
Dr Ross Barnett explores the causes of extinctions throughout history, from the mammoth to the dodo
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James Osborne
Welcome to the History Extra Podcast. Fascinating historical conversations from the makers of BBC History Magazine. From the depths of the Ice age to the 20th century, why and how have species gone extinct? And have humans always been to blame? In conversation with James Osborne for today's Everything youg Wanted To Know episode, Dr. Ross Barnett unpacks how the causes of extinction have shifted over time, and how looking back at the history of these lost species might help us tackle extinction in the future.
Dr. Ross Barnett
I think a good place to start and lay the foundations for this conversation, because it's such a broad topic, is prehistorically and historically speaking, why do different species go extinct? And how have the causes of extinction changed through time?
It's a really interesting and quite deep question because for a lot of the cases we don't really know. It's hard to pinpoint just one cause. So for instance, if we go far back in time, if we talk about things like dinosaurs or things from the deep past, then we have a fairly good idea of what happened. So for the case of the dinosaurs, we have the evidence of the Chicxulub asteroid impact and the kind of massive devastation that that wrought. And that's an example of an abiotic factor. So a factor that's not to do with any other living creatures. That's the kind of ultimate in the randomness of the universe. You have a big bit of space rock crashing into the Earth and causing devastation. But as we move forward in time, things get more complicated, especially when people are around. So people have had a huge impact on the planet. I don't think anyone could deny that. So there are cases from extinctions of the recent past, in the past decades and centuries, where we have very clear human causes. So thinking of cases like the thylacine or the Stevens island wren or the dodo. And humans can cause extinction through direct persecution, through direct land use change, but also, incidentally, through things like releasing goats or dogs or monkeys or all these other kind of animals that tend to hang around with humans and get released on places that we turn up at. So, I mean, that's the kind of very broad sweep. You have your abiotic and your biotic factors. So things like climate, asteroids, volcanic eruptions, these things have all been known to cause extinctions. And then you have the biotic factors, so human influence and also expansion of species.
So reflecting on some specific cases of extinctions that everyone's aware of, do we know if the extinction of the dodo, for example, is different to that of the mammoth?
Absolutely. So with the dodo, I mean, it's a classic case, because it's really the first time that in Western thought we were kind of confronted with the idea of extinction, the idea that things can disappear completely from the planet. I mean, you have to remember we're talking the 17th century, so this is before the kind of acceptance and realization of what fossils are. So this is before we know about dinosaurs, before we know about mammoths. This is a living bird, a kind of giant pigeon that had evolved in isolation on Mauritius, in the Indian Ocean, and in a unique intact ecosystem. So there were no humans around. It had its formed its own balance. And the dodo lived quite happily there until people turned up around about the 1590s. We had Dutch explorers heading to the East Indies for spices, stopped off there, and what they found was an amazing place, really a kind of Garden of Eden. You had, you know, giant tortoises, you had the dodo, you had all sorts of other birds which are now extinct, flightless as well, with no main predators. And it only took about 70 years before, the influence of people killing them directly, cutting down the forest that they lived in, introducing things like cats, monkeys, goats, pigs onto the island of Mauritius, animals that had never been there before, which the bona had no protection against. And you have to remember the dodo as well was a ground nesting bird. So it couldn't fly, it couldn't get up to the top of the trees to build a nest that nested on the ground. And if you have pigs and monkeys and other omnivores introduced, then that's it, they're not going to make it. And that's exactly what happened. But it's interesting that people were interested in at the time. Some dodos were exported to India, to England, as curios. This is really new to them. This enormous flightless pigeon was a real kind of rarity. And so in this case we have very good evidence that it is human cause, both through direct persecution and also through the kind of changes that people brought on it. So that's a very clear cut case. With the mammoth, it's more difficult because it's much further back in the past. We don't have historic records, which we do for Mauritius, we don't have that for the mammoth. All we have are the bones and the archaeology and the paleontology. And the mammoth is part of a kind of wider suite of extinction. So we lose the mammoth around about the same time. We lose things like the woolly rhino, the saber toothed cat, the giant sloth, all these other incredible, exotic, weird looking to modernized species. And so it's much harder to work out what's going on there. And there are various schools of thought with the mammoth and they've basically fallen to two kind of main camps with some kind of overlap. So the idea that climate change and that caused the mammoths to go extinct because they weren't able to adapt quickly enough to how the climate's changing. We know that from the end of the Pleistocene to the beginning of the Holocene, so that's the period about 10,000 years ago when we changed from the Ice Age to the modern period that we're in now, we know that the climate changed, but that's not the only time that happened. Lots of times in the past two and a half million years, the climate has switched from very cold to warm like it is today. So they'd gone through previous episodes of that and not gone extinct. But the last kind of change, we have humans around and we know that humans hunted mammoths. We have evidence in the archeology of that. We find mammoth bones with spearheads stuck in them. We find butchering marks on the bones. We have cave art of mammoths with what looks like spears sticking out of them. We have ivory that's been carved. So we have an awful lot of evidence, considering the small amount of overlap between humans and mammoths, that they were hunted. So I definitely think that there is a role for humans in the extinction of the mammoth, possibly in conjunction with climate change. But it's very difficult. I mean, we're talking about sort of 12,000, 10,000 years ago, so it's hard to make the call.
