Are rural raccoons becoming domesticated?

This is an iHeart podcast. Guaranteed human. Desk Divers, school runners, Jim Gurley's, breakfast is over. The long road to lunch begins. Your patience is thin, your stomach empty. Get yourself a Muller Light Boost Bowl. Greek style yoga with a delicious layer of real fruit compo, added vitamins and 10 grams of protein. All topped with a bit of granola. Because 11 a.m. Well, that's crunch time. Mmm, stunning. That sorted me out. Muller Light Boost Bowl. 18 month contract. Prices may vary. Verify at gigaklear.com. Howdy, Extraordinaries. The pop science community was alight recently after a paper came out that found evidence suggesting that raccoons are showing signs of domestication. Now, if you've been listening to our recent Listener Questions episode, you know that I'm wary of raccoons as pets, in large part because they carry a nasty parasite called raccoon roundworm. But what if raccoons are starting down the road to domestication and we can get rid of that parasite in domesticated raccoons? I don't see raccoons producing any valuable product. We probably won't be raising meat raccoons or dairy raccoons anytime soon, for example. So that probably leaves raccoons as pets, which sounds super cute. So will our children or grandchildren be taking their pet raccoons on walks when we're older? And just how far down the domestication trail have raccoons actually traveled? And, you know, while we're at it, taking another step back, just how well do we actually understand how domestication works in the first place? We're gonna dig into all of those questions today. Welcome to Daniel and Kelly's Domesticated Universe. Hi, I'm Daniel. I study particles and aliens, and I consider myself only partially domesticated. Hi, I'm Kelly Weenersmith. I study parasites and space, and I consider myself mostly feral. You do round up to a wild animal, don't you Kelly? I think so, yeah. Has that changed since you lived on the farm? Uh, you know, for a long time, it has been the case that you probably shouldn't bring me nice places, because I will say inappropriate things. I don't know that it's gotten worse. But you don't like poop on the furniture, do you? No, no, no, no. But I guess the probability that I talk about things like prolapses has gone up since I moved to a farm. So do with that, would you will. And we just set a record for zero to prolapse in like 30 seconds on the farm. I don't think that's a record, Daniel. I think I probably talked about prolapses in the intro already. What is the pearl of prolapse anyway? Is it prolapses really? Uh, I don't, it's not good. I don't, I don't know. I don't know. It feels like you should upgrade from prolapse to like, you know, what's beyond professional expert lapses or something. Oh, yeah. Well, you know what is good? What is good is our discord community. Yes. And their curiosity about the universe. That's right. And what's even better than good is our discord moderators. Oh my gosh, heavenly. Yes, they're amazing. They keep the conversation civil. And our community asks the most amazing questions. And one of our amazing moderators is Matt McCain. And he noted that there's this Popsae article going around the webosphere or whatever about how. About how raccoons appear to be becoming domesticated. And then there was this follow up where there was a video where this woman was very angrily talking about how. No, raccoons are not becoming domesticated. This paper was junk. And Matt was like, Kelly, we need the DKEU treatment. Hit us with it. Which means Kelly does like 20 hours of research and nerds out about this in fear of not being able to answer a question. Well, but so here's the thing. When I got that request, I was like, oh, finally something easy. Because the background for this paper is like the Russian Farmed Fox experiment, which I learned about in grad school. And I was like, bam, I know all about this. This is ironic foreshadowing. Oh my gosh, yeah, it took 20 hours. It took 20 hours. This was a lot. I have a theory that it's always 20 hours of research with you. Yeah, because everything has loose ends and you're like, wait, but what about this? And I wonder, and this is my question for you today, how much of that is driven by curiosity? You're like, wait, I need to understand how this thing works and how much of it is driven by fear. Ah, 50-50, I think. I think it's yeah, it's a little bit of both. I mean, part of why I love this show is that it's like I have an excuse to research something and dig in deeper. And then another part of it, especially when it's something that like overlaps with what I studied in grad school. Yeah, that you're supposed to know. That's right. Like if I get it wrong, it's going to be particularly embarrassing because they're going to be like Dr. Wiedersmith, you have an excuse for not knowing the medical stuff, but this, this. Would you ever get emails from your colleagues, other parasitologists who are like, actually, Kelly? Never. Not once. Really? All right. Hey, that's good. That's good. Well, maybe they don't listen. You sound disappointed. Maybe none of my friends listen. But, but no, so, you know, I should worry less, but I just, that's not, that's not my M.O., man. I'm anxious, but feral. Anxious, but feral. I need a T-shirt. Well, today we are going to worry our way into an understanding of domestication and whether raccoons are on the path to being the next dog. That's right. And we are going to start with confusion and end with confusion. That's where 20 hours of research got you. That is pretty, but well, that's where the field seems to be right now. And so what's amazing is that like the confusion starts at what is domestication? Okay. So let's start with that because I have a naive understanding that domestication is like my cat lives in my house and couldn't survive in the wild. Is that how scientists see domestication? Yeah. So that, that is one definition. So one definition I came across was essentially like a domesticated animal is an animal where essentially if you kicked it out of human habitations or humans weren't taken care of it anymore, it would die. And then trying to figure out the process that led to that is what you're studying when you study domestication. All right. Well, does that definition actually make sense? Because now that I think about it, I don't even think it applies to like cats. We've had cats that like just disappeared for a year and they seem fine. Exactly. Right. And so that is why this stuff gets complicated because there's plenty of cats that can live on their own and there are feral cat colonies. My goats would probably kick the bucket if they were out there on their own, but there have been, for example, pigs that get out and then they start wild boar groups. And so the question is, were they ever domesticated if that was the definition? And so you can argue about that definition. Yeah. And I remember visiting Tahiti for a boonduggle conference with my daughter and Hazel's favorite thing about Tahiti was not the beaches, was not the coral reefs, was not the sting rays that would like swim up to the water. It was the wild dogs. There were dogs everywhere and she would pet them and they would love her and they were friendly, but