瘤。

Instead of helping, 文法

它們非但不幫忙，

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

反而切斷了以前同伴的血液供應，

which will starve and kill the original cancer cells.

這會使原來的癌細胞餓死並被消滅。

Cancer is killing cancer.

這就是癌症在殺死癌症。

This process can repeat over and over, 片語搭配

這個過程可以一遍又一遍地重複，

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

這或許能阻止癌症成為大型生物的致命問題。

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

大型動物體內的超級腫瘤可能比我們意識到的還要多。

They might just not become big enough to notice, 文法

它們可能只是沒有長到能被注意到的程度，

which makes sense.

這是合理的。

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

一個2克的腫瘤占小鼠體重的10%，

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

但它不到人類體重的0.002%，

and 0.000002% of a blue whale.

對藍鯨來說則是0.000002%。

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

這三種腫瘤需要相同次數的細胞分裂並擁有相同數量的細胞。

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

所以一頭老藍鯨體內可能滿是微小的癌症，但它根本不在乎。

There are other proposed solutions to Peto's paradox,

對於皮托悖論還有其他的解答提出，

such as different metabolic rates or different cellular architecture.

比如不同的代謝率或不同的細胞結構。

But right now,

但現在，

we just don't know.

我們仍然一無所知。

Scientists are working on the problem.

科學家們正在研究這個問題。

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

弄清楚大型動物如何能對我們所知最致命的疾病之一擁有如此強大的抵抗力，

could open the path to new therapies and treatments. 慣用語

可能會為新療法和新治療手段開闢道路。

Cancer has always been a challenge.

癌症一直是一項挑戰。

Today,

今天，

we are finally beginning to understand it,

我們終於開始理解它了，

and by doing so, 表達脈絡

透過這一過程，

one day we might finally overcome it. 文法

也許有一天我們終能戰勝它。