When I was a young boy,

常常透過父親房間裡的顯微鏡

I used to gaze through the microscope of my father

觀察琥珀裡的昆蟲

at the insects in amber that he kept in the house.

牠們保存得非常完好

And they were remarkably well preserved,

其完好程度簡直令人驚奇

morphologically just phenomenal.

而且我們過去常想像

And we used to imagine that someday,

是不是有一天牠們會甦醒

they would actually come to life

然後會從樹脂裡爬出來

and they would crawl out of the resin,

如果牠們能飛的話 牠們是不是會飛走

and, if they could, they would fly away.

如果十年前你問我

If you had asked me 10 years ago whether or not

我們能不能把滅絕動物的基因組排序

we would ever be able to actually sequence the genome of extinct animals,

我會告訴你，不太可能

I would have told you, it's unlikely.

如果你問我們能不能

If you had asked whether or not we would actually be able

使滅絕的生物復活

to revive an extinct species,

我會說，做白日夢吧

I would have said, pipe dream.

吃驚的是，今天我實實在在的站在這兒

But I'm actually standing here today, amazingly,

告訴大家，絕種動物基因組排序是可能的

to tell you that not only is the sequencing

事實上這已成為現實

of extinct genomes a possibility, actually a modern-day reality,

復活滅絕動物的可能性已是能力所及

but the revival of an extinct species is actually within reach,

但可能不是復活琥珀裡的昆蟲

maybe not from the insects in amber --

- - 這隻蚊子曾是「侏羅紀公園」的靈感來源 - -

in fact, this mosquito was actually used

- - 這隻蚊子曾是「侏羅紀公園」的靈感來源 - -

for the inspiration for "Jurassic Park" —

而是通過凍土裡保存完好的殘骸

but from woolly mammoths, the well preserved remains

復活長毛象

of woolly mammoths in the permafrost.

長毛象是冰河時期特別有趣、特別典型的象徵

Woollies are a particularly interesting,

長毛像是冰河時期特別有趣、特別典型的象徵

quintessential image of the Ice Age.

牠們體型巨大，身披長毛

They were large. They were hairy.

有很大的長牙

They had large tusks, and we seem to have

我們好像和牠們關係密切 就像我們和大象一樣

a very deep connection with them, like we do with elephants.

可能因為大象和我們

Maybe it's because elephants share

有許多共同點

many things in common with us.

比如埋葬死者，教育後代

They bury their dead. They educate the next of kin.

有很緊密的社交聯繫

They have social knits that are very close.

或者可能因為我們在遠古時期就有聯繫

Or maybe it's actually because we're bound by deep time,

因為大象和我們人類一樣

because elephants, like us, share their origins in Africa

七百多萬年前起源於非洲

some seven million years ago,

隨著棲地和環境變化

and as habitats changed and environments changed,

我們人類和大象一樣

we actually, like the elephants, migrated out

遷移到歐洲和亞洲

into Europe and Asia.

遠古出現的第一種猛獁象是南方猛獁

So the first large mammoth that appears on the scene

身高四米，體重約十噸

is meridionalis, which was standing four meters tall

適宜在森林中生存

weighing about 10 tons, and was a woodland-adapted species

分佈在西歐地區、中亞地區

and spread from Western Europe clear across Central Asia,

並跨過白令陸橋

across the Bering land bridge

到達北美部分地區

and into parts of North America.

之後，隨著氣候再次變化

And then, again, as climate changed as it always does,

新棲地出現

and new habitats opened up,

便有了適宜在草原生存的種類

we had the arrival of a steppe-adapted species

即中亞地區的草原猛獁

called trogontherii in Central Asia

牠們把南方猛獁排擠到了西歐地區

pushing meridionalis out into Western Europe.

北美廣大的稀樹大草原出現後

And the open grassland savannas of North America

便有了哥倫比亞猛獁

opened up, leading to the Columbian mammoth,

牠們體型巨大，沒有長毛，分佈在北美

a large, hairless species in North America.

大約在五十萬年之後

And it was really only about 500,000 years later

我們非常喜愛和了解的長毛猛獁才出現

that we had the arrival of the woolly,

我們非常喜愛和了解的長毛猛獁才出現

the one that we all know and love so much,

牠們由白令海峽分布至中亞區域

spreading from an East Beringian point of origin

又把草原猛獁排擠到了中歐地區

across Central Asia, again pushing the trogontherii

又把草原猛獁排擠到了中歐地區

out through Central Europe,

在數百萬年過程中

and over hundreds of thousands of years

牠們反覆在冰河時期

migrating back and forth across the Bering land bridge

橫跨白令陸橋

during times of glacial peaks

和生活在南方的哥倫比亞猛獁

and coming into direct contact

有了直接聯繫

with the Columbian relatives living in the south,

牠們在那兒生存了數百萬年

and there they survive over hundreds of thousands of years

忍受嚴峻的氣候突變

during traumatic climatic shifts.

