Have you ever wondered if it was possible for humans to regrow body parts?

你們有想過人的身體各部位是否有可能再生嗎？

Why is it that when a person loses an arm,

為什麼當一個人失去了一隻手臂後，

only the wound is healed rather than the body regrowing their lost limb?

只能治癒傷口而不是讓失去的手臂再長出來呢？

In the spirit of Dr. Connors, let's find out.

讓我們延續 Connors 博士的精神，繼續看下去吧！

I just hope we don't all turn into Spider-Man villains.

我只希望我們不會全都變成蜘蛛人電影裡的壞人

So humans can't regrow their own limbs, correct?

所以，人類的四肢無法再生，對吧？

Well, that might not be entirely true.

嗯，這也不盡然是對的

As an embryo, long before your birth,

在離你出生還很久前，只是個胚胎時，

you may have had the ability to replace your developing limbs.

你可能有能力去替換生長中的肢體

Through scientific surgery, researchers have shown that at the embryonic stage of development,

藉由精確的手術，研究人員已經發現到，在胚胎發展階段

frogs can regenerate their developing limbs.

蝌蚪正在發展的肢體可以再生

This has even been shown in mice, which like humans, are mammals.

這也已經在老鼠，跟人類一樣都是哺乳動物，胚胎上發現此現象

It is yet to be proven the same with human embryos, but with this evidence,

雖這還尚未在人類胚胎上被證實，但從以上證據，

the theory is that vertebrate embryos, including humans,

理論上脊椎動物的胚胎，包含人類

can regenerate their limbs if they are damaged or amputated.

在肢體受到傷害或是截掉後都可以再生

However, other than a few special and small cases like the regeneration of fingertips,

然而，除了一些特殊或是小部分的狀況，像是指尖的再生外

humans don't really have this ability after birth.

人類在出生後就沒有這種能力了

But do any other animals?

那，其他動物呢？

It just so happens that salamanders have this super awesome superpower!

很巧地，蠑螈就擁有這種超棒的超能力

They are the only vertebrate that can regrow their limbs and many other body parts throughout their lifetime.

牠們是脊椎動物中唯一一種在牠們整生當中四肢以及許多身體部位都能夠再生的

In fact, the axolotl, a Mexican salamander, can regenerate almost anything,

事實上，美西螈，一種在墨西哥生長的蠑螈，幾乎身上所有部位

from their eyes, to their spinal cord, to even parts of their brain.

從牠們的眼睛，到牠們的脊髓，甚至到牠們某部份的腦都能再生

These adorable little guys are amazing!

這可愛的小傢伙真是神奇！

And I want 20 of them.

我想要20隻

So how do salamanders do it?

所以，蠑螈是怎麼辦到的呢？

Well, when a human loses a limb, their cells close the wound and a blood clot forms.

好的，當人類失去一截肢體時，細胞會將傷口密合而形成凝血

This leads to a scab over the wound and an eventual scar in the place of where the limb was.

這會導致傷口結痂，最後在肢體的受傷處留下傷疤

But for a salamander, scar tissue never forms—

但對蠑螈來說，牠們的受傷處不會形成傷疤

a striking difference between their regeneration and a human wound healing.

這是牠們的再生跟人類傷口的癒合很明顯的不同之處

A salamander's wound closes more rapidly and cells rush to the amputation site.

蠑螈的傷口會更迅速的收合，並且細胞會湧入肢體的截斷處

These cells revert back to a less specialized state and begin creating the blastema,

這些細胞會恢復為非特化狀態，然後開始創造出胚基

which is the bud of a new limb.

這就是新肢體的芽

As the blastema grows, it begins to form the outline of a new limb and the foot.

當這芽繼續成長，它會開始形成新肢體的外型跟足部

The cells begin creating new tissue by proliferating and differentiating into things like muscle and bone.

細胞會藉由增殖與分化來創造新的組織，像是肌肉與骨骼

The new leg lengthens, filling out the missing segments between the amputation site and the toes.

新的腳會再變長，會將肢體截斷處到腳趾的部分都填補起來

The whole process usually lasts around two months,

整個過程通常會持續兩個月左右

and then the salamander has a fully regenerated limb.

然後這隻蠑螈就會擁有一個全新的肢體

It's perfect for a cute little high five! Go science!

真是完美，擊個掌吧可愛的小傢伙！科學真是太美好了！

But in humans, the blastema never grows.

但在人類身上，胚基不會生長出來

Some scientists think that's because humans don't have

有些科學家認為這是因為人類缺少了

all the genes necessary to facilitate such a level of regeneration.

一些促進這種程度的再生所需要的基因

But others think that humans don't have this regenerative ability because

而其他人則認為人類沒有再生能力的原因是

it might make them more likely to develop cancers.

這可能會使人們更容易得到癌症

But even if humans could regrow their limbs, there still might be an issue.

但即使人們可以再生肢體，還是可能會有問題

Let's take a look back at that adorable little axolotl with the findings of two recent studies.

讓我們再回頭看看兩項最近在可愛的小美西螈身上的研究

The researchers found that, like biological wrecking balls,

研究人員發現，像是個生物破壞球

certain jumping genes need to be shackled in the axolotl's cells

某些在美西螈細胞內的跳躍基因需要被束縛住

or they might disrupt their process of regeneration.

否則它們可能會干擾再生的進行

They discovered that proteins found within the little water monsters allow them to prevent

他們發現了在這小水怪體內的蛋白質可壤牠們避免

these jumping genes from causing havoc.

這些跳躍基因破壞再生進行

So, regeneration is really complicated and maybe for right now, humans can't regrow their limbs.

所以，再生真的是很複雜的，也許現在人類的肢體無法再生

But these studies at least give scientists hope

但這些研究至少給了科學家一些希望

that we could learn better methods for treating human conditions,

讓他們能去研究出更好的方法來治療人類

like wound healing and regenerating simple tissues.

像是傷口的治療跟一些基本組織的再生

Hey, even becoming just a little bit more like Wolverine would be awesome!

哈，即使只能變得更像金鋼狼一點點都很讚！

I'm Blocko, and I'm the best at science communication.

我是 Blocko，我很擅長科學新知

And I have claws. Eat your heart out, Hugh Jackman!

而且我還有爪子，看招吧，休傑克曼！

So what do you think?

所以，你們怎麼看呢？

What limitations of humanity would you like science to be able to overcome?

你們想要科技去克服甚麼目前人類無法做到的事情呢？

Let me know in the comment section below!

在下面留言區讓我知道吧！

Have you ever wondered why winter doesn't kill all the plants and fish? Check it out here!

你曾好奇過為什麼植物跟魚都能在冬天生存嗎？點這裡觀看影片！

Lucky for our aquatic friends, when the temperature outside falls below the freezing point of the water

我們的水中朋友很幸運，當室外溫度降到冰點時

only the top layer of lakes or river typicallys freeze.

只有表層湖水或河水會結冰

As always, I'm Blocko and this has been Life Noggin.

如同以往，我是 Blocko，而這裡是 Life Noggin

Don't forget to keep on thinking!

別忘了持續思考！