You mentioned two specific species in that answer that will have had people's ears pricking up. Maybe it's the first time they've heard of them. And those species were the woolly rhino and the giant sloth. Just to dwell on those for a second, because they sound so amazing. What were these two species? Where did they live and how did they go extinct? What are their stories?
Okay, so the woolly rhino is exactly what it says on the tin. It's a very hairy rhino. It's related to the Asian rhinos, so things like the Javan rhino, Sumatran rhino, things that are very endangered today. And it lived all over Eurasia, so from France, England up to eastern Siberia. And the woolly rhino was a key part of the kind of mammoth steppe ecosystem. They were fairly common. We have cave art of them, so people saw them and drew them on the walls in places like Lascaux and Shobei. And we have mummies of them too. So we have woolly mammoth mummies, which are fairly well known, but we also have woolly rhino mummies, including of young calves and a few adults as well. Probably the most interesting woolly rhino mummy we have is from Ukraine, actually. It's from a place called Starunia. And it's pickled. So it had died in a swamp, which had over time, turned into a kind of salt mine, wax mine. So mineral oils had preserved it. And if you go to the Natural History Museum of London, you can see a cast of this woolly rhino. They had two enormous horns, lots of hair. People ate them as well. We have kind of evidence of them being eaten for food. They used their horns for various crafts as well, to make spear points and things. So, yeah, pretty cool species. Giant sloths also very, very cool. They're purely Pan American species, and it's not just one. So when we talk about ground sloths, there's a whole suite, like dozens of species, and they range in size from about sheep sort of sized to as big as a giraffe. So the largest species was 5 or 6 meters long, 8 or 9 tons. And the smaller ones, well, the smallest ones are the ones around today. But there are also smaller ones that lived in the, in the Caribbean. Things like Megalochnus neocnus, sort of sheep sized ground sloths lived there. And in between as well, there's bear sized horse sized things with names like Mylodon, notrotheriops, Paramilodon. And they were a uniquely kind of American innovation. They evolved in South America. They're part of the order of mammals called the Zenartra, the sloths and the anteaters and things like that. So we have species of ground sloth called Megalonyx jeffersoni. Mid sized kind of black bear sized sloth which we have bones of from Alaska. And we have really good fossils of those. Lots of complete skeletons. We even have some skin of them from South America from a species called Mylodon, which shows that they were hairy. And they also had a really interesting adaptation which is bony dermal ossicles. So these were bones that grew inside the skin a bit like you see in armadillos today as some kind of armor, essentially protection to the animal. Other cool fossils we have of ground sloths are, they're dung. So we have huge amounts of dung from ground sloths in places like Nevada, New Mexico, the sort of dry southwest of the United States, found in caves. And they're really interesting from a paleontological perspective because they can tell us about the diet. What were these animals eating? Were they eating things that aren't around anymore? They're eating species of plant that were found just outside the cave today. So yeah, all sorts of interesting things about ground slots. Oh, such a clutch off season pickup, Dave.
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Dr. Ross Barnett
So bear sized sloths and woolly rhinos in Europe living alongside humans. I think that's really amazing to think about. To go back to mammoths, you mentioned how the cause of extinction for mammoths is potentially quite complex and still contested. So to think about it this way, if humans had never crossed over with mammoths, if humans had never hunted mammoths, if humans had never interacted with them, do you think that woolly mammoths would still be around today or not?
