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.
Kad sam bio mali dječak, očevim sam mikroskopom promatrao okamenjene kukce u jantaru, koje je on držao u kući. I bili su izvanredno dobro očuvani, morfološki jednostavno izvanredno. I zamišljali smo da će jednog dana oni zapravo oživjeti i da će ispuzati iz smole, i, ako budu mogli, odletjeti.
If you had asked me 10 years ago whether or not we would ever be able to 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.
Da ste me pred 10 godina pitali hoćemo li ikada moći sekvencionirati genom izumrlih životinja, rekao bih vam da to nije vjerojatno. Da ste me pitali hoćemo li zapravo moći oživjeti izumrlu vrstu, rekao bih da je to maštarija. No, zapravo stojim tu danas, začudo, kako bih vam rekao da senkvencioniranje izumrlih genoma nije samo mogućnost, točnije današnja stvarnost, već je i oživljavanje izumrlih vrsta zapravo unutar dosega naših mogućnosti, možda ne kukaca iz jantara -- zapravo, ovaj je komarac korišten kao inspiracija za "Jurski park" -- ali vunenih mamuta da, iz dobro očuvanih ostataka vunenih mamuta u permafrostu.
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.
Vuneni mamuti su posebno zanimljivi, kvintesencijalni su lik Ledenog doba. Bili su veliki. Bili su dlakavi. Imali su velike kljove i čini se da smo imali vrlo duboku povezanost s njima, kao što imamo sa slonovima. Možda je to zato što su slonovi u mnogim stvarima slični nama. Pokapaju svoje mrtve. Educiraju potomstvo. Održavaju vrlo bliske socijalne veze. Ili je to možda zato što smo povezani milijunima godina, jer slonovi, baš kao i mi, vuku podrijetlo iz Afrike od prije otprilike sedam milijuna godina, i kako su se mijenjala staništa i okoliš, mi smo, kao i slonovi, migrirali u Europu i Aziju.
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.
Prvi veliki mamut koji se pojavio je meridionalis, visok oko četiri metara, težak oko 10 tona, vrsta prilagođena životu u šumi, proširio se iz zapadne Europe kroz središnju Aziju, a preko Beringovog prolaza i u dijelove Sjeverne Amerike. I onda, kad se klima promijenila kao i uvijek, i pojavila se nova staništa, pojavila se vrsta prilagođena životu u stepama zvana trogontherii, u središnjoj Aziji i istisnula je meridionalisa u zapadnu Europu. I široki pašnjaci sjevernoameričkih savana omogućili su pojavu kolumbijskog mamuta, velike, bezdlake sjevernoameričke vrste. I, zapravo, tek nakon otprilike 500.000 godina pojavio se vuneni mamut, onaj kojega svi znamo i toliko volimo, na prostoru od istočne Beringije, odakle je potjekao, pa širom središnje Azije, ponovno istiskujući trogontherii kroz središnju Europu, i stotinama tisuća godina migrirajući preko Beringovog prolaza i natrag za vrijeme vrhunaca ledenih doba i dolazeći u direktan kontakt sa svojim kolumbijskim rođacima koji su živjeli na jugu, i tamo oni preživljavaju stotinama tisuća godina tijekom traumatičnih klimatskih promjena. Tu imamo iznimno prilagodljivu životinju koja se nosi s golemim promjenama u temperaturi i okolišu i snalazi se jako, jako dobro. I tako oni preživljavaju na kopnu do prije otprilike 10.000 godina, a, zapravo, začuđujuće, na malenim otocima blizu Sibira i Aljaske do prije otprilike 3.000 godina. Znači, Egipćani grade piramide, a vuneni mamuti i dalje žive na otocima.
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.
A onda nestaju. Kao i 99 % svih vrsta koje su ikada živjele, izumiru, vjerojatno zbog klimatskog zatopljenja i gustih šuma koje se brzo šire na sjever i, također, kao što je pokojni, veliki Paul Martin jednom rekao, zbog izlova u pleistocenu, tako da su ih i lovci na veliku divljač istrijebili.
