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  • Translator: Joseph Geni Reviewer: Morton Bast

    當我還小的時候

  • 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