Raccoons that live near humans  do pretty well for themselves.

Just think of all the garbage cans overflowing with leftover pizza, half-eaten  fruit, and scraps of pet food! One group of researchers published a paper in 2025 that suggested that raccoons could be  adapting so well to living around us that their little faces may be  showing one sign of domestication, in the form of shorter faces.

Now, this story got around, and you may have heard about it in passing from someone getting way too excited about  their dreams of having a raccoon as a pet. And to be clear, raccoons are NOT PETS and  they won’t be anytime soon. Please, I’m begging, please do not cuddle the raccoons But, honestly, city raccoons  having stubbier snouts isn’t what’s most scientifically  interesting about this research.

See, we don’t even really understand or agree on what domestication  even is in the first place. But studying our neighborhood trash  pandas might be one way to find out. [THEME MUSIC] Alright, I know you may have clicked on this video because it had a thumbnail of a cute raccoon, and you probably want to learn  more about them right away. And I promise we will get there, but to figure out whatever may or may  not be going on with these critters, we first have to understand how  scientists think about domestication.

They have… a lot of thoughts. And  don’t always agree with each other. Domesticated animals feel like one of those  “you know ‘em when you see ‘em” phenomena.

And by “them,” I mean a very fluffy cat meowing at  you because she knows that it's time to play with the laser pointer but you're still at your little laptop and talking to people and working on scripts and it's getting late and she wants to play But even though domestic cats are  cute and kind of pathetic sometimes, they also add to our lives — they can help  keep mice away or be emotional support. So researchers consider domestication  to be a kind of mutualism, which is where two species have a  relationship that benefits both of them. And it’s a little more specific  than just living side-by-side.

Domestication is when one species — like humans — increases their own survival and reproduction  by somewhat controlling how another species — like housecats — survives and reproduces. That’s one definition, anyhow. For our purposes, we can say that humans  change domesticated species to suit our needs.

The differences between, say, an African wildcat and a domestic cat come  from thousands of years of genetic changes that reinforce our interspecies relationship. It’s not like raising a lion cub in your home will   suddenly flip a biological  switch and make it a pet. When researchers study domestication, they  look at way more than just cats and dogs, too.

Hundreds of crop plants, like rice or  potatoes, have been domesticated over time. Farmers control the survival  and reproduction of crops, and in return we get a resource  out of them: nutritious food. The wild versions of a lot of these plants  barely look like their cultivated cousins!

In any case, the specific evolutionary  changes and traits that emerge during the generations-long  process of domestication are   where biologists really start splitting hairs. We create scientific definitions  based on observations and experiments. So there’s not always a clear line  between domestication and other   kinds of interspecies relationships, or even  just adaptations to different environments.

A species that’s becoming  domesticated over time might change its appearance, its behavior,  its nutritional content, or any number of things that makes it  more useful to the domesticator species.   This concept of a sort of checklist  of traits that domesticated species have in common is called domestication syndrome. The English naturalist Charles  Darwin was a big proponent of the “you know it when you see  it” observational sort of biology. He actually wrote one of  the early scientific books that documented patterns in domesticated  animals compared to their wild counterparts. “The Variation of Animals and Plants Under  Domestication” was published in 1868.

It was a combination of Darwin’s own thoughts  and research being done by his peers. And even though Darwin didn’t explicitly  use the term “domestication syndrome”— that credit goes to botanists in the early 1900s— some of what he documented is still  foundational to modern-day studies. In plants, domestication syndrome could look like changes in fruits, growth  patterns, and seed dispersal – you want the seeds to disperse  less so you can collect them.

In animals, we’ve noticed things like lighter fur, floppier ears,  shorter muzzles, and curlier tails, along with behavioral traits like tameness  or differently timed reproductive cycles. But even though these traits  show up across different mammals— like rabbits, dogs, cats, goats, and cows— no domesticated animal has all of them. When researching the process of  domestication and domestication syndrome, some scientists have taken an experimental  approach and selectively bred animals to try and make them more domestic  across multiple generations, usually focusing on behavior.

People also study domestication in plants. But we’ll stick with critters for now because, ultimately, we’re here to  learn about raccoons, right? And we’ll get back to trash pandas… right after we keep the lights  on with this quick break.

Since you love SciShow, you’ll probably also be into  this video’s sponsor: Brilliant. Brilliant is an online learning platform  made for everyone from age 10 to 110. And they offer courses that  strengthen your math skills.

As an example, their math course on Proportional Reasoning is designed to help you understand  ratios and proportional relationships. Over the course of 30 lessons,  you’ll get to complete 357 exercises. Which gives you an idea of just  how interactive Brilliant is.

To learn for free on Brilliant for a full 30 days, go to brilliant.org/scishow,  scan the QR code onscreen, or click on the link in the description. Brilliant’s also given our viewers 20%  off an annual Premium subscription, which gives you unlimited daily  access to everything on Brilliant. These experimental studies can take  place over the course of months or years with fast-breeding animals like mice or rats.

Researchers can compare tamer  and more aggressive individuals, make note of differences, and  keep breeding the tamer ones to see if they can affect future generations. The most famous research that took this approach is the Russian Farm-Fox Experiment, which was started by the Russian  geneticist Dimitry Belyaev and his collaborators in 1959 and has continued in the decades since— even after his death. Over 60 years ago, Belyaev got 30 male and  100 female silver foxes from fur farms.

These fur farms had already been breeding  foxes in cages for their pelts for decades, so they weren’t exactly wild foxes, but they weren’t necessarily  gentle lap-foxes either. This starting population was chosen based  on how friendly they were toward humans. Belyaev and his team bred  them over and over again, and studied the next generations to  see if they acted more domesticated and what other traits appeared.

