Science Friday - Medieval Bones, Bird Ancestors And Dinosaurs. August 27, 2021, Part 2

Episode Date: August 27, 2021

A Skeletal Record Of Medieval England Society Whether you like it or not, a record of your life is constantly being chronicled. No, not through the internet or on social media—through your bones. If you’ve ever fractured a bone, that skeletal trauma stays with you forever, even after it heals. So researchers across the pond are using bones from medieval times to put together a picture of what life was like. The bones in the study came from ordinary people in medieval Cambridge in the United Kingdom, from between the 10th and 14th century. The researchers found that you can often guess who was working class, and who had more money based on what their bones looked like. In this re-broadcast, SciFri producer Kathleen Davis talks to Jenna Dittmar, a research fellow in osteoarchaeology at the University of Aberdeen in Scotland, about this new research.      Birds Are The Last Dinosaurs. Why Did They Survive? Sixty-six million years ago, thanks to the Chicxulub meteor—and possibly additional stressors like volcanic eruptions—85% of the species on Earth went extinct, and the Cretaceous period drew to a close. The loss of species included most dinosaurs, but not all. Today’s birds are the last of the dinosaurs, descendents of ancestors that didn’t just survive this mass extinction, but evolutionarily exploded into thousands of species distributed around the world.  Paleontologists are still searching for why birds didn’t die, and what traits their ancestors possessed that allowed them to inherit the planet, along with mammals and other survivors. Writing in the journal Science Advances last month, a team of researchers looked at a newly discovered fossil skull from a cousin of modern birds, a bird called Ichthyornis, which went extinct with the rest of the non-avian dinosaurs. Their logic was that if the brain of Ichthyornis was different from modern birds, that difference might explain why Ichthyornis died with the dinosaurs, while the ancestors of modern birds survived. Paleontologists Julia Clarke and Chris Torres, co-authors on the new research, join producer Christie Taylor for a conversation about the clues, the unknowns, and what fossils still can’t reveal. Plus, why studying the end-Cretaceous mass extinction could provide data for understanding what animals will survive modern global warming. 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 Irafledo. Whether you like it or not, a record of your life is constantly being recorded, and no, I'm not talking about social media. But through your bones, every time you fracture a bone, even after it heals, that skeletal trauma, that scar, stays with you forever. Researchers in Scotland are using bones from medieval times to put together a picture of what life was like. Here to tell us more about it is Cy-Frize Kathleen Davis. Hi, Hi, Kathleen. Hey there, Ira. Okay, so why are these bones so special? Well, they're special because they actually came from ordinary people in medieval Cambridge in the U.K.

So we're talking about people who lived sometime between the 10th and the 14th centuries. And these researchers found that you can often guess who was working class and who had money back then based on what their bones looked like. Really? How did the bones tell that to them? Well, that's what I wanted to find out. So I spoke to Dr. Jenna Dittmar, a research fellow in osteoarchiology at the University of Aberdeen in Scotland, who is the lead researcher of this study. And I started by asking her just this. What can we learn from bones? So this study analyzed human skeletons that were excavated from three different cemeteries in Cambridge, England. By comparing individuals that were buried in different locations within a town, we can begin to investigate

the lived experiences of these people and what types of spheres they could have occupied within medieval society. So for this study, for example, we looked at the skeletons of inmates from a charitable institution, which was a hospital, members of the clergy, specifically of an Augustinian friary, a number of wealthier individuals that were buried within a religious institution, and a number of what we call ordinary working members of the population. So by looking at people from multiple different walks of life, we're able to look at the differences that could have existed between these groups, but we're also able to get a better picture of the living conditions within the town, because the sample is broadly representative of what medieval society would have looked like

as a whole. So from this, we can begin to identify the hazards of daily life, that were experienced by everyone, as well as those that were unique to specific groups of people that we can tell based on their burial location within this town. So back then it seems like where you were buried actually said a lot about what kind of person you were. Absolutely. And it also told us a lot about where you fit within the social hierarchy of medieval England. So tell me a little bit about what you actually learned from studying these bones about what life was like back then. What was it like to be a person living in medieval Cambridge? So the economy in medieval England was largely based on agriculture,

and the vast majority of people would have been directly involved in agricultural activities and pursuits and would have spent most of their days working in the fields, plowing or herding or something like that. But there were actually a number of occupations that people could have had. So Cambridge was a medium-sized market town that had, that had a population of about 2,500 to about 4,000 people during the mid-13th century, and we know that close to 50 different trades would have been practiced. These included construction workers, which included carpenters, Tyler's, Stone Masons, and Thatchers, in addition to artisans like shoemakers and tailors.