所以這種生存能力極強的動物

So there's a highly plastic animal dealing with great transitions

對溫度和環境的劇烈轉變 適應得非常好

in temperature and environment, and doing very, very well.

牠們在內陸生活直到一萬年前

And there they survive on the mainland until about 10,000 years ago,

出人意料的，約三千年前

and actually, surprisingly, on the small islands off of Siberia

在西伯利亞外海的小島上 仍有它們的足跡

and Alaska until about 3,000 years ago.

當埃及人在建金字塔時

So Egyptians are building pyramids

長毛象仍生活在海島上

and woollies are still living on islands.

之後牠們就消失了

And then they disappear.

正如世界上 99% 動物一樣

Like 99 percent of all the animals that have once lived,

牠們也滅絕了

they go extinct, likely due to a warming climate

可能是由於氣溫升高

and fast-encroaching dense forests

和迅速往北覆蓋的茂密的森林

that are migrating north,

同樣可能是像已故保羅·馬丁曾說的那樣

and also, as the late, great Paul Martin once put it,

由於更新世時的人類獵殺

probably Pleistocene overkill,

所以是大型動物捕殺者讓牠們滅絕了

so the large game hunters that took them down.

我們幸運地發現了許多殘骸

Fortunately, we find millions of their remains

深埋在西伯利亞和阿拉斯加的凍土中

strewn across the permafrost buried deep

我們可以到那些地方去

in Siberia and Alaska, and we can actually go up there

把它們挖出來

and actually take them out.

其保存完好程度

And the preservation is, again,

像琥珀裡的昆蟲一樣令人驚奇

like those insects in [amber], phenomenal.

有牙齒，帶血的骨頭

So you have teeth, bones with blood

至少看起來還像血 還有毛髮

which look like blood, you have hair,

而且有完整的屍體和頭顱

and you have intact carcasses or heads

頭顱內仍有腦髓

which still have brains in them.

其保存完好程度和 DNA 的存活

So the preservation and the survival of DNA

取決於很多方面，而我必須承認

depends on many factors, and I have to admit,

其中仍有很多我們不理解

most of which we still don't quite understand,

但當生物體死亡時

but depending upon when an organism dies

其被埋葬的速度、深度

and how quickly he's buried, the depth of that burial,

埋葬環境的氣溫穩定度

the constancy of the temperature of that burial environment,

會從根本上決定 DNA

will ultimately dictate how long DNA will survive

在地質學時間範疇內 存活的時間長短

over geologically meaningful time frames.

可能會令在座各位感到意外的是

And it's probably surprising to many of you

其實埋葬年代並不重要

sitting in this room that it's not the time that matters,

保存時間長短也不重要

it's not the length of preservation,

最重要的是保存環境的氣溫穩定性

it's the consistency of the temperature of that preservation that matters most.

如果我們深入研究

So if we were to go deep now within the bones

在石化過程中倖存的骨頭和牙齒

and the teeth that actually survived the fossilization process,

曾被組織蛋白緊緊包裹著的 DNA

the DNA which was once intact, tightly wrapped

曾被組織蛋白緊緊包裹著的 DNA

around histone proteins, is now under attack

現在面臨猛獁體內的共生細菌攻擊

by the bacteria that lived symbiotically with the mammoth

現在面臨猛獁體內的共生細菌攻擊

for years during its lifetime.

所以這些細菌、環境中的細菌

So those bacteria, along with the environmental bacteria,

游離水和氧氣把 DNA 分裂成細小碎片

free water and oxygen, actually break apart the DNA

游離水和氧氣把 DNA 分裂成細小碎片

into smaller and smaller and smaller DNA fragments,

這些碎片裡最小的是10 鹼基對

until all you have are fragments that range

在最好的情況下

from 10 base pairs to, in the best case scenarios,

可能有長度為幾百鹼基對的碎片

a few hundred base pairs in length.

所以化石記錄裡的大多數化石

So most fossils out there in the fossil record

都完全缺乏有機特徵

are actually completely devoid of all organic signatures.

