IRA FLATOW, host:
You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow, continuing now with our woolly mammoth theme we've been talking about.
Scientists - who believes that this giant cosmic collision possibly killed the woolly mammoths 13,000 years ago, and along with some other really interesting animals that were around at the time - explaining that extinction.
Well, this week scientists announced that they have sequenced DNA from the mammoth, a favorite exhibit at natural history museums around the world - you see them usually standing there out in the lobby because they're so big.
And now, that has been done before, but those times they're usually using little bits of bone. These scientists got the gene sequence from strands of mammoth hair. They say this method could be used to do same for other animals that survive today only in museum collections, and that analyzing the genomes of ancient animals might tell us something about how and where they lived and what caused them to go extinct.
And I know what you're saying - if we've gotten ancient DNA from the hair, can we now make another woolly mammoth from the DNA sequencing. Let's not go there so quickly. We'll ask our scientists - the team of scientists published it this week in today's issue of the journal Science.
And joining me now to talk about the mammoth genome is one of the researchers, Tom Gilbert, assistant professor in the Biological Institute and it's affiliated with the Center for Ancient Genetics at the University of Copenhagen in Denver. And he joins us today by phone from Copenhagen. Thank you for staying up late, Dr. Gilbert.
[Post-broadcast correction: University of Copenhagen in Denmark.]
Dr. THOMAS GILBERT (Biological Sciences, University of Copenhagen): That's no problem, Ira.
FLATOW: Did I hear you correctly in saying that you got DNA from the mammoth hair itself?
Dr. GILBERT: Yeah, that's right, actually. The whole focus of our study is using the mammoth hairs in place of conventional things like bone or teeth.
FLATOW: And what advantage is there to that? The fact that you - maybe you can find more mammoth hair around than bones or something better?
Dr. GILBERT: No, no, it's not really that. It's really the fact we can actually basically shampoo the hair and get it really, really clean and then we can basically get really pure DNA out of a hair. This is a key advantage we are finding compared to bone and teeth, where often your DNA is very full of things like bacteria that would be in the sample. So it's the purity, really.
FLATOW: You know, we've seen on these crime scene shows on TV they have in the states - I'm sure you must have them over there, watching them - they always say that they have to have the bottom of the hair, you know, the living part of the hair to get the DNA out of it. Is that true in your study?
Dr. GILBERT: No. You see, that's the kind of the very interesting thing about the study. We went in, specifically avoiding that part of it and going for the hair shaft. I mean, it was based on a little bit of theory we had. I mean, we knew there was a bit of DNA in hair and we thought, well, let's give it a go. And we wanted to avoid the roots for various technical reasons, but the results really blew us away. It seemed that no matter what individual we tried, we got this fantastic DNA out of it. It really, you know, we're absolutely flabbergasted how well it worked.
FLATOW: Wow. 1-800-989-8255, 1-800-989-TALK, if you'd like to talk about the mammoth hair and the DNA coming from it. Also, in "Second Life," if you want to find our avatar, you can ask some questions. 1-800-989-8255. So you say you are really blown away by this?
Dr. GILBERT: Yeah. Well, I mean, the thing was we had a suspicion that there would be a kind of DNA called mitochondrial DNA surviving in there. Mitochondrial DNA is used for a lot of things, and actually our paper is kind of focusing on the mitochondrial DNA.
But the thing that really, really shocked us is we got this really pure nuclear DNA as well. And nuclear DNA is what the majority of the genome's made up of. And this is, you know, the basis to getting the whole genetic information on a mammoth is in the genome.
And, really, the - what people have been trying to do recently is use bone samples to get this, using some very neat, new techniques to sequence DNA. But the problem is although in an afternoon, on one of these new machines, you can get like 100 million nucleotides of DNA, with bone, over 50 percent of that is bacteria, so it's pretty inefficient.
But the thing that really impressed us with the hair was we were getting like, nearly 100 percent of it was the mammoth DNA. So we very quickly build up a huge amount of DNA data on the specimens.
FLATOW: Can you get a complete genome sequence, do you think?
Dr. GILBERT: That's the idea. We're actually in the process of doing that.
FLATOW: And, you know, I have to ask for my listeners who will be asking soon, can we then reconstruct and bring back to life a woolly mammoth?