Most of the specialized occupations were dominated by men, but we know that women also worked and received wages in this time. They could work brewing ale, for example, or washing clothes or pursuits like weaving. So another major subgroup of people that existed during the medieval period were members of religious institutions, such as friaries. And in the case of Cambridge, the university colleges. So people in this group had a highly specialized lifestyle that was governed by the specific institutional rules, and they varied greatly by the particular order that an individual belonged to. So the University of Cambridge existed back then?

Absolutely. It was founded about 1208. Wow. So you mentioned that there were some people who were a little wealthier in this community. What did those people do with their days, as far as you can tell? Typically people that were considered wealthier at this time. And when we're talking about wealth here, we're certainly not talking about members of the ruling class, all of the individuals within this study would have been what we would colloquially term as peasants. But even within that very large band of what we call the peasantry, there was quite a lot of differentiation in the kind of wealth that an individual could have. Some of the workers within this

sample certainly would have been tied to a piece of land and they would have worked for a lord, for example, plowing and doing these kinds of activities. But there would have been others that would have been involved in trading or they would have been merchants and they could have had a very different lifestyle to what we're thinking of as medieval peasants nowadays. Were there any specimens as you were going through these bones that stuck out to you in terms of what they probably went through in life? So in general, we found a lot of evidence for skeletal injuries. about 32% of the sample that we looked at had one or more fractures. But some individuals certainly stood out as having more severe injuries than others.

One individual, who was actually a friar, had very severe traumatic injuries. Both of his femurs were broken as well as his neck. Oh my gosh. And these were, yeah, these were perimortem injuries as well. So what that means is that these bones didn't have time to heal before this person would have died. And given the extent of the injuries, you know, both of his legs and his neck would have been broken, we expect that he died from whatever kind of accident that he was involved in. The injuries that he has are most similar to what pedestrians today experience when they're hit by a car.

So you said that about 30% of these spells, that you studied had maybe not as extreme as this example, but had some type of fracture that you could look at and say, okay, that's skeletal trauma. I mean, it seems shocking to me that so many people had this kind of trauma back then. I mean, was life just really hard back then? I mean, in general, I think, yes, it definitely was. There have been a number of studies that have reported fracture prevalence rates from archaeological sites all over media. medieval England that report very similar numbers of fractures to what we found in Cambridge. And all of this research, including ours, suggest that people, especially those that were

involved in routine manual labor, were at a high risk of being injured no matter where they lived in the country, which really isn't that surprising. We kind of expected to find this. But you have to remember that a family's survival during the medieval period was based on their ability to work for a living. And a severe injury of a family member could result in the starvation of an entire family. That's what this research really is trying to drive home. It's the lived experiences of these individuals. The Black Plague happened around this time period, if I understand this correctly. Can you see the impacts of that on the bones of the people that you study or in the remains? That is actually one of the research questions that the larger project that I'm

involved in is working towards. So I'm a post-doctoral researcher working for a project called After the Plague, Health and History in Medieval Cambridge. And our main research goal is to really try to identify the biological consequences of the bubonic plague epidemic, also known as the Black Death. So we have found evidence of Yersinia Pestis in a number of individuals from medieval Cambridge so far. And we're working to process the data to try to figure out exactly what. consequences the Black Death had on this population. I want to shift gears for a second. I know that you're originally from the States, so you may be able to relate to this. But every time I travel outside of the country, it strikes me that everything is so old. I mean, you have in many countries

modern buildings that are built on top of centuries old ruins. I mean, there are buildings from medieval times that are still standing in the UK and in Europe. Does being surrounded by old things, as a researcher who studies this time period, change how you look at the research? I mean, living in a city like Cambridge, where there are so many spectacular medieval buildings, does help you get into the mindset of what it must have been like for normal, everyday working folk to come into a place such as Cambridge,