they were also wild. Like they weren't living specifically in a human house, but they were also definitely connected to human society. Right. So they were dependent indirectly on humanity. Does that count as domesticated? Well, first check out our rabies episode for why that story is giving Kelly a hard time. For why that episode is increasing Kelly's blood pressure. But I mean, so they came from domesticated animals and they are, you know, maybe becoming less domesticated. But I think they would still, a lot of people would say they still count as domesticated dogs. But so let's go ahead to the definition that I'm going to use today. Right. What's that? So this is like a two part definition. And this is a definition that was sort of forwarded by Darwin and is still popular today because Darwin was one of the first people to start thinking critically about this domestication process. And essentially the first step of the process is that the animals start spending time near humans and they start to develop traits that allow them to spend time near us. So for example, they become less likely to run away. They become more adapted to, for example, eating or garbage. They become less aggressive because if they're attacking us, we're going to shoot and kill them all, for example. And so the first step is essentially them domesticating themselves and acquiring traits to spend more time in proximity to us because there's something about living near humans that they benefit from. Does that make sense? It makes sense. But the whole thing makes me wonder, like, why do we worry so much about the definition? Is it important that we draw a dotted line and say this thing is domesticated, this thing is not? We have a super crisp definition of domestication. I mean, I know every philosophy conversation starts with definitions, but in this case, why can't we just treat it as a spectrum and like there's more domesticated and less domesticated? Why do we have to say like this is domestication? Why is it important? Does it inform the science we do later? So this definition isn't a clean gradient, but it does have steps. And so you can ask where along this process is a species. And it becomes important to nerds because, for example, initially I thought this episode was going to start with a deep dive into the story of dog domestication. And so I spent a week reading about that before I went back and read the raccoon paper and I was like, oh, of course I need to start with the foxes. And then I was like, you idiot. And so anyway, turns out dogs domesticated, we think about 15,000 years ago. And I'm so glad I get to use some of that information now. So we're sure that 15,000 years ago during the place to see and we started domesticating dogs, but we think we might have started domesticating them as early as 40,000 years ago. That's a big difference. Huge difference, right? But so then the reason that we're having that debate is because the question is like, well, they kind of looked like wolves. And so at what point, like what combination of traits and behaviors do we need before we say that's a wolf and that's a dog? And like, what is the cutoff? And so we use things like what does their face look like and how were they interacting with people? So for example, if a dog is buried with a person or, you know, if an animal that is, you know, somewhere on the gradient between dog and wolf is buried with a person. Do we go ahead and say that's a dog because of how closely they're associated with the person? Trying to like nail down when an animal is domesticated sort of helps us, I don't know, categorize these things and help with these debates about like, when did a wolf become a dog, which we as humans care about. But you know, you can say, should I care as a non-scientist? I don't know, maybe not. But scientists care as they're trying to like get clean stories. Well, it makes sense to have crisp definitions so we can communicate effectively about the bigger question of like, what happened? What do we call it? I guess doesn't really matter as long as we agree on the labels so we can talk about the real science. Yeah, right. Cool. OK, so step one, we think what happens typically is that the animals come into contact with us more often. Selection changes them in a variety of ways to make it so that they can live near us a little bit better. And then the next step tends to be more like human purpose driven. So we say, OK, the wolves have been living with us for a really long time. They've become tamer, like they don't attack us anymore. Wouldn't it be great if we could hunt with them? And so then we like start bringing them into our communities and we start breeding the ones that are nicer or the ones that like retrieve the deer we just killed and bring it back to us. And so the second step is humans like purposefully breeding them for things that we want. All right. So first, you have unintentional selection where their evolution is being driven by being near humans, some of them benefiting from that and therefore having more kids, etc. And then intentional selection where humans are like, we like the ones that snuggle at night or whatever. That's right. Yes, exactly. OK, cool. That makes sense. Yeah. But again, lots of debate about the best way to define these things. And there are people who are like, if your definition includes a process, if the process is different, then, you know, you are already confusing yourself because you've included a process in your definition. And what if it worked differently, for example, for cats? Have you excluded cats now? Because maybe that's not how it worked with cats. And so anyway, lots of debate, but that's what we're going with today. So then there's been this long observation going back again to Darwin, where when animals are going through this like first step and maybe even partly through the second step where they are spending more times with humans and becoming more docile and just sort of generally becoming a little less wild. They often, but not always, start to acquire some similar looking traits. So for example, they often start to have some like white spots. So for example, if you picture a horse or a cow or some dogs, you might imagine like a lot of them have this little white spot at the top of their forehead. And that shows up less often in wild animals, but you see it a little bit more often in domestic animals. Across different species? Like cows, horses, dogs, cats. The idea is that as they get more domesticated, they get more white spots on their forehead. And I hope you're picking up on my tone of skepticism. That's yep. I am delivering the information right now. And then we will dig into the skepticism. I'm going to address that. All right. You're also more likely to get floppy ears in some cases, reduced ears in other cases, shorter muzzles. So like shorter mouths. Smaller teeth, more docile animals, smaller brains or smaller cranial capacities. The reproductive cycles change. So often in nature, animals will breed once a year. But when you have animals that are domesticated, you can often get them to breed any time of year, or maybe they'll have like two reproductive seasons instead of just one. So they tend to have more babies or they can