Science Friday - Old Things Considered: La Brea, Megalodon, Dino Footprints, Surviving History. Aug 25, 2023, Part 2

Episode Date: August 25, 2023

How Early Humans May Have Transformed L.A.’s Landscape ForeverJoin us on a time traveling adventure, as we go back 15,000 years to visit what’s now southern California. During the last Ice Age, saber-toothed cats, wooly mammoths, and dire wolves prowled the landscape, until … they didn’t. The end of the Ice Age coincided with the end of these species. And for decades, scientists have been trying to figure out a big question: Why did these animals go extinct? A new study in the journal Science offers new clues and suggests that wildfires caused by humans might’ve been the nail in these critters’ coffins. Guest host Flora Lichtman talks with paleoecologist Dr. Emily Lindsey and paleobotanist Dr. Regan Dunn, both curators at the La Brea Tar Pits and Museum in Los Angeles, California, about what we can learn from animals preserved in tar pits, how fire transformed the ecosystem, and why we have to look to the past for modern day conservation and land management. How Scientifically Accurate Are The Sharks In ‘Meg 2: The Trench’?“Meg 2: The Trench” is the sequel to the 2018 movie “The Meg,” in which a team of ocean scientists discover a megalodon, the largest shark that ever lived, thriving at the bottom of the Mariana Trench. Megalodon went extinct over 2.6 million years ago … or so the movie’s characters thought.When the team’s research sub gets damaged, a skilled rescue diver, played by Jason Statham, is brought in, who happened to have encountered the same megalodon years earlier. Over the course of the movie, the team discovers how this long-thought extinct apex predator survived, and what they can do to stop it before it wreaks havoc on the surface world.“Meg 2: The Trench” largely follows in that movie’s footsteps, but this time, it features not just one, but multiple megalodons. Oh, and they’re even bigger this time. Universe of Art host D. Peterschmidt chats with Dr. Sora Kim, an associate professor of paleoecology at University of California, Merced, about what science the movie got wrong (and right) and how these over-the-top blockbusters can inspire the scientists of the future. Scientists Discover Dinosaur ‘Coliseum’ In Alaska’s Denali National ParkResearchers recently discovered a rocky outcrop at Denali National Park in Alaska covered in dinosaur tracks, which they dubbed the “Coliseum.” It’s the largest dinosaur track site ever found in Alaska. The area has thousands of prints from generations of dinosaurs living about 70 million years ago, including: duck-billed dinosaurs, horned dinosaurs, raptors, tyrannosaurs.  Flora Lichtman talks with Dustin Stewart, former graduate student at the University of Alaska Fairbanks and paleontologist for the environmental consulting firm Stantec, based in Denver, Colorado, about this dino hotspot. Your Guide To Conquering History’s Greatest CatastrophesGuest host Flora Lichtman takes us back to some of the scariest, deadliest moments in history. Think along the lines of the eruption of Mount Vesuvius, the Ice Age, and the asteroid that wiped out the dinos. But we’re going to revisit them using what we know now—and science, of course—to figure out if and how we could survive those events.The idea of using science and hindsight to survive history is the premise of a new book, How to Survive History: How to Outrun a Tyrannosaurus, Escape Pompeii, Get Off the Titanic, and Survive the Rest of History’s Deadliest Catastrophes by Cody Cassidy. We have a new podcast! It’s called Universe Of Art, and it’s all about artists who use science to bring their creations to the next level. Listen on Apple Podcasts, Spotify, or wherever you get your podcasts.To stay updated on all-things-science, sign up for Science Friday's newsletters.Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Floralickman, filling in for Ira this week. For the next hour, it's old things considered. We're going way back in time to meet ancient creatures, think Megalodon and T-Rex, and hear what life was like in the really olden days. And we'll revisit some of the world's deadliest, scariest, scariest catastrophes, like the eruption of Mount Vesuvius and try to survive them, using science, of course. But first, let's take a trip to Southern California, about 15,000. years ago. It was the ice age and saber-toothed cats, woolly mammoths, and dire wolves

prowled the landscape. Until they didn't. And for a year, scientists have been trying to answer the question, why did these animals go extinct? A study offers new clues and suggests that wildfires might have been the nail in these critter's coffins. Joining me are two authors on this study, Dr. Emily Lindsay, paleoecologist, curator and excavation site director at the Libreia Tar Pits and Museum, and Dr. Reagan paleobotanist and curator also at the Libreia Tar Pits and Museum in L.A. Welcome to Science Friday. Thank you for being here. Thanks for having us. Hello, Fora. Thank you.

