EMILY KWONG, BYLINE: You're listening to SHORT WAVE...
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KWONG: ...From NPR.
NATE ROTT, HOST:
Lately, Audrey Rohe has been a bit preoccupied with a girl named Elma (ph). Well, Elma is her nickname. Short for...
AUDREY ROWE: Elmayuujey’eh (ph).
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ROTT: It's a name given to her by the Healy Lake Village Council, the Mendas Cha-ag people, a tribe native to interior Alaska.
ROWE: The way that they translate it is hella-looking (ph). It's a name that's given affectionately towards things that are interesting-looking but not necessarily beautiful. So it's like a name for, like, your ugly pet dog, for example.
ROTT: How do you know my dog's ugly and hella-looking?
ROWE: (Laughter) Oops.
ROTT: It's true. Audrey is a paleoecologist and Ph.D. candidate at the University of Alaska Fairbanks, and she's been studying Elma's tusk because Elma is a woolly mammoth.
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ROWE: So Elma lived about 14,000 years ago, and her tusk was found at one of the oldest - if not the oldest - uncontroversial archaeological sites in Alaska.
ROTT: Uncontroversial because there's no dispute that humans were present there, too. The site is littered with human tools, and this is interesting because, as far as we know, humans only overlapped with woolly mammoths in interior Alaska for about a thousand years. Somewhere in that 1,000-year period, Elma lived and died. Audrey is now studying data from Elma's tusk to track the massive 1,000-kilometer journey she and her herd took through Alaska and northwestern Canada, and she's hoping to figure out just what did Elma in.
ROWE: Everyone always wants to know - is it the humans that did them in or not? Humans are to blame for plenty of extinctions around the planet, but this area has an extra little twist, which is that this was the time of great change in terms of the habitat itself.
ROTT: That's right. There could be another culprit - the end of the ice age. Fourteen thousand years ago, Alaska was rapidly changing.
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ROWE: Things were getting warmer. Things were getting wetter. And that would have allowed trees and shrubs to start migrating in a little bit - creeping in in some of the moister areas, like riverbeds.
ROTT: The habitat was changing in a way that mammoths like Elma just weren't built for, and humans were starting to pop up in the area as well.
ROWE: So it's sort of a chicken-and-egg thing - like, are they there because you've got tons of mammoths? Did the mammoths go extinct because humans were hunting them? Or is it the other way around - were humans able to penetrate this area because it was getting warmer, wetter - just more hospitable to humans?
ROTT: Right. 'Cause eventually, I mean, like, mammoths - right? - go extinct.
ROWE: Eventually mammoths do go extinct, yeah - and not too long after this period, actually, in interior Alaska.
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ROTT: Today on the show, we trace Elma's grand life and journey - through a single tusk - and we take our best guesses at who or what killed her. I'm Nate Rott. You're listening to SHORT WAVE, the science podcast from NPR.
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ROTT: OK, Audrey. Let's talk about our girl, Elma. Where did she live? Like, what was she about?
ROWE: What was she about? Yeah. From our movement studies, we found that she was born somewhere in what is today the western Yukon - sort of on the edge of where she really could have lived because there were ice sheets guarding interior North America at that time. There was the Cordilleran ice sheet and the Laurentide Ice Sheet. She spent about a decade wandering around. And then, about halfway through her life, she underwent a long movement westward for about two years of her life, traversing all the way to interior Alaska, where she spent the rest of her life and mysteriously died, even though she, as far as we know, was pretty healthy, according to the chemicals in her tusk. And she was at the peak of health in terms of her age, too. So she was about 20 years old. I like to think of mammoth timelines as being sort of similar to humans. So they mature at around 15 years of age, kind of like humans - you know, puberty.
ROTT: It took me a little longer, but yeah. Right around then.
ROWE: (Laughter) More or less.
ROTT: Yeah.
ROWE: But my adviser did a similar study of a 30-year-old male mammoth. He underwent a lot larger movements, especially after the age of 15 or so - after puberty. So from that, we're starting to infer from these two studies that mammoth movements and structure of behavior would have been similar to modern elephants. So today, modern elephants live in matriarchal herds - at least the females do. Whereas, when modern male elephants go through puberty, basically, they're kicked out of the matriarchal herd. They wander on their own, trying to find mates in different herds, and they just move around a lot more.
ROTT: Huh. OK. When I was reading some of your study, I was wondering - is it - like, is it normal for a mammoth to move that much? Or, I mean, was Elma just kind of having, like, a hot girl summer, you know? I didn't know.
ROWE: Yeah. It is - it does seem kind of strange - this two-year movement pattern. She does not return to where she was. We can only infer things. We can never know why she - and, presumably, her herd - decided to take this long movement westward. And so what we infer is that maybe resources started to dry up in the Yukon, and they went out looking literally for greener pastures and found them in Alaska.
ROTT: Tale as old as time - always looking...
ROWE: Yeah.
ROTT: Grass is always greener on the other side of the ice sheet (laughter).
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ROTT: So how did you learn all this information? I mean, how did you - how were you able to infer and figure out her movements and everything, given that she died 14,000 years ago?
ROWE: Yeah. So elephant and mammoth tusks kind of grow like stacked ice cream cones. It's like, every day, a new layer is added. A new cone is added to the top of the stack.
ROTT: Ah.
ROWE: And as they're building this stack, each day, they're laying down material from the nutrients that they ate. As they're walking around, they're picking up, basically, bits of their environment from the food they're eating, from the water they're drinking, and then laying it down in this permanent record that is their tusk. So we split open the tusk, and we analyze the isotopes all the way from the tip, which would have been close to birth, to the end of the tusk, closest to the mouth. And that end of the tusk would have been really close to - if not the day of - her death.