especially during the later medieval period when some of these buildings would have been constructed, because you're still able to walk in the streets that the medieval people would have also walked. And you can go to the locations where these people lived and you can see the places where they died. And it's a great privilege to be able to do this. Medicine has changed a lot, obviously, since the Middle Ages. But I'm wondering if you think it could be possible to do the kind of research that you're doing now on these people who lived, you know, back several centuries,

if it would be possible potentially to do an analysis on our bones in, you know, say, 500 years? This is a really interesting question. And I think certainly before we can answer a question like this, we need to consider how burial practices in modern times are different to those during the medieval period. So there was no such thing as embalming during the medieval period. the bodies weren't preserved in the same way that bodies are now. Another way that burial practices have changed quite drastically in modern times is the increase in the number of individuals that choose to be cremated.

And a study like this wouldn't be possible looking at cremated remains in the same way that it would be with remains that were buried traditionally in a coffin. But on the other hand, I really hope that it is. looking at the medical advances and the way that fractures are now approached by modern medicine. You know, the inclusion of things like pins or plates could, in 500 years' time, could tell you a lot about the types of medicine that was practiced during this time. We do this in the past as well, actually. You know, we find sometimes wooden dentures buried with individuals or prosthetic limbs.

I mean, one of the very first prostheses actually came from ancient Egypt, and it was a prosthetic big toe that was placed on the foot of a mummy. So, I mean, we can learn a lot about a society by the types of medical interventions that they had at the time. Well, this has been great. Thank you so much, Dr. Dittmar, for taking time to chat with us today. Yes, thank you very much. Dr. Jenna Dittmar is a research fellow in osteo-archiology at the University of Aberdeen in Aberdeen, Scotland. For Science Friday, I'm Kathleen Davis. We have to take a short break, and when we come back, why did birds survive the mass extinction event that killed other dinosaurs?

We'll look at bones and brains. This is Science Friday. I'm Ira Plato. You know, I spent a lot of time watching my bird feeder this pandemic. was a kind of nice thing to do with all that time. And we've talked about birds a lot in the past on this program, how smart they are, how their vision works, even some of the physics of how their feathers can be so brightly colored. And with me today is another sci-fi staff member who likes birds a lot herself, producer Christy Taylor. And I have a feeling this story is, I'm sorry to say it, bird-brained, but in a good way. Hey, Christy, right?

Hey, Ira. Yeah, I think that's a fair assessment. All right. Tell us about your birdie news. What's on your mind today? Well, I don't know if it counts as news, but remember the end Cretaceous mass extinction event. Sure. It was that 65 million-year-old meteor strike, and I remember it just like it was yesterday. It was a really long time ago, but it was also a really big deal, right? The climate changed really drastically, thanks to all the dust in the air. And we can thank that event for the loss of 85% of species on Earth at the time. Wow, 85%. Yeah, that's more than four out of every five species. And that includes most of the dinosaurs that were living on the earth at that time. Yeah, but we do have some dinosaurs

around now, don't we, aren't birds, dinosaurs? You're right. Yeah, chickens, herons, all of them. Ancestors of modern birds survived, and they exploded into the thousands of species that we see today. So did mammals, which is why we're here. And in a lot of ways, we can think about the existence of modern birds as a murder mystery, kind of like a game. of Clue. Only the mystery isn't who killed them. It's why didn't they die? What traits did birds' ancestors have that let them stay alive and keep evolving? Like Clue, I'm going to take a wild guess, though, and suspect the answer does not involve a lead pipe. You're correct, Ira, though I think that may be the most sure we can be about anything at this point. But I brought

into researchers who have been exploring this question, gathering the evidence, asking lots of questions, and with the help of a brand new fossil skull finding, they have some ideas that the size and shape of the brain is involved in this survival mystery. So Dr. Julia Clark is a professor of vertebrate paleontology at the Jackson School of Geosciences at the University of Texas, and Dr. Chris Torres is a postdoctoral researcher in bird paleontology at Ohio University,

and I should note that we talked to them in front of a live studio audience on Zoom. I started by asking Julia to help us set up the murder scene a little bit better. Why is it so mysterious that the ancestors of modern birds survived while a lot of other species did not? I think it's really interesting to think when we think of the question of why we have one group of dinosaurs that's still around with us today, and we lack all of these other species that are so charismatic and are all the dinosaurs that we probably grew up thinking about as a kid. But I think it's also important to think about all the other survivors. So the other major group, the cousins of the dinosaurs, these are the crocodilians, they also

survive. Turtles survive. Lizards survive. And then we have mysteries like terosaurs are gone. They're gone at this by 66 million years ago. And they share a lot of problems with our. murder mystery, our survivor mystery, and birds, because they tend to not fossilize, not to be present in a lot of different fossil settings, settings for in which fossilization occurs.

