Ep 143: From Steppe to Stable (with Ludovic Orlando)

Ep 143: From Steppe to Stable (with Ludovic Orlando)

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How and when did humans domesticate the horse? How did horses shape our language, culture, and history?

On this episode, we talk with Ludovic Orlando, a research director for the French National Center for Scientific Research and founding director of the Centre for Anthropobiology & Genomics of Toulouse. Ludovic is also the author of the new book Horses: A 4,000-Year Genetic Journey Across the World. We talk with Ludovic about when, where, and how horses were domesticated, with a particular emphasis on the role of genomics in those discoveries. We also discuss several famous horses and our entangled history with this amazing creature.

Cover art by Brianna Longo

• Episode Transcript

  Marty Martin  0:04  

  Hey, Cam question for you, but I think I already know the answer. Are you a dog person or cat person?

  Cameron Ghalambor  0:10  

  Oh, come on. You know, I'm a dog person, although I have owned a cat before, and I used to not like cats, but I've come to appreciate them. But when push comes to shove, I'm definitely a dog person.

  Marty Martin  0:22  

  Yeah, I've always been a dog person, too, which partly explains my two dogs, Loki and Taz. When my kids wanted pets and they were older, it had to be dogs. But when they were younger, and I was traveling a lot for research, we first got them a cat that they named Olaf. And I gotta be honest, he's pretty awesome, too, and he's grown on me as well.

  Cameron Ghalambor  0:40  

  Yeah, like I've said, you know, I get along with cats, and our former cat and I got along okay, but the cat, it had a mind of its own, and it wasn't always looking for companionship I guess. And I know many cats are sweet, and you know, that's okay, but for me, the best time is when I come home from work, I open the door, and Dashi jumps all over me, and then he runs over to the couch, and I follow him to the couch, and we play and tumble, and it's a highlight of my day.

  Marty Martin  1:10  

  Yeah, I mean, that's definitely one of my favorite parts as well, and it kind of makes me wonder this aloofness in cats. It's not an appealing kind of behavior. Why did humans ever domesticate cats in the first place?

  Cameron Ghalambor  1:23  

  Well, great question, and actually great timing to ask that question, because there's a super cool paper that just came out in science last week on the origins of the domestic cat, or to be specific, Felis catus. So the old idea was that actually no one really domesticated the cat, at least not to be pets. Cats became domesticated when our ancestors decided that it was good to keep cats around, because they killed mice, and killing mice was good for keeping the grains around. So the pet thing probably came secondarily.

  Marty Martin  1:56  

  Oh yeah, I saw that paper. It was by Marco De Martino, Claudio Ottoni and a bunch of others, and they found that the story of cat domestication was much more complicated than we first thought. The domesticated cat in Europe didn't come from the Levant 9500 years ago, or even Egypt about 3500 years ago, as was originally thought. Instead, it seems there were probably two much more recent introductions of the ancestor of domesticated cats, the African wildcat, or Felis  lybica, into Europe.

  Cameron Ghalambor  2:24  

  Yeah. So the first introduction to Europe was probably about 2200 years ago, from northwest Africa into Sardinia. And the other came from somewhere else in North Africa a bit more recently, probably in the last 2000 years.

  Marty Martin  2:40  

  Right. So although cats might have been prominent in Egyptian art for more than 4000 years, if those cats were domesticated then,  those domesticated cats didn't reach Europe until quite a bit more recently than anthropologists originally thought.

  Cameron Ghalambor  2:53  

  Yes, and a very cool story, but I still prefer dogs.

  Marty Martin  2:57  

  Okay, fine. Switching gears. How do you feel about horses?

  Cameron Ghalambor  3:00  

  Horses. I'm terrified of horses. Is this show just going to be about you asking me what my favorite domesticated species is, or do you have a point here?

  Marty Martin  3:08  

  Oh, well, kind of both. We're going to talk a lot more about domestication, but we're going to stick with the domestication of this other iconic species, the horse. It's the research focus of our guest today, Ludovic Orlando, who's been a research director for the French National Center for Scientific Research since 2016, the founder and director of the Center for Anthrobiology and Genomics since 2020 and the author of the new book: "Horses: a 4000 year genetic journey across the world".

  Cameron Ghalambor  3:34  

  Of course. And I forgot to tell you that in honor of dropping this episode with Ludo, I re-watched the 1981 Clash of the Titans the other night. You know, the original one with all the stop motion action, not the more recent CGI one. And what was most amazing about it was how majestic Pegasus, the horse was, the winged horse that flies through the sky in between the monsters and never spooks. We should have asked Ludo about Pegasus.

  Marty Martin  4:03  

  Yeah, but every horse owner knows that Pegasus is 100% fictional and not just a flying part, real horses won't walk past their own shadow if it shows up at the wrong angle.

  Cameron Ghalambor  4:12  

  Exactly, which is why Pegasus is a great starting point for a conversation about horse domestication. If ancestral horses were prey animals with anxiety levels that would make a chihuahua look stoic, how could we ever domesticate them?

  Marty Martin  4:27  

  Great question, and this very issue probably partly explains why horse domestication happened so recently compared to most other domesticates. It took a very special horse lineage to transform a high strung grazer into what we'll hear was truly an engine of human history.

  Cameron Ghalambor  4:42  

  And clearly it's still a work in progress, as even Secretariat and Mr. Ed would probably see a plastic bag as an existential threat.

  Marty Martin  4:51  

  Hahaha, before we get to horses with Orlando, remember that we're still in fundraising mode.

  Cameron Ghalambor  5:00  

  Our goal is 500 paid Substack subscribers, and we're well on our way there. Thanks so much to all of our new subscribers. We're doing really great in gaining the number of paid listeners that we need to keep making episodes.

  Marty Martin  5:16  

  And when you subscribe, you'll get access to full shows, as well as all of our back catalog. And for the next few weeks, for every 20 new paid subscribers, we're also going to randomly pick a subscriber, new or old, to receive a Big Biology tshirt or a poster with the cover art from the show. And you get to pick the image.

  Cameron Ghalambor  5:34  

  So for a chance to win and just to support our cause, go to big biology dot sub stack.com and sign up for as little as the cost of a cup of coffee per week, you can do your part to keep the episodes coming. As you'll see on substack, it's up to you to decide how you want to support us.

  Marty Martin  5:57  

  And in fact, if you can't afford a subscription, that's fine. We'll never let money keep you from listening and learning about biology. So if you can't afford a subscription, you can sign up at sub stack for free.

  Cameron Ghalambor  6:09  

  But if you are a paid subscriber, prizes are not the only part of what you get. Paid subscribers also get access to behind the scenes discussions from Marty and me about the show, as well as extra audio from our guests about their lives and hobbies.

  Marty Martin  6:27  

  So please go to big biology dot substack dot com, and sign up today. It's the holiday season, and what better way to help your niece, nephew, son, daughter or family friend prepare for college or grad school than by giving a subscription to big biology.

  Cameron Ghalambor  6:41  

  And for you, PIs out there, consider giving your lab members a gift subscription to big biology.

  Marty Martin  6:46  

  Thanks again for all of your support on substack, but also a great big thanks to all of our patrons and other donors that help us keep the lights on. And Happy Holidays to all.

  Cameron Ghalambor  6:55  

  I'm Cameron Ghalambor. 

  Marty Martin  6:56  

  And I'm Marty Martin.

  Cameron Ghalambor  6:58  

  And this is Big Biology.

  Marty Martin  6:59  

  Hello Ludovic Orlando, Welcome to Big Biology. 

  Ludovic Orlando  7:13  

  Thanks for having me. 

  Marty Martin  7:14  

  Yeah. So we invited you on to talk about this amazing new book, "Horses: a 4000 year genetic journey across the world." Full disclosure, I've never been a horse person, and I don't mean any offense by that. I've loved every horse ride I've ever taken. I've just not been around them much, but that just meant that most of the material in the book was new to me, and it was, you know, fun to read, and so many amazing facts. But I want to start by asking, How did you get into horse science? Was it an accident, some relation with a hobby or a family history, how did it start?

