Name: 【知識小百科】為什麼大象很少得癌症？ (Why Elephants Rarely Get Cancer)
Uploaded: 2025-03-30T21:01:10.000Z
Duration: 8 min 16 s

If you want to be a good science communicator, you gotta know how to hook people.

如果你想成為一名優秀的科學傳播者，你必須知道如何吸引人們。

And that includes crafting a title that can entice people to learn about a subject that can be technical.

這包括製作一個標題，吸引人們去了解一個可能是技術性的主題。

轉承詞

Sometimes, though, science does all the hard work for you.

但有時，科學會為你完成所有艱鉅的工作。

Elephants' giant hot testicles might be the reason they get less cancer.

大象的巨型熱睪丸可能是它們患癌症較少的原因。

And yes, that is a real headline based on a real scientific idea called the hot testicle hypothesis.

沒錯，這是一個真實的標題，它基於一個真實的科學觀點，叫做 "熱睪丸假說"。

Thanks to some super protective genes, elephants are really good at not getting cancer.

得益於一些超級保護基因，大象真的不會得癌症。

In fact, research suggests that elephants are up to five times less likely to die of cancer than humans.

事實上，研究表明，大象死於癌症的機率比人類低五倍。

But this hypothesis posits that these genes didn't originally evolve to fight cancer at all.

但這一假設認為，這些基因最初的進化根本不是為了抗癌。

Elephants may be special in this way for another reason.

大象之所以如此特別，可能還有另一個原因。

And it has to do with their giant hot testicles.

這與他們巨大火熱的睪丸有關。

Our story begins in the genome of an elephant.

我們的故事從大象的基因組開始。

Specifically, a gene called TP53, which controls the development of molecules called p53 proteins.

具體來說，一種名為 TP53 的基因控制著名為 p53 蛋白質的分子的發育。

But these proteins are also called the guardians of the genome, because they protect against harmful mutations that pop up during a cell's life cycle.

但這些蛋白質也被稱為基因組的守護者，因為它們能防止細胞生命週期中突然出現的有害突變。

In order to replicate, a cell also needs to duplicate the DNA inside of it.

為了進行復制，細胞還需要複製其內部的 DNA。

But that duplication process is never 100% perfect.

但是，複製過程永遠不會百分之百完美。

You basically get a few typos in the new DNA.

在新的 DNA 中，基本上會出現一些錯別字。

So p53 proteins have the very important job of kicking off the process of DNA repair, to edit as many of those mutations as possible.

是以，p53 蛋白的一項非常重要的工作就是啟動 DNA 修復過程，儘可能多地編輯這些突變。

And if that process fails, the p53 proteins can also activate a cell's self-destruct mechanism, stopping the mutation from spreading any further, and preventing the cell from harming the rest of your body.

如果這一過程失敗，p53 蛋白還能激活細胞的自毀機制，阻止突變進一步擴散，防止細胞傷害身體的其他部分。

This makes p53 proteins excellent at fighting cancers.

這使得 p53 蛋白具有出色的抗癌能力。

Lots of other animals have these proteins, as well as the TP53 gene that codes for them.

許多其他動物都有這些蛋白質，以及編碼這些蛋白質的 TP53 基因。

In fact, humans with a mutated version of TP53, a condition called Li-Ferromani syndrome, have a 70% chance of getting some kind of cancer over the course of their lives.

事實上，TP53 基因突變的人，即李-費羅馬尼綜合徵患者，一生中患某種癌症的機率高達 70%。

But here's where we're different from elephants.

但我們與大象的不同之處就在這裡。

The human genome has a single copy of the TP53 gene, like nearly every other species.

與幾乎所有其他物種一樣，人類基因組中只有一個 TP53 基因拷貝。

But elephants have 20 copies, and they're all slightly different.

但大象有 20 個拷貝，而且都略有不同。

Which means they can make a bunch of different versions of p53 proteins with various different effects.

這意味著他們可以製造出許多不同版本的 p53 蛋白，產生各種不同的效果。

It's this suite of tumor-fighting proteins that gives elephants extraordinary defenses against cancer.

正是這套抗腫瘤蛋白質賦予了大象非凡的抗癌能力。

But exactly why elephants evolved to have such a suite isn't totally clear.

但大象為什麼會進化出這樣的套裝，目前還不完全清楚。

Elephants are really big, and a bigger body has more cells.