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.
Na sreću, milijune njihovih ostataka nalazimo razasute po permafrostu, zakopane duboko u Sibiru i Aljasci i mi, u stvari, odlazimo tamo i iskapamo ih. I očuvanje je, ponovno, kao i kod onih kukaca u [jantaru], odlično. Tako imamo zube, kosti s krvlju, koje izgledaju kao krv, imamo dlaku, i netaknuta trupla ili glave koje još uvijek u sebi sadrže mozgove.
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.
Očuvanje i preživljavanje DNK ovisi o mnogo čimbenika i, moram priznati, većinu njih i dalje posve ne razumijemo. No, ovisno o tome kad organizam umre i koliko je brzo ukopan, kolika je dubina ukopa, i ujednačenost temperature okoliša u kojem je ukopan, konačno će biti određeno koliko dugo će DNK preživjeti kroz geološki značajne vremenske okvire. I vjerojatno začuđuje mnoge od vas koji sjedite u ovoj sobi da nije vrijeme ono što je važno, niti duljina očuvanja, već je najbitnija ujednačenost temperature tog očuvanja.
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.
Znači, ako bi sada promotrili kosti i zube koji su preživjeli proces fosilizacije, DNK koji je jednom bio netaknut, čvrsto omotan oko proteina histona, sada je pod napadom bakterija koje su živjele u simbiozi s mamutom godinama, za vrijeme njegovog života. I te bakterije, kao i bakterije iz okoliša, oslobađaju vodu i kisik, zapravo, razbijaju DNK na sve manje i manje fragmente DNK, sve dok jedino što imamo nisu samo fragmenti od 10 baznih parova do, u najboljim slučajevima, nekoliko stotina baznih parova u duljini. Tako da je najveći broj fosila u evidenciji zapravo potpuno lišen svake organske strukture. Ali nekoliko njih zapravo imaju DNK fragmente koji preživljavaju tisućama, čak i milijunima godina. I koristeći najnoviju "clean room" tehnologiju osmislili smo načine na koje možemo izdvojiti ovaj DNK od ostalih supstanci, i nikome od vas nije iznenađujuće da, ukoliko uzmem mamutovu kost ili zub i izdvojim njegov DNK, dobijem mamutov DNK, ali, također dobijem i sve bakterije koje su nekoć živjele s mamutom, i, nešto složenije, dobijem sav DNK koji je preživio u tom okolišu s njim, dakle, bakterije, gljivice itd. Ponovno, nije iznenađujuće da će mamut očuvan u permafrostu imati približno oko 50% svog DNK, dok će nešto poput kolumbijskog mamuta, koji je živio i bio ukopan u umjerenoj klimi imati samo 3-10 % DNK.
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?
No, dosjetili smo se vrlo pametnih načina na koje zapravo možemo razlikovati i izdvojiti DNK mamuta od drugih DNK, i, s napretkom u sekvencioniranju, možemo izvaditi i bioinformatički ponovno složiti sve te male fragmente i smjestiti ih u DNK okosnicu kromosoma azijskog ili afričkog slona. I tako, čineći to, zapravo možemo dobiti sve točke diskriminacije između mamuta i azijskog slona, i što, onda, znamo o mamutu?
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.
Pa, mamutski genom je skoro potpuno kompletiran, i znamo da je zapravo jako velik. Ipak je to mamut. Tako se genom hominida sastoji od oko tri milijarde baznih parova, no genom slona ili mamuta je za oko dvije milijarde baznih parova veći i većinom je sastavljen od malih, ponavljajućih dijelova DNK zbog čega je zapravo vrlo teško ponovno posložiti čitavu strukturu genoma.
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.
Ova informacija nam pruža odgovor na jedno od najzanimljivijih pitanja o vezi između mamuta i njihovih živućih rođaka, afričkog i azijskog slona, koji su svi imali zajedničkog pretka prije sedam milijuna godina, no genom mamuta pokazuje da on dijeli najbližeg zajedničkog pretka s azijskim slonom, prije oko šest milijuna godina, dakle, mamut je nešto srodniji azijskom slonu.