  Ludovic Orlando  7:43  

  No, that's a great question. And thanks for reading my text, actually, so I'm not a horse person either, right? So. And in fact, the last chapter of that book is the story about me and horses. How did it start and how did it unfold? And in fact, for probably 44 years of my life, my history with a horse was one of a failure. You know, I could have met that animal, but I always missed it. You know, it started at high school when, you know, I was given the choice to do sport a day a week and I will be sailing or horse riding. And of course, I went sailing, right? And so, and it goes on and on and on, including during my PhD work, actually, when I was, you know, lucky enough to meet some very, very prominent scientists interested in horses, trying to convince me that that animal was something worth studying, and I was more interested in Neanderthals and cave bears, you know, extinct species, as opposed to this, this species. 

  Ludovic Orlando  8:35  

  But then at some point, and this is, I guess, the serendipity we have as a scientist, in our lives, right? I came across when I, when I just started my group at the University of Copenhagen, back in 2010 I came across one fossil which was from a horse. And that fossil was something special, because it was dating back to 780,000 years ago, almost, you know, almost a million years old. And so we started studying that, just for the sake of testing whether it will be possible to do whole genome sequencing, that is, sequencing the whole DNA of an extinct animal, when it's that old in the past. The world record at that time was around 50,000 years. We made it to 780,000 and of course, to succeed in doing that, we had to invest a lot on thinking, what is a horse? How can we study the evolution of a horse? And so by doing this work, I just realized, but very naively, in fact, that the horse had everything to it. You know? I mean, it was not only the animal, the textbook animal of evolutionary biology, but it was equally so, the one of human history, because we built that world, you know, on the horseback for many thousands of years. And the minute I realized that I think I was booked, you know, as a scientist, because I just, I just found the animal that, you know, integrated all my interest evolutionary biology and history.

  Marty Martin  9:58  

  Did you write the book now for a reason? I mean, presumably you could have waited. You're still doing a lot of research, and we'll talk about that. But is there some particular reason that you decided now was the time to write the book? 

  Ludovic Orlando  10:08  

  Absolutely. So, you know, we started 2010 as I said, and for pretty much 15 years, you know, we've been after three main questions, and I guess most of the people will be surprised to hear that we did not know any answer to those questions, and those questions were really simple. It was when, where and how did we domesticate the horse for the first time. You know, when you think about, you know, cows or sheep or goats or other animals, we have the answers to those questions, but for horses, we did not. And of course, those questions, it's easy to ask them, it's far more difficult to answer them. And so for 15 years, we've been after those answers. And I thought that now was the time, because we could actually very confidently bring the answers to those questions. You know, we found really, when and where and how did we succeed in doing so?

  Cameron Ghalambor  11:03  

  Good. Well, I'll confess I'm also not a horse person, and the time I have, I've spent around horses, I guess I'm a little bit embarrassed to say that I find them very intimidating. I mean, they're large animals, and when you stand next to a horse like you, you know you feel small. So you alluded to, you know, the simple questions. So I think maybe that's a good place for us to start our conversation of, you know, what is the, the evidence for especially when and where horses were first domesticated, the the subtitle of your books as a 4000 year history. And it really unfolds like a detective story, I think you know, with lots of different clues about key events, but also integrating not just genetic information, but also a lot of archeological information. I know this covers a lot, but let's start to summarize the evidence and how you concluded the geographic origin and timing of domestic horses. And maybe this will first take us to a site in Kazakhstan that you went to.

  Ludovic Orlando  12:19  

  Yeah, so absolutely, maybe, I should say a few words about why did we not get any evidence before we got these answers to those questions right? Is that, as opposed to cows, for example, when we domesticated the horse, we didn't start by changing their morphoanatomy big time, you know, they didn't become like giants overnight. And so if you don't have such a large shift in how they look, archeologists will not have necessarily obvious hints to tell that horse was a domestic one and the other one was not, right? So it becomes the frontier between domesticated animals and wild animals, because becomes a lot more blurry, to some extent, right? So, and because it was blurry, there was a number of suggestions that it could have been one in one region or in another one. For example, you know, archeologists for decades really have used hints such as, oh, what is the context in which those animals are buried? Is it with us? If this is close to us, then probably this means something like a relationship between us and this animal. But really, you know, some people could have been buried with a hunted horse as well. So that's why when and where was really difficult to track. And so this is not for the lack of trying. You know, people have tried over and over again for decades, really, but not conclusive enough.

  Ludovic Orlando  13:29  

   So our take was radically different, right? So I'm a geneticist. I'm trained in molecular biology and computational biology, and so the little I know is about this, how can we leverage the text information that is present in the DNA sequences? And that text is probably recording a number of things, things such as, how many horses were around at a given time in the past, which colors did they have? What were the traits they were having, and these sort of things. And so our bet was that probably if we sequence DNA back in time, so for example, 100 years ago, 200 years ago, we could actually replay backwards in time the movie of domestication, to some extent. Imagine that you have a picture of the horses roaming around today, around the world. Then you travel 200 years ago, maybe you will see where their ancestors were living. And so probably it's not going to be the whole world, but probably a subset of that area, right? And so now, if you move 500 years earlier again, then you will probably narrow down this sort of region where they were domesticated first. And so it sounds very easy. It is actually exactly what we've been doing. The difficulty was go get around and get fossils or archeological remains throughout the whole planet to sort of replay the genetic movie. And so this is where, I guess, I'm the one speaking and I'm the one writing the book. But you have to picture that this is literally several hundreds of collaborators and contributors who have actually excavated the world, really, for decades. Without them, none of that will be possible. 

  Ludovic Orlando  15:22  

  And, of course, like I guess very often in science, we've been extremely lucky, because the genetic movie we could replay was absolutely informative because of the way domestication happened, right? Imagine, for example, that domestication was a sort of idea that many people had around. And so, for example, someone in the US, someone in my country, in France, or in Italy or in Russia, will have got the same idea at the same time and started to do that. There will be many regions to actually track down, right, which might be more difficult to unfold.  But in our case, that was hardly two regions, in fact, one of which we can show was a region where everything started but also collapsed. Those people that you alluded to in central Kazakhstan, 5.5 thousand years ago, we call them the Botai people. They had this particular way of burying themselves and also a particular way to to live. They were actually settled people, not nomads, but they were hunter gatherers, right? And what they were interacting with the most was horses. And there is a moment when they started to, you know, the horse population started to collapse, and they needed somehow to secure their resource a lot more. So that's how they started to interact with the animal to make their resource, the meat, more stable over time. But at some point those people collapsed. They actually vanished, as many people actually vanish in history. And so the horse went back feral. So this first attempt was not the success we know about. You know, by that I mean the horse that we ride today, with more or less talent. 

  Ludovic Orlando  17:01  

  But there is a second time, which is 4.2 thousand years ago, between four and 4.5 1000 years ago. You know, it takes a few centuries to really create this creature. But then, and this is actually not in Central Asia. This is still in the steppic region, but this is in the lower Don-Volga region, somewhere north of the Caucasian mountains, probably southwest of Russia, if you see the geography of this region that way. So those people in this region, not the Botai people at all. They reinvented a new way to interact with the horse. And, at that time, this animal, whatever it was, became the global thing that we call the domestic horse. In our data, we see that from that minute part of the world, you know, a region of a few hundred kilometers, really, the horse was really confined to this very small territory, but they bred out a new type of bloodline there, and this bloodline made history, because in a few centuries, we saw it expanding and spreading across the first the Old World, I mean, Eurasia, and then way later on to other places, including Africa, America and so forth. So because of this process, being to some extent simple, you have one people at some point creating something that becomes so fashionable that the whole world wanted to have it. Think about, you know, mobile phone today, right? We didn't have them 30 years ago, and all a sudden, all of us have them because it was that nature of a process we could be quite confident in the answer we could have to these questions.

  Marty Martin  18:40  

  Yeah, okay. So all of the horses that are here today derive from this group, but the horses that were sort of originally domesticated, what was their distribution and what kind of diversity was there for horses around the time of this event?