I think that they would still be here. I think we have to ask the question, you know, why aren't they? If we think of Asian elephants as the equivalent of a woolly mammoth, then, yeah, they would probably still be here if humans hadn't been around. We have to explain why we have African elephants and Asian elephants in Africa and South Asia when we don't have woolly mammoths in North America and northern Eurasia. And one reasonable explanation is that when humans encountered mammoths and ground sloths and woolly rhinos and all these other megaponic for the first time, they would have been naive to us as hunters. So humans turn up, we're, you know, not that big, we don't have sharp claws, we don't have sharp teeth. If you're an elephant sized animal, you're not going to be bothered in the same way that, you know, around a watering hole. Elephants aren't bothered by zebras or by ostriches, but that's like a massive, massive problem for the mammoths because we are incredibly dangerous. We have the technology, we have the tools, we have the adaptations to make us incredible hunters. And we see this in the archaeological record, just with the record of lithics, of stone tools. These things are incredibly dangerous, incredibly lethal. And the evidence of that is found in the mammoth bones, which still have bits of stones taken out of them. So the first encounters between humans and mammoths probably would have been bad for the mammoths because they would not have recognized us as the hunters that we are. Whereas if we look at Africa and South Asia, these are the places where humans have been around the longest. This is where Africa is, where we evolved as a species. And so we evolved in a kind of delicate evolutionary dance with things like elephants, zebras, white rhinos, black rhinos, giraffes. These creatures knew us before we were human and evolved in tandem with us and were able to recognize us as soon as we were a threat and adapt their behavior to us. And this is why I think we have megafauna still in Africa and South Asia, because they were able to adapt in lockstep with us.
So just to stick with this for one more second, then, do we know how humans hunted mammoths?
Well, I think it's important to recognize as well that we don't have to be, you know, slaughtering them before humans turn up. Mammoths live in a kind of paradise for them. They have all the grass they can want. Once they reach a certain growth stage, they're not going to be bothered by predators, so they just have to make it. And we know from elephants that have a very long gestation period, only give birth to one calf at a time, that they're in a fairly delicate balance. It doesn't take much to tip it. And the same would have been true for mammoths. We're thinking about mammoths being pregnant for probably about 24 months, giving birth to one calf at a time. And you don't really have to take that many of them before they can't replace themselves. So it's not like a widespread indiscriminate slaughter. All it has to be is like a couple of mammoths a year, enough to feed the people that are expanding out across Eurasia. And that can send numbers into a downward spiral. And we know from the archeology and the paleontology that they were incredible hunters. We have bones from a site called Yana RHS in Siberia, which has hundreds of mammoth bones, including some which still have bits of flint stuck in them. And we see that the scapula, the shoulder blades, repeatedly, they have impact points from human weapons. And you have to remember in a mammoth, the shoulder blade is in front of the heart. So these are incredibly skilled hunters, able to hit the vital spots time and time again to kill mammoths, which are the largest animals in their landscape. So we were talking about incredible hunting technology. Spears, kind of throwing weapons, we're talking about group hunting strategies where people have their own kind of roles, are able to use the same techniques again and again on different mammoth groups, and hugely successful. I mean, these are people that are eating mammoth reliably and using their remains not just to eat, but their kind of leather, their fur, their ivory as well, which is a hugely important resource in the kind of treeless steppe grassland that these people would be living on, using their dung, using everything. I mean, the mammoths, I imagine, would have been a one stop shop for everything that people would have needed.
Okay, We've spoken about how extinctions can be caused not by Humans by environmental factors. And we've spoken about how species can be driven extinct by humans. And within both of those two broad categories, there's lots of distinction. So, for example, the dodo went extinct for a slightly different reason than the mammoth, albeit both with humans being heavily involved.
Yeah, so, I mean, certainly as long as humans been around, as long as we've been moving around the planet, I think we've been causing extinction. And probably the clearest place you'll see this is on islands, so places like Mauritius, New Zealand, Madagascar, places where you have isolation and evolution in the absence of humans and then humans turning up. So there's, you know, there's thousands of examples of this. The dodo is probably the most famous. But you have the elephant bird in Madagascar, you have Moa in New Zealand, you have the solitaire in Rodriguez, you have the Stevens island wren. You have all these kind of unique island adapted species which just aren't able to escape from the influence of humans. Once we turn up and start modifying the landscape in these island environments, which are naive to our presence, I think.