大象真的很大，更大的身體有更多的細胞。

更多的細胞意味著更多的細胞分裂。

And every time a cell divides, it's an opportunity for something to go cancerously wrong.

細胞的每一次分裂，都有可能引發癌症。

Elephants are also long-lived, which means more cell divisions during their lifetime.

大象的壽命也很長，這意味著它們一生中有更多的細胞分裂。

This means they might naturally be at higher risk for developing cancer.

這意味著他們患癌症的風險自然會更高。

So over time, evolution found a way to compensate by giving them extra copies of a cancer-fighting gene.

是以，隨著時間的推移，進化找到了一種補償方法，即給它們額外拷貝抗癌基因。

But whales are also gigantic and long-lived.

但是，鯨魚也是巨大而長壽的。

And they don't have multitudes of p53 proteins.

Instead, there's some evidence that they evolved their own unique adaptations for fending off cancer, which means they don't have to rely as much on p53.

相反，有證據表明，它們進化出了自己獨特的抵禦癌症的適應能力，這意味著它們不必那麼依賴 p53。

So maybe elephants evolved these cancer defenses simply because their size and longevity put them at risk.

是以，也許大象進化出這些癌症防禦系統僅僅是因為它們的體型和壽命使它們面臨風險。

Maybe elephants originally evolved these proteins for a completely different purpose— to protect their extremely hot testicles.

也許大象最初進化出這些蛋白質是為了一個完全不同的目的--保護它們極熱的睪丸。

But before I explain that sentence, we're gonna do an ad.

但在我解釋這句話之前，我們先來做個廣告。

Thanks to Incogni for supporting this SciShow video.

感謝 Incogni 對 SciShow 視頻的支持。

Incogni's mission is to help you avoid cybercrime and personal privacy breaches.

Incogni 的使命是幫助您避免網絡犯罪和個人隱私洩露。

Data brokers collect and sell personal information, like social security numbers and login credentials, putting you at higher risk of identity theft.

數據經紀商收集並出售個人信息，如社會保險號和登錄憑證，使你面臨更高的身份被盜風險。

So Incogni reaches out to data brokers on your behalf and requests that they remove your personal data.

是以，Incogni 會代表您聯繫數據經紀人，要求他們刪除您的個人數據。

With their Family and Friends plan, you can let four additional members benefit from the exact same service you do.

通過 "家人和朋友 "計劃，您可以讓另外四名成員享受與您完全相同的服務。

You can try it for 30 days and get a full refund if you aren't happy with the service.

您可以試用 30 天，如果對服務不滿意，可以全額退款。

To take your personal data back and get 60% off an annual Incogni plan, use the code SciShow at incogni.com slash SciShow, or click the link in the description.

要收回您的個人數據並享受 Incogni 年度計劃六折優惠，請在 incogni.com slash SciShow 上使用代碼 SciShow，或點擊描述中的鏈接。

Testicles, obviously, are where the body produces sperm cells.

睪丸顯然是人體制造精子細胞的地方。

And this process requires temperatures to be just right.

而這一過程需要恰到好處的溫度。

If things get too hot, the sperm could end up with damaged DNA.

如果溫度過高，精子的 DNA 可能會受損。

And damaged DNA makes it really hard for sperm to do its job of helping to create a fully functional animal.

而受損的 DNA 會使精子很難完成幫助創造功能完善的動物的工作。

Most mammals have an internal body temperature that's kind of too high for sperm production, and they get around that by dangling the testicles in a scrotum.

大多數哺乳動物的體內溫度過高，不利於精子的生成，它們通過將睪丸懸掛在陰囊中來解決這個問題。

Down there, the testicles don't just get a little bit of cooling airflow.

在下面，睪丸不僅能得到一點冷卻氣流。

The scrotum also has a special network of blood vessels where one half of them, the veins, can siphon away heat from the other, the arteries.

陰囊還有一個特殊的血管網絡，其中一半（靜脈）可以從另一半（動脈）虹吸走熱量。

It's a process known as countercurrent exchange.

And it's happening in some of you right now.

現在，它就發生在你們當中的一些人身上。

So altogether, a typical human body has an internal temperature around 37 degrees Celsius.

是以，一般人體的內部溫度在 37 攝氏度左右。

Meanwhile, if it's also got some scrotum-based sperm factories, they're hovering around a cool 34 degrees Celsius.