have babies at a greater range of times throughout the year. And finally, they tend to have like juvenile traits that they retain into adulthood. So you know how babies are like super cute and you're like, oh, puppies are the cutest. Those traits that made them so cute when they were younger just tend to stick around when they're adults, which make us humans look at domesticated animals and still say even when they're adults, oh, you're so cute. And partly that's because they still have some of those baby traits. I see. And I could imagine a mechanism where we select for animals that we find cuter or dumber or more convenient in some way. So it's not totally implausible. The white dots on their forehead, though, I struggle with because is that like universally seen to be cute? Is that the idea? No. And so first of all, I should I used white dots in their forehead as one example of what they call depigmentation, which is just generally you tend to have more white or more brown regions where you just tend to have like less dark colors. OK, so we use the word syndrome. It's called domestication syndrome to describe this. And essentially, the idea here is that it's a package of traits that you tend to get. You don't always get all of them, but you get some of them as domestication is happening. So say what you're selecting for is wolves that don't bite people anymore. This is just a thought experiment. OK, so the idea is when you get wolves that don't bite people anymore for some reason, maybe we don't really understand it. A bunch of these other things seem to change as well. They also end up becoming lighter in color and also their mouths become a little bit shorter and their teeth get smaller. Now the question is why would that happen? Yeah. And the going hypothesis for why it happens is called the neural crest cell hypothesis. So here's the idea. Very early in mammalian development, we have a set of cells called the neural crest cells. These cells are stem cells, and they are going to turn into the cells that make your melanocytes. These are the cells that give us pigmentation. We've talked about these in a bunch of listener question episodes. They're going to go on to produce the cells that make the bones that make our head and our teeth. They're going to go on to make cells that make up our nervous system. And they essentially go on to make a bunch of cell types that are related to the features that we were just talking about. All right. So there is a connection between those features. They have like a common origin, something upstream where if you tweaked it, it might affect all of those features downstream. Yes. Right. And so the going idea right now is that something about selecting for being less aggressive changes something about what the neural crest cells are doing. And that changes all of these other traits. All right. Now that there's a mechanism, I'm a little bit less skeptical. All right. You shouldn't be because. Here's the thing. All right. So first of all, sometimes you see this package of traits come together. Sometimes you don't. You mean in which animals you see these together in which animals you don't. Yeah. Right. And we don't really have a good framework yet for predicting like say you were going to take lions and domesticate them. I'm being ridiculous. Right. But like say you decided. That's not ridiculous. That sounds awesome. I would love to have a house lion. Yeah. Right. Yeah. Maybe. Why can't biology make that happen for me? I don't know. I feel like that's something like people in the mafia try to do. So that and Mike Tyson and Mike Tyson has a house. All right. So Daniel becomes a mafia boss and he says, oh, hey, you know, I'm not going to do a mafia voice. Okay. So Daniel becomes a mafia boss and he starts a breeding program for lions. Yes. And so the question is, can we predict if the lion is going to have floppy ears and shorter teeth? Or if he's going to end up with a smaller brain and a shorter muzzle, like which of those traits that we were talking about, are we going to predict will change in that lion? We're not at the point yet where we can predict are all of them going to change or just a subset of them. But it kind of makes sense because you might expect a bunch of them to change initially. But then when once you've got that lion domesticated, you could say, OK, well, what I really want now is a lion that is completely white. Because then I can sell them to the circus, right? And so now you're like selecting for certain traits. And so now instead of just like selecting for a docile animal and seeing what you get, now you're selecting for like very particular traits. And so you might expect something totally different to happen. Right. And so once humans start getting involved, you might not expect to see this particular package of traits. And so that might confuse a lot of things also. For example, I might want my lines to look ferocious instead of cute because that's the whole point to intimidate all my mafioso colleagues. Exactly. So that would confound your little syndrome there. That's right. Yes, you're selecting for longer teeth and stuff like that. So anyway, amazing example we've come up with here. And so we're really good at this. OK, so one problem is this syndrome, quote unquote, is highly variable. You don't always see it showing up. We can't predict which traits are going to show up in which animals. And this neural crest hypothesis is really hard to test. And a lot of times when you find evidence that a gene is associated with domestication, people will say, oh, OK, that gene is associated with what's happening with the neural crest cells. But it's also associated with a bunch of other stuff because as Benjamin De Beauvoir told us, genes do lots of things. And so just because a gene is associated with what the neural crest cells were doing doesn't mean it's not associated with a bunch of other stuff. And so maybe it's not the neural crest cells that mattered. Maybe it's something that happens at a completely different stage of development. And so we have not really pinned down that neural crest cells are what's important. It could be something totally different. So even though we have a mechanism that sounds convincing and there's some data to support it, there's plenty of people who are saying, we really haven't pinned this down. We don't really know what the mechanism is. And there's a bunch of people who are like, and there's so much variability. I don't even believe this domestication syndrome thing exists. And there's another danger there also, isn't there? Because I imagine that people will try to use these domestication markers as a way to argue that an animal is or isn't domesticated. And just because there are consequences of being domesticated doesn't mean that they're necessarily a signal of domestication. In the same way that you might get a cough if you have COVID, but having a cough doesn't mean you have COVID. There's lots of potential ways to get a cough. Yes. So you have to do a Bayesian disentangling if you really want to be careful about drawing your conclusions. Right, exactly. OK, so now we've dug into where we are now. But I think it's important to look at a classical experiment that sort of set up our