Okay, Emily, take me to LaBrea around 15,000 years ago before the extinctions. What was it like there? So up until really around 15,000 years ago, you would have seen a sort of juniper woodland environment here. You had oak trees as well, and you had a landscape that looked something like the African savanna does today. You had big elephant relatives, the mammoths and mastodons, of course. You had big cats like our iconic saber-tooth cat as well as American lions and jaguars, dire wolves. You had camels and horses and bison and even enormous hippopotamus-sized swaths.

wandering around the landscape. Hippopotamus-sized sloths. It was incredible. So, Reagan, what was it like in the aftertimes? After the megafauna had perished, things were quite a bit different. All of those trees suffered, and what you had in their replacement was a chaperal vegetation or shrubs and short-statured trees and also a lot of grass that are plants that are fire-adapture. today. And these are the plants that dominate our Southern California chaperal ecosystems today.

What about animal life? Animal life following the extinction is much like animal life of California today. So we have things like mountain lions and skunks and weasels and deer and foxes and some of these smaller statured critters, especially coyotes, the sneaky coyote. It's been around for a long time. and it visits the tar pits today even. Well, I was going to ask, actually, how, do LaBreya's tarpits, are they a part of this story? Are they helping you sort of reconstruct what these ecosystems were like? Yes. So this is actually one of the most important fossil sites in the world that just happens to be in the middle of modern Los Angeles.

And the reason it's so important is that for about 60,000 years, these shallow pools of liquid asphalt have, been trapping tens of thousands of animals as well as plants. So we have an incredible record of the Southern California ecosystem, more or less continuously from about 60,000 years ago up to the present. Just a big pool of fossils. Many big pools of fossils that turned into underground asphalt preserve fossil deposits. And the preservation of the asphalt is so good that, that we can actually get a lot of chemical information out of the original bone and plant material that's preserved, including very precise radiocarbon dates. Wow. Let's get to this megafauna extinction. Is it a mystery why these animals went away? I guess I assumed it was, like, as usual, humans killing them or killing the food they ate. But is it more complicated than that? You know, this is a topic that has been debated for about 70 years now. And the reason it's debated is that there were actually two processes happening at about the same time. So you have the Earth is coming out of the last major ice age where we had, you know, more than half of North America covered in glaciers. For instance, same situation in Eurasia. So the Earth is undergoing these pretty extreme and pretty rapid climate warming, which of course is.

having significant impacts on plant communities and animal communities that depend on them. And related to these processes, you also see human populations spreading out around the world. In some cases, they're arriving on continents for the first time, or their numbers are increasing in places where they've been living for some time. And so there's been these sort of two camps of scientists arguing about whether the climate changes or the human activities that were primarily to blame for this extinction event. And the reason we haven't really been able to tease it out is that you have these processes happening almost simultaneously. And we haven't up until now had a very good chronology

or radiocarbon dated record to know exactly when many of these species disappear. Okay. And so in your new study, you found that fire played a role. role. Will you tell me more about that, Reagan? Yes, absolutely. Prior to the megafaunal extinction, and in fact, in the last 33,000 years of history in the Southern California area, there is very little evidence for fire from that early time period up until the extinction event, about 13,200 years ago. There's a little bit of charcoal, and that's how we measure the wildfire occurrence. from the bottom of Lake Elsinore. You just see this little blip in charcoal.

But then beginning around 13, 200 years ago, you see this dramatic spike in the amount of charcoal in the bottom of the lake. And what that represents is really about a 400-year-long period between 13.2 and 12.8,000 years of pretty intense wildfire or certainly a very enhanced wildfire regime. And it's not like that any time previous,

in those 33,000 years. And following the extinction event also, you see this fire regime continues into the Holocene. Do you have a sense of what caused the fires? Yeah, you know, the timing of the fires is certainly suspicious. We know that there had been significant warming in the 1,000 years before the fires began. And we know that there was significant drought, pretty much coincident with the time period of the fires, but also the number of humans that were living in North America at that time was really increasing during that exact time period. And so we hypothesized that we have this climate that is primed for wildfire activity, and then we have the arrival of human beings who brought with them their most effective

tool, which they carry to every continent they go to, and that is fire. And in Southern California, these ecosystems prior to this, were fairly naive to an ignition source like humans. So basically, climate change set up the conditions and humans let the match. Is that the hypothesis? Yep. That's exactly our hypothesis. And how big a role did these fires play in these animals, like in these animals extinction? I mean, would we still have woolly mammoths trundling around Beverly? Hills if people weren't lighting fires 13,000 years ago? Well, that's a good question. I was just thinking that today and wondering.

I'm not really sure. You know, there were a lot of different things going on in different areas. And what we describe in the paper is the extinction event that happened here in Southern California. And so what we hypothesize is that these animals, especially large animals, are going to be affected by these fires because a lot of these large animals migrate through these areas. And so if you have intensive burning, you're burning migration routes, you're burning cover. The animals are lacking shade. You're changing hydrologic regimes.