與此同時，如果它的陰囊裡也有精子工廠，那麼它們的溫度就會徘徊在 34 攝氏度左右。

Their testicles are located deep inside of their bodies, near their kidneys.

它們的睪丸位於身體深處，靠近腎臟。

So they can't just hang them out to cool like humans do.

是以，它們不能像人類那樣把它們晾在外面乘涼。

But also, elephants can run even hotter than we do.

但是，大象也會比我們跑得更快。

Their body temperature tends to hover around 36 to 37 degrees.

它們的體溫往往徘徊在 36 至 37 度之間。

But on a hot day, which is most days in their tropical homes, they can get into the 40s.

但在炎熱的日子裡，也就是在熱帶家園的大多數日子裡，它們的溫度能達到 40 多度。

This means their testicles are constantly in danger of overheating.

這意味著它們的睪丸隨時都有過熱的危險。

Now, elephants are not the only mammals with internal testicles, and therefore in need of some way to handle this problem.

現在，大象並不是唯一體內有睪丸的哺乳動物，是以需要一些方法來解決這個問題。

For example, whales have a network of heat-shedding blood vessels that operates similar to our own scrotal cooling systems.

例如，鯨魚有一個散熱血管網絡，其運作類似於我們的陰囊冷卻系統。

And hyraxes, which are close cousins of elephants, despite not looking like them at all, have simple physics on their side.

而鬣狗是大象的近親，雖然長得一點也不像大象，但它們也有簡單的物理學原理。

It's the inside of a mammal's body that generates heat.

產生熱量的是哺乳動物的身體內部。

And the skin dumps all of that heat into the outside world.

皮膚會將這些熱量全部排出體外。

A small animal, like a hyrax, has lots of skin area compared to their size, so they shed heat pretty quickly.

與體型相比，小動物（如鬣狗）的皮膚面積很大，是以散熱也很快。

It has way more internal volume compared to its surface area.

與表面積相比，它的內部容積要大得多。

So they are much better at generating heat than they are at shedding it.

是以，它們產生熱量的能力比散發熱量的能力要強得多。

Which brings us back to the hot testicles problem.

這又回到了睪丸發熱的問題上。

Those p53 proteins which repair genetic mutations and destroy malfunctioning cells during cell division.

這些 p53 蛋白能修復基因突變，並在細胞分裂過程中摧毀功能失常的細胞。

They might be excellent tools for safeguarding sperm production in an environment where the temperature is too high.

它們可能是在溫度過高的環境中保護精子生成的絕佳工具。

And with this in mind, back in 2023, one researcher proposed the hot testicle hypothesis.

有鑑於此，早在 2023 年，一位研究人員就提出了 "熱睪丸假說"。

The elephant's incredible array of TP53 genes originally evolved in response to their endangered sperm.

大象令人難以置信的 TP53 基因陣列最初是為了應對它們瀕臨滅絕的精子而進化而來的。

In which case, their decreased risk of getting cancer would just be a happy side effect of increased protection for their hot testicles.

在這種情況下，他們罹患癌症的風險降低，只是對他們發熱的睪丸加強保護的一個令人高興的副作用。

Now, of course, the reason could ultimately be a mix of both of these things.

當然，歸根結底，原因可能是這兩方面的綜合。

It doesn't have to just be the fact that elephants have a lot of cells that divide over the course of their very long lives, or just the fact that they need a way to keep their sperm in working order.

這不僅僅是因為大象在漫長的一生中有大量細胞分裂，也不僅僅是因為它們需要一種方法來保持精子正常工作。

Research into elephant evolution suggests that the number of TP53 genes in their DNA expanded around the same time as other genetic changes that are associated with having a larger body size.

對大象進化的研究表明，大象 DNA 中 TP53 基因的數量與其他與體型較大有關的基因變化同時增加。

Bigger bodies present both a higher potential risk for cancer and make it harder to shed excess heat.

肥胖的體型既增加了患癌症的潛在風險，也增加了排出多餘熱量的難度。

So becoming elephant-sized might have created problems in the cancer department and the sperm department at the same time.

是以，變成大象大小可能會同時給癌症部門和精子部門帶來問題。

And the evolution of a fleet of tumor-suppressing proteins might have been a solution for both problems.

而抑制腫瘤的蛋白質群的進化可能是這兩個問題的解決方案。

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【知識小百科】為什麼大象很少得癌症？ (Why Elephants Rarely Get Cancer)

process

evolve

combat

capable