That leads us nicely into a question we had from a listener, Leighton, where he's asked to hear more about the distinction between species becoming extinct naturally and unnaturally. Is that a categorization that you recognize and that you identify?
I think it's a very important distinction, but it's a very hard one to make. So certainly in the past 500 years, I think you can count on the one hand the number of extinctions that have been recorded which weren't due to humans in some way or other. And now we're at the stage where even things like sea level changes and things like that are going to be produced by humans, like anthropogenic climate change is now going to be impacting onto populations. We're seeing kind of melting of glaciers, we're seeing retreat of tree lines and things like that. And those are going to have an effect on the species that live in those habitats. So certainly in the past there have been examples where species have gone extinct through things like volcanic eruptions on islands. But certainly during historical periods, I can't think of more than one or two that haven't been human caused either directly or indirectly. A good example to bring up for this is the case of the Stevens island wren. So Stevens island is a small island in the Bass Strait between the north and south islands of New Zealand, previously uninhabited like the rest of New Zealand. And New Zealand has no native land mammals. It's a purely bird dominated ecosystem and they have a Whole bunch of unique endemic species there. They used to have moa, these giant ostrich like birds, and a whole suite of other kind of exotic flightless things. They still have really cool species like the kakapo, a flightless parrot, the takahe, a flightless rail, but they also used to have flightless passerines. So passerines are the group of birds which robins, dunnocks, blue tits, coal tits, all these familiar British garden birds belong to. It's the largest grouping of the bird family. And the only flightless members of that family used to live in New Zealand. And the Stevens island wren was found on Stephen island because it had gone extinct in the rest of New Zealand when people turned up. And it was quite happy there, living happily its little flightless life until they decided to put a lighthouse on Skevens island in the 1870s. And so in 1879, when the first people arrived at the lighthouse, there were still Stephen Islands wren hopping around all over the place. They were quite common. But the lighthouse keepers brought a cat with them called Tibbles. And around about 1894, Tibbles started to bring Stephen island wrens to the lighthouse and they were recognized as distinct and sent off to various scientists who confirmed that they were a unique species, a flightless songbird. But by 1895, so within a year of the cats turning up on Stevens island, there were no more Stevens island rants. So here we have a complete extinction down to humans. I mean, essentially the proximate cause is the cat. But humans have brought the cats to Stevens Islands where they've not been before, and they've decimated, more than decimated, exterminated the last population of this unique flightless songbird, now extinct thanks to Tibbles, the lighthouse cat.
One very deadly cat. Yeah, we've talked about humans causing extinctions now then through cats, or through hunting, or through the result of climate change. But now when we're talking about extinction, it's also hard to avoid the prospect of humans undoing extinction through something called de extinction. This obviously sounds like sci fi, and perhaps unsurprisingly, it's the topic we have the most questions on. But it's another broad topic. So let's start with what is de extinction?
So de extinction is a term coined by my friend and my PhD supervisor, Professor Beth Shapiro, who wrote a book called how to Clone a Mammoth. And de extinction just means returning something from extinction. And I think in her definition she's mainly talking about using genetic technology to extract DNA from extinct species and then somehow Clone them back into life. I'm not surprised you get lots of questions about this because whenever we published a paper using ancient DNA it's pretty much the first question we always get asked as well. It's an expanding field, we're not there yet and it's very sci fi at the minute. There are many, many steps that would have to be taken before we ever actually see a living, de extincted species back on the planet.
So we had a few questions specifically about the scientific plausibility of it. And it sounds like we're not quite there yet, but we could get there. So I think the natural question next is why would scientists want to do this? What would be the potential advantages? Or is it just as simple as we're doing this because we can?
Yeah, well, I think it's very important to remember the words of Dr. Ian Malcolm from Jurassic park about they were so preoccupied with whether they could, they didn't stop to think whether they should. And that is something that should be guiding us. Certainly we're not at the stage where we can, let alone whether we should. There are all sorts of reasons why you'd want to bring back some species. So things like the thylacine or the dodo or the Stephen island wren or the Steller sea cow or all these other things which have gone extinct recently and which definitely have a human cause. I think we all share some responsibility for that. And if we can change that, if we can rectify that, then I think that the onus is on us to maybe try and do that. Something like the thylacine, the Tasmanian wolf, it's the largest marsupial predator of recent times, went extinct in Tasmania in 1936. It had been mercilessly persecuted directly by landowners in Tasmania. It was kind of painted as a sheep killer. And at that time Tasmania was a massive, essentially a sheep farm. And so bounties were placed which encouraged the extermination of this unique species. And so, you know, protection was granted just a couple of months before the last specimen died. The last individual died in a zoo in Hobart, Tasmania, fully protected, but no one's ever been able to find another one since then. So I feel like we definitely, in the case of the thylacine and many other species, we have a responsibility to right a wrong whichever way we can. If we can do that by de extinction and that would be great.