So the water on the surface runs off. It could have created a more arid climate to begin with, just burning off all the vegetation. of course, a lack of resources just in the sense of just food. And so if you have that happening, these impacts happening in enough places that you're going to slowly sort of dwindle populations to a point where they have problems reproducing.

And then these isolated populations can't reach each other. And you have this fragmentation going on, which then you have, you have a reduction in the in the genetic drift and and so you can imagine how widespread fires could reduce the habitat in such a way that you would have reduction in the populations to the point where they other stresses and perhaps human hunting could have really taken them out in addition emily does this study tell us anything about how we should be managing southern california's ecosystems today you know what

I think a real surprise that all of us came out of this study with was the realization that what we consider to be the native landscape or native ecosystem of Southern California, that's our fire adapted chaparral, never existed before humans showed up. And we know that certainly going back millennia, and now it looks like potentially going back more than 12,000 years, humans have been actively managing that landscape. But it looks now like it was actually a human-created landscape. And so I think when conservation biologists and land managers are thinking about how are we going to manage sort of the native vegetation, and support native wildlife in this habitat, we really have to go back and consider, well, what is the role of humans in developing and managing this ecosystem?

Because I think conservation biology has traditionally viewed sort of the best possible conservation conditions as removing all humans from a landscape and just leaving everything alone like it was before any humans were there. And we know that at least in the case of our ecosystem here in Southern California, that's simply not realistic or possible. Totally fascinating. That's all we have time for, but I want to thank you both for joining me. Thank you, Flora. It's been a pleasure to be on the show this afternoon.

Thanks for having us. Dr. Emily Lindsay, paleoecologist, curator and excavation site director at the Librae-Tar Pits and Museum, and Dr. Reagan Dunn, paleobotanist and curator also at the Libraeatar Pits. and museum in L.A. After the break, a voyage to Alaska's Dinosaur Coliseum. Stick with us. This is Science Friday. I'm Flora Lichten.

Up next, a boat ride to the Mariana Trench to meet an ancient creature that makes jaws look gentle. A fish so frightening, it even makes Jason Statham's chiseled face crunch up in fear. We've got company. That's the biggest man I've ever seen. Biggest make anyone's ever seen. That's the apex predator.

Step aside, Barbie. Out of the way Oppenheimer. I'm talking about the central character in Meg 2, a new science action flick out this summer. Sci-fi producer Dee Peter Schmidt saw the monster movie and talked to an ancient shark scientist about what she made of it. Okay, Dee, before we get into that, tell me about your viewing experience.

How was it? I had a lovely viewing experience. I saw it in a nearly empty theater last Wednesday at noon. My favorite time and way to see a movie. Exactly. And tell me, just give me a quick synopsis of the plot. Yeah, it's about a group of ocean scientists, and they're trying to research this hidden cordoned off part of the deepest part of the ocean where all these ancient sea creatures have somehow survived, including Meglodon, which is the Meg in question in the movie. They were the biggest shark to ever swim in the ocean.

They were 60 feet long and were swimming around. two and a half million years ago. So this megalodon is real? Totally real shark, yeah. This is kind of like a historical reenactment movie. It doesn't get more real than this. No, it's a little exaggerated for the movie. So I wanted to, you know, talk to an ancient shark researcher about how legit the science was. And I had a great conversation with Dr. Sora Kim. She's an associate professor of paleoecology at University of California, Merced. And here's that conversation. Dr. Sora Kim, welcome to Science Friday. Hi, thank you.

So I'd love to start off by asking what you thought of the Meg 2, both as an ancient shark researcher and what you thought of it as someone who just likes to have a good time at the movies. I'll start off with someone who likes to have a good time at the movies. I thought it's great. And in terms of my role as a scientist, I think it's really important to have movies that represent science and scientists that are also very entertaining. And maybe sometimes all the science isn't perfect, but it's still important to have that role out there in pop culture. Yeah. Before we get into the movie, can you give us just an overview of Megalodon, what made them unique?

When were they swimming in the ocean? Megalodon is, you know, the most awesome apex predator, basically. And I think that that's why they capture the curiosity and imagination of everyone. The teeth are as big as an adult hand. And when people don't know what Megalodon is, I just described the big teeth. And then I'm like, yeah, if you've ever seen images on the internet of people standing inside of a shark jaw, like, that's a Megalodon jaw. And there's just no way not to be awestruck with something of that size. But there's a lot that we don't know about Megalodon as well.