  Ludovic Orlando  18:55  

  Yeah, so that's a very good question. In fact, for our work, you know, we have replayed the genetic movie to the domestication start, but in fact, to before that time, you know, up to 780,000 years ago, actually, you know, so, so we have a fairly good understanding of their diversity, when it comes to the genetic diversity that that is written in DNA text, to some extent. And so the that was a big surprise to me, because, you know, for today, the world of horses is very simple domestic or what we call the Przewalski's horse, you know, there is 60 million domesticates around the world, 3000 or so Przewalski's horses, native from Mongolia. So a very simple situation. If you do this genetic movie backwards in time, to say, four or five thousand years ago, by the time the domestication started, you realize that there were dozens of genetic types. In other words, there were dozens of blood types, but things that were massively different. For example, in my country here, we had a number of lineages of horses. That were different to Spain next door, or different to Germany next door. And in fact, you should picture the diversity of horses before us, to some extent, as a sort of regional differentiation of populations. And that happens genetically only if that animal doesn't move around too far. You know, if animal move around too far, they mix, and so that means that they will share the same DNA text. And so, because they were so differentiated, what we learned, that was really my surprise, was that before us, the horse was not mobile. It was an animal that basically lived where it was born and died where it was born, to some extent, right? So in terms of number of lineages, it's dozens, literally, and I'm absolutely sure we haven't finished uncovering them all. You know, it's dozens, but what is really important to understand is that they had a geographic structure. In other words, in different parts of the world, you had different types. And so that's why we could answer the where question, because we only had to track back in time the genetic ancestries that make up the modern horse, to some extent.

  Marty Martin  21:13  

  The structure that was there was that in any way related to people? I think there was allusions in the book about, sort of the geography keeping different populations isolated from each other. But that wasn't something driven by people, per se, for food or milk or anything like that. It was just the natural sort of goings on of horse populations.

  Ludovic Orlando  21:30  

  Yeah, I think. So one of the main drivers before people was climate, in fact. So we have a number of results in our work where we show that, you know, by and large, when climate goes cold, populations expand, populations of horses. I meant, right? It's not a general rule for all the mega herbivores, but for the horses, it holds. And so when it gets warmer, it shrinks. So you have a situation in which you know, for example, you're in the US. So imagine Beringia, this sort of large continent that was a bridge between your continent, the Americas, and my continent, Eurasia, depending on the climate, you know, the sea levels were higher or lower, and if this was lower, all of a sudden you had a bridge, a physical bridge, bridging those two continents. When you have that which is climate driven, of course, there are populations of horses that can go both ways. So you realize that, depending on the climate, you will have a world that will be a lot more plastic for horses or a lot less, basically. And so what we think is that with the global warming that followed the last glacial maximum, we are talking about, you know, anywhere after 19,000 years ago to 12,000 years ago, populations of horses started to collapse a bit. And that's also one of the reasons why archeologists and paleontologists could not answer those simple questions, is that they don't have tons of fossils, you know, physically, there were fewer and fewer of them. So as there were fewer and fewer, it took more of migration for one population to connect to the next. And since they were not natural movers, they did not connect, henceforth they were differentiating, basically.

  Cameron Ghalambor  23:12  

  So if I for our listeners, if we could imagine a phylogenetic tree. If I can, like, kind of summarize this sort of detective story. So you went to this place in Kazakhstan, the Botai region, and you found that, you know, there was this lineage of horse that was there that was sort of domesticated. When you looked at all the other domesticated horses, you found that the only horse that actually mapped to the to this Botai  region was the, I always, I've always pronounced it Przewalski's horse by pronouncing the "P" , but maybe that's not the correct pronunciation. And all other modern horses were on a completely separate lineage. And, and where you, where this sort of story took you, was this, this region north of the Caucasus Mountains, along the Caspian Sea. So you talked about the the climatic shifts, and at this time, this would be like, if we had to imagine the environment, mostly like a grassland steppe environment, and so this, this was an area I think, that was not glaciated during the Pleistocene, so it did act kind of like as a refugia for for the horses to sort of proliferate. Is that a kind of an accurate sort of summary?

  Ludovic Orlando  24:40  

  Yeah, yeah, it's absolutely fair to say that. So if I may add, one thing is that, you know, why did we focus on the Botai region in the first place, right? This is something that I want to clarify here. You know, as researchers, when we start such projects, we of course want to get the answers immediately, right? So and. And so the Botai, I think for us, was a sort of shortcut, because archeologists had a number of hypotheses as to where and when horses were first domesticated. It's not like we started with no hypothesis. There were actually tons of hypotheses, no answers, but many hypotheses. And the hypothesis that was the most consensual, even though it is still debated today, in fact, was the Botai thing. And the reason was very simple, is that archeologists in the Botai region, in Central Asia, 5.5 thousand years ago, they see people interacting with almost only one mammal, the horse, you know, and that they can be confident about that because, you know, they do the excavations for three decades, and they they uncover 300,000 bones and teeth, you know, tons. 99% of those materials are actually horse, like, you know. So it means that, by no , there is no animal that has interacted with those people so much they can also archeologists unfold not only the bones, but actually enclosures. So in other words, animals were near their houses, parked and staying near where they lived, you know. So it sounds like they were intricately related to this animal. And there is even a third evidence for that is that if you look at, not the DNA this time, but you know the pots that they uncover, those archeologists, sometimes you have the dietary crust, you know things that they were actually cooking, that are preserved for 5000 years. And so when you do what the geochemists, chemical, if you will, analysis of those crusts you realize that it used to be horse milk. In other words, you have people interacting with tons of horses, keeping them near them and also drinking their milk. So that was actually a very, very, very, very tempting to say, okay, at Botai horses were first domesticated. And so we went there. We collaborated with people doing the excavations for decades. We sequenced many of them. And you know, that was a big surprise to us, because our expectation was that it all started there. They should be the direct ancestors of what we call today the domestic horse, those you have in the US, those that I have in my country. But in fact, we found the exact opposite. They were the ancestors of the 3000 animals that we call the Przewalski's horses. So I don't pronounce the P, but I don't know which of us is actually right.

  Cameron Ghalambor  27:32  

  I'll follow your lead.

  Ludovic Orlando  27:33  

  Right. You know it's funny, because Przewalski, if you say cheval in French, it means horse, basically. So that's my way to actually stick to the pronunciation.

  Marty Martin  27:44  

  Ah, that'll be my way to remember. Yeah, that's good. 

  Ludovic Orlando  27:48  

  Yes. So what we found that those Botai horses were actually not the ancestors, so not the mother of all the domestic horses, but the only one we called wild, the Przewalski horses. So that's how we say, "Wait a minute. It can't be real." When we had this result, you know, we had that in 2016, and 17, we spent a year trying to kill that result. And because we couldn't kill it, we published it in Science, in fact, and that was the start of something I could not have anticipated, because if you say it's not Botai, then you have to say where, where. And then, if you don't have a such a neat candidate, you have to go for anywhere else and anywhere else. It's a large planet we have, right? So that means a lot of work waiting for you

  Marty Martin  28:35  

  The detective story. 

  Cameron Ghalambor  28:36  

  Yeah. So this Botai culture has this close relationship with the horse. They domesticate it, the culture collapses, and then we see the emergence of domestication. This would be like quite a bit southwest of the Botai region, 

  Ludovic Orlando  28:54  

  Northwest, northwest. 

  Cameron Ghalambor  28:56  

  Or northwest, but still in the same type of habitat. So I mean, you talk a lot in the book about, you know, the close relationship with humans, but in terms of the the main drivers of domestication is the sequence of events, sort of thought to be that horses were first hunted for food, and then they were sort of kept in enclosures, maybe to have a stable food source, and then they became a source of maybe milk, and then eventually transportation and warfare and all these other things, is that, would that be the kind of accepted sequence of events?

  Ludovic Orlando  29:40  

  By and large, absolutely. But I want to, I want to clarify one thing, not in a linear way, right? I mean, not like if there was a progress, someone at some point envisioning this sort of path forward. Basically all this came with a lot of serendipity, I guess so, because the environment was changing and the cultures involved, and so forth. So hunting first, absolutely, we've hunted horses for at least 300,000 years, us and Neanderthals, pre-Neanderthals and so forth. So horses are not an exception. We needed to hunt animals to actually survive our past and become the kind of species we have become. So, yes, the surprise is that it lasted for a long time, you know, to put that in perspective, cows were domesticated about, you know, 10,000 years ago, maybe 9,000-10,000 years ago, sheep and goats, 11,000 years ago, even pigs, 7000 years ago, you know. So by that, I mean that we had as humans made the transition to, say, farming and herding a lot earlier with other animals. The mystery with the horse is that this transition came in very late, about four to 4.5 thousand years ago. So it took a long time for people to realize, or to even need, what this animal had to offer, basically, you know. So I think hunting, fair. Then hunting plus milking, we shouldn't view, I think, that the minute you start to domesticate an animal, you stop doing what you used to do before with that animal, you know. And in fact, there are some regions where horses are still hunted today, you know. So basically, it's not once you have an innovation, you forget about the past. So there is a moment where you could do both. 