So they tend to, what we're doing is we're trying to solve this survivor mystery, but with very limited data. And so we have to approach this question two ways, which you'll kind of see in the work that Chris has led on this new fossil, which is thinking, okay, what can we study? What is, if we look at all our living birds today, these are the survivors and what they have in common, what is not present in the ones that go extinct? They're close cousins that flu that are about the same body size that also went extinct. And why do things that are very different, you know, stick around?

The fossils we still have to decode this mystery are very limited. And so every time we get a new insight, it shifts that picture a little bit. But what's so fun about this mystery is we still have a heck of a lot of hypotheses to rule out. And we have, you know, if we were at the murder mystery party, we would need, we still have, you know, Colonel mustard and, you know, so we can, every new fossil gives us new important insight, but are we there yet? Or are the murders still occurring inside the house? I don't know.

Maybe I took that metaphor too far. But that's my brief murder mystery summary. Chris, why investigate the brain as a clue? Like, why is the brain the part that you wanted to? focus on? The really cop-out answer is because we could. For the longest time in the bird fossil record, especially of early birds, the brain has been effectively a black box. There's just been an almost total lack of data from that region for early birds. And this new fossil that we worked on finally preserved data from the brain. And so we were able to tap into this really rich source of data that

we hadn't been able to access before. But more substantially, it's because the brain is a really important organ for life, as one might expect. There's a lot about the way we live our daily lives that's tied to the brain. And so we can study the brain to gain a lot of really cool insights into how these organisms lived their lives. We're talking about organisms in the case of Ixthornis, for example, kind of the star of our new paper, this early bird. It's 70, 80, 90 million years old. And so we're dealing with really precious and incomplete remains. And so we're looking for any kind of data that we can for insight into how the whole organism, when it was outliving its life, was living its life. And the brain, at least the external shape of the brain,

which is what we're really talking about here, is a really important source of information. And it's a really useful set of clues for reconstructing what these organisms were like when they were still alive. How do you look at the brain of an animal whose brain has not been fossilized? Because we don't have fossil brains here. We have skulls, right? Right. Yeah, exactly.

So we're dealing with proxies for the brain. And so this is something that makes birds so convenient to study because birds have really complex gigantic brains. And part of what makes them so complex is that their skulls, just like in mammals, their skulls totally wrap around the external surface, the outside surface of the brain, which means that any given bird skull is effectively a mold for its brain, or at least the external surface. It's important to know we're talking about the outside, not the inside. So it gives us, it's basically a mold of the brain.

And so if we have a particularly complete fossil bird skull, we can use that to reconstruct the outside of the brain and compare it to other extinct birds, near relatives of birds, non-avian dinosaurs and living birds that we can go out and observe today. Okay. So we found a skull. We are looking at skulls to interpret what the brain was shaped like. I think this is the part where we talk about what you found, right? So you looked at, and you mentioned this bird Xythornis, and you compared that to modern birds. What did you see? So this was actually one of the earliest fossil birds that was described or known, in detail shortly after archaeopteryx. So within 20 or so years of archaopteryx. And Charles Darwin

actually wrote to Onathel Charles Marsh, the original describer of Ictheornis. That's the genus of the species that we refer the skull to, Xeornis Dispar. And he said, wow, what great evidence for evolution. It looks so close to living birds, but it has teeth. And that clearly means it's not part of a living species. So Darwin was so excited about the species back when it was described. And so you asked Chris about the brain, and I'll let him get into the brain here of Ictheornis in a second. But what was important about Ictheornis was that it was this very close cousin of the, we say, the radiation of all the birds we have today. So that's like the common ancestor of all the birds we have today and all of its descendants. So Icteornes was a