Sharks don't have bones, their entire skeleton. There's some calcified cartilage, but it's not actually bone, and all we have are their teeth. They're wide and pointy. You can find them, you know, on some beach shores. My first megalodon tooth I found while I was on a college field trip, and scientists stuck their shovel into the side of a cliff and pulled it out, and there was a megalodont tooth. Yeah, I know, right? Like, when does that ever happen? And I wasn't even interested in studying sharks at the... that time, but everybody was like, whoa, that's so cool. So speaking of the teeth from these extinct sharks and what they can tell us about these long-lost animals, why are shark teeth such a good candidate

for that kind of research? I oftentimes say that it's mostly that shark teeth are great because there's so many of them. For us, you know, we have two sets of teeth, our baby teeth and then our adult teeth, and then once you're out, like, that's it. But sharks, are continuously replacing their teeth. So that's estimated that a single shark might go through like 10,000 teeth in its lifetime. But on top of that, sort of the newer science that my group and others have been able to pursue is to look at the chemistry within the teeth. So when teeth are forming, they're using elements and nutrients that are within the shark's body

or within the environment. And then they're basically putting that into the enameloid, which is akin to our enamel on our teeth. And with our enamel, you know, you go to the dentist and we put on fluoride. And that fluoride helps your enamelid be stronger. And sharks, they actually have that totally naturally accluring where their teeth, their anemoid already has the fluoride embedded in it. So they preserve for, you know, tens of millions of years. That's ridiculous. I had no idea about that. So kind of diving into the movie now, the movie portrays the meg as over 80 feet long. Were they really that big? Not likely. I mean, we don't have a lot of information in terms of what the shape and length of a megalodon was. Most scientists that do this type of research, their guesses are more like 50 or 60 feet, but we don't actually have a complete skeleton of a megalon yet.

Still pretty big, sounds like. Yes, plenty big, but not 80 feet. And in the movie, the Megalodon can swim faster than a jet ski. It can make these super sharp hairpin turns. Do we know how fast and agile Megalodon actually was? There have been some estimates based on sort of the width and the shape of the vertebrae, but we don't really have any really solid way to make these estimates. The reality is when you're really good.

big. It's really hard to speed up and also, you know, make quick turns because there's momentum involved. So I think it makes for great movie, but I'm not sure that the science can totally back that up. Fair enough. And then as far as looks go in the movie, it basically just looks like a great white shark just like kind of blown up. Since we, you know, we don't have skeletons of it. Do we know what it actually looked like? Again, we are kind of in the dark. Previous we thought that Megalodon was closely related to white sharks, and we consider white sharks to be the Apax predator shark in our waters today. So I think that's where the linkage came in. But more recently, there's actually been a lot of evidence that Megalodon isn't even within the same genus or group as white sharks. And so they're like more distantly related to white sharks. A lot of our ideas for the shape and the shape and The lifestyle characteristics of Megalodon come from this association with white sharks. But there's not really a great reason scientifically for that necessarily, except that they're both apex predators.

Yeah. What impressed you with the science in the movie? Well, I was very excited to see their depiction of the diversity in the marine ecosystem when they're in the deep water in the Marianas Trench and how they characterize. what that ecosystem could look like and how vibrant it was and the different types of organisms and stuff, I thought was really cool. And I guess one thing that I was super excited about in the movie is that shark science is really dominated by men and white men at that. And it was really nice with Meg 1, but also with Meg 2, that there was a little bit more cultural representation beyond that. I realize it was only one type of cultural representation beyond that, but it was cool that Asians were represented in the movie.

Yeah, absolutely. I know your lab has been doing some work with that. Is that right? Yes. I do a lot related to broadening participation and diversity, equity, and inclusion in my group. And I think that a lot of my connecting with science communication and such stems from a group called minorities in shark science who have been making huge strides and pushes in having more representation in Shark Week or Shark Fest and in doing science communication. Absolutely. Yeah. Thank you for bringing that up. I saw this review of the Meg, too, on a site called The Conversation that was written by a paleobiologist named Jack Cooper. and he was talking about how he was inspired to go into this field of study because he saw a documentary about extinct sharks growing up. And even though these films might not be the most scientifically accurate, how do you feel about them being these kind of like potential vehicles for people to get into ocean science? Yeah, I think that that's exactly what they should do and why I even do interviews like this,

is that any vehicle that we can use to get people interested and excited about, science, especially given the issues that we face right now with global climate change, human impacts on marine ecosystems. It's super important that any way that we can possibly get people interested, excited, and engaged in science, that we take advantage of it. So it's only inevitable that the Meg 3 is going to get made. If you were in the writer's room, what would you want from the next movie? I think that I would love to see more diversity of sharks featured.

I mean, there's some really cool sharks throughout the evolution of sharks. They've been around for, we think, you know, over 400 million years. That's a really long time. The other thing that would be cool if they want to keep with sort of definitely the megalodon and this time period of the Miocene pliocene is depicting some of the marine mammals that were around. They are ancient toothed whales that we don't really have around today. And so one of the theories for why Megalodon when extinct was that given their big size that they would need to eat big things, those big things are probably whales. And during this time period, there was a shift in the climate and in marine ecosystems and perhaps that their prey, the whales, you know, were in jeopardy.

