Science Friday - Ancient Bone Proteins May Offer Insight On Megafauna Extinction

Episode Date: June 24, 2025

Australia is known for its unusual animal life, from koalas to kangaroos. But once upon a time, the Australian landscape had even weirder fauna, like Palorchestes azael, a marsupial with immense claws and a small trunk. There was Protemnodon mamkurra, a massive, slow-moving, kangaroo-like creature. And Zygomaturus trilobus, a wombat the size of a hippo. They’re all extinct now, and researchers are trying to figure out why. Host Flora Lichtman talks with researcher Carli Peters about ZooMS, a technique that allows researchers to use collagen from ancient bone fragments to identify species, offering clues to those ancient extinction events. Peters recently described using the technique in the journal Frontiers in Mammal Science.And, a recent study in the journal Nature Astronomy hints that our own Milky Way galaxy may not be doomed to collide with Andromeda after all. Till Sawala, an astrophysicist at the University of Helsinki, joins Flora to talk about the finding.Guests: Dr. Carli Peters is a postdoctoral researcher at the Interdisciplinary Center for Archaeology and the Evolution of Human Behavior at the University of Algarve in Faro, Portugal.Dr. Till Sawala is an astrophysicist at the University of Helsinki.Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Hey, I'm Flora Lichtenen, and you're listening to Science Friday. Today in the show, wombats the size of hippos, 10-foot-tall kangaroos, and a new technique to identify mysterious biological samples. In museums and universities over the world, there are so many of these bags of bone scraps that no one really has looked at since. So there's still a lot of work to do. If you think about Australia, one thing that probably comes to mind are the animals that live there. from koalas to kangaroos to a surprisingly large selection of creatures that can kill you. But once upon a time, the Australian landscape had some even weirder fauna, like a marsupial with immense claws and a small trunk,

or a slow-moving kangaroo-like creature that walked on all fours. A wombat, the size of a hippo. They're all extinct now, and researchers are trying to figure out why. Writing this week in the journal Frontiers in Mammal Science, researchers describe one tool they're using to hunt for clues. It's called ZooMS, and it uses samples of ancient protein, not DNA, to identify what animal a bone came from. Joining me now to talk about it is Dr. Carly Peters. She worked on this project at the Max Planck Institute of Geoanthropology in Yena, Germany, and is now a postdoctoral researcher at the Interdisciplinary Center for Archaeology and the Evolution of Human Behavior,

at the University of Algarv in Faroe, Portugal. Welcome to Science Friday. Thank you so much for having me. It's great to talk to you more about what we've been doing. Well, you had me at giant wombats, obviously. Tell me a little bit about them. So basically, the animals that we studied are all extinct now. And they're all giant versions of what you could still find in Australia today.

So you would have the giant wombat for a giant kangaroo. And you also have creatures that don't really have anything similar today, like the Pallarchesta's, the creature with the giant claws that you were talking about. There's not really any closely related animal alive anymore today. When you say giant wombat or giant kangaroo, how giant are we talking? We generally put the term megafauna on any animals that are larger than 45 kilograms. What we're talking about here, for example, the giant wombat, you can kind of think like hippocized. So a lot bigger than your average wombat today. And the kangaroo, I must know.

I believe it's about two to three meters tall. Really big. You wouldn't want to run into it. That's like almost 10 feet tall. Yeah, you're right. I don't think I'd want to run into it. When did they live? So many of these animals went extinct during the...

late quaternary, which is the period before the one we live in now. So basically they went extinct around 50,000 years ago. And they lived for hundreds of thousands of years before that of obviously multiple different species of the same type of animal. But they ultimately went extinct about 50,000 years ago. You know, I think when listeners hear giant wombat, the burning question on everybody's mind is obviously would a giant wombat have giant, cube-shaped poop. This is something I've wondered myself as well. And unfortunately, I don't have a good answer to that.

We haven't found any of their copperlides, which are fossilized poop. Let's keep hoping. Yeah, it would be really cool to get the answer to it, though. What are the other big questions about these animals? So there's a big debate mostly about, first of all, their exact timing that they all went extinct. But the other burning question is what actually caused their extinction. About 50,000 years ago is also around the same time period that humans first entered Australia. So there are people who argue that human colonization of Australia caused the extinction of these animals.

But there was also climate change at around the same time. So that could have also been a factor. There's people who argue that it's a little bit of both. But really, we don't know why they went extinct. And how does your technique, Zoo MS, help with figuring that out? One of the major issues that we have when we try to look at why these animals went extinct is that we don't really have a lot of data for them. So, for example, diprotodon, which is another one of these extinct marsupials,

they're best represented in the fossil record, and there's about 12, 13 well-dated fossil remains for them all over Australia. So that's not really enough data points to get to a good theory testing of why they went extinct. So now that we have the collagen peptide markers that we developed for our study, we can use them to find more of these animals in fragmented fossil remains. So your method is a way of identifying bones, what animal they come from, and it uses collagen, not DNA. Is that right? Yes, that's correct. Why not use DNA? What does collagen offer that DNA doesn't have?