close cousin to that. In fact, it's the best represented in the fossil record of things that are close to that radiation. And that's why it was going to be so cool to finally get some insight into its brain. Yeah. So when it comes to their brain, so exactly why Ichioris is so interesting is why we're so fortunate to have this particular specimen, because it has a mostly complete skull, and that includes three-dimensionality, which is also a crucial aspect of this. It's not just that we have the parts,

that we have them in position relative to where they would have been in life, which led us reconstruct most of the brain and compare it to a bunch of living birds, and then a relatively small sample, but it's the best we've got of early birds and near-bird relatives, Early birds in this case really just refers to archaeopteryx, which is the earliest known bird. And so we had an idea of what the brain of archaeopteryx and some more distantly related dinosaurs look like.

And so we had an idea of why living bird brains, at least the external surface, why it was shaped differently from these other dinosaurs. A lot of the differences revolved around the forebrain, the cerebrum. Living birds have enormous cerebral hemispheres. And those are a really important part of the brain and how it works. The cerebral hemispheres are where a lot of higher cognitive functions occur. It's where memories are stored. It's where learning happens. Language is processed.

Senses are processed. So we knew there was a major difference between non-bird dinosaurs and living birds. Living birds have this enormous cerebral hemispheres. More distant relatives don't. A major question has been, where did that come from? where along the line leading towards birds did that evolve? When did that first appear? When we looked at Ictheonus, we found that its cerebral hemispheres were much more like archaeopteryx and other non-bird dinosaurs and very unlike living birds. It had relatively small

cerebral hemispheres. And because Ictheonus is so closely related to living birds, we were able to hypothesize that that trade of having really large cerebral hemispheres probably was unique to living birds. And so it fit the pattern that Julia referenced earlier, which is we're looking for traits that are present in the survivors and absent in the casualties to try to help explain why the survivors survived. And so when we observed this state in Ictheornis, this condition of having relatively small cerebral hemispheres,

it indicated that having these large cerebral hemispheres fit that pattern and likely contributed in some way to the survivorship, to the exceptional survivorship of living birds. through that end Cretaceous mass extinction event. Tell us about what you see in these brains, not just that the cerebrum is bigger. Real estate is at a premium in the skull. And so if you're going to expand something, something else is going to have to give way. Something else is going to have to shift out of the way so that can happen.

And so we see this general reshaping of the brain. So if you look at the brains of early birds, their brain is vaguely linear. you get one structure, the cerebrum out front, the optic lobes or the midbrain in the middle, as might be expected by its name, and then the cerebellum is at the back. But in living birds, that is totally shifted so that what was formerly the midbrain is now totally underneath what is formerly the forebrain. And so the change in shape is so fundamental that even those words are not very descriptive anymore. So we see this general reshaping that happens as a consequence of this relative expansion of the cerebral hemispheres.

One way I would describe looking at the different images of brains is that the Ixiornis brain is almost like a train. I see little train cars from the cerebellum at the back to the cerebrum at the front. But like the modern bird brain is much more a smushed thing. I don't know. It's folded and smushed. It's not very technical. It's hard to describe.

And we, that's an obstacle we faced in the paper itself. Like what's the most reasonable way and conservative way? of describing the shape here without using words that means something else. Yeah, it's a very abstract shape. Just a quick reminder, this is Science Friday from WNYC Studios. I'm talking to paleontologist Julia Clark and Chris Torres about fossil birds and what we can learn about their brains. I want to get to what this shape might actually mean. We're talking about Ictheornis, which didn't make it, and we're talking about modern birds, which did. So what about a brain shape like this might actually promote survival. So I can talk about what the expansion of the cerebrum might mean. The short answer is,

no, no, it's not super clear. So like I mentioned earlier, the brain is incredibly complex, right? There's so many functions associated with the brain. Just saying it's incredibly complex is an understatement. And so, and again, I want to emphasize that we're looking at the external surface of these brains. The brains themselves are three-dimensional structures. And And so the neurons, the brain cells are all below the surface. And it has to do with their organization and their connectivity and their density that is where all of the cognition, all of the brain function actually happens. And so what we're looking for is some fossilizable feature, some feature in the fossils that gives some hint as to what's going on below the surface. And shape, relative size and shape of these structures, hints at that.

