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  • Translator: Joseph Geni Reviewer: Morton Bast

  • When I was a young boy,

  • I used to gaze through the microscope of my father

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

  • And they were remarkably well preserved,

  • morphologically just phenomenal.

  • And we used to imagine that someday,

  • they would actually come to life

  • and they would crawl out of the resin,

  • and, if they could, they would fly away.

  • If you had asked me 10 years ago whether or not

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

  • I would have told you, it's unlikely.

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

  • to revive an extinct species,

  • I would have said, pipe dream.

  • But I'm actually standing here today, amazingly,

  • to tell you that not only is the sequencing

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

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

  • maybe not from the insects in amber --

  • in fact, this mosquito was actually used

  • for the inspiration for "Jurassic Park" —

  • but from woolly mammoths, the well preserved remains

  • of woolly mammoths in the permafrost.

  • Woollies are a particularly interesting,

  • quintessential image of the Ice Age.

  • They were large. They were hairy.

  • They had large tusks, and we seem to have

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

  • Maybe it's because elephants share

  • many things in common with us.

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

  • They have social knits that are very close.

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

  • because elephants, like us, share their origins in Africa

  • some seven million years ago,

  • and as habitats changed and environments changed,

  • we actually, like the elephants, migrated out

  • into Europe and Asia.

  • So the first large mammoth that appears on the scene

  • is meridionalis, which was standing four meters tall

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

  • and spread from Western Europe clear across Central Asia,

  • across the Bering land bridge

  • and into parts of North America.

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

  • and new habitats opened up,

  • we had the arrival of a steppe-adapted species

  • called trogontherii in Central Asia

  • pushing meridionalis out into Western Europe.

  • And the open grassland savannas of North America

  • opened up, leading to the Columbian mammoth,

  • a large, hairless species in North America.

  • And it was really only about 500,000 years later

  • that we had the arrival of the woolly,

  • the one that we all know and love so much,

  • spreading from an East Beringian point of origin

  • across Central Asia, again pushing the trogontherii

  • out through Central Europe,

  • and over hundreds of thousands of years

  • migrating back and forth across the Bering land bridge

  • during times of glacial peaks

  • and coming into direct contact

  • with the Columbian relatives living in the south,

  • and there they survive over hundreds of thousands of years

  • during traumatic climatic shifts.

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

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

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

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

  • and Alaska until about 3,000 years ago.

  • So Egyptians are building pyramids

  • and woollies are still living on islands.

  • And then they disappear.

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

  • they go extinct, likely due to a warming climate

  • and fast-encroaching dense forests

  • that are migrating north,

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

  • probably Pleistocene overkill,

  • so the large game hunters that took them down.

  • Fortunately, we find millions of their remains

  • strewn across the permafrost buried deep

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

  • and actually take them out.

  • And the preservation is, again,

  • like those insects in [amber], phenomenal.

  • So you have teeth, bones with blood

  • which look like blood, you have hair,

  • and you have intact carcasses or heads

  • which still have brains in them.

  • So the preservation and the survival of DNA

  • depends on many factors, and I have to admit,

  • most of which we still don't quite understand,

  • but depending upon when an organism dies

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

  • the constancy of the temperature of that burial environment,

  • will ultimately dictate how long DNA will survive

  • over geologically meaningful time frames.

  • And it's probably surprising to many of you

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

  • it's not the length of preservation,

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

  • So if we were to go deep now within the bones

  • and the teeth that actually survived the fossilization process,

  • the DNA which was once intact, tightly wrapped

  • around histone proteins, is now under attack

  • by the bacteria that lived symbiotically with the mammoth

  • for years during its lifetime.

  • So those bacteria, along with the environmental bacteria,

  • free water and oxygen, actually break apart the DNA

  • into smaller and smaller and smaller DNA fragments,

  • until all you have are fragments that range

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

  • a few hundred base pairs in length.

  • So most fossils out there in the fossil record

  • are actually completely devoid of all organic signatures.

  • But a few of them actually have DNA fragments

  • that survive for thousands,

  • even a few millions of years in time.