但仍有一些 DNA 碎片

But a few of them actually have DNA fragments

存活了上千年

that survive for thousands,

甚至上百萬年

even a few millions of years in time.

通過最先進的無菌科技

And using state-of-the-art clean room technology,

我們已經找出了幾種

we've devised ways that we can actually pull these DNAs

可以從殘骸中萃取出 DNA 的方法

away from all the rest of the gunk in there,

而且，在座應沒有人會感到意外

and it's not surprising to any of you sitting in the room

即使我能在猛獁象骨頭或牙齒裡

that if I take a mammoth bone or a tooth

提取出猛獁象 DNA

and I extract its DNA that I'll get mammoth DNA,

也會隨之提取出所有和猛獁共生的細菌

but I'll also get all the bacteria that once lived with the mammoth,

再麻煩的是，我還會提取出

and, more complicated, I'll get all the DNA

當時環境中所有存活下來的 DNA

that survived in that environment with it,

像是細菌、真菌等等

so the bacteria, the fungi, and so on and so forth.

所以保存在凍土裡的猛獁象

Not surprising then again that a mammoth

僅有 50% 屬於猛獁 DNA

preserved in the permafrost will have something

同樣不令人意外

on the order of 50 percent of its DNA being mammoth,

而哥倫比亞猛獁

whereas something like the Columbian mammoth,

生活及埋葬的環境屬溫帶氣候

living in a temperature and buried in a temperate environment

這讓其 DNA 只有 3% 到 10% 的內生性

over its laying-in will only have 3 to 10 percent endogenous.

但我們已經找到一些巧妙的方法

But we've come up with very clever ways

藉此我們可以捕捉和區分

that we can actually discriminate, capture and discriminate,

猛獁 DNA 和非猛獁 DNA

the mammoth from the non-mammoth DNA,

並經由最先進的高通量基因組測序技術

and with the advances in high-throughput sequencing,

提出這些猛獁 DNA 碎片

we can actually pull out and bioinformatically

利用生物資訊技術

re-jig all these small mammoth fragments

將之重新排列於

and place them onto a backbone

亞洲象或非洲象的基因組骨幹上

of an Asian or African elephant chromosome.

這樣我們就能得到

And so by doing that, we can actually get all the little points

所有區分猛獁象和亞洲象的基因變異

that discriminate between a mammoth and an Asian elephant,

所以我們對猛獁象了解多少呢?

and what do we know, then, about a mammoth?

猛獁象基因組快趨於完整了

Well, the mammoth genome is almost at full completion,

我們知道這個基因組非常巨大

and we know that it's actually really big. It's mammoth.

原始人類的基因組大概有 30 億鹼基對

So a hominid genome is about three billion base pairs,

但是大象或猛獁象的鹼基對

but an elephant and mammoth genome

比人類基因組多出 20 億鹼基對

is about two billion base pairs larger, and most of that

大多數是重複的短 DNA 片段

is composed of small, repetitive DNAs

因此重新排列這個基因組結構非常困難

that make it very difficult to actually re-jig the entire structure of the genome.

這些資訊讓我們能夠回答

So having this information allows us to answer

一個跟猛獁象與其現代近親

one of the interesting relationship questions

非洲象和亞洲象

between mammoths and their living relatives,

有關的有趣問題了

the African and the Asian elephant,

七百萬年前，牠們有一個共同的祖先

all of which shared an ancestor seven million years ago,

但是猛獁的基因組顯示

but the genome of the mammoth shows it to share

猛獁和亞洲象最近的共同祖先

a most recent common ancestor with Asian elephants

是在六百萬年前

about six million years ago,

所以猛獁和亞洲象比較親近

so slightly closer to the Asian elephant.

拜近來純熟的古 DNA 技術之賜

With advances in ancient DNA technology,

我們現在可以開始排序

we can actually now start to begin to sequence

那些其他已滅絕猛獁的基因組

the genomes of those other extinct mammoth forms that I mentioned,

我只想說其中兩種

and I just wanted to talk about two of them,

長毛象和哥倫比亞猛獁

the woolly and the Columbian mammoth,

這兩種猛獁在冰河時期生活得非常近

both of which were living very close to each other

這兩種猛獁在冰河時期生活得非常近

during glacial peaks,

當北美的冰河規模非常大時

so when the glaciers were massive in North America,

長毛象被迫遷徙到冰河過渡帶

the woollies were pushed into these subglacial ecotones,

開始和生活在南方的親戚接觸

and came into contact with the relatives living to the south,

共同分享避難處

and there they shared refugia,

後來發現，牠們不只分享避難處

and a little bit more than the refugia, it turns out.