Over the years, these researchers documented  similar traits in the ever-tamer foxes, like more white spots in their coats,  floppier ears, a more squat and cuter face, and even wagging tails like domestic dogs. So they concluded that whatever  genes affected the calm, pet-like demeanor of these silver foxes also had effects on other developmental  processes and biological traits. And they’re still curious how much  more domestic these foxes can get.

The most generous interpretation of this research is that Belyaev and his team figured out a way to condense the long evolutionary  process of domestication into a couple decades instead  of thousands of years, because of the really close human involvement. Basically speedrunning what natural  selection does, well, naturally. But there have been critiques too.

In a 2019 paper, the authors say that these experiments  undoubtedly teach us about tameness in foxes and the genetics related to behavioral changes, but they might not actually provide  evidence for domestication syndrome. They argue that domestication  syndrome is too hand-wavey of a term, because we still don’t have a core list of  traits reported in all domesticated mammals. For example, only domestic pigs  seem to have decreased brain size relative to the rest of their bodies.

And some breeds of domestic animals  have floppy ears while others don’t. I’m telling you, my cat can  airplane ear with the best of them. In other words, domestication syndrome  can be something of a hot topic.

Some scientists don’t seem to  be as interested in building a canonical list of domestication syndrome traits. Instead, their focus seems to be on  explaining the biological mechanisms that might lead to traits we  associate with domestication. Some focus on the balance of different hormones being produced or released at different times.

Others focus on how parasitic infections might affect all the biological systems  that are involved in domestication, or how developmental processes  might get interrupted to make adult animals look and  act more cute and baby-like. And in 2014, a team of scientists proposed  that neural crest cells or NCCs could be driving the physical  and behavioral changes that   happen to species during domestication. Neural crest cells form really early in   the development timeline of  any animal with a backbone.

They start out forming where the backbone will be, but migrate throughout the embryo  to form different structures. They’re a kind of stem cell, which basically means that they’re generalists and can become a lot of  different specialized body parts. NCCs help form parts of an animal’s  head, tail, and their melanocytes— which control the color of skin, fur, or hair.

And all those body parts also  show up in domestication syndrome. The core idea this team proposed  is that domestication leads to some sort of reduced  activity of neural crest cells Either not as many NCCs form to start with, they don’t move as easily  through the developing embryo, or they grow slower once they  actually start forming structures. And—importantly—because NCCs  are in all vertebrate species, this idea can be tested by comparing  domesticated vertebrates to wild ones.

Plus, NCCs could affect the development  of different animals in different ways, so the Neural Crest  Domestication Syndrome hypothesis could explain why there’s no one-size-fits-all  domestication syndrome checklist. So this is where that viral  raccoon study comes in. Have I kept you waiting long enough?

Raccoons are vertebrates! So they have neural crest cells  that drive their development, just like cats and silver foxes and humans. Some populations of raccoons have been  living alongside humans for decades, and eating our trash, bird seed, and pet food.

Fortune favors the bold, in  this case the bold raccoon who doesn’t run away from your trash  can when you start yelling at it. According to the researchers, this could be acting as a  selective pressure on the raccoons to live more closely alongside humans. So they could conceivably  be developing adaptations   that are in line with domestication syndrome.

And, raccoons are not really  being bred by humans right now. We’re not experimentally creating domestic  raccoons like Belyaev did with silver foxes, so this possible domestication  process is much slower, like the natural selection that  led to our cat and dog friends. And even though it’s tempting to jump ten  steps ahead of the researchers’ conclusion, this paper isn’t making any claims  about raccoons being domesticated!

It doesn’t say anything about a  mutualistic relationship with them, where they help us somehow  and we control their survival. This team was specifically trying  to study whether urban raccoons had one visible trait that appears on that  general domestication syndrome checklist and could be caused by NCCs. And that trait is: a shorter snout.

So these researchers looked at 19,495  photos of North American raccoons from the citizen science website iNaturalist, where anyone can share pictures  of the world around them. After the team divvied up the photos and screened them one by one to make sure  that the raccoon was the correct species and their head was clear  enough to measure their snout, they ended up selecting a mere 249  of those images for further analysis. Based on the locations tagged on iNaturalist, they split these images into 211 “urban” raccoons that were snapshotted in counties with more  than 20,000 people and 38 “rural” raccoons from counties with fewer people.

Then, they got to measuring  all these raccoon snouts. And, after some data analysis, they found that urban raccoons had 3.56%  shorter snouts than their rural cousins. Actually a little underwhelming  once you get under the hood.

However, because other research  involving urban foxes and mice has also found a pattern of  shorter snouts on city-dwellers, the authors suggest that the proximity to  humans could bring about this physical change that may be linked to domestication. But that does not, by any stretch,  mean they are domesticated. At best it’s a baby step.

And there could be other explanations. For example, climate affects  the snout length of raccoons, and could throw a big confounding  variable into the mix. More research is definitely called for.

Understanding domestication  will take a lot of time, smart questions, and different experts— geneticists, biologists, ecologists,  anthropologists, and so on. All the -ists! Except physicists, I don’t think we’ll be in this After all, we’ve lived alongside  cats for thousands of years and can’t claim to completely  understand how they were domesticated.

So that’s also why the authors of that 2025 paper suggested that other domestication  researchers look a little more closely at these trash pandas! Even if a couple experiments  have shown that tameness is linked to the physical traits  of domestication syndrome, like a shorter snout in a couple animals, there’s simply too much we don’t  know about raccoons right now. What we do definitely know is that raccoons carry a ton of infectious diseases  that could make you extremely sick!

So can you invite that raccoon that  digs through your barbecue scraps into your house as a pet? No. And will you be able to have a raccoon  as a pet in the relatively near future?

Also no. I’m sorry, but I promise… we’re just looking out for you. [ OUTRO MUSIC]