belief in the domestication syndrome and ends up being a really important cornerstone for the raccoon experiment, which I promise we're going to talk about eventually because that's what the episode's supposed to be about. All right, let's take a break and when we come back, we're going to hear all about the foxes. And I want to hear about the domestication of dogs because I'm fascinated by ancient human history. And you did all that research, so we're definitely going to have to talk about it. I don't have any notes ready for that, Daniel. OK, we're back and we're talking about domestication of animals, making them cute, making them live next to you, making them snuggle up to you at night, making them feel like they are part of the human family. Yay! All right, so we talked about the domestication syndrome in the last segment and a bunch of our thinking about the domestication syndrome came from one epic experiment that started in 1959 in the Soviet Union. It was started by a geneticist named Dmitry Believ at the Institute of Psytology and Genetics in Novosibirsk, Siberia. Just as an aside, anyone who knows about Soviet history, he was starting this experiment like around the time when you could get killed for doing genetics experiments that were not like in line with what Lysenko believed for how genetics should work. And his brother was a geneticist who got killed for like disagreeing with Lysenko. So anyway, this is intense, an intense period to be a geneticist in the Soviet Union. But he had this goal. He knew that since Darwin, there was this package of traits that people associated with domestication. He had this idea that if you took foxes and selected specifically for tameness, the genetics and the hormones that made that animal tame would also change a bunch of stuff about that animal. Alongside it. Reasonable. And so you would get those other traits that would change too, and you'd get these tamer animals. And so he said, let's go ahead and claim that we are breeding animals to try to get better fur for coats and stuff so that Lysenko doesn't get us all killed. But what we're actually doing is breeding for animals that are going to be tamer. And over time, he was able to become a lot more upfront about what the experiment was actually about. So just to make sure I understand, he's got a bunch of foxes. He's going to choose the tamest ones every generation and breed them. And then he's going to pay attention to other traits that change alongside tameness, even if they're not directly the things he's selecting for. Yes, exactly. Cool. He has in his mind the kind of traits that he's going to be looking for because this idea of a domestication syndrome, it wasn't called that at the time. But this idea of a domestication syndrome was already in people's heads because Darwin had been describing it for a while. But this seems very impractical to me. Like, dumb biologists usually choose to do experiments on animals with very short life cycles so they can have lots and lots of generations in an afternoon, whereas this experiment might take 5,000 years to show any results. No, this is amazing. But I mean, I think everybody's excited about domestic dogs, right? And so he wanted to pick an animal that was kind of close to dogs and see, like, can you make foxes that are like dogs? Because that would be amazing. Like, if you could do that, everybody would pay attention, right? Because everyone loves dogs. And I'd want one too. That sounds really cute. Yes, right? Me too. Me too. And so in 1959, this experiment starts. And another thing I love about the experiment is he found a woman to run it because at this time he was running an institute. And so he got a woman named Ludmilla Trout to start it. They start with 30 male foxes and 100 vixens, which are female foxes, from a fur farm in Estonia. And they knew that these foxes were already tamer than wild relatives because they had a history of being in fur farms for a while. And so domestication had already essentially started. They knew that. So they started breeding them. The pups stayed with just mom for about two months. Then they were caged with just their litter mates. And then at three months, they were caged alone. And periodically they would take them out and they would try to, like, not have humans interact with them outside of these observation periods. They would take them out and they would essentially interact with them briefly. And when they were interacting with them, they would collect data on how the fox pups interacted with the people. This is like them trying to assess the tameness of the fox. And this is not learned tameness. This is not like I handle you every day from when you're a puppy and see if you eventually get used to me. This is like you're encountering me for the first time outside of your cage. Do you, A, bite me, making you a class three fox? Do you, B, allow me to pet and handle you but show no, like, emotionally friendly response to experimenters? That was a quote. So essentially, like, you will put up with me, but you'd really rather not. Or class one is, quote, friendly towards experimenters wagging their tails and whining. Like, like your dog does when you get home. Whining. OK. Yeah. Just a. Yeah. So like excited to see you. They'd get class one foxes and then the class one foxes would breed with other class one foxes because that's what they were trying to get more of. And very quickly, they started to see more and more tame animals. And in fact, by the sixth generation, they were becoming so friendly that they added an elite class. And the elite classes were animals that were like really excited about engaging with the humans. They would like whimper to get their attention. They would sniff and lick them and they were essentially starting to act like dogs by the age of one month. And how long does six generations take in foxes? This must have been like a decade. I don't remember reading that in the papers. I'm going to admit, I just looked it up on Google how long until they're able to breed and it looks like they're able to breed at nine to 10 months old. So. What? Yeah. So they're able to breed pretty easy, but it does look like it's at least a year per cycle, maybe a little bit more than that. Another awkward fox question you probably didn't look up. Awesome. Will foxes just breed with anybody we choose for them to breed? Like you put two foxes in a cage together and there's no question it's going to happen. Or some foxes like, not feeling it or I prefer a different style of fox or whatever. I did read that foxes that are particularly not friendly are difficult to breed and captivity at all. And so I think it could be if you like massively stress a fox out, they just have no interest in breeding, period. Yeah. But the more comma foxes, the more receptive they are. It could be that they put some pairs together and the female or the male were like, no, thanks. And maybe they would just try a new pair. They didn't find each other, particularly foxy. I didn't see that coming. And I should have amazing, amazing. But this result already says something interesting. If by selecting for friendliness, you get more and more friendly foxes, that tells you that like friendliness is genetic. Yes. Yep, it does. That's cool. And by the 10th generation, 18 percent of the babies qualified as elite. By the 20th generation, 35 percent were elite and 40 years into the experiment, which they are still doing. 