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Lessons From A Defrosted Baby Mammoth

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Lessons From A Defrosted Baby Mammoth

Science

Lessons From A Defrosted Baby Mammoth

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IRA FLATOW, host:

You're listening to SCIENCE FRIDAY. I'm Ira Flatow. Picture this. About 40,000 years ago, a herd of mammoths drinks by a lakeside. One of them, a baby, walks too far in and she tumbles into the lake and panics. She inhales the muddy water, struggles and then drowns. Eventually her body drifts to a part of the lake that freezes into permafrost and there she stays frozen for tens of thousands of years. And two years ago, a Siberian reindeer herder sees something strange on a sandbar. And when he looks closer, he recognizes a creature that his tribe believes is a bad omen, an animal from the underworld. So he and a friend contact people from the nearest museum in St. Petersburg.

Museum officials trek to Siberia and are amazed when they see her, the little mammoth, almost perfectly preserved, frozen in time, and they name her Lyuba, after the reindeer herder's wife. Well, today Lyuba is the cover girl for the most recent issue of National Geographic magazine. And one of the scientists who's exploring the secrets to be found in her preserved tissue stomach and other organs and her DNA, he is here to talk to us.

We'll found out why he had to eat a draft horse - he had to eat a draft horse in the process. Our number 1-800-989-8255, 1-800-989-TALK, and you can go to our Web site and Twitter us at SciFri if you'd like to submit questions. Let me introduce my guest. Daniel Fisher is professor of geological sciences and curator of the Museum of Paleontology at the University of Michigan in Ann Arbor. Welcome to SCIENCE FRIDAY.

Professor DANIEL FISHER (University of Michigan): Thank you. Pleasure to be here.

FLATOW: Where was the - where was the mammoth found?

Prof. FISHER: She was found in sort of the North Western corner of Siberia, which is about where the European part of Russia meets the Asian part of Russia, just north of the Ural Mountains.

FLATOW: And tell us about this nomadic reindeer herder and his family.

Prof. FISHER: They are from a group of people known as the Nenets. They - many of them live now by fishing, but most of them live by herding reindeer. Probably, say, 400 or 500 years ago they would have been hunting reindeer. But 400 years ago they took up a slightly more domesticated version of that pursuit.

FLATOW: And now how did this baby mammoth, how did Lyuba last so long in such good condition?

Prof. FISHER: Well, part of the answer certainly is that she was frozen into the permafrost, this essentially permanently frozen soil sediment that makes up much of the ground surface at these high latitudes. This is well above the Artic Circle. And that's a stable, physical, chemical environment in which lots of kinds of things, tissues of plants, of animals are easily maintained over - over long, long periods of time. The oxygen, the bacterial processes that normally degrade organic tissue, are slowed down essentially to a complete pause under those circumstances.

FLATOW: But she had been dug out. She must have started to decompose at some point there, no?

Prof. FISHER: Well, we would think that. In fact, that was one of the big mysteries of working on this specimen. She had been, lets say, dug out the by the river that has naturally eroded from the river banks and then carried downstream probably in the spring flood of 2006 and at that point was deposited as the flood waters receded on this sandbar that flanked the river. And as we can reconstruct it, she lay there for almost a year, because she was found just before the next spring floods in May of 2007.

So that means that she was laying by the river in the full 24 hour sun of the Siberian summer of 2006. And it was - it was completely mystifying to us how she escaped degradation during that time, either by bacterial decay or by scavengers. The answer to that seems to be that her body had undergone a sort of natural pickling process mediated by a certain group of bacteria that produced lactic acid within - within tissues. And these sort of soured her, pickled her, so that other bacteria and certainly mammalian or avian scavengers turned up their nose at her essentially and said, hmmm, I'll go for something more familiar.

FLATOW: That's interesting. But I understand that in proving this theory, you had to experiment and eat a draft horse.

Prof. FISHER: Yes, that's true, although the sequencing is a little different from that. The draft horse actually was part of an earlier series of experiments on storage of meat in ponds, something that the work that we did in North America actually led us to think that early humans - early Pleistocene humans in North America did when they hunted, killed and butchered mastodons and mammoths. The problem was essentially what do you do with the leftovers in that circumstance. And the answer was one way you can deal with them and one way that we have well documented at a couple of sites is to store large carcass parts in ponds.