So other than the moral case you just made about righting past wrongs, is there any kind of conservation impact that could positively stem from de extinction?
Absolutely. And I think we're almost at the stage where we're seeing that right now. So if we know how to bring back a thylacine or a mammoth or a dodo or something, then we could use that technology on currently endangered species. So things that are at real imminent risk of extinction at the moment, which there are too many examples to mention, but we're sort of at the stage where we're seeing that. So the black footed ferret is a small mustelid that's found in North America. It was thought to be extinct at one stage, but they found a small colony of survivors and they've been intensively breeding them in captivity for the past 30, 40 years, at least. Having all descended from one colony, they're not very diverse, which is a problem. All it would take is one accidental transmission of a novel disease to wipe them all out. But some scientists have been working on not just cloning these individuals, but also reintroducing the diversity that they've lost by examining the diversity bound in museum specimens of the black footed Barrett and then reintroducing that back into the kind of surviving population. So we are seeing kind of overlap between the methodology and the techniques used in de extinction with the kind of current problems in conservation and how we can kind of produce a synergistic approach to help both sides.
I think that's quite a compelling case for why learning about past extinctions, prehistorically and historically could be relevant to conservation today. And I think it makes a good case of why people should spend time thinking about it. I guess, to conclude, if there was one extinct species that you could either go back in time and see, or bring forward in time and see, what would that be? What do you think is the most fascinating extinct species and why?
Oh, man, that is a great question. Don't know what it says about me that I've got too many examples to possibly choose from. I could go for the kind of puck, list one and go for the dodo. That may be cool. Can you imagine a world where you could have a dodo as a pet or see them back in their home? The one that maybe. The one that maybe sort of tugs on my heartstrings the most is Steller's sea cow. So Steller's sea cow is basically a giant manatee. So it's the largest of the Serenidae, the kind of sea cows and manatee family, and it used to live around the Bering Sea. We have fossils from all around the Pacific Rim, but by the kind of 17th, 18th century, it was only Found around a couple of islands in the North Pacific. And it was happy there. It was like a gentle grazer of the kind of kelp forests that were found on the sort of shallow shores there. But unfortunately, some Russians and a German naturalist were shipwrecked there. So Vitus Bering and his naturalist, Georg Stellar, were sent by the Russian government to explore the kind of fringes of the Russian empire in the 1740s. And they got into a lot of trouble. They kind of suffered from scurvy. They shipwrecked on an island which is now called Bering island, which was one of the few places that they could find sea cows. And they were in real trouble. I mean, this is a frigid North Pacific island. They were there at the beginning of winter, but they found that there was these giant sea cows. And they're huge, they're like 9 meters long, 10 tons, scaly kind of skins, docile, intelligent, harmless. And these shipwrecked sailors, starving, found that they were incredibly easy to kill and tasted amazing. So Steller survived and he made his way back to Moscow and was able to tell them that they found these islands where there's like thousands of sea otters, thousands of arctic foxes just there for the hunting. And this is a time when burrs of these particular animals were hugely sought after. And so lots of people went there to hunt these fur bearing animals. And then they survived off the sea cow. And that's it. It was extinct by 1768. So that's like less than what, 30 years between discovery and extinction. And seller, the guy who discovered them and whose name they now have, the Steller Seacoast, he wrote a book called the Bestius Marinus, which talks about his expedition and talks about the sea cow in length. He was a Chinese naturalist, so he was able to describe them. But it's really poignant the stuff he talks about. So he says that the blubber that they had tasted amazing, that their meat was like veal, that he even drank the milk of the kind of nursing females. He talks about their kind of lifestyle. So they, like elephants, they had a long gestation period and gave birth to one calf, but they looked after it. So they had kind of family units. And the guys that were shipwrecked there were able to just wade out to them, sic a boat, hook into them and drag them onto the shore and then just sort of flay them alive essentially to get to the meat. And, you know, Steller talks about how these animals mated for life. They had kind of partners that would try and rescue them when they were being kind of played on the shore that they would cry. I mean, it's just really heartbreaking. If you ever read this kind of stuff, they would be a good candidate for de extinction. They were a keystone species. They were, you know, the grazers of the kelp forest. They kept that ecosystem ticking over and they just sound, you know, just really kind of beautiful animals that were just absolutely destroyed by desperate people in desperate times. And it feels really sad.