  Ludovic Orlando  31:34  

  And this is the way I picture the Botai people. They were settled hunter gatherers. We know that from the archeology. And when you're settled, you know, if your resource becomes thin, you don't have the luxury to go walk and found another place, because you're settled. So we think that because the horse population shrank, they were sort of forced to develop a sort of more resilient or sustainable relationship with this animal, because for them, it was a matter of survival. So you realize that if you picture the situation like this, it's not necessarily that some great minds of the Botai people came with a genius idea of, "Oh, let's do something out of the blue." It's probably because their environment required them to actually sort of adapt their life ways into what became the new situation. But those people is not just as a culture they vanished. They also vanished as people. We lose their DNA trace of humans also. So you have a situation where they did not make it actually, right? And so that's probably also why the horse could actually go back into the wild, survive into what we call today the wild animal, the Przewalski's horse. 

  Ludovic Orlando  32:50  

  And because of other environments somewhere else, you know, the climate change around 4.2 thousand years ago, the climate became a lot drier in the region of the southwestern Russian steppe, and so probably it triggered a sort of new series of innovations. I'm not saying that people, you know, were climate experts at that stage, but clearly their survival depended on them being able to find their food, move around and so forth. So if they were herding already sheep, cows, as we know, maybe by having the horse now as a mobility engine, right, as a sort of vehicle. Then for them, it became a lot easier, or maybe more possible, to go somewhere else faster. So that means to find some pastoral lands in an easier way than they could before. And so that was a sort of relationship that was purely driven, I think, by economy, right? What is it that I need to make it as a human group, basically? But of course, I mean we, I mean, you don't have a long history with horses, you said, right? But there are horse people around lots. And what strikes me with horse people is that they can actually communicate with the animal. You know, they have developed such a great perception of what the animal intends to do or is going to do, and so probably, you know, there is also this that was unfolding. Maybe some people felt attracted a lot more to this animal than to another one, right? Because they feel like one. And really, Horse people will tell you that a lot, right? I don't need words. I already understand that that sort of other, other kind, basically. And so 

  Cameron Ghalambor  34:32  

  The horse whisperer.

  Ludovic Orlando  34:34  

  Exactly. And so if you have these sort of things adding on, right? You don't necessarily need to have just one incentive, but actually depending on the region, for very different reasons, people started to interact their own way with this sort of new bloodline that was sort of engineered, where we said, like Southwestern Russian steppe.

  Marty Martin  34:54  

  Yeah. You said, just a minute ago. And this has intrigued me. I didn't know until reading the book that the horse was. Really the last major domesticate, right? So is it, in light of what you're saying, I think maybe I know the answer, but I'm wondering, do you think we can ever get to an answer about, you know, was it it's sort of ability to be a mode of transportation that the other domesticates don't really lend themselves to? Is that what sort of set it off and or is that also why maybe it took so long to domesticate this species when, you know, there was thousands of years of success with others. Is it just really hard for this species? Or why is that?

  Ludovic Orlando  35:32  

  I don't think so that it's really hard. And the reason why I'm saying that is that we did it twice, you know, and probably, and probably many more times, because we only see the successful attempts, right? We don't see those that failed, really. So, so probably, people have developed a number of interactions. And so also in our data, you know the one that kick started, what we call horse domestication, anywhere somewhere between 4-4.5 thousand  years ago. It's not so long, it's a few centuries, right? I mean, centuries sounds like, okay, it's a long time. But in fact, you know, it's pretty much a blink at the evolutionary timescale, basically. So because of that, I don't think it's so complicated. Also, you know, I can be backed up by some of my colleagues who have attempted to domesticate de novo, for example, foxes, silver foxes, and they managed to do that in really, a dozen of generations, which means in like in my lifetime, I could have domesticated that animal if I intended to do so. So I think we should. We should refrain from thinking that interacting with life around is so impossible, so difficult. In fact, you just have to find the right keys, you know, to understand enough of the animal so that you can have them start with their own agency, actually start to engage in this sort of bilateral human, non-human, animal relationship. So but for sure, with our data, what was the trigger was this mobility thing. Because, you know, it was a tiny bit of the world where you had this bloodline, and in 300 years at most, at most, all of in a sudden, it was all across Eurasia, from Spain, the Atlantic to Korea, the Pacific, right? So it's, it's insane in terms of how fast that thing went. And of course, when you have the horse, it doesn't give you only movement. Of course, you will have movements, but warfare will be totally upside down with the horse. Imagine yourself as a pedestrian at war, charged by an army on horseback

  Marty Martin  37:45  

  Yeah, you're terrifying Cam here.

  Ludovic Orlando  37:49  

  Right. It's one of my nightmares as well, right? So clearly, imagine this. So that means that even though you wouldn't have naturally engaged with the animal, now you didn't have the choice anymore. If your enemies have the horse. You have no choice. You must have it as well, otherwise you will be eradicated at war, right? So, basically, you can see yourself entertaining process that was a sort of evolutionary arm race that the horse started.

  Cameron Ghalambor  38:22  

  You mentioned the Silver Fox, and so maybe this is a good transition to some of the genetic methods that we that you use in sort of asking these kinds of questions. One part of the book that I found really fascinating was, you know, how the effective population size of domestic horses just really blew up after domestication, and that people really seem to gain control over reproduction of horses to really increase their numbers. But then also, you know, like in the case of the Silver Fox, the there, there seems to be also this domestication like syndrome, where maybe you're selecting for one trait, like, you know, maybe to be tame and not try to be maybe, like less aggression, as an example. But then when you select for this one trait, all these other traits, morphological, behavioral, physiological, also kind of get dragged along. So do you feel like, you know, we'll talk more about like specific genes. But do you envision that artificial selection or domestication, is causing a lot of correlated changes so that there's these combinations, or have the genes and the traits kind of evolved more independently and then kind of come together in different combinations?

  Ludovic Orlando  39:58  

  No, I think you absolutely spot on saying that they have interacted a lot, right? So basically, obviously, it will take more than a mutational change to transform an animal into something else. Of course, if you mutate one gene, you will have a trait that may be changed, or a series of traits, right? But interacting with an animal is complex. It takes the behavior, as you said, it takes also them to be compatible with the food that you're providing them with. It takes a number of things, right? And for sure, those things are complex genetically. And by complex, we mean they involve a number, a large number of variations, right? So, but in our data, what we see is that some of the earliest changes that we could spot involves genes that are involved in behavioral control, and so it fits with the model and your narrative, in fact, where you will have a sort of first step, where, naturally, you will select the animals that will be more likely to interact with you. As a breeder, Imagine yourself, right. You have the world as a choice. The world includes like, very wolfy, like horses and very, very gentle horses. Maybe you will naturally interact with the latter and not with the former, basically. And so even though they did not necessarily intend to select for such a tamer behavior, it was simply more practical for them to eventually interact with the more tamed ones, right? So basically, you have a scenario where even without understanding genetics, even without knowing anything like DNA or anything you will generation after generation, sort of purge out from your pool of animals, those variants that are the least likely to be compatible with your with your experiment, and you will enrich for those that will help you interact more and more so with the animal. 

  Ludovic Orlando  41:53  

  And so if you have a first step where behavior triggers everything, there is a number of studies that we could leverage now to realize that through behavior you have during the development of animals, you have a series of tissues and cell lines that will be actually reprogrammed as well. So it's not because you select on behavior that it doesn't change things as different as the size of a muscle or the skin color, for example, simply because, in the development, some of the tissues and organs that are formed, they depend a lot on the same primer  cell lines, if you will, right? So if you touch that cell line, you touch indirectly, all the descending lines, to some extent. And so that's how, by selecting one thing, you will have actions and consequences that will be multifaceted. And so there is this hypothesis that was made popular about a decade ago, of the neural crest hypothesis, which is neural crest is a sort of cell line that is very important during the development of mammals, because it will create cells such as melanocytes, the cells that give you your skin color or my skin color, but also other kind of stuff, muscle and other things. So by selecting on something that affects that neural crest, you will directly select for a series of other things. So we picture what happened as a first step behavioral, as something that was probably filtered through behavior, but co-affected many traits at the same time.