40 years. Wait, they're still doing this today. Yes. It's an ongoing experiment. It's an ongoing experiment. 40 years in 70 to 80 percent of the pups each generation are elite. Wow. I love super long running experiments. Like knowing how science works and how funding works and organization and recruiting students whenever having anything run for more than a few years is incredible. So like decades long experiments. Yeah, absolutely incredible. And they went through some lean periods, like when the Soviet Union fell apart and they just went to Russia. You know, I read some papers where they were talking about like we had to sell some of our elite pups to like rich people to try to get funding. We had to it was it was tough. But anyway, they're still going. OK, so they also noted some physical changes. For example, right when a fox is born, it tends to like not be afraid of much of anything. Like its mom is just kind of taking care of it. It's exploring the world. It's hard to scare a fox. Right. And in the wild, the fear response kicks in around six weeks of age. But for the foxes that had been bred to be tame, fear responses didn't kick in until about nine weeks of age. And so the thought was that was giving them like a longer window to engage with people and learn that people are OK so that maybe they wouldn't become afraid of people. That last part is conjecture. But fear responses were taking longer to kick in. Stress hormone levels, if you measured them in the foxes, were lower. And so it looks like just sort of in general, life was less stressful for the foxes that were calmer. By the eighth to the tenth generation, they had a star shaped white pattern on some of their faces. What? Yep. Oh my gosh. Some of them had floppy ears. Some of them had tails that were starting to roll, not all of them. They had different amounts of serotonin in their brain. So like even their brain chemistry was starting to change. And by about 15 to 20 generation, they had shorter tails and shorter legs. Some of them were showing some like muzzle changes. They had like overbites or underbites. Not all of the foxes had these changes, but some of them did. And they were starting to reach sexual maturity about one month earlier. And they were on average giving birth to one additional pup and they had longer mating seasons. So you were starting to see changes in reproduction as well. So we're hitting on some of those domestication syndrome traits that we were talking about. And this is like within a human lifetime, you were able to start seeing these traits, which is amazing. Like we don't know how long it took in dogs. But like with very focused selection, you were able to start seeing some of these traits show up already. Wow. That's amazing. But I guess one concern I have with the whole experimental design is, you know, it's not like blind in any way. If these folks are invested in this outcome, they could have chosen four foxes that were tame and four foxes that like had white patches on their foreheads. Right. Yeah, totally. OK, so first of all, the white patches on their forehead would have to show up, though. You don't usually get those in the wild. So the fact that it shows up might say something about what the neural crest cells are doing. Because part of the idea is that the neural crest cells just like aren't getting where they need to go. And so you start getting white patches because you don't get melanocytes where you're supposed to have them. So the white patch showing up at all, like even if someone was selecting for it, the fact that it shows up at all suggests something about the mechanism working. But there have been actually a lot of critiques recently about this study. And there's this book called How to Tame a Fox. And while I was reading the book, I kept thinking, man, it sounds like they're trying to be really careful. But also there's like a stage where they're like, well, what if we take one of them and it lives with us in our house and it's like and then at one stage they say, well, maybe this is an experiment that is on humans, too, in our response to these things over time. Because it is a two way thing. And I'm like, it is a two way thing. But it just I think to me, it just showed how impossible it is to disentangle humans wanting to snuggle cute foxes and dogs. Like and so I can easily imagine that there was a little bit of bias where not only are you selecting for docile animals, but if you start to see a little curl of the tail, maybe you're willing to like imagine that an animal is a little bit more docile if you also see the curly tail because that is so cute. And like you need to breed that animal. And so not that I want to cast dispersions on any of these researchers, like they do seem amazing. OK, but recently there was a big brew. Ha, ha, about this paper because OK, so Lord et al. Twenty twenty wrote this paper being like the domestication syndrome is like kaput and we should stop talking about the Farmed Fox experiment because it turns out that actually the Farmed Foxes came from Fox farms in Canada that were started in the 1880s. And on these farms, they were selected for things like white spots in the fur because they wanted to sell that fur. And it's been known that some of these animals were like a little bit tame because they showed some photos of the foxes like sitting on the lap of someone. And so the people who wrote this paper were like, maybe the researchers didn't even know the foxes came from Canada. But a couple of things. I'm not sure if the people who wrote this paper were frustrated that people seem to have not understood the Farmed Fox experiment or what. But like when you read Ludmilla Trout's papers, she mentions like, you know, these animals had been domesticated before we got them. And she references papers where they had mentioned that they came from Farmed Foxes in Canada. And like, I think they knew all of this and they had mentioned all of this in the papers. And so none of this felt new to me. I was like, I'm pretty sure all of the papers that I read had said all of this stuff before. But maybe people weren't reading the original papers. Certainly that happens in science a lot where people read references of the original papers instead of reading the original papers. But anyway, so it is the case that these animals were a little bit tamer than you would expect wild animals to be and had already been selected for some white pigmentation. Although Ludmilla points out that the white spot on the head is a totally different mutation that hadn't really been seen in the Canadian foxes before. And just because the animals had been a little bit tame already, doesn't change the fact that when you selected for it even more, they got all of these additional changes. Yeah, the experiment is about the changes, right? The input foxes will affect that, but they don't control the changes. Right. And so that that was Ludmilla's counter argument, because I, you know, I read this like chain of arguments and counter arguments. And so it was it was a whole