Dr. GILBERT: You know, that's the billion-dollar question because if we do, you know, I'm going to open myself a mammoth ranch…
(Soundbite of laughter)
Dr. GILBERT: …and sell it off people around the world. It's a tricky one, and I'm not going to say no. In the past, you know, a couple of years ago, what I would have said is, you know, the first problem is you've got to get the genome. And until, like, basically now, we were doing this in very small fragments. We were doing like 200 base pairs at a time and trying to get three billion bases that way. It takes a long, long time.
Using this method, we can very quickly get the whole genome. So that's not the problem now. The next problem there, of course, is whether we can actually -whether it could be taken and actually, you know, got into something that's going to come alive. If you think about in vitro fertilization, you know, that people go through all the time, it's pretty tricky business. And that's just with humans, right?
Dr. GILBERT: Working with a mammoth, where there's no actual living cell that's really close to it is going to make it very, very hard. So I'm not going to say no because the techniques are changing so, so fast that it may well be possible in the future. Right now, though, we're probably still not quite there.
FLATOW: What - tell us what the great advantage of the mitochondrial DNA is, and exactly, if you could explain, what that part is, a little bit.
Dr. GILBERT: Sure. Inside a cell, you've got a thing called the mitochondria, and that's what a lot of people refer to as the kind of factory of the cell. It's where you basically metabolize the energy, where you produce the energy that keeps the body living. Now, mitochondria originally, actually - they come from bacteria that were kind of taken in by cells millions or billions of years ago even. So they've got their own little DNA genomes. They're only 16,000, 17,000 base pairs long, unlike the nuclear genome, which is billions of base pairs long.
But one of the neat things about them is they're passed down from mother to children, and it's always down the female line. And for various reasons, we can use these to look at a whole load of things to do with animals. We can look at, for example, how closely related animals are to other animals. So if you've got a mammoth and you've got, for example, the African elephant and the Asian elephant, and you want to know which one is the closest relative, you can compare the mitochondria of them and see this.
You can actually throw in a time factor. So, actually, DNA can be roughly estimated as mutating at a certain rate. And if you count the number of mutations, you can basically get an idea of how long ago things separated so we can start to say, well, you know, when is the last time that an elephant and a mammoth shared a common ancestor.
The other thing we can do there is we can actually compare it within a species. So, for example - now, in this kind of study where we got 10 new mammoth mitochondrial genomes, we can start to look at the diversity in mammoths themselves. I mean, you can say things like, you know, was the diversity in the mammoths, who lived the whole way across Siberia, the whole way across North America, was it similar to what we see in elephants, or was it much more restricted, or was it much more diverse?
And this kind of tells you the same as what you're talking about earlier with extinctions because often, a hallmark of a really healthy population is a lot of diversity. It shows that it's big and it's breeding and moving around. And when you've got a big, healthy population, I mean, people start saying, well, you know, maybe a little thing like the humans coming in might have wiped them out, things, you know, it's harder to kind of believe than if you know that you've got a very kind of restricted population because there's not much variation and stuff. I mean, this is great with this new meteor hypothesis because that is the kind of thing that could wipe out a huge, you know, healthy population in no time…
Dr. GILBERT: …because, you know, it's not just a few guys with sticks prodding them. This is like, you know, a massive impact wiping it out.
FLATOW: Yeah. Well, if all those other animals are wiped out and if some of them had hair, could you find the hair from those animals, too, and do a DNA analysis?
Dr. GILBERT: Well, yeah, I would say. The thing about hair is obviously, you don't go outside and find yourself neck deep in hair every time you look around. Well, hair obviously degrades away.
Dr. GILBERT: I mean, we shed hair every day. But it does preserve in the right conditions. The right conditions for real long-term survival is actually things like the cold. So, the permafrost is the place to go for that. And, you know, the whole way across sort of northern Canada and northern Russia, there's a lot of permafrost. And as you know, it's melting now and things are coming out, and they're starting to find hair at a surprisingly fast rate. I mean, you'd have heard this year about this fantastic baby mammoth they've found, you know? It looks like an elephant kind of thing.
More and more of these are coming every year, and there's more and more hair coming in. So we're starting to get hair from woolly rhinos that went extinct, from mammoths. And we can start to hope, you know, we might run into like short-faced bears, you know, sabertooths, all these kind of things.