  Cameron Ghalambor  43:30  

  So those genes had a lot of pleiotropic effects, basically.

  Ludovic Orlando  43:33  

  Right. Exactly, exactly. 

  Marty Martin  43:35  

  So we want to come back to the genes, but I think that there's so many iconic horses, individual horses, historically, then we should talk about a few of them. I don't know if you have a favorite. I have a couple of suggestions, but do you have a favorite?

  Ludovic Orlando  43:50  

  It's hard for me to pick up one. You know, my favorite? Let me think for a second about this, right? I mean, which are the ones that I'ves loved the most working with so I guess it's a very hard one, because for me, you know, all of them were so important to actually unfold those questions. But I can, of course, mention immediately, I guess three and for three different reasons, right? So one is because I'm in France. I'm French, and we have this guy that we call Napoleon, obviously.

  Marty Martin  44:21  

  I've heard of him I think yeah.

  Ludovic Orlando  44:23  

  In the early 19th century, and this guy was, as you know, an emperor. It didn't last for long, but he was for a decade, an emperor. And he was a notoriously bad horse person, right? And so, but you have those portraits of him riding a very, very nice and aristocratic kind of looking like white horse, one of those is very famous because he won against the Persians at the Vienna, at Vienna. And so that horse has a name. It's called Le Vizir. And I happen to have sampled Le Vizir because, because we know where it was buried and We could, it was restored. And you could actually, if you travel to Paris, you could see it, right? You could actually almost touch it. I've touched it because we sampled it. And so this is one of those examples where it's not because it's Napoleon, but in fact, you realize here through this example, then you can touch history. I mean, the big history, the history of those people who have made the world we live in basically, right? And yet, that's just the animal that can show you this. So that will be my first example. 

  Ludovic Orlando  45:27  

  But of course, when it comes to horses and history, you have like legends. Think about Bucephalus, which is the horse of Alexander the Great, right? I mean the first steppe empire, transcontinental empire, of history somewhere around 2.3, 2.4 thousand years ago. If you think more recent in time, Genghis Khan, the great Mongolian empire, right? Also an empire that stretched from Hungary in Europe to pretty much China, right? So, thousands and thousands of kilometers, so, but I guess you know, this is the beauty of the horse, that in any place around the world, people have developed their own relationship, even the people who are not the big guys of human history, right? They had something that they developed, and only them developed with this animal.

  Marty Martin  46:14  

  Yeah. So I grew up in Virginia, and one of the special ones to me is Secretariat. It was sort of born not too far away from where I grew up. So but tell us maybe there's one that I thought was particularly interesting to talk about. Maybe two, because they're different in sort of their historical roles as Vizir and such. What about Aiken Cura and Kurt? Maybe? Tell us a little bit about those two. Yeah.

  Ludovic Orlando  46:38  

  So they are very interesting, both of them. I mean, the first one that concur, because that was a horse that was very important for the sport industry, basically, right? And so there are countries like mine where soccer is the actual big sport that people play, right? But there are some other places of the world, like Argentina, where they love soccer, but they also love horses, and especially polo, right? So, and in the Polo I didn't know this before I started to become interested in horses, but in the Polo industry, believe it or not, at the sort of equivalent of the World Cup, you have some teams that are made of horses, all of which are clones, right? So they derive from the very same original animal, basically, right? And they play officially, like some of the biggest competitions on the planet, right? So this example that you list shows us this, that today for horses, it's not just about history. There is a future that is unfolding now, right? And of course, genetics is not just a tool to let us know about the past. That's a tool that can influence the future of horses, especially in the Polo industry, right? Because more and more so, people are cloning their favorite horses for very good reasons. And maybe in a few years they will sort of engineer them, you know, in terms of, as opposed to select generations, over generations, it takes time, a lot of resources. Maybe you could shift the DNA text a bit so that you plug in the sort of new biological module to your favorite horse, basically. And this is a reality. I'm not talking about science fiction here. This is something that I've seen firsthand when I visit, and I have a chapter about this in my book when I visited some of the biggest companies doing some horse head genome editing and cloning. 

  Ludovic Orlando  48:34  

  And so the other one that you mentioned, Kurt, is also very interesting for the very same reason, because that's the first cloned Przewalski's horses ever. It has been cloned in Texas, actually, so not far from where you are. And it was cloned about four years ago, if I remember very correctly, around 2021 and this one particular horse was cloned, you will think, Okay, why on earth would you clone a Przewalski's horse? There are 3000 of them today, all of which descend from 12 to 15 founders, you know, so not so many. Imagine the human population reduced to 15, and this is like 3000 of us later on. So not so many. Why would you clone something? In other words, that is already super clonal? But in fact, you know, the people who have started doing that, they realize that by cloning, especially if that was females, so that's not the case for Kurt, but you have to think for longer term. So if you were to clone females, all of in a sudden, that individual, that copycat of the same genetic combo, right, will be given the possibility to reassort their genome with many different males, basically. So in one generation, could create a sort of reassortment of gene combinations, basically. Whereas in the real world, you will have to be waiting many generations for that individual to keep reproducing. And there's only so many generations, any given individual can reproduce, right? A mare will, you know, maybe, will get to reproduce, maybe three, four times during their lives, and never, an infinite amount of time. So there are people around who are actually trying to leverage the tools of modern reproductive biology, including cloning, but also genome editing, to sort of help safeguard some of the lineages that will be threatened otherwise.

  Marty Martin  50:33  

  Yeah, yeah. And Cam wants to talk, maybe more specifically, about some of the genetic variants that you've done, but we can't ignore the mules. I really would think it was a missed opportunity to sort of move right by the mules. So again, growing up in Virginia and Washington, George Washington's fondness for mules. How about Lord Fauntleroy? I mean, just in general, Tell us. Tell us about the importance of mules. It may be him in specific.

  Ludovic Orlando  51:01  

  No, I mean, I'm very glad that you bring that up, because, you know, I have one chapter, and I call that chapter the other horse, and the other horse is mules, basically, because we owe them so much in our history, right? So, because you have to realize that we think about horses are the noblest kind of animal on earth. And I'm quoting Comte de Buffon, who was a natural biologist living in my country in the 18th century. Anyway, so we think about the horses and the speed and everything, but if you think about mules, and normally mules, you immediately picture them, in French, being a mule means being stubborn, right? It means, like, literally, it's very pejorative. It's something that you don't want to be qualified, like being a mule. But, on the contrary, when you are close to mules, you realize that there are a lot more sure footed than horses and donkeys. They don't need much to actually thrive, in terms of volumes of water, in terms of feeds and so on and so forth. And they can, because of that, they can survive pretty extreme environments, you know. So they could go and run for, like a very long time indeed, not the fastest on the planet, but certainly some of those animals with the highest stamina, probably, you know, the largest endurance, I guess. And of course, because of those qualities, people in the past leverage the mules. 

  Ludovic Orlando  52:24  

  The problems of the mules, though, is that they come with one very difficult thing, is that you can breed mules in the sense that if you take a donkey, Jack, so the father and horse, mare, the mother, you reproduce them with each other, it creates a mule, be male or female. But the big problem with that individual is that it cannot propagate. It cannot reproduce, so it will be sterile, right? So of course, if you need mules, you need to be very motivated to produce them, because you need to have donkeys and horses, right? So you need, in other words, to be knowing what you're doing in terms of controlling the reproduction, but you probably need to be wealthy as well, because you need to sustain two parental populations instead of one, right, basically. 