And they then undergo this bacterially mediated preservation process that keeps the meat really in very reasonable condition for - for months and months, sometimes over a year. Now, the - the connection with Lyuba was - was actually somewhat late to dawn on me. It was really only after we had thawed her out as part of the process of dissection and sort of surgical investigation that we did in St. Petersburg as one of the later stages of our analysis that I began to realize that there was a smell that was not - it was not unpleasant. It was not even particularly strong, but it was familiar and it gnawed at me for a while before I connected it with the earlier experience of eating pond-aged draft horse.

(Soundbite of laughter)

FLATOW: So (unintelligible) you did prove that the pond was able to keep, to preserve the Lyuba, the same we preserve the draft horse.

Prof. FISHER: Yes, the same process that has essentially put her tissues into a different state that made them much less likely to decompose…

FLATOW: Yeah.

Prof. FISHER: …when she was finally eroded out.

FLATOW: Well, what can you learn from her now? What's the gist of what you'd like to do?

Prof. FISHER: Sure. There's a deal of, you know, individual nuggets of information on mammoth anatomy and biology that are really very interesting to consider. But there's also a bigger prize essentially that we've been able to grab hold of through our work on her, and that is that she's given us an opportunity to test some of the methods that we use for extracting biological information from fossil remains. These methods involve looking at tusks, sometimes also the chewing teeth, premolars, molars of an animal. The tusk and other teeth grow through addition of layers of material.

And the structure and composition of these layers give it the evidence of things like diet, local climate, certainly the animal's nutritional condition. They give us lots of insight into the world that these animals inhabited. But all too - all too often we have only the tusk and we apply our methods and we get our information, but how are we going to check to see whether that information is - is really at the straight scoop. And what Lyuba gives us is an animal where we have our usual source of information, the tusks and the teeth, and for that matter the bones and so forth. But we also have the rest of her body, and that lets us see just how good a condition she was in. It gives us - for instance, on the subject of diet it gives us her intestinal contents. And we can then make a direct comparison between what the rest of Lyuba offers and what the information we get from her tusks. And yes indeed, the methods work. It means that we can apply these much more broadly with confidence gained from this sort of ground truth access.

FLATOW: Now I'm sure that people are going to ask you, well, you must have gotten viable DNA out of Lyuba. Can't you grow us another mastodon from her?

Dr. FISHER: We certainly have DNA from her. Viability is a slightly more ticklish issue. Actually, her DNA is much less fragmented than most ancient DNA. It's really - well, my colleague Hendrick Poinar at McMaster University, who did the work on her DNA, said that it was better preserved than any mammoth DNA he had worked with.

So I think that she's a wonderful candidate for further advances in the study of the mammoth genome. However, at this point, as I'm sure you and most of your listeners know, there are a number of technical issues that currently stand in the way of any real cloning effort, and so while we're going to learn a lot about mammoth populations and mammoth biology and history from this. At the moment, we're not going to be raising our own mammoths.

FLATOW: One last question in the minute or two we have left. Was there anything surprising about the anatomy since you had such a well-preserved specimen?

Dr. FISHER: Sure. One of the biggest surprises was this very well-marked hump on the back of neck, which we realized early on was made of fat, but in the later stages of the work, we further realized that - at least we have very strong evidence that this is actually brown fat, which is a special tissue that's capable of inducing its own metabolic activity that generates heat.

And so it's part of the thermal regulatory system of some mammals, and in this case it seems that it's likely that this was part of the temperature control system for young baby mammoths that allowed them to be born a little earlier than they might have been otherwise and get sort of more of a good running start through their first summer to be in good enough condition to survive their first Arctic winter.

FLATOW: Very interesting, Dr. Fisher. I want to thank you for taking time to be with us today.

Dr. FISHER: Oh sure. It's my pleasure.

FLATOW: Good luck to you.

Dr. FISHER: Thank you.

FLATOW: Congratulations.

Dr. FISHER: Oh, thank you very much.

FLATOW: Daniel Fisher, professor of geological sciences and curator of the Museum of Paleontology at the University of Michigan in Ann Arbor, talking about Lyuba, who's on the cover of National Geographic this month.

We're going to take a break and switch gears. We're still going to talk about animals but about CSI detectives who - well, they're detectives for animals. I mean, it's not the kind of show you see on TV. Maybe there will be one after we talk about it. We're going talk about it, so stay with us. We'll be right back talking about CSI for animals, also the author of the book "Animal Investigations." Laurel Neme will be here. So we'll be right back talking about that subject. So stay with us.

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