And so what this is telling us is that there's, of the myriad functions associated with the cerebrum, some or many or few of those would have been linked to survival. Again, it's not clear what those functions actually were. It may never be clear what those functions are because the brain is so incredibly complex and surface shape is so relatively simplistic. It may be that we're never able to directly say, okay, it's bigger, which means this, but it does help narrow down some functions that may be associated with that expansion of the forebrain. And if we can turn to modern neuroscience and look at bird brain researchers,

looking at the actual functions of bird brains, comparing those to the brains and other reptiles, we start to get an idea of what those functions may have been, and we can start to hypothesize or at least speculate as to what the links would have been. Well, I'm going to pick up. I'm going to pick up here. Yeah, so I think the key thing to point out in kind of a context is that we actually have, as you get these fossils, these incompletely known fossils from the Mesozoic, of things that did not survive. So there are very few features we know are unique to living birds. And what Chris has described is something that we newly point out may be unique to those survivors. what it means in terms of like ecological flexibility, is it enhanced visual system? But this is speculation at this point

because it's sort of like if you found a computer chip and that has a ton, it runs your whole phone, everything that your phone does. And you want to say, what's the reason my phone survived the break that's on this chip? I mean, it's a heart, because it's such a, it controls so much

It's involved in so many different pathways, the brain, like the forebrain alone in birds. So, you know, that's not an easy lead. That's why Chris went, we're going to have to take a short break, but when we come back, what the end-cretaceous mass extinction has to do with us now. And more bird paleontology with guests, Julia Clark and Chris Torres. This is Science Friday. I'm Ira Flato. We're listening to producer Christy,

Taylor's interview with bird paleontologist Julia Clark and Chris Torres about their research suggesting modern birds escaped extinction 65 million years ago with some help from their brains. This interview was recorded in a live taping on Zoom, and to find out how you can join us in a future Zoom call-in, visit ScienceFriiday.com slash live stream. All right, now back to the interview. We're actually going to go to a listener question now. And I'm going to start with Candice from Arizona. Candice, if you're able to unmute yourself, go ahead and ask that question. Yes, thank you.

This is a great program. I'm interested in your research and whether it shows if the ancestors of today's birds had the ability for their bird to change rapidly when there was a lot. changing environment, such as what we have with climate change right now. That is a great question. Julia or Chris, does either one of you feel more eager to answer it? Yeah, yeah, yeah. I think in terms of rapid climate change, right?

Global, rapid, catastrophic climate change is thematically similar to what we would have seen then and what we're seeing now causes obviously vastly different. So the environment was changing incredibly rapidly. And so like Julia indicated, there's all these functions that would be associated with the cerebral hemispheres, these higher cognitive functions, so to speak. And so all of these functions, or at least some of these functions, may have been associated with behavior of plasticity, the ability for the organisms that had those organs, the ancestors of living birds, to have a wide repertoire of possible behaviors, wider and more plastic, more changeable, more adaptable, than their co-evolved species, other species that would have been around at the time, which would have conceivably, potentially have prepared them for rapidly changing environments. And so we might have expected to have seen this plasticity in a wide range of behaviors, whether it is moving across

the world, where they're feeding, when they're feeding, what they're feeding on, learning new behaviors, so basically modifying their own behavior as the world is rapidly changing. I think that got into her question. Julie, do you have anything to answer that? Well, I think it's an interesting question. I was just reading a question in the chat that was sort of around the same thing. And what we can't parse is whether the survivors are, as Chris alluded to, perhaps have ecological differences, that then creates natural selection for larger brains.

Or if larger brains have evolved and that behavioral flexibility, if we are very vague about it, precedes the actual extinction event. So oftentimes what we have is that you, for example, You can't have natural selection for a more, let's say, efficient wing until you have the natural selective force of moving in air. And so this can be a difficult thing to parse in terms of causing, like the brain would, which is responding. Is there something that leads to, you know, overall larger size? and this comes up a lot in human evolution debates, for example. But it's a really good question on the part of several of our listeners. Well, and I think actually this is a great time to sit back and ask, who cares?

Like, why would it matter? Why the Ornus didn't make it? And all of these other birds and their ancestor did. Like, does it change anything about the world that we inhabit today? Yeah, because it's happening again, right? Like we're in a mass extinction. It's happening right now. And so a lot of research, rightfully so, is focused on, you know, how do we stop this?

