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Plus, you get to feel good about supporting public media while you listen. So end the year on a high note and invest in a public service that matters to you. Visit plus.npr.org today. Thank you. You're listening to Shortwave from NPR. In North America, raccoons are everywhere. The common raccoon is native to forest habitats, but a lot of them live in urban areas, close to humans, like the one that I'm pretty sure lives in my front yard. And the one that fell through that ceiling in the Virginia liquor store broke all those bottles then was found passed out drunk next to a toilet. He's okay. He sobered up and was released. Not to mention how much they've invaded pop culture. They've been in cartoons. You thought I was a good friend of yours? Miko. In video games. There's even a baseball team named after them. And they've collected a lot of nicknames over the years. Night prowler, masked marauder, garbage goblin. Trashpanda is my favorite one. It's just so cute. This is Rafaela Lesch. She's a zoologist and assistant professor of biology at the University of Arkansas at Little Rock. And recently, Rafaela and her team published a study that is causing excitement because the findings may point towards raccoons beginning to domesticate themselves. When I think of domestication, my mind immediately goes to cats and dogs, mostly cats because I have four of them. And how these cute little angels became our pets is a long story. As in, it happened millennia ago. Cats seem to have been attracted to human settlements because our trash had a lot of rodents around. That was basically like an easy buffet. You know, like there's so much food that you can hunt down. It's worth it to stick around. And then again, if you're in close proximity to humans, you kind of have to adapt to be friendly enough to them that you're not getting removed from the breeding population, but also bold enough so you can make use of those rodents and trash heaps. Rafaela says that raccoons may be following in their footsteps. So today on the show, are urban raccoons becoming domesticated? Can we be sure? And does this mean that you might have a pet raccoon in your lifetime? I'm Regina Barber and you're listening to Shortwave, the science podcast from NPR. So Rafaela, you were the lead author of a raccoon study that's been getting a lot of attention. What question did your team want to answer? So in a scientific context, what we wanted to answer was, does urbanization or an urban environment potentially kickstart a domestication event in raccoons? And really that was going to be that first look at, is there any potential, any more potential in that question? Is it worth to invest more time and funding and money into looking into this in more detail? And on the more class and personal level, we also wanted to address that just from our own sense of curiosity. And I had basically created this framework from the start. So they knew that we were going to work on the domestication syndrome and urbanization and then I introduced them to the whole scientific context, the theoretical background. And that's really where we then started working on the actual research question, data collection, data analysis and all that. Right. Okay. So let's take a step back and talk a little bit about the domestication syndrome hypothesis this work is based on. What exactly is it and how do we identify it? Yeah. So there's two parts to that answer. So if we tackle that domestication syndrome first, domestication syndrome really describes traits that we see across domesticated animals. So for example, smaller brains, floppy ears, curled tails, shorter snouts, like a kind of like a white patching or white depigmentation showing up across the body. So all of these traits we refer to as domestication syndrome. And as I said, it occurs across all domesticated animals, but not every single trait shows up all the time. So we might see a snout reduction in dogs, but that might not be present in cats. White patches seems to be one of the most ubiquitous. Smaller brains also seems to be one that pops up quite a lot. But this combination of traits can show up in all domesticated animals. And we're still trying to figure out how exactly that works. So the most popular hypothesis that we have at the moment is that any domesticated animal had to undergo a selection for tameness, so to say. So animals that enter that domestication pathway would have to adapt to living in close proximity to humans. And that adaptation requires them to basically be somewhat tolerant and friendly towards humans because if you're not nice around humans, you usually don't live a very long life. Right, yeah. You will become food. Yeah, exactly. You will become food or a rug or something like that. So you have a fairly strong selection pressure for friendly individuals or tolerant individuals. And over many, many generations, that selection for tameness, according to that hypothesis, changes the migration and proliferation of neural crest cells. And these cells are important. For example, if you have fewer of those cells, you might have organ systems that rely on those develop in a slight deficiency. So for example, the craniofacial skeleton might be receiving fewer cells, which could explain that shorter snout. So that's kind of like the general idea that we have, explaining how we get from a wild animal to that domestication syndrome. It is the most popular hypothesis we have. Personally, I think it's a really good hypothesis, but we also don't fully agree that that is it yet. We're still working on testing that hypothesis. Yeah. Where did you, where did you and your students get all that data to answer this question? So we used iNaturalist. iNaturalist is like this huge platform where anyone can upload images. It was really exciting to have this amazing huge data set where we could really look at a question that basically spans the entirety of the United States, which if you had to go out and collect that type of data just by yourself, you'd be busy your entire life. Yeah. You and your students looked at nearly like 20,000 photos of raccoons. And in the end, you did find that these raccoons, they