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.
S napretkom u DNK tehnologiji, sada možemo započeti sekvencionirati genome drugih izumrlih vrsta mamuta koje sam spomenuo, a želim razgovarati samo o dvije vrste, vunenom i kolumbijskom mamutu, koji su živjeli vrlo blizu jedan drugome u vrijeme vrhunaca ledenih doba, i masivnih glečera u Sjevernoj Americi, te su tad vuneni potisnuti na subglacijalne ekosustave i došli su u kontakt sa svojim rođacima koji su živjeli na jugu, i tamo su dijelili refugij, a čini se i malo više od refugija. Čini se da su se međusobno razmnožavali. Izgleda da to nije rijetka pojava kod surlaša, jer ispada da će veliki mužjaci slonova iz savane nadvladati manje šumske slonove u borbi za njihove ženke. Tako su veliki, bezdlaki kolumbijski mamuti nadvladali manje vunene mužjake. Nažalost, to me malo podsjeća na srednju školu.
(Laughter)
(Smijeh)
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.
Ovo nije trivijalna činjenica, s obzirom na ideju da oživljavamo izumrle vrste, jer ispada kako se afrički i azijski slon mogu međusobno razmnožavati i imati potomke, i da se ovo, zapravo, slučajno dogodilo u zoološkom vrtu u Chesteru, VB, 1978. godine. To, dakle, znači da možemo uzeti kromosome azijskog slona, modificirati ih u sve one pozicije koje možemo razlikovati od genoma mamuta, staviti to u stanicu kojoj smo uklonili jezgru, diferencirati ju u matičnu stanicu, potom to možda diferencirati u spermu, umjetno oploditi jajnu stanicu azijskog slona, i, dugom i napornom procedurom, vratiti u život nešto što izgleda ovako. No, to ne bi bila identična kopija, zbog nedostajućih DNK fragmenata o kojima sam govorio koji nas sprječavaju da izgradimo identičnu strukturu no, imali bi nešto što izgleda prilično slično kao što je izgledao vuneni mamut.
Now, when I bring up this with my friends, we often talk about, well, where would you put it? Where are you going to house 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.
Kada ovo spomenem u društvu prijatelja, često raspravljamo gdje bi ga, zapravo, smjestili? Gdje bi mogli smjestiti mamuta? Nema odgovarajućih staništa niti podneblja. No, to zapravo i nije tako. Ispada da postoje široka podneblja na sjeveru Sibira i Yukona, u koja bi mogli smjestiti mamuta. Opet, bila je to vrlo prilagodljiva životinja koja je preživjela ogromne klimatske varijacije. Tako da bi se lako mogla smjestiti u ovo područje, i moram priznati da postoji dijete u meni, dječak u meni koji bi volio vidjeti ova veličanstvena bića kako hodaju permafrostom sjevera još jednom, no moram priznati da se odrasli dio mene ponekad pita bismo li to smjeli učiniti.
Thank you very much.
Hvala vam puno.
(Applause)
(Pljesak)
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?
Ryan Phelan: Nemojte otići. Imamo pitanje za vas. Sigurna sam da se svi pitamo sljedeće. Kad kažete: "Bismo li smjeli?", čini se kao da ste suzdržani po tom pitanju, a ipak ste nam to prezentirali kao nešto vrlo ostvarljivo. Zbog čega vaša suzdržanost?
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.
Ne mislim da je suzdržanost. Samo mislim da trebamo dobro razmisliti o posljedicama naših djela, i sve dok vodimo dobru i kvalitetnu raspravu poput ove sada, mislim da možemo doći do dobrog zaključka o tome zašto to učiniti. No, samo želim da si prvo uzmemo vremena i razmislimo zašto to činimo.
RP: Perfect. Perfect answer. Thank you very much, Hendrik.
RP: Savršeno. Savršen odgovor. Puno vam hvala, Hendrik.
HP: Thank you. (Applause)
HP: Hvala vama. (Pljesak)