FLATOW: You know who's going to love to hear this - about your research? Is Jane Goodall.
Dr. GILBERT: Oh, yeah. I imagine she would.
FLATOW: Well, because she believes that Sasquatch exists.
Dr. GILBERT: Yeah.
FLATOW: And she believes, you know, that you will find hair and fur and be able to use DNA. But, you know, now that you're - if you can just find the fur and if it's true and that you can use the hair itself instead of just the root part.
Dr. GILBERT: And if you get enough Sasquatch hair, it will be a pretty trivial little question.
Dr. GILBERT: I mean, one thing that's worth saying about the work now is that right now, this is in its infancy, and we're using about 0.2 point grams of hair, which is - it doesn't sound like much but it's a little, you know, quite a bit clumped, it's not a couple of strands.
But actually this is based on the machine we use to actually sequence the DNA. This is a fairly new machine. It's - people aren't familiar with it yet and they haven't customized their techniques with it yet. And it's very, very conceivable that, you know, in the next couple of years, people are going to get down to really using tiny amounts of DNA. And then we are really are entering the realm of, like, you know, one, two hairs getting huge amounts of data and answering questions. In fact, just like that, you know, is Sasquatch Sasquatch? Is it a bear or is it, you know, or is it somebody's put it out there for a joke?
FLATOW: Hmm. 1-800-989-8255. Let's go to William(ph) in Saratoga, California.
WILLIAM (Caller): Hi.
FLATOW: Have you - turn your radio down, okay? Talk on the phone and turn your radio down for me?
FLATOW: Have you…
WILLIAM: Hold on, my mom's turning it down.
FLATOW: Oh, that's good. Have you got a question?
WILLIAM: Yeah. How did they producing it - how did they find it inside? Did they find it inside of something?
FLATOW: Yeah. Tom, was it just lying on the ground? How do you find the mammoth hair?
Dr. GILBERT: Yeah, that's a pretty good question, actually. They're found in a whole load of ways. I mean, one way they find them is you've got guys out there in huge bulldozers, actually kind of out there and then mining on the surface. And I mean, one of the famous ones is they were just driving the bulldozer along the side of a hill, pulling off the soil and actually this light gray thing just rolled past the bulldozer down to the ground. And the guy stopped and got out, and it was a mammoth's head just, you know, lying there. He'd just unburied it.
Another famous one that we worked on is called fishhook mammoth. And as you might guess, it's got something to do with fishing, and this one was actually - these guys were fishing and, you know, their rod got caught on something in the lake they were fishing. And, you know, sort it out and there was a mammoth down there. You just practically stumble over them all over the place in Siberia.
FLATOW: Okay, William?
FLATOW: Thanks for calling.
WILLIAM: You're welcome.
FLATOW: Have a good weekend. 1-800-989-8255.
Bjorn(ph) from Sacramento on "Second Life" asks, does Ice Age footprint evidence give you any clue?
Dr. GILBERT: Does Ice Age footprint evidence?
Dr. GILBERT: So we're talking about just the footprints found frozen in the ground?
FLATOW: I guess so.
Dr. GILBERT: Yeah, that's a really good question. And I'd imagine it's possible because it's - I mean, once it's frozen, there will be skin cells left. And actually, I've heard stories of, you know, a guy actually collecting, for example, fox footprints in the snow. So just like, you know, the print you see on the snow when a fox is going across fresh snow and taken and got DNA from it. So, we haven't tried it but it's a cracking idea.
FLATOW: Okay. We're talking about mammoth and their DNA this hour on TALK OF THE NATION: SCIENCE FRIDAY from NPR News. Talking with Tom Gilbert, assistant professor of Biological Institute Center for Ancient Genetics, University of Copenhagen.
So are you depending a lot on museum collections now to start sending you their hair?
Dr. GILBERT: You know, that's very much it. Well, we've been very lucky in this study because when we have the first idea, I was sitting and thinking, like, you know, where on Earth am I going to get myself some hair from? And I just had a few connections and wrote them and people knew people. And these curators at the museums are fantastic. There are guys all over the world saying, yeah, we've got a bit of mammoth hair. And at that time, we didn't even know if it was going to work. So here's - you know, we were sitting there quite guilty thinking, well, you know, I hope we don't, you know, get rid of their hair for nothing.