thing drama in biology. That's right. And so one interesting point that the Lord at all paper made, though, was that like when people talk about the domestication syndrome, they talk about it as though it is a thing where when you domesticate animals, you get all of these packages of traits that change. But there's tons of variability and you don't always see it. And they were really highlighting that we talk about it like it's a thing that definitely happens, but it's a thing that happens in an inconsistent way. And we don't have a good framework for predicting it. And people talk about the Farmed Fox experiment as if it proved that domestication syndromes happen. But this is one example in one place. And it hasn't been sort of like we don't have a consistent framework that looks at a bunch of different animals. All right. And that is important to keep in mind when we are about to jump into the raccoon experiment. All right. One more thing to keep in mind before we finally talk about the raccoon experiment is one of the things that we've been talking about is how the domestication syndrome is often associated with changes in the shape of the head and in particular, like shorter snouts. There was a group of researchers that looked at wild foxes by looking at fox heads that were in museums and were collected from around the time when foxes were probably collected to go into the Canadian Fox farms that would have subsequently provided the animals that would have ended up in the Russian farm to Fox experiment. And they looked at measurements on those heads and compared them to the domesticated foxes from Russia. So this is like an effort to sample foxes before they were even selected for the fur farms. That's right. Yes. This is an effort to really get like what do wild foxes look like? What do their heads look like? They looked at the heads of the domesticated foxes from today from the Russian Farmed Foxes. And the Russian Farmed Fox experiment also has what they call a control treatment where essentially they randomly breed the animals that are still aggressive. Oh, OK. So those are supposed to look like the wild animals. And what they found was that their controlled animals that were bred in Russia have very similar head shapes to the animals that are super tame and are super friendly that were bred. So it looks like selecting for being super friendly is not necessarily what's changing the shape of the head. Right, because selecting for tameness or not both led to changes in the shape of the head. Exactly. So something about being in captivity does seem to change the shape of the head because the head was very different than the wild foxes. But the difference between the very docile and the aggressive farmed foxes, there was some difference, but it was very small. And the difference between the wild ones was huge. So something about being in captivity changes head shape. And it's not necessarily selection for being super friendly and snuggly. So it turns out it's complicated and it depends. Exactly. Yes, it's complicated and it depends. OK, so there was a lot more complication we could have talked about. We only have an hour. Sometime I have to get to the raccoons. Daniel's being very patient. Let's take a break. And when we get back, I will actually address Matt's question. OK, we're back and we are talking about domestication, how it influences animals, if it influences animals and what it can tell us about raccoons. But before we move on to the raccoons, Kelly, I have to blow your mind by asking a question that will really, really surprise you. Oh, OK, go ahead. What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the raccoon's? What is the Latin name of the Silver Fox? Volpe's Volpe's. Yeah. And as you know, I'm not a big fan of Latin names, but this one is super cool because it's doubled. Why is it doubled? I do you know? I don't know. Are you just trying to trick? You're just asking to trick me. I specifically didn't look it up because I was like, I'm not going to bring it up because Daniel doesn't want me to. I'm not asking to trick you. I assumed you have this deep well of knowledge about Silver Fox's and their Latin names and you rejoice in the Latin inscrutability of it. Oh, no, thank you. But I stopped looking it up because I was like, well, Daniel's what's the point in looking it up if Daniel's not going to let me say it? This is part of my Kelly domestication experiment. All right. All right. So now I'm going to Google what does Volpe's mean? Volpe's is Latin for Fox. I see. So the Latin. So the Latin name of Silver Fox is Fox Fox. Fox Fox. Yes. That's right. It's a pretty Foxy Fox. So yeah, it makes sense. Yeah. Yeah. They studied Fox Fox's. All right. So let's move on to raccoon is raccoon is. Oh, no, it's Pryon loader. Come on. Oh, no. Frog proc on loader. I can't say it. I didn't practice it. You're saying we have for failure. Now, every time you're not going to know, but tell us about the raccoons and math question and whether raccoons are becoming domesticated. All right. So we're specifically talking about a 2025 paper in frontiers in zoology by Apostolov et al. This is a paper out of Rafael Alessia's lab. And it is called tracking domestication signals across populations of North American raccoons. Scientific name via citizen science driven image repositories. So all right. So here's what they did. Have you heard of I naturalist, Daniel? I'm naturalist. I naturalist. I naturalist. No, I have no idea what that is. Oh, man. OK, so it's this amazing image repository where you can like take a picture of something, load it up. And if you know what it is, you can say like, I am at this location and here is what the species is. And other people can like weigh in about whether you got the species ID right or not. Or if you want to know what it is, you can like experts can weigh in to tell you what it is. And it's just essentially location information, photos and species identification information. So you can try to figure out what it is that you're seeing no matter where you are around the world. Cool. It's not just cool, Daniel. This is amazing. This is amazing. It's mind blowing. Thank you. It's an international network of Latin names all around the world. Yeah, I thought you were getting the attitude right, but then you went to Latin names. And now I think you're being sarcastic. But anyway, all right. So there is a database of something like 20,000 photos of raccoons from all over the United States. And the authors were wondering, OK, are raccoons in urban areas? So essentially raccoons that are living closer to us, eating our trash, for example, showing signs of a domestication syndrome relative to raccoons that live in the woods. So like a raccoon that lives near me might look different than a raccoon that lives in Irvine, because it is in a higher density area and might be eating from a trash can, whereas there's a lower density of people out here. So a raccoon out here might need to forge for its own food. Does that make sense? Yeah. So in urban areas, they interact with humanity more. And the question is whether this unintentional interaction with raccoons is changing raccoons in the way we might expect from domestication syndrome hypothesis. Exactly. Yes. And