How do we fix this? But I think a lot of research needs to focus on what's the world going to look like afterwards, assuming we can stop things, assuming that we can do something to rein in what we're doing, how do we predict what the world is going to be like? And a lot of that has revolves around who's going to be around when this is all done. And by understanding that, by understanding what traits influence survivorship, we can make really informed scientific decisions about, for example, conservation. It helps us to figure out, okay, we're spending money.

Where do we spend that money? And what science is going to influence our decision making when it comes to that? And so by understanding these traits in birds, by understanding comparable traits in all of the other lineages that survived, we get an idea of what traits and what traits in the same. influence survivorship. We can start to make predictions about which organisms may be successful. And if they are successful, how are they going to change? What's going to change about them going forward? And so we only get those insights by looking at how it's happened before. And so insights like these are those insights. Is it over simple, like looking at these comparisons of brains

to say that smarter animals are probably more likely to make it? Gosh, that is such a great question, because I always think about crows. So I end my class at UT talking not about, we do human evolution, and then I talk about crows. And because I think that we too often emphasize the peculiarities of our own intelligence and not that of our co-travelers on this planet who look very different from us. And crows and ravens have been, where I grew up in California, have been expanding their range so enormously.

And there are so many amazing videos you can watch of crows and ravens really and read scientific studies of their adaptability in human-modified environments. And they are the biggest brain of our survivors. So parrots and corvids, the crows and ravens, have the absolutely largest brain per body size of our extant birds. And it doesn't mean survival of the smartest necessarily,

but we do see a lot of adaptability in these large brain species to human modified environments, which is most of the Earth at this point. And I also want to plug that what we're seeing now and trying to understand in real time, we're looking back 66 million years through a dirty lens at incomplete data. Our world would look very different without this mass extinction event that just boom, shifted everything.

So in some ways, it's a good reminder. Short-term events have completely reshaped the Earth system. And what we're doing is kind of trying to make sense of how exactly that worked. because identifying causal features or causal factors in survivorship and extinction is really difficult to do. I actually want to piggyback off something that Julia just said, which is this human-centric notion of intelligence and smartness. And I think it's important to remember that any trait that influences survivorship is entirely contextual. And so what we call smart starts to lose meaning when we're talking about things that are increasingly further removed from us, right? So fish, what we consider intelligence, starts to unravel when we're looking at fish, let alone insects, let alone plants, right? It's not even a term that's really applicable to plants, and yet they're wildly successful in all over the world.

We have one anonymous question that I'm just going to read. And their question is, looking at hummingbirds and hawks, one wonders about the cerebellum and its role in balance during flight. Is there evidence of changes that led to backward flight in hummingbirds or rapid disqualification? as we see in Raptors. Yeah. So that question is one that we would love to be able to answer. That gets it associating function with external shape. It's really non-trivial and it's really difficult. Like I mentioned earlier, and I keep stressing, right, the brain is really complex. And so a change in shape, a change in relative size, relative volume, or mass can have

cascading effects, right? They can, they can affect, probably do affect every function associated with that shape. But because brains are so incredibly complex, you could have really major neuronal change, major changes at the cellular level, which affect the functions of the brain. You could conceivably have really major changes below the surface with no change at the surface, which means that we would have, we might, we may not have any direct evidence for the that shift in function and any associated shifts in behavior. And so trying to constrain that, get an idea of how much neuronal change can there be, how much neurological change, how much behavioral change can there be before you start

to see meaningful changes, observable changes in the shape of the brain is a direction of research that lots of labs around the world revolve around trying to answer that question. Number one, how much change can there be before you start to see it at the surface? Number two, how much superficial change do you see? And number three, can you go backwards, right? Once you see that change in structure, can you make a meaningful connection? Ideally, you can to the changes in behavior, changes in function, changes in neurology that preceded that shift. I just wanted to add to it the way we are studying this is we want to look at closely related species.