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

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

  • away from all the rest of the gunk in there,

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

  • that if I take a mammoth bone or a tooth

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

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

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

  • that survived in that environment with it,

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

  • Not surprising then again that a mammoth

  • preserved in the permafrost will have something

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

  • whereas something like the Columbian mammoth,

  • living in a temperature and buried in a temperate environment

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

  • But we've come up with very clever ways

  • that we can actually discriminate, capture and discriminate,

  • the mammoth from the non-mammoth DNA,

  • and with the advances in high-throughput sequencing,

  • we can actually pull out and bioinformatically

  • re-jig all these small mammoth fragments

  • and place them onto a backbone

  • of an Asian or African elephant chromosome.

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

  • that discriminate between a mammoth and an Asian elephant,

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

  • Well, the mammoth genome is almost at full completion,

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

  • So a hominid genome is about three billion base pairs,

  • but an elephant and mammoth genome

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

  • is composed of small, repetitive DNAs

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

  • So having this information allows us to answer

  • one of the interesting relationship questions

  • between mammoths and their living relatives,

  • the African and the Asian elephant,

  • all of which shared an ancestor seven million years ago,

  • but the genome of the mammoth shows it to share

  • a most recent common ancestor with Asian elephants

  • about six million years ago,

  • so slightly closer to the Asian elephant.

  • With advances in ancient DNA technology,

  • we can actually now start to begin to sequence

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

  • and I just wanted to talk about two of them,

  • the woolly and the Columbian mammoth,

  • both of which were living very close to each other

  • during glacial peaks,

  • so when the glaciers were massive in North America,

  • the woollies were pushed into these subglacial ecotones,

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

  • and there they shared refugia,

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

  • It looks like they were interbreeding.

  • And that this is not an uncommon feature

  • in Proboscideans, because it turns out

  • that large savanna male elephants will outcompete

  • the smaller forest elephants for their females.

  • So large, hairless Columbians

  • outcompeting the smaller male woollies.

  • It reminds me a bit of high school, unfortunately.

  • (Laughter)

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

  • to revive extinct species, because it turns out

  • that an African and an Asian elephant

  • can actually interbreed and have live young,

  • and this has actually occurred by accident in a zoo

  • in Chester, U.K., in 1978.

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

  • modify them into all those positions we've actually now

  • been able to discriminate with the mammoth genome,

  • we can put that into an enucleated cell,

  • differentiate that into a stem cell,

  • subsequently differentiate that maybe into a sperm,

  • artificially inseminate an Asian elephant egg,

  • and over a long and arduous procedure,

  • actually bring back something that looks like this.

  • Now, this wouldn't be an exact replica,

  • because the short DNA fragments that I told you about

  • will prevent us from building the exact structure,

  • but it would make something that looked and felt

  • very much like a woolly mammoth did.

  • Now, when I bring up this with my friends,

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

  • Where are you housing a mammoth?

  • There's no climates or habitats suitable.

  • Well, that's not actually the case.

  • It turns out that there are swaths of habitat

  • in the north of Siberia and Yukon

  • that actually could house a mammoth.

  • Remember, this was a highly plastic animal

  • that lived over tremendous climate variation.

  • So this landscape would be easily able to house it,

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

  • the boy in me, that would love to see

  • these majestic creatures walk across the permafrost

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

  • that part of the adult in me sometimes wonders

  • whether or not we should.

  • Thank you very much.

  • (Applause)

  • Ryan Phelan: Don't go away.

  • You've left us with a question.

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

  • it feels like you're reticent there,

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

  • What's your reticence?

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

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

  • about the implications, ramifications of our actions,

  • and so as long as we have good, deep discussion

  • like we're having now, I think

  • we can come to a very good solution as to why to do it.

  • But I just want to make sure that we spend time

  • thinking about why we're doing it first.

  • RP: Perfect. Perfect answer. Thank you very much, Hendrik.

  • HP: Thank you. (Applause)

Translator: Joseph Geni Reviewer: Morton Bast

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B2 US TED mammoth dna elephant extinct woolly

【TED】Hendrik Poinar: Bring back the woolly mammoth! (Hendrik Poinar: Bring back the woolly mammoth!)