  Ludovic Orlando  53:09  

  But nonetheless, there are moments in history, for example. So going back to your direct question, there are moments in history.  And the history of the US is very much a history where mules played a big role. Imagine the vast lands of Northern America somewhere around, you know, of course, you just mentioned the late 18th century, early 19th century. But in fact, even earlier than this, right? You have thousands of kilometers around. It makes your life easier to grow across these lands if you have mules, especially in landscapes that will be mountain landscapes, for example, right? So, of course, they have played a lot, or a big role, moving people around, goods and more diseases as well, but even earlier in history, right? If you think about, for example, my country, France, you think about the Roman period, probably, you know, the first century before our Common Era, to the fifth century of our Common Era. This is a moment where mules are ruling. You know, you have pretty much a third of the equites are mules, and the two thirds are horses. So they are almost equivalent to horses. And the reason is that the Roman people, those who had this Western European empire that we call the Roman Empire. They had an empire that stretched over thousands of kilometers as well, and they had to maintain their frontiers with their enemies, basically. And so it was key to have an animal that could carry for thousands of kilometers, you know, weapons, all the things, food and so forth, news that you need to keep using when you are at war, basically. And what is really striking is that when this empire collapsed, so when the incentive to really use the key features of that animal vanished, well, we don't see the mules anymore. People do not produce mules anymore in my country. So in the Middle Ages, mules are gone, to some extent, because the economy has become a lot less global, but the more a lot more local, basically. So you see how economy and really the incentive what people wanted to do. Well, they found ways to exactly achieve what they wanted to achieve in a sort of economical way we can.

  Cameron Ghalambor  55:22  

   We could spend many hours, I think, talking about all the various breeds, but maybe let's sort of transition into one breed, the Arabians, and how they were sort of iconic in terms of being bred for endurance, but also as a consequence of being bred for this endurance, there were also maybe some some drawbacks to that. So can you talk a little bit about why is it this particular breed of horse has such high endurance relative to other breeds, and then maybe also some of the negative consequences that maybe came along with that?

  Ludovic Orlando  55:59  

  Sure so that will be not necessarily specific to Arabian because the same could apply to many other breeds, basically, that we have selected for one purpose. But by doing that, of course, we could not control for all the sort of side effects that came with it. But the Arabian horse is a good illustration of that. So let's discuss about this one. So the Arabian horse is world famous for the way it looks, you know, it looks very different to other animals, like it has a very different profile, and it is like very thin legs and a very high tail, for example. So the minute that thing was invented, it became really popular, you know, and that we see in our data, because it spreads with the Muslim expansion in the night in the ninth century throughout Europe and also throughout Asia. In other words, people really fancy this sort of nice looking horse. And even myself, when I see those animals today, I can't help myself to find them really appealing, you know, they are really elegant animals. So for that reason, people have selected them. But also obviously, given where they come from, the Oriental lands that are very dry, very arid, deserted, kind of landscapes, people have selected them for endurance. As you were saying, you have to realize that typically, an Arabian horse race is not a horse race that will go for a couple of miles, you know, it will be for 120 or 160 kilometers, right? So, 100 miles, basically. So these animals can actually run pretty much forever, you know, in and so obviously that makes them super appealing. 

  Ludovic Orlando  57:38  

  So the same kind of work that I've been doing to try to answer, when, where, how did we domesticate the horse? People are actually using genetics to answer different kinds of questions. And, for example, one of the questions they are interested in is, what makes this physiology of the Arabian horse so different to the one from, I don't know, the Quarter Horse, which is some of the fastest horses on the planet as well, but not as endurance, for example. So, and they have actually listed a number of genes and biological pathways where they can tell, okay, this was heavily selected, okay? And so I don't necessarily need unless you want me to do to let you to go through that list, but you have a diversity of biological characters that are driven by that list, right? So things involved in the way cells, for example, will detoxify as they're are doing the muscular effort. You know when you, for example, maybe, maybe you're a runner, right? And when you run for too long, you realize that the next day you have pain in your muscles, right? Basically, this is because your cells have not done what they were supposed to be. They had there was they were supposed to do. They accumulated some acid, for example. And so those cells, for the Arabian horse, they are champion at removing this sort of acid that is formed during the efforts, for example, which helps them keep running for longer. 

  Ludovic Orlando  59:01  

  So these sort of things are very well understood. Of course, not everything has been understood, but genetics has helped people move forward. But at the same time, when you select for, imagine one letter somewhere in the DNA, well, you will probably coselect for all the other letters that are joined to this letter, right? Simply because they are seated in the vicinity of that letter. And of course, those letters, not all of them, drive something interesting for you, right? Some will have some neutral effect. You don't care. It doesn't change the biology, but some will have a slightly or a more mild deleterious effect, something negative, right? And so what our work has shown is that is true for the Arabian horse, but it's equally true for pretty much all the breeds, those that we have created in the last, say, 200 or 300 years, there is an inflation and excess of deleterious mutations in the DNA of those breeds today. In other words, if you sequence the animals like 300 years ago or now, what you will see is the trace of these adaptations, those we favored, but at the same time, those that we couldn't remove because we were doing the selection that the selection process that way, and those we couldn't remove, many of those are actually deleterious, which is actually another thing that I should stress, is that the kind of work we are doing, it's not just for the sake of fundamental science. You realize here with this example that it could have applied consequences, because we could identify those mutations that we may focus on to try to remove them from the gene pool of those particular breeds to sort of improve, long term, their genetic health.

  Marty Martin  1:00:46  

  So we've hit a lot of the conspicuous characteristics of horses, and color is definitely one of them, from the spotting in the Appaloosa to, you know, just the general but one of my favorite examples from your book was you sort of cite revelations, and you talk about the four horse, four horses, usually say horse men, but four horses of the apocalypse. And I never thought about it before, but it's, you know, the red, the black, the pale and the white. And so, you know, you use that as a setup to this melanocortin receptor gene. And you know, we could talk maybe about the TRPM and the Appaloosa. Just tell us what we need to know about horse colors and the sort of major ways that your research is revealed to genetics underpinning that.

  Ludovic Orlando  1:01:26  

  So the first thing to say, I guess, is that we, like the community, the research community, understands a great deal of what are the genetic drivers of horse coat coloration like it's not the case for many systems, but in horses, we do. So that means that those very mutations that are causal, not associated with really causal, for leopard spotting, for being a black or chestnut or a white horse, or a grullo, all this is very well understood which, which is a sort of advantage for people like me, because we didn't have to discover what was the role and what were those mutations in the first place. Our take was more knowing which mutants, which mutations drive the traits. You will, if you have DNA, be able to predict the color of an animal in the past. It doesn't look like much, but in fact, it is a lot, because you realize that colored photography has been invented very recently in human evolution. In fact, photography even was invented in the second half of the 19th century. So that means that before the 19th century, we have no way to tell the color of a horse, you know. And so because of that, you have a number of models that people have promoted, such as, oh, colors were so important from the very first day, because, as a herder, I need colors to count my horses or to know which is which, basically, if they all look like the same, you know. And it doesn't look like necessarily stupid to think like that, right? So you realize that with the DNA you have, in the case of the horse, the chance to be able to predict traits that do not fossilize. You know, archeologists, archeologists, they see bones and teeth, never flesh. But with the DNA, to some extent, you can predict with high accuracy the color of your horse. And so I can list you at least one or two examples about what we discovered about this. 

  Ludovic Orlando  1:03:28  

  So, for example, and I will stretch my example as far back in time as I can think about, imagine yourself as a hunter gatherer living 22,000 years ago in Europe. It was the last glacial maximum around you. You know, it's not like a very, very it's not the world was very different. And some of them started to paint animals on the walls of the caves, right? So basically, we call that parietal art. And you see animals coming in different colors, in different flavors. So you have Bay horses, the most frequent color ever with horses, the sort of brownish kind of color. But you also have, in some of the caves that are near where I live, 200 kilometers here from my house in southwestern France, where you see leopard spotted horses. It's just that they were painted 22,000 years ago. So of course, people, paleontologists this time, thought, "Okay, is it like that horse existed?" In other words, is it a sort of early form of photography, this sort of cave painting they were doing, or is it a sort of fantasy horse that I'm seeing because maybe that coat coloration did not exist? So you see that with the DNA, there's no way without DNA you can answer this question. It's too complex. There is no photographs and so forth. But with the DNA, if you sequence animals that were around that cave, maybe you will be able to tell whether or not leopard spotted existed at that time. And what strikes me is that when we and others actually did that work, we found, yes, indeed, they were around. So probably you realize that through this work, which is starting from horse coat coloration, it gives yourself a chance, not only to put colors on the past, but in fact, to put yourself in the minds of the first artists, right, basically, what is it they wanted to achieve? Is it just painting nature or representing something supernatural, something that could not exist? And in that case, we could demonstrate it was probably a naturalistic representation of the world. And that example, I could decline that at will for every single time period. But of course, we've been doing the same for every single time period. 