And so some of the recent research that we have suggests that there could be other factors as well. But there was definitely a lot going on. And there was a much more diversity in terms of marine predators. And if Megalodon could survive below this fictional thermocline, then there should be other organisms from that time period that were also able to survive. And it would be cool to see some of that as well. Yeah, absolutely. Well, Sora, thanks for taking the time to talk about this ridiculous movie. Absolutely. It was super fun to watch, so I was very entertained.

Dr. Saur Kim is an associate professor of paleoecology at University of California, Merced. For Science Friday, I'm Dee Peter Schmidt. Thank you, Dee. For more of our Science Goes to the movie's stories, subscribe to Dee's podcast, Universe of Art. We're continuing our journey back in time with a visit to a one-of-a-kind. dinosaur stomping ground. Researchers recently discovered a rocky outcrop at Denali National Park in Alaska, covered in dinosaur tracks. They've dubbed it the Coliseum.

It's the largest dinosaur track site ever found in the state. The area has thousands of dino prints from duck-billed dinosaurs, horned dinosaurs, raptors, raptors, to rancers, living about 70 million years ago. Joining me now to talk more about this dino hotspot is my guest. Dustin Stewart, former graduate student at the University of Alaska Fairbanks. He's currently a paleontologist for the environmental consulting firm, Stan Tech, based in Denver, Colorado. Dustin, welcome to Science Friday. Hi, thank you for having me.

How did you find this treasure trove of Dino Tracks? So it actually had quite a long story in the summer of 2015. a crew went out there and they noted that there was a large trackway which was from a single dinosaur that walked through some mud and they knew that the area was significant but they didn't really know how significant it was until we got out there.

What did you find? We found the entirety of it by kind of going at the right time. It's a quite a long hike from the road. So we got there late in the afternoon and we looked the wall and we're like, yeah, we definitely see some. We didn't think it was going to be as large as we thought until the sun started setting. And then the angle of the sun kind of perfectly hit this wall. And it just blew up the entire area and exposed thousands of tracks all within a 10 to 15 minutes.

time span and we were just shocked. Yeah. That sounds magical. Yeah, it really was. Can you idea a species just by its bumpy webbed print? Basically no. It's kind of a taboo to put a species name on a track unless you see a series of footprints and then there's a skeleton at the end of it. Like it's dying steps or something. Yeah, exactly. But in every other case, you don't really want to do that because we don't want to associate a track with a certain dinosaur and then find out later, oh, hey, there's this completely new dinosaur that was never discovered before that has a very similar foot. What we do is look at other sites throughout the state of Alaska. There is a particular site. This is the Prince Creek formation. And that's a...

one has a lot of dinosaur bones. And it's around the same time as where we're finding our tracks. So you have some clues. Yeah, exactly. We have some clues. So what do you suspect was stomping around this area? So we have dinosaurs such as serotopsids, like the horn dinosaurs and a lot of duck-built dinosaurs. And what was special about this place is we are also finding meat eaters along with it. We have larger, not as big as T-Rex, but a large Tyrannosaur that was up there. And we have raptors that we can tell because they have two toes. You can think of their large kind of movie claw that sticks up in the air. That doesn't make a footprint. And so finding those alongside of predators, prey from all these different species was kind of exciting. So why were so many dinosaurs hanging in the,

this particular area? Part of it is that it's just such a large area. And then on top of that, it is over the occurrence of multiple layers. And so these are different events that I couldn't put a time frame on, but it could be seasonal or yearly or decade-long flooding events that create these environments that are good for producing dinosaur tracks. the kind of go-to theory is they are all attracted by something and the water, the very fluvial system that is there kind of directs us to thinking, oh, this might be a place where they're

converging to get some water. So it's a watering hole for dinosaurs and then maybe also a buffet for these carnivorous dinosaurs. Exactly. Yes. Wow. How unusual is a find like this? This is kind of a once in a lifetime, at least for me. This was very clearly the largest track site that we know of so far in Alaska. And so we still have a lot of searching to do. Wow. Well, congratulations, Dustin, on a once in a lifetime dinosaur find. I mean, how many people can say that?

Yeah, it was a dream country. I had a fantastic time out there. That's all the time we have for now. Now, I'd like to thank my guest, Dustin Stewart, former graduate student at the University of Alaska Fairbanks. He's currently a paleontologist for the environmental consulting firm, Stand Tech, based in Denver, Colorado. After the break, we'll revisit some of the world's deadliest catastrophes. That sounds fun, right? And how you could survive them, using science.