But I mean, yeah, this is a part of the great thing about the method is, of course, hair is really, really common in museums. I mean, you know, people like to collect things. Some of the really famous early biologists like, you know, Darwin, for example, or Linnaeus, they were out there collecting things and putting them in the museums.
And so there are all sorts of, like, you know, basic skins, hairs, pelts, just cuttings of skins, all sitting around that could be worked on with fairly, you know. I mean, it's quite nice because before when we were working on bone, we'd basically get a bone and drill a big hole in it, which is not the most sightly of things. But with the hair, we can, you know, just take a few clippings, it's basically not noticeable, and get a load of new information that wasn't available before.
FLATOW: How soon can you know whether the mammoth is related to the present-day elephant or some other animal that we have around today?
Dr. GILBERT: Pretty soon. I mean, actually the - we're not the first to do the mammoth's mitochondrial genome. We're the first to do it this way and there was a couple of very nice studies done. In fact, one this year, using something called a mastodon. The mastodon is a kind of another sort of elephant-head animal. And they've basically shown that the Asian elephants - so the ones you get in, you know, India and Southeast Asia - are the closest relatives to the mammoth.
Now, there's a few questions about when exactly they separated, and that's kind of stuff that we're starting to work on now. We haven't gotten any results right now, but it will be in the very near future. We'll know some pretty, pretty definitive things.
FLATOW: Mm-hmm. Would you be able to know where the mammoth descended from, what its ancestor was?
Dr. GILBERT: That's one of the hopes. I mean, we'll be able to, for example, look at, you know, was it just one species of mammoth roaming around Siberia or was there possibly more? I mean, the genome information might give hints that there was more than just like one type. We'll be able to know roughly where it come from, but a lot of this stuff is already known from the morphologists, you know, the guys who do a lot of really good work on the fossils.
Our stuff is going to be more about actually looking at the population of the mammoth themselves and seeing, you know, like, I say was it like one big mixing population…
Dr. GILBERT: …or were they very isolated, that kind of thing.
FLATOW: Well, we know there were mammoths in North America, right? We know there're mammoths…
Dr. GILBERT: There certainly were, yeah, the Colombian Mammoths.
FLATOW: Yeah. So they were pretty well spread out.
Dr. GILBERT: They really were. And actually, I tell you, when we were testing for hairs, I did come across an old reference telling me they've got some American mammoth hair in the American museum, and actually, they've got some up in, I think it's in Fairbanks. And that's one of the things we'd quite like to try because, you know, we're really keen to find out are these things very different or not? I mean, back in those days, there was something called Beringia, and it was kind of solid land the whole way from Europe across to the Siberia and then across to America. So instinctively, we're thinking it's all just one big population because, you know, the sea wasn't there like it is now.
Dr. GILBERT: But it will be fascinating to try it.
FLATOW: So what's your next step?
Dr. GILBERT: The next step? Well, with mammoth, there's the genome project that my collaborators at Penn State, who I've been doing all this work with, they're fully churning out data there to try to get the genome. And we're going to be looking also at basically what the data is telling us. In this paper right now, we've really just published the method saying, look here's this really great method for getting DNA from hair.
But the next step is now to look at the data and say, well, you know, what can we learn from the data? What's this mammoth stuff telling us?
FLATOW: Yeah. You know, but the tool that you've discovered is invaluable, I would think.
Dr. GILBERT: Yeah. Well, we like things pretty useful. And I say it's - right now, I mean, the machines are new. It's relatively expensive, what we're doing. But that's because things are new. I mean, with all things, when they're brand new they cost a lot. I mean, look at the iPhones. They, you know, came out not so long ago at one price and they've dropped a lot already.
That's going to be the same with the sequencing techniques. It's going to be dropping, dropping, dropping. And very soon, we're going to be in a situation where you take yourself a little bit of tissue like hair, do this little test, takes, you know, a few hours, and you get a lot of information. You learn a whole load of new things.
FLATOW: Well, good luck to you.
Dr. GILBERT: Thank you.
FLATOW: Thank you for taking time to be with us today, and have a good weekend.
Dr. GILBERT: You too.
FLATOW: Tom Gilbert, assistant professor in the Biological Institute at the University of Copenhagen in Denmark on the phone from Copenhagen.
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FLATOW: Have a good weekend. We'll see you next week. I'm Ira Flatow in New York.
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