did have some physical changes. There were some with shorter snouts. Why does this matter? So the shorter snouts matter because basically we hypothesized that in the city environment, we would be finding shorter snouts because they would be on the pathway to domestication compared to rural raccoons. So the fact that we did find that urban animals have shorter snouts, that is a good first indication that urban raccoons might be on the pathway to domestication. And that's like that first puzzle piece. And there's many more puzzle pieces we have to add to be 100% sure about that. Yeah. Could it be that the iNaturalist photos don't accurately represent the full range of raccoons? Why or why not? Yeah. So the thing is, yeah, any photographic data that we have, there's a tendency that animals that are less afraid are easier to photograph. So there is a good likelihood that we have a bias in those data. But also, if we were to go out and trap raccoons, let's say on our campus, we want to put little GPS colors on them to look at their movement. If we put out a trap, there's a good chance after, let's say, we capture seven different raccoons on day eight, we get raccoon number one again because it has kind of figured out that, hey, I get peanut butter in there and they might poke me, but it's not that bad, so I'll just come back. So the problem with this in animal research is that we really always have some bias in our data. It's very hard to not have some type of almost like personality bias in there where you usually get the bolder animals of a population in front of your camera, in your traps. That I would say is just one of those downfalls about just working with wild animals in general. It is really, really difficult to get a very super clean, non-biased data set because you just have that variability across the population in personality. Yeah, that makes sense. Okay, another thing that actually I would love to ask you about, when we were looking into domestication syndrome and how it's been observed, one study kept coming up and it's this Russian fox experiment. What did that study involve and was it successful in breeding domesticated foxes? Yeah, another Russian fox for experiment was started by Dmitry Belgyaev. They basically wanted to domesticate a population of foxes within a human lifespan and they took foxes from Canada that were already in a fur farm set up and then basically continued to select those for the most tamest individuals and those foxes now would be considered domesticated. That specific line that has been selected for tame behaviors, they are incredibly friendly and eager to interact with humans. That could be a population of foxes that you can consider domesticated. Yeah. Okay. Like you said, it was done on a fairly small sample with foxes that have already been on this path to domestication. They were in this farm. Does that mean we could be wrong about domestication syndrome? Is there still controversy? Their argument really was not that they started this whole process, that they weren't already pre-domesticated. They were really just trying to accelerate that process in almost step two rather than that initial step one. That criticism around the fox experiment is very much present in domestication research and I think probably until we're able to really test the neural crest domestication syndrome hypothesis in a lot of detail, I assume that criticism won't go away because the neural crest domestication syndrome hypothesis also to a large degree is connected to the fox experiment. I think a lot of that criticism is also connected to that hypothesis in general. Personally, I don't quite see all those points of criticism as an actual... Like in validation of the hypothesis. Yeah, exactly. Yeah. And you mentioned earlier that this is very beginning stages of asking this question, are raccoons becoming domesticated in urban areas? What are the potential blind spots of this study? Yeah. So the blind spots here really are that we just looked at the entirety of the US and it was really that first glance of is it worth to investigate more? So we did not consider different subpopulations or subspecies or different nutrition and all of that. So we really just wanted a very simplistic study designed to look at does an urban rural continuum show up with any differences in snout length, but we did only correct for climate. We did not look at different diets. We did not look at subpopulations. So that is something that would have to be a next step where ideally you go in and collect, for example, anatomical data from skulls from different populations where you know what their diet is like. So you can tease apart effects of climate, diet, subpopulations. So that would have to be the next step. So this was really the first kind of like, is it worth looking at this more? And now the answer is yes. It has potential. So now we have to follow up with more in depth research into different populations. So are we like thousands of years away at best probably from pet raccoons? If this is real? Yeah. So if they really are on the pathway to domestication, then it most likely will be thousands of years. So don't go out and pull a raccoon out of trash can put it in your living room. If they are on the pathway to domestication, this would be very early stages. So it's an adaptation to human environment, but they're not pets yet. Rafaela, thank you so much for talking with me about trash pandas. I love raccoons actually. Anytime, anytime. Thank you so much for having me. If you liked this episode, don't forget to follow us on the NPR app or whatever podcasting platform you use. Also, if trash pandas are one of your favorite animals, check out our episode on rabies vaccines dropped from the sky. And you could also check out how a dog aging project can help pets and humans live healthier lives. We'll link to them in our episode notes. This episode was produced by Hannah Chin and edited by our showrunner Rebecca Ramirez. Tyler Jones checked the facts. Jimmy Keely was the audio engineer. Beth Donovan is our vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Shorewave from NPR. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you. Thank you.