This is Science Friday. I'm Flora Lichten, and we're continuing our time travel adventure. It's 70 million years ago. You're running through a hot swampy forest, stumbling through ferns, and on your tail is a hungry T-Rex. What do you do? Run, hide, climatry, accept your fate? Do you have any chance of escaping? Well, science says, maybe.

This magic treehouse-esque experiment is the premise of a new book, How to Survive History. We'll travel back in time to world-changing events, think the asteroid that wiped out the diner. the eruption of Mount Vesuvius, the construction of the pyramids, and we're going to play a game. If you were plunked down in the middle of one of these scenarios, what would it take to survive with 2020 hindsight and science on your side? Joining me now to play this out is Cody Cassidy, author of How to Survive History. He's based in San Francisco. Cody, welcome to Science Friday.

Thank you so much for having me. I'm excited to be here. Cody, how did you get the idea for this book? You know, I was searching around for a story to write for Wired magazine, and I stumbled upon a study that seemed to suggest I could outrun Tyrannosaurus Rex. It was a study that looked at the sort of distance of their footprints and the height of their pelvis and sort of determined that their top speed was around 12 miles an hour. And so I sort of went outside and tested that. And I didn't quite run faster than that to my disappointment. But when I looked into it further and sort of looked at the advantages that prey have to their faster predators when they're being chased, I sort of came to the conclusion that I probably could outrun the full-grown Trenosaurus Rex. And I had so much fun thinking about that. And I sort of realized that I could apply those sort of same lessons to other ancient disasters. And it was a sort of fun way to not only learn about these disasters, but sort of learn about cultures and the history and have a lot of fun doing it along the way.

I'm still surprised that you have a chance against a T-Rex. I'm going to put myself in those shoes. So I'm not athletic, okay? I'm pretty sure I couldn't get to 12 miles per hour, although I really don't have a sense of how fast it is. But how would I do it? If I'm confronted with a T-Rex, what do I do? So, for example, a brisk jog is about seven miles an hour.

So it is a little bit, it is a little fast, but it's attainable. And the way I think you might be able to do it is they attach some accelerometers to Cheetah and Impala. And even though the Cheetah runs at 53 miles an hour and the Impala ran at about 40, the Impala gets away at about two-thirds of the time. And it does it by actually a counterintuitive strategy. It doesn't run at its actual top speed when it's escaping the Cheetah. It sort of maintains its maneuverability. And as the cheetah catches up and gets within one or two steps, it sort of swergs. Like zigzagging?

Is that what I should picture? Exactly. It actually is a strategy I employed on the playgrounds when I run from faster bullies, and I'd sort of forgotten about this. So judging by those numbers, you should be able to escape even if you're a little bit slower than the 12 miles per hour that the T-Rex runs. How do we know that T-Rex wasn't fast? It feels so counterintuitive because they seem like such a mega-preditor.

Why do we know that they were topping out at 12 miles per hour? Well, they couldn't actually run that the T-Rex. was about 6,000 pounds. So it would have shattered its leg if both legs were off the ground at any one point. So it was more of a fast walker. Oh, wow.

And it couldn't really have walked much faster than 12 miles an hour. Although I should add that that is only the full-size Tyrannosaurus Rex. It actually was a much more dangerous animal to humans when it was a teenager because it was only about 2,000 pounds. And in that case, could actually run

at about 33 miles an hour, which suggests even if you employ the tactics of the Impala, unless you're sort of a a top high school track star, you'd be in trouble running and it would be best to hide. Okay. So if I, yeah, if I run into a like a teenager T-Rex, I either have no chance or I need to find a hiding spot. Yes, you need to employ different strategies than running. Maybe climbing a very tall tree. So one of my favorite chapters in the book was the one about surviving the chick's-loob asteroid, the one that smashed into the earth and killed off the dinosaurs. Put me,

on Earth, the day of impact. Like, what would it be like leading up to that boom? This surprisingly, you would have seen it. This is about 66.5 million years ago. And if you were in the Northern Hemisphere, you would have surprisingly seen it coming a few days in advance. At first, it would have looked sort of like the faint star in the sky. And then the next night, it would have sort of been the brightest.

And then the next night, it would have sort of outshined the moon and then the sun. And then it would have hit Earth, in this case, the Yucatan Peninsula, with the energy of about 100 million times the largest thermonuclear weapon ever detonated. And so the results were catastrophic and sort of comprehensive. It vaporized the shallow sea above the Yucatan and sort of hit the bedrock of the earth

sort of with the same effect that a cannonballer would have hitting a pool. Sort of gouged a wall of Earth 20 miles high. 20 miles high? Yeah, exactly. And sort of the cavity breached Earth's mantle. And so all that earth, that 20 mile high wall of Earth would have sort of rained back down globally. The most catastrophic effect was some of the rock down there is actually oil and sort of coated Earth stratosphere and sort of a black paint and chilled.