That is a very tragic story and perhaps the best case for de extinction I've ever heard, because that is a wrong that I would very much like to write. Dr. Ross Barnett, thank you so much for time. It's been wonderful talking to you.
It's been a pleasure. Thank you, James.
James Osborne
That was Dr. Ross Barnett, the author of the Missing Links the Past and Future of Britain's Lost Mammals, which was published by Bloomsbury Wildlife. Thanks for listening. This podcast was produced by Lewis Dobbs.
History Extra Podcast Summary: "Extinct Animals: Everything You Wanted to Know"
Release Date: February 2, 2025
Introduction
In the "Extinct Animals: Everything You Wanted to Know" episode of the History Extra Podcast, hosted by James Osborne and featuring historian Dr. Ross Barnett, listeners are taken on an enlightening journey through the history of extinct species. The conversation delves into the multifaceted causes of extinction, the profound impact humans have had on biodiversity, and the emerging concept of de-extinction. This summary encapsulates the key discussions, insights, and conclusions drawn during the episode.
Understanding the Causes of Extinction
Dr. Ross Barnett begins by laying the groundwork for understanding why different species have become extinct over time. He categorizes extinction causes into abiotic factors (non-living environmental factors) and biotic factors (living influences, primarily human activity).
Abiotic Factors: These include catastrophic events such as asteroid impacts and volcanic eruptions. For instance, the extinction of the dinosaurs is attributed to the Chicxulub asteroid impact, an event that caused widespread devastation independent of biological interactions.
"For the case of the dinosaurs, we have the evidence of the Chicxulub asteroid impact and the kind of massive devastation that that wrought." [02:31]
Biotic Factors: These are primarily human-induced, including direct persecution, habitat destruction, and the introduction of invasive species. Historical examples discussed include the dodo, thylacine, and Stevens Island wren, whose populations were decimated by human activities within a relatively short timeframe.
"Humans can cause extinction through direct persecution, through direct land use change, but also, incidentally, through things like releasing goats or dogs or monkeys or all these other kind of animals." [03:00]
Case Studies: Dodo vs. Mammoth
The episode contrasts two iconic extinct species—the dodo and the woolly mammoth—to illustrate differing extinction dynamics.
The Dodo (Raphus cucullatus): Native to Mauritius, the dodo's extinction in the late 17th century is a textbook example of human-induced extinction. Dr. Barnett highlights how human arrival led to deforestation, direct hunting, and the introduction of invasive species that preyed on the dodo.
"It's a classic case… human cause, both through direct persecution and also through the kind of changes that people brought on it." [04:29]
The Woolly Mammoth (Mammuthus primigenius): Extinct approximately 10,000 years ago, the mammoth's decline is attributed to a combination of climate change transitioning from the Pleistocene to the Holocene and overhunting by early humans. Unlike the dodo, the mammoth's extinction is less clear-cut due to the lack of historical records.
"There is a role for humans in the extinction of the mammoth, possibly in conjunction with climate change." [07:00]
Other Notable Extinct Species
Dr. Barnett also explores the woolly rhino and giant sloths, providing insights into their habitats, lifestyles, and the factors leading to their extinction.
Woolly Rhino (Coelodonta antiquitatis): Spread across Eurasia, the woolly rhino thrived in the mammoth steppe ecosystem. Human activities, including hunting and habitat alteration, contributed significantly to their demise.
"They used their horns for various crafts as well, to make spear points and things." [08:41]
Giant Sloths: Native to the Americas, these ground-dwelling mammals exhibited a range of sizes and possessed unique adaptations like bony dermal ossicles for protection. Their extinction is linked to both climatic shifts and human hunting practices.
"These are people that are eating mammoth reliably and using their remains not just to eat, but their kind of leather, their fur, their ivory as well." [16:45]
Human Impact on Extinction
A significant portion of the discussion centers on the pervasive role humans have played in driving species to extinction, especially on isolated islands where ecosystems evolved without human interference.