it's very cool when you come up with a really grand hypothesis that's hard to test and then figure out a way to test it with existing data. Yes. Super cool. Yes. Amazing. Amazing. And so they were like, all right, we've got all of these photos that people have taken. And we could ask if raccoons in urban and rural environments have different snout lengths. Right. And so we would guess that the raccoons that are eating your trash have a shorter snout based on the domestication syndrome idea than the raccoons that are out in the woods near Kelly. And so they took the pictures and these pictures don't have like rulers on them, unfortunately. So you can't get like absolute measurements, but they wanted to get ratio. So essentially what they did was they took pictures and they measured the relative distance between the tip of the nose and the tear duct. So they had to be able to see the eye and then the distance between the tip of the nose and where the bottom and the top of the ear connected to the rest of the skull. And so if you have a shorter snout, then the distance between the tear duct in the eye and the nose is going to be shorter relative to like the whole head length. Does that make sense? I think you're saying that they measured the nose to ear distance and the nose to eye distance and they use that to get a ratio to say like, how snouty are you? Because they couldn't get absolute measurements on these raccoons. They're just pictures of raccoons. You can't tell. Is this a really huge raccoon or is it really just close to the camera? Beautiful. Yes, exactly. Thank you. That's what they did. But they can't use anything in the images to like calibrate. I mean, like if you see a raccoon that looks like the size of a house, you know, it's not actually the size of a house. And usually there's something else in the image that can tell you, oh, this raccoon is really close up or something. But anyway, I'm sure they thought of that and tried it and it's too hard. Yeah. Yeah. I mean, some of these images don't really have any helpful landmarks. And so so anyway, they they didn't do that for whatever reason. OK. And so then the next step, they had these 20,000 images, but they wanted to make sure they weren't reusing images of the same raccoon. So just in case one person every day took 50 pictures of the same raccoon and loaded them all up, they they only used one image from each person who uses iNaturalist. Oh, OK. And then they made sure that they were only using images of raccoons that were alive or freshly dead or raccoons that were I know, or raccoons that were facing the right way. Because, you know, if a raccoon is sort of facing at the wrong angle, you might not get the right ratio that you're looking for. And so after they passed the images by a bunch of different criteria, they ended up with 249 images, which is pretty small samples. That's the sound I made. That's the sound I made. It's not just that it's a small sample size, but it's a huge selection effect, right? Yeah, one of these criteria could easily be biasing their sub sample. I agree. And they ended up with 38 rural raccoons and 211 urban raccoons. Well, so pretty small subset for the rural raccoons, which are supposed to be like the baseline, 211 urban ones. OK. And so then they made those measurements that we talked about, making the ratios data. There were a lot of different authors, and it looks like a bunch of different authors were making these measurements. And they weren't all getting the same measurements. So one one author one author looked at the different measurements made by the different members of the team. 13 images and found 68 percent inter-rater reliability, which doesn't sound great to me. So the way I've used these measures in the past has been like if I analyze the same photo five times, this is a measure of how similar those analyses are. So if I get a one, that means every time I analyze the photo, I get the exact same answer. Or you can have five different people analyze one photo. And if they all get the same answer, then the answer would be one. And if they all get a different answer, then the answer would be zero. And so I looked up the paper that was cited in this paper for how these reliability analyses should be understood. And the paper says that if you get a value less than point five, you've done like a poor job of being reliable. If it's between point five and point seven five, that's moderate. Good is between point seven five and point nine and excellent is greater than point nine. So this paper had point six eight, which puts it at moderate reliability or moderate consistency in answers. That tells me like why are you writing this paper? Like go back to your study design and start over. What frustrated me is that two hundred and forty nine images is not a lot of images. And so I would have just been like, OK, three people are going to each measure every single image and we're going to like average or we're going to like I don't know, we're going to do something like there. Two hundred and forty nine images is not a lot. We're going to find some way to make sure that we're all getting the same answer. Why can't they just write a computer program to analyze these images? Yeah, yeah, that were that. I don't know. That might have been hard, but they just needed to find a Daniel. So anyway, that that amount of reliability sounded a little low to me personally. Yeah. Anyway, so so then they looked up USDA plant hardiness zone. So they essentially were looking for a possible impact of like weather on snout length because these were raccoons from all over the United States. And then they looked up some census information to figure out if these raccoons were rural raccoons or urban raccoons. So they looked at where these raccoons were tagged on iNaturalist to figure out if they were found in the middle of a city or out in the middle of nowhere. And then they did some statistical modeling. And essentially what they found was that in warmer areas, snouts tend to be shorter. So there's an impact of climate. And they found that there was an impact on urban areas where urban raccoons did tend to have shorter snouts. And so that is in the direction that we expected. They found that they had three point six ish percent shorter snouts between rural and urban raccoons. And I assume they did some statistics and found that this is a meaningful difference for these samples. Yeah. But it's worth noting that they had initially done a model that included a bunch of years. But when they did that more complicated model that included a bunch of years, it had what's called a high variance inflation factor. We're not going to get into statistics. They ended up deciding that it was better to restrict the data to what they saw from 2020 to 2024. So after looking at an even smaller subset of the data, that's where they got that three point six percent snout reduction. So it ends up being a pretty small data sets. But I mean, their their conclusion to be fair is pretty conservative. OK. Essentially, what they say is we want to highlight raccoons as a new opportunity for observing early stage domestication patterns in a mammalian model system with no possibility of introgression or hybridization with other