ROTT: Whoa.
ROWE: Yeah. So by doing this isotope analysis along that whole length, we learn a lot about location she was in because you are what you eat, and your food has a signature of where you were when you ate it. And we learn a lot about her nutrition. So we know that - we know she didn't starve to death. That's for certain.
ROTT: Cool. All right. So I'm curious about this tusk thing, 'cause it - I mean, I - it almost reminds me of, like, dendrochronology - right? - how we, like, can bore into a tree and learn something from all the different rings. So it's kind of the same. You basically can look through this almost, like, history of the mammoth - right? - by just looking at these layers that stack up on the tusk.
ROWE: Yes, exactly.
ROTT: Cool. That's - you can learn a lot from a tooth.
ROWE: Yes, I love it.
ROTT: You mentioned that Elma was roughly 20, right? She had just gotten out of her, like, teenage years.
ROWE: Yeah.
ROTT: But she was totally healthy when she passed away. So how did she die?
ROWE: Yeah. We can't rule out, like, some sudden disease that hit her really fast and knocked her down. There's no smoking gun at Swan Point. In Europe - in Siberia, there's a couple examples of, like, almost literal smoking guns, where you have human tools embedded in mammoth vertebra or ribs or whatever - clear evidence of human hunting. We don't have anything like that in Alaska, but we have means and motive. So the exact same types of tools that were used in Siberia are the ones that were found in the Swan Point site in Alaska. It's very good evidence that the same people who lived in the Asian side of Beringia walked over and then lived in Alaska in short order and before their tool culture had time to change. We can't for sure say that Elma was hunted, but there's a lot of evidence that it was possible and that it was desirable.
ROTT: Yeah.
ROWE: It would've been a big package of meat for them. Her tusk was actually used as a tool itself.
ROTT: Oh, wow.
ROWE: So a piece of it was removed, and there are a lot of indentations on the outside of the tusk, which means that it was probably used as an anvil just to hit objects against it.
ROTT: Whoa, interesting. So it's not only just - you're not just potentially killing a woolly mammoth because you want to eat. It's also that you want to be able to use the tusk, for example, as a tool.
ROWE: Right. Yeah, ivory was a super useful material.
ROTT: Huh. OK, so you can't definitely say - like, you're not going to run in a murder conviction for humans - right? - on this. But is there another contender? Is there another thing that you suspect could have killed Elma?
ROWE: Well, adult mammoths didn't have, really, many viable predators. I mean, that's the whole point of being big. You see this evolution of large herbivores throughout Earth history - is just herbivores grow bigger and bigger and bigger and bigger, and they're just outgrowing their hunters.
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ROTT: How does she - how does her story and kind of what you've learned from her - how does that weigh into this bigger debate about whether or not it was humans versus climate change that kind of eventually led to the demise of woolly mammoths in North America and across the world?
ROWE: Yeah. A lot of large megafauna would have been suffering because of the Holocene - because of the climate changes that happened - the bigger ones that just take so much longer to reproduce, especially. I mean, like I said, mammoths don't hit puberty until 15-ish...
ROTT: Yeah.
ROWE: ...And their gestation period is 22 months.
ROTT: Holy moly. Whoa.
ROWE: Right. Yeah. So if they suffer losses, they don't recover in a hurry. If you look at what survived the Pleistocene into the Holocene in interior Alaska, there's some really interesting similarities between what survived. So Alaska used to have horses, right? Not anymore. Alaska used to have saiga, which are these, like, little antelopes that still exist in, like, Mongolia...
ROTT: Yeah.
ROWE: ...You know, the steppe of Eurasia. But those are both grazers. And the things that do survive are things like moose and caribou, which are browsers, which means that they eat, like, twigs and things - not grass. It's part of the reason why I always say that mammoths probably wouldn't be able to live on this - in this habitat today. But humans helped, probably.
ROTT: So we don't have an answer to this large, gaping kind of...
ROWE: It's a complicated story. No. There's no singular answer.
ROTT: Yeah.
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ROTT: Can I ask a question that just - like, I always - I work on climate change usually, and I ask this all the time, right? But like, why does it matter today that we have an answer to what happened to Elma and to woolly mammoths in interior Alaska?
ROWE: Well, a lot of conservationists are seeing this on their own - that the animals that they're trying to keep alive today, but is most difficult, is larger animals - like, you know, white rhinos.
ROTT: Yeah.
ROWE: So I think studies like this are just evidence of that happening throughout Earth history.
ROTT: Kind of informing us of where we're going by looking into the past.
ROWE: Yeah.
ROTT: That's super cool.
Well, Audrey, I am very into the story of Elma. I'm very into the idea that woolly mammoth tusks are just, like, a big stack of ice cream cones.
ROWE: (Laughter).
ROTT: I will never look at a tusk the same way again without thinking about that. Thank you, Audrey. It was good to meet you.
ROWE: Bye.
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ROTT: Before we head out, a quick shout-out to our SHORT WAVE+ listeners. We appreciate you, and we thank you for being a subscriber. SHORT WAVE+ helps support our show. And if you're a regular listener, we'd love for you to join us so you can enjoy the show without sponsor interruptions. Find out more at plus.npr.org/shortwave.
This episode was produced by Margaret Cirino and edited by our showrunner, Rebecca Ramirez. It was fact-checked by Brit Hanson. Gilly Moon was the audio engineer. I'm Nate Rott. Thank you for listening to SHORT WAVE from NPR.
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