  Ludovic Orlando  1:05:40  

  And so getting back to the four horses of the Apocalypse, we actually tracked which colors were the most popular during the middle Middle Ages in Europe, basically where the archeological record is the most the most important for that time period. And so our idea was, do they come always with the same frequency those colors or not? And the reason for asking such question is that colors in horses are not random, you know, especially in the case of the four horses of the apocalypse, you know, there is one that is actually plague, right? Bringing plague to men, to humankind, basically, so killing a lot of us. black will be, you know, the strength or the war coming in, and so all the different surges of this world. So probably, if you have such a mindset, very heavily influenced by the Christian religion at that time, maybe you will fancy having a white horse more so than the other horses that will bring play, basically. And so what we found, to make a very long story short, is that, well, the colors were not static. There were changes in frequency through time. So it means that there were some colors were fashionable and some were absolutely not bankable, depending on the time period. And, for example, the one of the colors that we sort of like today, the chestnut, you know, those red horses you talked about Secretariat a while ago, right? He was a chestnut. This particular color change in popularity through time and it was a lot less frequent in the beginning of the Middle Ages. It became a lot more popular later on and then declined again through time.

  Cameron Ghalambor  1:07:24  

  So I'm curious if we go back to the ancestor to the domestic horse. So obviously humans had some control over crossing different different individuals and maybe having some control over then the color patterns. But = in the sort of wild ancestors to domestic horses? Do we have a big enough of a sample size to know whether there was segregating variation in the genetic variation for these colors, or was there more like fixed color pattern differences geographically in different areas?

  Ludovic Orlando  1:08:05  

  No, I mean, that's a very fair question. So, of course, when someone asks you, do we have enough information, the fair answer will always be "No", right? We need more, right? But we have sequenced now close to probably 300 ancient horses from before the domestication time, and that goes from the Americas into Eurasia, basically, right? So assuming that those 300 or so are enough, what we could definitely tell is that there is segregating variation in pretty much all the regions, right? So for example, these TRMP9 mutation that actually is causal for Leopold's protein. This mutation was actually in Western Europe, in France, but also in Germany, and also as far east as the Ural Mountains in western Russia, somewhere around 15 to 30,000 years ago. So clearly, these variants were probably segregating in the ancestral population to them all before they actually differentiated into independent lineages. The same goes for the Botai horses, for example, that very mutation segregated within the Botai of course, at different frequency. It was a lot rarer in the Botai horses. It was a lot more frequent in Western Europe. But at the end of the day, these mutations, pretty much all of them were co-segregating. There are exceptions. Obviously, I'm not saying that everything was co-segregating forever, but you have to picture the past as a lot more diverse than what we want it to be in general, right? We think that the past because it's the past is probably less complex, less advanced, somehow, than modern times. In fact, when it comes to horses, it's a lot more diverse in the past than it is today, because this domestication process acted as a sort of massive bottleneck that reduced the range of possibilities for horses. 

  Cameron Ghalambor  1:09:56  

  Yeah. So I guess, yeah. My motivation, I guess, for asking. That question was just that a lot of the color variants were already there, as opposed to being new mutations that arose after the domestication process started. 

  Ludovic Orlando  1:10:12  

  Yeah. So this is true for those we have looked at, for example, the many mutation driving the white coloration were segregating, not for a long time, not for 20,000 years ago, but a few thousand years before the domestication, they were around. The same goes for the chestnut mutation. The same goes for a number of mutations that are actually even driving beyond coat coloration, the differences even some genetic disorders, you know. So some of those mutations were around. But it's also one of the mutations that we've spent years of our lives studying was segregating for at least a thousand years, two thousand years before the domestication, and that mutation, we could demonstrate, was a sort of driver for the rise of horse-based mobility. Right? That was a mutation which had a number of effects, but amongst the effects that were the most striking is that it eventually made the horse back flatter and also increased dramatically the motor capacity of the animal. We can measure that. I mean, we've done funny experiments, I guess, for measuring this, where we put this mutation in mice using genome editing to see how it will change the mice. Of course, they don't transform them in horses, but you see that the curvature of the spine is very different. It becomes flatter. That's how we can say this. But also, you can measure the strength of the limbs in mice. You could actually train them so they can learn how to run on a rotating device, for example. And when you do that, you realize that this mutation eventually makes them able to keep running and running for longer than they could without the mutation. So clearly, there were mutations that were around. They were segregating. None of them really crossed the human agenda, right? They were around. But at some point in human history, in that specific region of the world, the southwestern Russian steppe that we mentioned 4000 years ago, they came across the human agenda. Now people realized, oh, wait a second, those animals, they didn't know they were carrying those mutations, but what they can certainly tell is that their motor capacity was actually enhanced to some extent. And this is where people leverage the possible is the genetic possibilities that were naturally offered to them.

  Cameron Ghalambor  1:12:35  

  I guess I should add that the, I think what you were talking about is this GSDMC locus and and for our listeners who are interested in learning more about that, you recently had a paper in Science that talks about this work, so we encourage people to go check that out as well.

  Marty Martin  1:12:52  

  Well, one more gene, and then we'll turn sort of really directly to what horses have meant to us, although this is definitely a gene that meant something to us. Can you talk about DMRT3 briefly and ambling? Because, I mean, that's sort of just a it's such a quirky story, but such an important change.

  Ludovic Orlando  1:13:11  

  Yes, I remember myself reading that paper in Nature in 2012. I'm not the author of that discovery, so I can actually say all the good things that I truly mean about that work. You know, it made the cover of nature, which is rare enough to stress, basically, and those people. So that's a group led by Leif Andersson in Uppsala University in Sweden. They actually worked out all the biological mechanism that are underlying the rise of ambling in horses. 

  Ludovic Orlando  1:13:39  

  So, what is ambling? So, ambling is a particular gait that some horses have, right? So horses, if you have been on the horseback once in your life, you realize that they move their legs in diagonal, right? So the fore left with the back right and vice versa, right? So, but the amblers, the natural amblers, they don't do that. They will do they can do that, but they can also do a different kind of gait, which is the same legs of the same side walking together, so they bring the left legs together and the right and so on and so forth. And when you do that, the it's easier for you to ride the horse, because the horse doesn't jump up and down at each and every step, basically. So it's a sort of smoother experience of horse riding. And so the same way as we could leverage the knowledge that the other labs have discovered on what drives genetically a trait, we could know the mutation that drives ambling to actually tell did the horse amble at a given point in history? And again, this is what really fascinates me, the capacity we have to with DNA to see beyond the bones and the teeth. Basically we see movements, which is mind blowing to some extent, because what we discover as archeologists is dead bones. Right so, but you see movements, and so when we do that thing, and, of course, I don't want to insist, but when it comes to the biology, those people have done a lot more than just discovering the mutation they have explained the genetic pathways that reprograms where neurons will actually, you know, interact with other types of cell to transmit the nervous message to the right muscle, basically, so that the leg will be contracted at the right pace. Basically, it has, it's not just again. For the sake of fundamental science, you know, some trotters who are amblers, are also those that are more likely to win the races. Basically, you know? So it also improves racing performance. So it can actually gives you quite some financial incentives to really understand what this mutation is doing, basically, right. But for us, we just tracked when that mutation emerged. And, believe it or not, right, this mutation was not around, it seems, before the ninth century. So it's a mutation that actually emerged we don't already where, probably somewhere around Northern Europe or UK, and then it became more fashionable during the mid-medieval times onwards, right? And so we find it in UK in the ninth century, but then in the 12th and 13th century, they are already in Mongolia, for example. Not all horses will become amblers, but some of them started to carry this mutation in a larger geographic range than it used to be. I should add one thing is that not all horses are natural amblers. You could also, if you're a horse person, train your horse to become an ambler, right? So you could actually train that during their life. But some are really natural amblers. And in some populations I'm talking about, I'm thinking about the Colombians or Peruvian Paso Finos, you will see that those horses are really dancing with ambling, basically. So, yeah, so

  Cameron Ghalambor  1:17:05  

  Obviously, the history of horses and the history of humans are so intertwined. You know, you talked in the beginning of the book about, I think it was a German philosopher or historian that referred to the sort of pre-Calambine versus post-Calambine age. So pre-horses, post-horses. And I, you know, after reading your book, I couldn't help but agree with that completely, and right out of the in the first chapter, I mean, you, you really caught my attention because, you know, you, you, you remind the reader that it was not that long ago that every city in the world was full of horses doing very important things. You know, I think most of those tasks have been replaced by cars and trucks and things like that, but we forget about just how important the horse was. But if we go back even further, and we just think about even distribution of human languages and how language has spread, that history is also very closely tied to our relationship with horses. So can you speak a little bit? Maybe a favorite example of how language and horses share this common, common history. 