Islands as Vulnerable Ecosystems: Species like the Stevens Island wren exemplify how isolated populations are particularly susceptible to human-induced changes. The introduction of predators, such as cats, led to the swift extinction of these unique birds.
"Once we turn up and start modifying the landscape in these island environments, which are naive to our presence, I think." [18:21]
Comparison with Contemporary Megafauna: Dr. Barnett posits that if humans had not interacted with species like the mammoth, they might still exist today, drawing parallels with modern-day elephants in Africa and Asia that have co-evolved with humans.
"I think that they would still be here. I think we have to ask the question, you know, why aren't they?" [13:28]
De-Extinction: Science Fiction or Future Reality?
The conversation transitions to the intriguing topic of de-extinction—the scientific endeavor to revive extinct species through genetic technologies.
Definition and Current Status: De-extinction involves extracting DNA from extinct species and cloning them back to life. While the concept captures the imagination, Dr. Barnett emphasizes that the technology is still in its infancy and faces numerous scientific and ethical challenges.
"De extinction just means returning something from extinction. And I think in her definition she's mainly talking about using genetic technology to extract DNA from extinct species and then somehow Clone them back into life." [23:18]
Ethical Considerations: Reflecting on Dr. Ian Malcolm's cautionary words from Jurassic Park, Dr. Barnett underscores the importance of contemplating the moral implications of de-extinction before pursuing it.
"They were so preoccupied with whether they could, they didn't stop to think whether they should." [24:31]
Conservation Potential: Beyond correcting past wrongs, de-extinction holds promise for contemporary conservation efforts. Techniques developed for reviving extinct species could enhance genetic diversity in endangered populations, offering new tools for preserving biodiversity.
"We could use that technology on currently endangered species... reintroducing that back into the kind of surviving population." [26:21]
The Tragic Story of Steller's Sea Cow
One of the most poignant narratives discussed is that of Steller's sea cow (Hydrodamalis gigas), a gentle marine mammal that was hunted to extinction within three decades of its discovery.
Discovery and Exploitation: Discovered by Georg Steller in the 18th century, these large, herbivorous sea cows were easily hunted by shipwrecked sailors desperate for sustenance.
"They could just wade out to them, sic a boat, hook into them and drag them onto the shore and then just sort of flay them alive essentially to get to the meat." [28:16]
Rapid Extinction: The voracious hunting by humans led to the complete eradication of Steller's sea cow by 1768, highlighting the devastating speed at which human activities can eliminate a species.
"It's really heartbreaking... they just sound, you know, just really kind of beautiful animals that were just absolutely destroyed by desperate people in desperate times." [28:16]
Conclusion
Dr. Ross Barnett's insightful exploration into extinct animals underscores the complex interplay between environmental factors and human activities in shaping the course of biodiversity. The discussion not only illuminates historical extinctions but also bridges the past with present and future conservation challenges. The episode invites listeners to reflect on humanity's role in the natural world and consider the possibilities and responsibilities that come with emerging technologies like de-extinction.
"Learning about past extinctions... makes a good case of why people should spend time thinking about it." [27:38]
The History Extra Podcast episode serves as a compelling reminder of the fragility of ecosystems and the profound impact that even a single species can have on the tapestry of life on Earth.
Notable Quotes
"For the case of the dinosaurs, we have the evidence of the Chicxulub asteroid impact and the kind of massive devastation that that wrought." – Dr. Ross Barnett [02:31]
"Humans can cause extinction through direct persecution, through direct land use change, but also, incidentally, through things like releasing goats or dogs or monkeys or all these other kind of animals." – Dr. Ross Barnett [03:00]
"It's a classic case… human cause, both through direct persecution and also through the kind of changes that people brought on it." – Dr. Ross Barnett [04:29]
"I think that they would still be here. I think we have to ask the question, you know, why aren't they?" – Dr. Ross Barnett [13:28]
"They were so preoccupied with whether they could, they didn't stop to think whether they should." – Dr. Ross Barnett [24:31]
"That's really heartbreaking... they just sound, you know, just really kind of beautiful animals that were just absolutely destroyed by desperate people in desperate times." – Dr. Ross Barnett [28:16]
Further Information
For more insights into the lives and extinctions of Britain's lost mammals, listeners are encouraged to explore Dr. Ross Barnett's book, Missing Links: The Past and Future of Britain's Lost Mammals, published by Bloomsbury Wildlife.
This episode was produced by Lewis Dobbs.