Sunlight dropped on Earth by about 90 percent and global temperatures fell by almost 50 degrees. Because that black paint that was kicked up from the asteroid is now in the sky blocking the sun? Exactly. And it's above the rain cloud. So even though it ignited sort of global fires, that ash sort of was wicked down by rain. But because the sort of paints was above the clouds, it stayed up, it stayed a lot for almost 10 years. Okay. So if I wanted to survive, where do I need to be? So I should, I should note that this is one of the more difficult ones to survive.

One of the experts I spoke with took quite a lot of convincing before he gave me even a survival plan. Like the chances are slim even if everything goes right. Exactly. Okay. But your best chance is to be on the opposite side of the world of the impact. And this is somewhere near the equator about where Indonesia is today where it didn't totally freeze. And there were some animals that did survive, particularly animals that nested in the ground. So I would suggest finding a deep cave because there's sort of a rain of fire is going to come down on the earth as all that earth reenters the atmosphere.

If I were on the other side of the earth, would I feel the impact? Would I hear it? Like, what would I know it had happened? Yeah, the sonic boom of it entering the atmosphere actually reverberated around the globe a couple of times. The impact also rang Earth like a bell, which sort of fractured earthquakes sort of broke out globally as a sort of dislodge all the tectonic plates. So you would certainly know it happens. And then you would have a little bit of time to get into your cave. And you should also get above the coastline because 1,000-foot tsunamis wrapped around the Gulf of Mexico and a 600-foot high wave. hit Europe and it would be a little bit smaller on the, on the, where it is now, Indonesia, but certainly a danger as well. Okay, so I'm in my cave. Then what? So even if you survived

the initial impact, the sort of rain of fire and the global tsunamis, the cooling earth eventually kills land animals larger than a raccoon. It kills all the dinosaurs other than the birds. And our ancestors survived, but they were about the size of a shrew. So food becomes an issue for for a large animal like yourself. But in the river estuaries, I would suggest you hunt because turtles did survive and other animals, fish and of course, sharks, though those would be harder to catch. So you have to survive about 10 years, but after that, the earth did make a recover. On a pescatarian diet, I feel like I could make that work. Yeah, it's, you know, our ancestor did, and they were about the size of a shrew at the time. So I suggest not eating them because it's

actually unclear how many of those did survive. So you might have some sort of catastrophic butterfly effects there. But there might be enough. Okay. So I want to hear a little bit about the research process for this book. Did you just have like a million strange Google searches while you were writing it? I did have, of course, yes, a lot of strange Google searches. And I sort of a lot of science papers and reading how the different impacts affected the earth, such as the asteroid. But I think My favorite part was sort of asking the experts, people who had worked on the ground, such as in Pompeii or what they would have done if they were there. I sort of found those answers the most interesting and in many cases surprising. What was the fact that surprised you the most that you learned? Well, speaking of Pompeii, when I spoke to the archaeologist who's done quite a lot of work there and I asked him how he would have survived, he suggested actually you run toward the volcano, which I found surprising.

But he said he'd the timing of the eruption and the way the wind, the way the wind blew that morning would actually mean that if you ran toward it and then passed it, you would have the best chance. Well, let's go to Pompeii. So you start this chapter at a bakery. So let's say I'm ordering a square of focaccia and a few miles away Mount Vesuvius starts erupting. Would I notice? Like, would I know that that's happening? Certainly. Yeah. If you ever been to. Have you ever been to Pompeii that sort of Mount Fasuvius sort of looms over the town? It's only about five miles away. And so immediately the earthquake would hit and the gas cloud would have started, the gas cloud would have started rising.

But fortunately, the early stages were not the most dangerous. Because the wind blew the cloud that morning, it sort of rained the ash on Pompeii, but it sort of fell as a snow initially. But this was the most important period. Some people decided to take cover from the falling. ash, and some people decided to run. And certainly running was the best option. Okay, so what should I do? I should not stay put. Where should I go? Well, because the wind blew south that morning, it actually carried the cloud further, and Pompey is south of the eruption. It carried the cloud further in that

direction. So even though your initial instinct, which in many cases I should add is probably the right one in volcanic eruptions, but in this case would not have been the best decision. We know, for example, The elder died in Stabia, which is a good few miles south of Pompeii. So you have an option to run east, but that is blocked by mountains. So it would make your escape slower. You could try to sail away, and certainly some did, but the wind was against you, and there were some sort of small tsunami waves that the earthquake caused. So really, the best option is to run past the volcano.

