Episode 315: Dogs and Cats

Thanks to Fabiana and Hazel for their suggestions this week, where we learn more about dogs and cats!

Further reading:

Gene mutation that makes dogs small existed in ancient wolves

Feline genetics help pinpoint first-ever domestication of cats

Cats Learn Names of Their Feline Friends

A cat (Dracula, specifically, with Dracula the toy):

A dog, in case you’ve never seen a dog before:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to revisit two great topics suggested by two great listeners, Fabiana and Hazel. They suggested dogs and cats, respectively. We’ve covered both before, but there’s always more to learn about any animal. Let’s look specifically at two recent studies that can add to our knowledge.

We’ll start with Fabiana’s suggestion of dogs. Results of a study published in January of 2022 examined the genetics of wolves and dogs to see how small dog breeds developed. We’re not completely sure how domestic dogs are related to wolf species alive today, since dogs have been domesticated for tens of thousands of years, and were probably domesticated at different times in different places by different groups of people, and potentially domesticated from different species of wolf, and since wolves and dogs can interbreed and produce fertile offspring. It’s very complicated, to say the least.

Wolves are roughly the same size throughout the world, depending on species and environment. The gray wolf, which is native to the northern parts of North America and most of Eurasia, stands about 2 and a half feet tall at the shoulder, or about 85 cm, and weighs around 88 lbs, or 40 kg, on average, although wolves who live in warmer areas tend to be smaller. There are certainly dog breeds bigger than this, but there are lots of dog breeds that are much, much smaller. I mean, the Chihuahua only grows around 9 inches tall, or 23 cm, and usually barely weighs 6 lbs, or 2.7 kg.

The prevailing belief is that small dog breeds came about because people bred the smallest dogs together and chose the smallest puppies from that pairing to breed to other small dogs. That’s true, but the genetic capacity for small size had to be there to start with in order to breed a 6-lb Chihuahua from an 88-lb wolf, no matter how many generations of dogs were in between. Researchers knew the genetic code for this size difference had to be somewhere, but it took a decade of study before they found it.

Once they found the growth hormone mutation that could allow for very small size when expressed, they searched for it in over 200 dog breeds to see if it was there in all dogs. Sure enough, it was. The scientists hypothesized that the genetic mutation showed up after dogs were domesticated, somewhere around 20,000 years ago. To test this, they looked for the mutation in the genetic profiles of both living and extinct canid species.

To their surprise, the mutation was present in all of them, including the genetic profile of a Siberian wolf that lived 54,000 years ago. Without this mutation, we wouldn’t have Chihuahuas or Yorkshire terriers or other small dog breeds that so many people love. That means the mutation was beneficial for domesticated dogs, but at the same time it was mostly non-beneficial for wild canids.

When dogs were domesticated around 20,000 years ago, and possibly well before that, the world was in the middle of a glacial maximum. The climate throughout the entire Earth was considerably colder than it is today. Ocean levels were lower because so much water was frozen, with ice sheets covering northern Europe and North America to a depth of about 2 1/2 miles, or 4 km. Northern Asia had fewer ice sheets but was much dryer than it is today. In fact, the world was a lot dryer overall, so places that weren’t covered in ice were more likely to be deserts, leading to massive dust storms and just a general dustiness throughout the world. Most of northern Africa and central Australia were what’s called “tropical extreme desert,” which doesn’t sound like any fun, but a lot of Asia was a polar desert. Most of Europe and eastern North America that wasn’t covered in ice was tundra or taiga, and even the most hospitable parts of the world were mostly open woodland and savannas. In other words, this was a world that favored really big animals like mammoths and woolly rhinoceroses and giant deer and buffalo and moose, and wolves needed to be big in order to hunt this megafauna.

But the world wasn’t going to be so cold for much longer. The ice sheets began to melt as the climate worldwide warmed up around 19,000 years ago, which led to sea levels rising and all sorts of other dramatic changes. Humans took their dogs and migrated to lots of places where they’d never been able to live before. Before this, dogs were probably mostly hunting partners, but as life got easier for people as mild winters and rainy spring weather became more common, dogs were more likely to be pets as well as working animals. People started selecting for smaller dogs, since a small dog eats less and is just plain cute. If it weren’t for that little genetic mutation in canids, the smallest dogs wouldn’t be all that much smaller than a Labrador.