  Ludovic Orlando  1:18:27  

  Yeah. So, I mean, this is a, I mean, there's a book to write about that very question, in fact. For me, it's a couple of chapters only, but there's a lot to be told here. So the first thing is, how important horses were yesterday. Indeed, they were massively important. My favorite example for illustrating that, not that I like the example, because it's really a bad situation, but since you are in America, I cannot help but telling this story that in Boston in November 1872 there was a very important flu, also across the Americas, equine flu. So a horse flu, right? And so it was not nasty for horses, but, like, most of them became sick, so they survived, you know, like, it's only three, four percent of them who died from the flu, but they were sick for a couple of weeks, actually for three weeks. And so if you have the horse population in Boston at that time, but that will be the same in New York, in every big city across Northern America and across the world, in fact. You will realize that there is a number of things we couldn't do anymore. So that means that the economy of a whole city could not work. Think about, you know, the things you move across the city, the people that go to work and go back to the suburbs or areas, think about even firemen, they could not actually go across the city and do their job about, you know, fighting the fire. And at Boston, because there were no firemen that could be used the fire engines, because there were no horses to move across with the fire engines, well, a whole neighborhood was lost to flame. And this story, I could actually change Boston for another city, or change the date for another date, and I can tell the same story ever and ever again, anywhere else in the world. 

  Ludovic Orlando  1:20:14  

  So indeed, yesterday, it was really an important animal for us, and including up to the Second World War, we tend to think that horses were not useful at all from the late 19th century. In fact, just the German army lost four millions of horses in the Second World War, right? So even though we had Panzers and planes and everything, we also had horses in big numbers. So that's the first thing I wanted to say, and that's why I think, like the person that you just mentioned, there was an age of before the horse and an age of after the horse. It's sad to some extent to think along those lines, because clearly now we are at the age of after the horses were deprecated. So it's a third kind of age for humankind, because we don't use horses so much so anymore, but not so long ago, they were critical. 

  Ludovic Orlando  1:21:10  

  So about languages? Well, there is tons of things to tell here. I think the story that I report the most about in my book is the one about Indo-European languages and their rise. So Indo-European languages are some of the most diverse language family on the planet, the language that we are using today, English, but my language, French or Italian or even Sanskrit are Indo-European languages, and there's a whole diversity of such languages. And there is a question about when that mother language started to spread, to differentiate into all those different languages that I just named, right? Hundreds of them. And so if one common ground to all Indo-European languages is to have some words that are associated with horses. So it could be four legged animal referring to the horse, but it could also be some kind of colors that only exist for horses, or the association of that animal and chariots, for example. And if you find such vocabulary common to many Indo-European languages, chances are that it was spoken in the modern language, the proto Indo-European language, before it expanded across the planet and differentiated so for a long time. In fact, for more than 150 years, people have related the expansion of this horse that I mentioned, the domestic horse, with the expansion of Indo-European languages, right? Because the vocabulary could spread that way. So people have done the same work as we've done on humans, not horses, so the people speaking and not the animal that was spoken about. And what they discovered is that indeed, there was a population of humans living in pretty much the same territory as the proto domestic horse, if you will. That expanded about 5000 years ago. Those people expanded in big numbers, so much so that by expanding, they reshaped the genetic landscape of Europe massively, somewhere around 5 thousand years ago, 4.7 thousand years ago. In our work, we don't deny that those people expanded, for sure they did. I mean, we also did some human work, so we actually agree with this model, but we see that the horse becomes a thing a bit later. The horse expands around 4 thousand years ago, 4.2 thousand years ago, which is at least 500 years or more later than what I've said. So we have a situation that is more complex than what I've just told it's not people and horses expanding hand in hand at the same time, with the horse giving an advantage to the people so that they can conquer larger areas. But in fact, this is in the same region first the humans expanded, maybe with a few horses that we cannot, I mean, we cannot rule out the possibility that horses was not the key driver, but were involved in this. But what we see in our data very clearly is that later on, the horse became another thing. It became this sort of mobility agent that helped people move across. And so what is interesting when it comes to languages is that by 4.1 thousand years ago, around 4.2 thousand years ago, there are people that have a particular material culture. So the material culture is what archeologists can find in the excavation, you know, the way they buried themselves, or what kind of pots they were making, and this sort of artifacts they were producing. 

  Ludovic Orlando  1:24:48  

  And so if you think about southwestern Russian steppe, where horses were invented, basically, we see that at that time, not only horses expand into Central Asia and into East Asia, but also people. Those people have a name. They are called the Sintashta. They were probably Indo-European speaking people. And those people, they had the chariot, they invented the spoke wheel. So the spoke wheel is the kind of wheel that is not plain so light wheel that horses can actually pull, as opposed to the plain wheel that only cattle can actually pull, because they are so massive and so heavy. So we have a situation where people, not the early wave of people spreading because they spread before the horse, but then the second wave that actually also had this sort of indo European language spread with the spoke wheel and the horses and gain a larger territory across the steppes.

  Marty Martin  1:25:49  

  There's so many things to talk about. We've only, well, I guess we've a little bit more than scratched the surface, but not much. I'm getting mindful of your time. And so instead of asking you about horse conservation, and believe it or not, horse as pests, there's many things we could talk about. Is there anything that you wanted to hit that we haven't prompted you to say any particular topic or favorite breed or anything like that?

  Ludovic Orlando  1:26:13  

  No, I think I just want, I mean, thanks for your time and the questioning I enjoyed, really, my time, really. The thing is that I want to add, if anything would be what I discovered in this scientific journey, right? I mean, we started this for understanding better our relationship with the horse, when, where and how. I started with those questions with you today. But what I discovered on the way, something totally different, is that really the power that the horse has to bridge people, basically. And I could see that firsthand, you know, because, I mean, in my work, I've been traveling across the world, literally in Northern America, working with First Nations, in Mongolia, working with horse people there in China and so on and so forth. And I don't speak their language most of the time, you know. And this is really striking to realize that when they realize what you're interested in is the horse, then all of in a sudden, without words again, you start communicating, because the horse is the bridge, basically. And so this is this power that this animal has. Probably other animals have similar powers. But for me, in my personal experience, this was a reminder that life is around you know that in my life, daily life, I hardly come across, you know, animals, plants and everything, because I live in a city, but at the time of the world being threatened with a biodiversity crisis and everything, I found it not only just refreshing, but reassuring to some extent, that some other life forms, including the horse, were around and were only asking for more probably sustainable interactions with us. 

  Marty Martin  1:27:54  

  Excellent. Well, that's a great that's a great note to end on, and the book is so incredibly inspiring. That message is just is throughout. It's really a fantastic read, yeah.

  Cameron Ghalambor  1:28:03  

  And so the book is published by Princeton University Press and is available now. Marty and I really, really enjoyed it. And thank you for taking the time today to talk to us.

  Ludovic Orlando  1:28:16  

  Thanks for having me. That was a pleasure. You.

  Cameron Ghalambor  1:28:38  

  If you like what you hear, let us know via Bluesky, Twitter, Facebook, Instagram, LinkedIn, Threads, or leave a review wherever you get your podcasts, and if you don't like something, we'd love to know that too. All feedback is good feedback.

  Marty Martin  1:28:52  

  Thanks to Steve Lane, who manages the website, and Molly Magid for producing the episode.

  Cameron Ghalambor  1:28:56  

  Thanks also to Caroline Merriman for help with social media, Brianna Longo, who produces our awesome cover images, and Clayton Glasgow, who blogs about topics covered in the main show. Check out his work on our Substack page.

  Marty Martin  1:29:08  

  Thanks to the College of Public Health at the University of South Florida, our Substack and Patreon subscribers, our donors and the National Science Foundation for support.

  Cameron Ghalambor  1:29:17  

  Music on the episode is from Podington Bear and Tieren Costello.