So to see how fast can the brain shape evolve. And that's what Chris is directly involved in studying now is like, so if a totally new feeding behavior occurs within the last million years or less, like on what are geologically tiny time scales, how much shift in the shape of the brain occurs. And that is, I think, the necessary next step that he's pursuing and we're pursuing to look at that, to start answering these questions that we can bring to the fossils in deep time. Is there anything fossils themselves can't tell us about why animals survive these

mass extinction events and how birds have been evolving in this time? There's a lot that we do not have in our fossils, right? We don't have the whole insides. We don't have, you know, what were their of lungs like. I mean, what we're looking for is fossilizable correlates, things that can enter the rock record, and those are generally mineralized tissues like bones or teeth or the tight wrapping of the brain, right? So those are things that we get fairly regularly when we have a fossil. So everything else, you know, we don't have. I think the big question with the extinction event is also where our fossils come from. We need a global record. We can't just know what happened in North America. And almost everything that we know about extinction comes from at this event comes from North America.

And so we need a global perspective. And that's the reason that we've been trying to get new data from the farthest conceivable regions from the impact site, which was in Mexico. present-day Mexico, to see what's happening there. Right? And I think the other challenging thing, the things that we may, you know, we're getting a lot of new proxies for like, okay, what was the first day like? You know, they, like my colleagues at UT here, drilled the crater itself. How fast does life come back?

We are learning new things about really core questions related to extinction, but there are so many to ask. So if you know any budding paleontologists out there, there is a lot still to learn about this particular event and extinction in general. Just a quick reminder, this is Science Friday from WNYC Studios. Talking to paleontologists, Julia Clark and Chris Torres

about what fossil birds can teach us about who survives and who doesn't, especially in times of mass extinction. Julia, you refer to this need for a global, fossil record, but what kind of fossil find, you know, as you sort of scour the globe, both of you, would kind of change the game? What is your dream in terms of answering these questions we've been discussing? Yeah, so my, I want more brains. I just want more brains. So you're the zombie in the room, okay. I'm the zombie in the room, yeah. No, it's having really nice skulls, which would be great for a thousand different reasons.

But so, so having this one specimen, this new specimen of Victorinus, through so much light on the extinction of most dinosaurs and helped us understand so much how and why living birds were the only dinosaurs that we know that survived. But our, the grand total of early bird brains that we now have data on has gone from one to two, which is still incredibly tiny. It's a really, this is like if we're going to have a second brain, if we're going to have two brains, the earliest known bird and then arguably the closest relative of living birds are the two best ones to have. But there are so many other species out there that we don't have data for. And each of those species could represent a totally unheard of, unpreicted brain shape that could give us all this insight into how those organisms were living their lives and what the environment was like, what the ecosystems were like. having more brains would help us fill in the context within which the ancestors of living birds were living when this extinction happened. And so I just want more really nice,

complete skulls so I can have their brains. And just so I'm hearing you, you're saying like, we could even find a skull that completely trashes in scientific terms, everything that you're proposing in this paper. Oh, yeah, absolutely. Yeah, that's true of every paper. And I think it's really important for authors especially to acknowledge that it's conceivable that there's data we could collect that could totally trash our hypotheses. And so what we did in this paper was we had the newest and the broadest source of data yet published because we were able to build off of everybody who came before us and provide something new. And that gave us some new perspectives on what may have happened and helped us refine some hypotheses, reject others. And so more data could totally

change the game. And so I want those data, whether they change the game or not, I want those data. I am picturing a Secret Santa gift exchange in which Chris just gets tons of skulls. So thank you for that. I'm also expecting that. Well, thank you both so much for joining me. We are out of time. We have gone longer than I could have ever dreamed in such a wonderful way. So thank you both for joining us today. Yes, thank you. Thanks for having us. This is great. Julia Clark is a professor of vertebrate paleontology at the Jackson School of Geosciences. That's at the University of Texas in Austin. And Chris Torres is a postdoctoral researcher studying bird paleontology and their brains at the University of Ohio in Athens.

Thank you, everyone so much for joining us today. I'm Christy Taylor. Thank you, Christy. Really interesting story. And that's about it for today's show. Oh, one more thing. Do you have young listeners and future astronauts in your life who have burning questions for a real life, NASA scientist. We're taking kids' questions at our Zoom call-in on Monday, August 30th,

scientist Katie Stack Morgan will talk about her work with the Perseverance Rover on Mars. Wow, that's going to be really cool. And you can RSVP on our website, ScienceFriety.com slash live stream. That's sciencefriiday.com slash live stream. Have a great weekend. We'll see you next week. I'm Ira Flato.