If you run, there's a coastal road. It takes you to the town of Herculaneum, which is right at the base of Pompeii and a sort of luxury resort for Romans. But you shouldn't actually stop there because the first pyroclastic surge, which is what happens when the volcano loses, the gas cloud loses its sort of power. And instead of rising that the stratosphere falls to the ground and rolls sort of like a superheated sandstorm and moving at highway speeds. It's a cloud hot enough to melt lit. Fun. That first hits Herculaneum around 3 o'clock in the afternoon. You have to keep going.

Does that head to Pompeii, too? It does, yeah. That hits Pompey later in the afternoon, which is what eventually buried the town and why we see all those perfectly preserved sort of plaster encasings of the bodies there and why you should not stay there and take cover. But if you make it all the way to Naples, which is about 13 miles, and you have five hours. So that's like sort of a fast walk. You should be fine.

But it's quite hot, I should add. So just make sure to stay hydrated. This is Science Friday from WNYC Studios. I'm Flora Lickman talking with author Cody Cassidy about his new book, How to Survive History. Let's zip over to ancient Egypt during peak pyramid building time. If I wanted to be part of this great infrastructure project, how would I get conscripted to work? So conscripted actually is the right word for ancient Egypt and building. the pyramids. Those who built carried the rocks were actually probably farmers along the Nile

and were conscripted sort of like a modern conscription army during the summer when the Nile's flood floods the farmlands there and makes the land so fertile but also idols the farm the farmers. So Faro Kufu had this huge workforce that was sort of was kind of nothing to do during the summer and he would conscript them to lift the rocks of his great pyramid. That sounds like a terrible job. How did people feel about it? You know, surprisingly, it looks like there was a sort of a spirit-to-corps kind of developed amongst these unleasing workers. They would have team names.

We can see these sort of graffeted into the pyramid. One of them was called Kufu's drunkards. They also ate quite well. There's a tremendous amount of beef bones that have been found, which was an expensive meat, and sort of indicative of the level of resources that Kufu devoted to building his great pyramid. What are the risks to my survival? Well, there are quite a lot of risks. There's a cemetery at the base of the pyramid with workers, and many of them show significant fractures of the arms and legs.

And in this book, I sort of focus on the heaviest stone in the pyramid with this 80-ton black granite rock found almost 200 feet up. It forms the roof of Kufu's tomb. Hauling a rock of that size would have a lot, tremendous number of risks. it certainly violates OSHA's recommendations of hauling 50 pounds. It suggests that there were probably at least 300 workers were hauling this up a ramp. It was about 11% grade. And when you're pulling that much weight, there's actually quite a lot of danger of the rope snapping. There have been some really gruesome disasters when there have been some tug-of-war,

large tug-of-war teams. And so I suggest not standing at the front of that hauling team because if a rope snaps, It actually can hurtle back towards the polar as a sort of fast enough speed to actually remove limbs. So certainly stand back and stand at the back and don't lift with your back either. Use your legs. Is there still debate about how the pyramids were built or people settled on aliens? There's certainly no debate about the fact that they use ramps. The biggest debate is the design of the ramp on how to pull up the stones.

They certainly sat stones on sleds and then used their sort of, mud, slicked surface to haul them up. But if you speak to the archaeologists who've actually been there and worked on it, they suggest to me that there's really no debate at all. They actually see the quarry at the base of the pyramids. It's still there if you visit it. And there is a ramp leading up from the base of the quarry to the surface. And if you continue that trajectory, it would arrive at basically about the mid height of the pyramid, about 200 feet up at about an 11% grade. And then they think it just sort of did one loop around the back of the pyramid to the top. So, you know, there's no shortage of existential threats and catastrophes in the world that we live

in now. In looking back and doing this book, has this made you think differently about our current predicaments? Totally. I think a lot of these disasters, I was surprised, repeat themselves. You know, Pompeii is still within the shadow of an act of Boccurts. I still live on a fault line. I think a lot of these disasters surprisingly repeat themselves and they repeat themselves in a similar way. Hopefully this has less relevance toward today, but sort of the sacks, the way cities were sacked and the way famines occurred usually occurred in the same way. And the instructions were actually the same, in which case a lot of times I only wrote about one category of disaster in this book because were I to write about

medieval sacks or medieval famines that occurred hundreds and sometimes thousands of years apart, it would actually be similar instructions. So that was one thing that I think echoes today and would echo forward. Cody Cassidy is the author of How to Survive History. Thanks for joining me. Thank you so much for having me. To read an excerpt from Cody's book, visit ScienceFriday.com slash survive. If you missed any part of this program or you'd like to hear it again, subscribe to our podcasts. Join us throughout the week on social media or with our newsletters, ScienceFriday.com

or email us the address is SciFri at ScienceFriday.com. Ira's back next week. Thanks for joining us. I'm Flora Lichten.