牠們並與南方的猛瑪雜交

It looks like they were interbreeding.

這對長鼻目動物來說不稀奇

And that this is not an uncommon feature

因為後來發現

in Proboscideans, because it turns out

大型熱帶草原雄象在追求雌象時

that large savanna male elephants will outcompete

會打敗體型較小的叢林象

the smaller forest elephants for their females.

所以體型巨大且沒毛的哥倫比亞猛獁

So large, hairless Columbians

打敗了體型較小的雄性長毛象

outcompeting the smaller male woollies.

這讓我想起了我的高中生活

It reminds me a bit of high school, unfortunately.

（笑聲）

(Laughter)

假如我們想要復活滅絕的物種

So this is not trivial, given the idea that we want

這就很重要了

to revive extinct species, because it turns out

因為亞洲象和非洲象

that an African and an Asian elephant

能通過雜交繁衍後代

can actually interbreed and have live young,

1978 年在英國切斯特的一個動物園裡

and this has actually occurred by accident in a zoo

曾意外發生過這種事

in Chester, U.K., in 1978.

這意味著我們可以用亞洲象染色體

So that means that we can actually take Asian elephant chromosomes,

並把它於我們發現的基因位置

modify them into all those positions we've actually now

修改成猛獁基因組

been able to discriminate with the mammoth genome,

然後放到無核細胞中

we can put that into an enucleated cell,

讓它分化為幹細胞

differentiate that into a stem cell,

可能最後會分化為精子

subsequently differentiate that maybe into a sperm,

再人工植入亞洲象卵子

artificially inseminate an Asian elephant egg,

經過漫長艱苦的過程後

and over a long and arduous procedure,

就會產生一個這樣的動物

actually bring back something that looks like this.

這並不會是一個準確的複製長毛象

Now, this wouldn't be an exact replica,

因為我剛才提到的 DNA 重複片段

because the short DNA fragments that I told you about

會妨礙我們創造一個精確的複製品

will prevent us from building the exact structure,

但是看起來和感覺起來

but it would make something that looked and felt

會很像一個真實的長毛象

very much like a woolly mammoth did.

當我向朋友們討論這個的時候

Now, when I bring up this with my friends,

我們總談到，那你把牠放哪裡啊?

we often talk about, well, where would you put it?

你會讓一頭猛獁象住哪裡?

Where are you housing a mammoth?

根本沒有合適的氣候和棲地

There's no climates or habitats suitable.

其實並非如此

Well, that's not actually the case.

因為在西伯利亞北部和育空地區

It turns out that there are swaths of habitat

有足夠的合適棲地

in the north of Siberia and Yukon

能夠提供猛獁生活

that actually could house a mammoth.

請記住，猛獁是適應力極強的動物

Remember, this was a highly plastic animal

牠們經歷過驚人的氣候變化

that lived over tremendous climate variation.

所以這片地區會很適宜牠們生活

So this landscape would be easily able to house it,

我必須承認，我內心中的小男孩

and I have to admit that there [is] a part of the child in me,

我必須承認，我內心中的小男孩

the boy in me, that would love to see

渴望看到這偉大的生物

these majestic creatures walk across the permafrost

再次行走在北方的凍土上

of the north once again, but I do have to admit

但是我必須承認，成熟的我有時會想

that part of the adult in me sometimes wonders

我們到底是不是該把牠們復活

whether or not we should.

謝謝

Thank you very much.

（掌聲）

(Applause)

Ryan Phelan: 先別走

Ryan Phelan: Don't go away.

你給我們留下了一個疑問

You've left us with a question.

我保證大家都會問這個問題 當你說「該不該」時

I'm sure everyone is asking this. When you say, "Should we?"

我感覺你有所保留

it feels like you're reticent there,

但你已告訴我們復活猛獁的可能性

and yet you've given us a vision of it being so possible.

你在遲疑什麼?

What's your reticence?

H. Poinar: 我不認為那是遲疑

Hendrik Poinar: I don't think it's reticence.

我覺得我們必須仔細考慮

I think it's just that we have to think very deeply

我們這個行為的後果和影響

about the implications, ramifications of our actions,

只要我們經過真誠深刻的討論之後

and so as long as we have good, deep discussion

就像我們現在這樣，我覺得

like we're having now, I think

我們就能找到一個解決方案