There's two main things. The first one is that proteins, and that includes collagen, but also other proteins, they tend to preserve better in the fossil record. So, for example, the oldest DNA that's been recovered at the moment is from a permafrost of about a million years old, if I'm correct. But proteins can preserve for a lot longer. The oldest preserved proteins so far are, up to 4 million-year-old eggshells. They also preserve better in harsher environments. So for DNA, you often have to look at really cold regions of the world. But obviously, Australia is not very cold. So that doesn't really help you there. And the other reason is that this technique is a lot cheaper to do. So with this technique, you can analyze thousands of bones for a fraction of the cost

of what you would get if you would do DNA analysis on them. That's fascinating, because I think I would have, assumed, when I think of collagen, I think of my skin, I think of it in my cartilage, like stuff, I assume breaks down actually more easily. Yeah. So this is surprising to me. Yeah, it's, you are correct. Collagen is the main protein component in skin and in cartilage, but it's also actually the main protein in your bones. It's what keeps your bones flexible. And because it's in this mineral environment of the bone, it preserves well over time. And is one animal's collagen different from another's?

It depends a bit on how evolutionarily distant they are. So, for example, you wouldn't be able to tell apart a wolf from a dog. They're too similar. But you can tell apart a horse and a donkey or a sheep and goat. So it depends a bit. It's variable. What about ancient humans? Can you tell the difference between a Neanderthal and a modern human using this?

No, unfortunately, we can't. But we can identify that it's a human or closely related to a human. So then you could still send it for DNA afterwards once you've identified it as a human. That's what people tend to do. So to then get more detailed data on it. So is this technique that you're using, is it made possible by new technology or was it a new idea? Like what advance led us to this technique? So the technique itself was first developed in 2009, and it was mostly brought on by developments in mass spectrometry, which allowed people to actually study in more detail the protein sequences and mass from a lot of different materials. And because of all of these developments, people on the brink between archaeology and chemistry were looking into whether we could use it. in archaeology as well. And that's why it was first developed mostly for European animals. Hmm. Are there other proteins that you could use in this way to, you know, figure out what animal a remain is from? Yes, you can. You can use keratin, which is obviously in your hair and nails. People use it sometimes to look at old textiles to see from which animals the textiles were made from.

You could also do a similar thing with egg shell. So you have specific proteins in egg shell, and then you can tell from which species a specific shell is from. So for example, if you want to look at which birds were exploited by people in the past, you can look at eggshell remains from archaeological sites in that way. So here's the thing I don't understand. I mean, I understand you're sort of making a reference library. So you can say, okay, this bone is from this animal. And so then I can sort of like map the signature of this protein. that corresponds to this animal. But what if you encounter an animal you've never seen before?

Yes, I've had this in my research in the past. Sometimes you can kind of tell what broader taxonomic group it's in. So for example, in Australia, sometimes I've had where I can tell it's a marsupial, but I just can't really say which one, because it's not, we don't have the reference data available for it. But sometimes you really can't tell. And it's just a question mark still. Are there huge protein databases the way that there's like DNA databases, you know, a reference library basically? Yeah, there is some stuff, but it's still very much in its infancy. It also very much depends on whether a specific animal is interesting for modern clinical trials as well. So the databases are lacking a lot.

And at the moment, if you want to specifically do this type of work that I do, they're your best off if you want to focus on European medium-sized mammals. They're the best represented in the library. Yeah, yeah. That's where it started and it's still best represented. Okay, so how do you apply this? Is it like you go in the field and you dig stuff up and you use this method or are you going back to museum collections?

Like, what's the use case? So for what I've done, I've mostly worked with museum collections. So basically an archaeology. or a paleontological team who work at a site, they dig up, everything they find, their remains. And then first, a paleontologist or a zoo archaeologist, which is someone who looks at the animal remains at archaeological sites, they would look at the material and based on specific elements or features of a bone, they would be able to tell which bone it is and from which animal. But then there are a lot of remaining fragments that are too tiny to see what they are from.

So they normally, they get bagged up and they get put in either museum storage or university storage. They'll be saved, but they'll never really be looked at again. They're like the scraps, the bone scraps. Yeah, that's normally what I call it, too, the bone scraps. And then what I've done is I've gone through these museum collections to select from these bone scraps material to sample and to then identify later on. That's so cool. So you're using all of these parts of the collection that would have just maybe, you know, collected dust and not told us anything.

Exactly. That's also what I find very fascinating about it. And of course, in museums and universities over the world, there are so many of these bags of bone scraps that no one really has looked at since. So there's still a lot of work to do. Is there a bag of bone scraps you're dying to test? I know, it's difficult to tell because you don't know what you'll find, right? At the moment, I'm working at a new institute, working on new projects, and it's really cool to see hopefully some ancient human remains or from these extinct animals where we don't really get much data from them. I don't know. There are so many interesting things that you could, in theory, find. I don't know. There's so many cool sites. I'm an archaeologist. I love all the sites. Thanks so much for joining us today. Yeah, thank you so much for having me.