already domesticated mammalian species. Basically, they're like, maybe early domestication is happening here. The raccoons aren't going to be like mating with our cats or wild pigs or something like that. And so this is a system. Why not? Why can't we have a cat raccoon hybrid? That sounds super cute. Sure. Yeah. Well, I, you know, we're going to have Scott Egan on the show to talk about what is the species and how give you an answer, Daniel. And so there's a lot of room for further work. So, for example, this study also didn't look at whether or not the raccoons were males or females and sexual dimorphism, which is, you know, when males and females look different, that could have also explained some of this variability. There's also some raccoon subspecies throughout the United States that look a little bit different. That could have explained some of the variability, too. I think you could do an experiment and this is gross, but hear me out. There's a lot of raccoon roadkill around the United States. You could have people go out and collect raccoons from urban areas and rural areas all across the United States, get those actual measurements or actually even, you know, collect the craniums and make a lot of different kinds of measurements and, you know, really start to get at some of these values in a more concrete way. You could know if they're males, know if they're females, know where they came from. But this is like an early attempt to answer this question using citizen science data. And like, I love citizen science data, but it also comes with so many complications that come with using data collected, you know, for purposes that it wasn't necessarily intended for by people who, like, you know, one of the filters they had to use was, is this even a raccoon? You know, so like there might have been people who were like, it's a raccoon, but it's a bobcat or like, you know, and so, you know, they were trying to see what the best they could do with this data set was. And, you know, they got an interesting answer consistent with the hypothesis. I don't feel like I would say we've got a slam dunk here, but good reason maybe to go out and try to collect the data in a bit more of a hands-on rigorous way. And there's lots of interesting issues there. Like maybe people in urban versus rural environments are taking pictures of raccoons for different reasons, right? Urban people are more scared of this. They're showing it to their landlord or something. And rural people are like, hey, cool, you're my friend, the raccoon. And that could be influenced by how cute or how scary they look. And there's all sorts of possible complications there. Yeah, right. Yeah. And you'd have to think about, you know, could the roadkill ones be biased in any way? Like are the rural raccoons that are on the road like the more aggressive raccoons because they're the ones that are willing to get to the road. And so, you know, any experiment where you're taking advantage of a sample of animals that you can easily get your hands on, you've got to wonder how those data are biased in some way that made it easy for you to get those data. All right. So then zoom out and big picture it for us, Kelly. Do you think that this domestication syndrome thing is real? Is it useful? What do you think the future is going to tell us? All right. So here is my gut feeling. I do feel like when you select for one trait in an animal, those traits are usually controlled by like genes and hormones that influence lots of other traits. And so I think most of the time when you domesticate an animal, you should expect a lot of things to change. And it wouldn't surprise me if a lot of the time when you are selecting for something like animals that are less likely to bite, a lot of the same traits would change in animals that we domesticate. And so I imagine that we will find a domestication syndrome has like, I don't know, maybe two or three traits that are pretty consistently changed across species. I'm not going to bet my life on that. But like, it wouldn't surprise me if we found that. And so, yeah, I guess that's what I would guess. All right. That makes sense. Let's send this back to Matt to see if we have answered his question. Thank you, Kelly and Daniel, for giving us a more grounded look beyond the pop science articles. I came for the raccoons, stayed for the Fox drama. I am disappointed, though, that we don't have raccoons as pets anytime soon. I was a bit skeptical, too, of the small sample sizes and the pop science takes that made it seem like raccoon domestication was happening. And we were witnessing it in practically real time. So I'm really happy I brought it to you guys. Thanks for giving it the DKEU treatment. Fun fact that none of you asked for, though. Vulpus Vulpus isn't the only animal to get the double Latin treatment. For the Western gorilla, we have gorilla gorilla. Plus, if Daniel goes full mafia like villain, he's got a wicked, smart, friendly and classy discord community to build up his future empire. So come join us as we talk about the universe, space, geology, biology, other things that end in ology. The secret to a great discord, obviously, is having a pet section. Our members are high energy and enthusiastic, intelligent people from all walks of life. And we'd love for more of you to join in on the conversations and obviously share your pets, honestly, is one of the moderators, too. We have a rarity when it comes to discord communities. Everyone here is wicked, friendly and smart and extremely civil without needing constant intervention. So really, the biggest credit goes to our discord community for keeping it that way. We hope to see you and your pet soon. Thanks, Daniel and Kelly. All right. Thank you very much, everybody on the discord for creating such a fun and inclusive community. If you think the internet is toxic, you have not been to the DKEU discord. It's a bastion of creativity and support. Come join us for conversation. And pet photos. Short snouts and long snouts all are welcome and goats. When I finally do become a mafia villain and get my own pet lions, I'll post pictures on the discord. I can't wait. Thanks, everybody for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us. Daniel and Kelly's extraordinary universe is edited by the amazing Matt Kesselman. He really is a wizard. You can also find us online on Blue Sky, Instagram and X, D and K universe. Come engage with us. You can email us at questions at Daniel and Kelly.org. We really do want to hear from you. And you can find our website, www.DanielandKelly.org, where you'll also find an invitation to join our discord where everybody comes and talks about the amazing universe. And we also have the most amazing moderators. This is an I heart podcast. Thanks for joining us. Your holiday starts with the airline Oxford's premium coach service to Heathrow and Gatwick airports up to every 20 minutes, 24 hours a day. 365 days a year. The airline is the most frequent luxury coach service to Heathrow and Gatwick from Oxford. Leave your car at home and start your holiday early. Just sit back, relax and enjoy our fast, direct and reliable airport service day or night. Book now at the airline.co.uk. This is an I heart podcast. Guaranteed human.