The researchers took a gene from glowing jellyfish and inserted it into the unfertilized eggs of house cats.

研究人員取出螢光水母的發光基因，並將它注入家貓的未受精卵之中。

It was a neat trick, but they had a bigger goal in mind.

雖然這是個蠻吸睛的小把戲，但他們心中有個更遠大的藍圖。

They also made the cats more likely to be resistant to a feline form of AIDS, by, again, manipulating their DNA.

在研究過程中，他們也讓螢光貓具備較能夠抵抗「貓愛滋」的能力，當然也是靠著控制牠們的 DNA 來做到這件事。

And cats aren't that different than humans.

而貓咪和人類並沒有太大的不同。

In fact, we share around 90% of our DNA with them.

事實上，我們的基因大約有 90% 都跟貓咪一樣。

So why can't we engineer humans in the same way?

那為何我們不能用相同的方式來改造人類的基因呢？

Well, we can—engineer ourselves to be resistant to life-threatening illnesses, that is.

其實我們可以做到，用基因編輯的方式讓我們可以抵抗致命的疾病。

In fact, one scientist claims that he's genetically engineered two babies using a revolutionary tool called CRISPR.

一位科學家就宣稱他用革命性的工具—CRISPR 創造出了 2 名基因編輯寶寶。

But what exactly is a CRISPR baby, anyway?

但 CRISPR 寶寶究竟是什麼？

Would you like to be 6 feet tall or never bald?

他們會長到一百八十公分高嗎？還是永遠不會禿頭？

The secret to traits like these lies in the 6 billion letters of your genetic code.

這些表徵的秘密都藏在你體內的 60 億個遺傳密碼之中。

But there could be something else in there as well: mutations.

但這麼做可能還會發生一件事：突變。

Genetic mutations are linked to at least 6,000 medical conditions from sickle cell anemia to Huntington's disease.

基因突變會造成至少 6000 種病徵，像是鐮刀型紅血球疾病和亨丁頓舞蹈症。

But what if you could make those mutations simply disappear?

但如果你可以直接讓突變消失呢？

That's where the gene-editing tool CRISPR comes in.

這就是基因編輯工具 CRISPR 派上用場的時候了。

CRISPR is made from specialized proteins and other compounds found in certain bacteria.

CRISPR 由特殊的蛋白質和在特定細菌中找到的化合物所組成。

Normally, these proteins protect the bacteria by destroying enemy invaders like viruses.

一般而言，這些蛋白質會藉由消滅病毒等入侵者來保護細菌。

But the inventors of CRISPR figured out how to turn those proteins against genetic mutations and other genes linked to disease.

CRISPR 的發明者想出一個方法，讓那些蛋白質可以對抗基因突變和造成疾病的基因。

First, they give the proteins coordinates of the wanted gene.

首先，他們會先給予蛋白質目標基因的位置。

Then, CRISPR runs a seek-and-destroy function.

接著，CRISPR 會搜索目標基因並加以摧毀。

After that, other molecules are dispatched to repair the gene with new, healthy DNA.

最後，其它帶著健康 DNA 序列的分子才會被派遣去修復基因。

And just like that, you can edit the human genome.

如此一來就可以編輯人類的基因組。

But while the edits may be quick, their changes can last for centuries, especially if you're editing the DNA in an embryo.

雖然編輯基因不會花上太多時間，但它造成的影響卻會持續千千萬萬年，尤其是當你編輯胚胎基因時。

Embryos start out with a single cell that eventually replicates into millions and then trillions more.

胚胎從單細胞開始發育，最終會複製出幾百萬、幾兆個。

So if you alter that initial cell first, you're manipulating the ingredients for every cell that follows later in life.

所以如果你改變了最原始的細胞，你也會影響這個生命體之後所複製、分裂出的所有細胞。

And those same altered cells can be passed on from generation to generation.

這些被編輯過的細胞也就會一代接著一代地傳下去。

That's one reason why most experiments on human embryos haven't left the lab.

這就是為什麼大多數以人類胚胎進行的實驗都只能留在實驗室裡。

That is, except for the work of Dr. He Jiankui.

除了賀建奎博士的。

He claims to have used CRISPR to target and knock out the CCR5 gene in human embryos, which is linked to HIV infection.

他宣稱自己使用 CRISPR 修改了讓人類感染愛滋的蛋白質—CCR5。

And then he did something that shocked the scientific community.

接著，他做了一件震驚科學界的事。

He implanted the embryos into several women, one of whom gave birth to genetically modified twins.

他將修改過的胚胎植入數名女性體內，其中一名生出了一對基因編輯過的雙胞胎。

Resistance to HIV aside, most scientists say the procedure was too risky.

即便他們可以對抗愛滋病，許多科學家表示這個過程太過冒險。

At least two studies suggest that edited cells might actually trigger cancer.

至少有兩篇研究指出，基因編輯過的細胞可能會導致癌症。

And another found that CRISPR can accidentally take aim at healthy DNA.

其他研究則顯示，CRISPR 會在無意中攻擊健康的 DNA。

So while CRISPR could make us immune to disease, who knows what else we might get on the side?

所以雖然 CRISPR 能夠讓我們免於一些疾病，但誰知道它有哪些我們還看不見的影響呢？