And good luck. Good luck with the scraps. I will. There's so many waiting for me. Dr. Carly Peters, postdoctoral researcher at the Interdisciplinary Center for Archaeology and the Evolution of Human Behavior at the University of Algarb in Faroo, Portugal. After the break, some may be good news. The Milky Way might be safe from a cosmic collision, although key word might. The old calculations were not wrong. We just explore a bigger space of possibilities. and what was predicting in the past is definitely one of the possible outcomes is just not the only possible outcome. Hi there, it's me, Ira.

You've probably heard me say that we are all in this together, and right now you're proving it. I have been so encouraged by our friends and listeners that have stepped up to support Science Friday in this critical moment. Thank you. It's clear that many of you value science, public media, and Science Friday. So if you haven't made a donation, you can still join me. me and have an impact. Go to

ScienceFriday.com slash donate. Any amount you can give helps to sustain Science Friday programming in this critical moment. Again, that's sciencefriiday.com slash donate. And thanks. Before we go, some good news, or news that sounds good, anyway, our galaxy may not be heading for a smash-up with neighboring galaxy Andromeda after all.

Andromeda is hurtling at us at over 100 kilometers per second, and it was long thought that we were in for a collision, but new calculations suggest that's not a sure thing. Joining me now to talk about it is Dr. Tillsavala, astrophysicist at the University of Helsinki. He recently wrote about this in the journal Nature Astronomy. Welcome to the show. Thank you very much for having me. This is a thing that I didn't have on my worry list, and now I feel like I just get to write it down and cross it off. I guess it's possible to answer this question. in several ways. So the merger, even if it happens, as was previously predicted,

would still take about four and a half billion years. So I don't think that's something any of us to have to worry about. But we do find indeed that even this merger in the far future is not certain. We find, in fact, only about a 50% chance that there's any merger in the next 10 billion years. And for a merger in less than 5 billion years, we now see only about a 2% chance. Was this a surprise? The short answer is yes. I was initially interested in a completely different question related to the future evolution of the Milky and Andromeda. I wanted to understand how the cosmic environment might influence this.

But as a starting point, I thought I would revisit this prediction. I had expected that we'd basically be able to confirm this prediction. But we found that in fact, when we included all the observational uncertainties and also when we considered a more complete system, including the effect of the Milky Way's most massive satellite galaxy, yeah, we only found a 50-50 chance, and that was a big surprise. So it sounds like the old calculations weren't wrong. You just have now more data to work with. Yeah, exactly.

In the past, people have considered the effect of the next most massive galaxy in the local group, the Triangulum Galaxy or M33. But we find that actually we need to go one step further and also include the effect of the large Mediterranean Cloud, which is a dwarf galaxy, a satellite galaxy of the Milky Way. It's important to stress that the old calculations were not wrong. We just explore a bigger space of possibilities. And what was predicted in the past is definitely one of the possible outcomes

is just not the only possible outcome. Well, what are we missing out on if we don't collide with Andromeda? What would happen precisely depends a lot on when that merger will happen, what the energy of the orbit will be at that time, what the relative inclination of the two galaxies will be at the... that time. So how precisely the merger will play out, I would say it's so early to say that we currently have two large disk galaxies in the Milky and Andromeda, and the most likely outcome of such a merger is that they would essentially be destroyed and constitute a new

elliptical galaxy that would form after some time. For a brief period, there would be an intense period of star formation, it's called starburst, but that would produce a lot of young stars, which would result in intense radiation. The two supermassive black holes in the center would also find each other in merge that would create even more radiation, which would eventually shut off star formation. So the long-term result of that merger would be basically that the two large disk galaxies that currently constitute the local group, including our own galaxy, the Milky Way and Andromeda,

they would cease to exist. And then its place, after some billions of years, would be enlyptuical, a galaxy that would not have much new star formation and would basically slowly, slowly fade. So that would be the long-term future. And yeah, it's important to say that's still very much one possible scenario. You know, this is a thing that may or may not happen in the next 10 billion years. Why do you care about this? I think that's a really good question.

So, I mean, on one level, we know for certain that the sun will explode in about 8 billion years, even before that it will make Earth uninhabitable. The calculations are in about maybe one billion years. So this is all beyond human lifetimes. I think it's just something that I'm curious about because it affects my own galaxy, even though I might not be around when that merger will happen. I think it's just part of human curiosity that we like to know.

And what actually fascinates me is, yeah, the question of why we're interested and why we might even prefer one outcome over a number. another. At least personally, I can say I prefer the milky way to continue to live, even if there's no impact on my life or human lifetimes, I think. But why that is, I think there's more question for maybe psychologists compared to astrophysicists. Thank you so much, Till. Okay. Dr. Till Savala, astrophysicist at the University of Helsinki. Thanks for listening. If you like the show, rate and review us wherever you listen. Or just go straight to Goros,

of marketing, take a friend's phone, and subscribe them to this podcast. Please help us get the word out about Science Friday. Today's episode was produced by Charles Bergquist. I'm Flora Lichtman. Thanks for listening.