Next, Hazel suggested we learn more about cats. Cats were domesticated a lot more recently than dogs, and a genetic study published in December 2022 determined that all pet cats in the world today are descendants of wild desert cats domesticated about 10,000 years ago in the fertile crescent in the Middle East. As we learned in episode 166, this was around the time that people were developing farming, and farming means you need to store grain. If you store grain, you attract mice and other rodents. Wildcats started hanging around farms and houses to catch rodents, and since the humans didn’t want the rodents, they were fine with the cats. Farms that didn’t have any cats had more rodents eating their stored grain, so it was just a matter of time before humans made the next logical step and started taming wildcats so they could trade cats to people who needed them.

The study was led by a feline geneticist named Leslie Lyons, and I only mention her name because it’s so perfect that someone with the last name Lyons would study cats and their relatives. Lyons and her team compared genetic samples taken from cats throughout the world and determined that all domestic cats are descendants of animals who originally lived in the Fertile Crescent. This is the same conclusion as a 2008 study by a different group of scientists, but the genetic tools used these days are much more sophisticated.

Cats definitely started out as working animals just like dogs did, but it probably wasn’t too long until people were treating them like pets. Cats are cute and soft, and people just like animals. We know that cats were treated as more than just a useful thing to have around because of an archaeological discovery from 2004. A human burial site on the island of Crete dated to about 9,500 years ago contained the remains of a human along with jewelry and other items, but also the remains of a cat. The cat had been buried separately in its own tiny grave right next to the person. There’s no sign that the cat was killed on purpose, so it’s possible it died separately and was buried next to the person who loved it.

Two separate studies were published in 2022 about cats and names. One study determined that cats who live in a household with at least one other cat learn the other cats’ names as well as their own. The other study determined that cats who live in a household with more than one person learn the names of their people. Personally, I don’t know how my cats can possibly know their names considering I call them by so many pet names, including puppy and bunny and squishmallow and you horrible little monster. However, in an unscientific study conducted just now by me, with a sample of one, when I called Poe’s name, he looked up at me and Dracula, who was lying on the bed next to me, looked at Poe. So I guess they’ve figured it out.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 232: Almost Domesticated

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Thanks to “dog freak Ruby,” we’re going to learn about some animals that aren’t exactly domesticated but aren’t really wild either.

Further reading:

Memories of Ángela Loij

Mongolian horse and its person:

Mongolian horses:

OH MY GOSH HEART HEART HEART (photo from this website):

Dingos!

An artist’s rendition of the Fuejian dog (left) and a picture of the cuelpo (right):

The cuelpo, happy fox-like canid:

A very fancy rat:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Before we get started, and before I forget again to tell you about this, I’m planning a bonus Q&A episode for August. If you have any questions about the podcast, podcasting in general, me, or anything else, feel free to email me at strangeanimalspodcast@gmail.com, or otherwise contact me through social media!

A few episodes ago I mentioned in passing that the Australian dingo is a type of feral dog. It’s a more complicated situation than it sounds, so while I didn’t want to confuse the issue at the time, I kept thinking about it. Then I remembered that a listener emailed me a while back wanting to know more about how dogs were domesticated. We covered the topic pretty thoroughly back in episode 106, but I realized that there’s an aspect of domestication we didn’t cover in that episode. So thanks to “dog freak Ruby,” here’s an episode about a few animals that are only semi-domesticated.

Domestication, after all, isn’t a switch you can flip. It’s a process, and depending on the animal species and the circumstances, it can take a really long time. It’s not the same thing as taming an animal, either. An individual animal might become tame with the right treatment, but that doesn’t mean any individual of that species would react the same way. Domesticated animals show genetic changes that their wild counterparts don’t, changes that make them more likely to treat humans as friends instead of potential predators.

Generally, a fully domesticated animal requires some level of care from a human to survive, even if it’s just feral cats living near humans so they can find and kill rodents and avoid most predators. Feral domesticated cats don’t live the same way as their wild ancestors do. But sometimes it’s not as cut and dried as it sounds. While mustangs and other feral horse populations are considered domesticated animals, they live like wild animals and don’t need humans to survive. They mostly just need humans to leave them alone so they can thrive on their own. But if you capture a mustang that’s lived its whole life in the wild, with the right treatment it will eventually become tame, because its ancestors were bred for thousands of years to trust and depend on humans.

That brings us to our first semi-domesticated animal, the Mongolian horse. Yes, I’m still really into Mongolia and the Hu, and I’m excited to say I have tickets to see the Hu twice in concert this fall, if everything goes well. I’ve been listening to a program called the Voice of Mongolia in English, which is primarily a shortwave radio program but it’s also released as a podcast, and it talks about various aspects of Mongolian culture. Recently they had an episode about horses, so some of my information comes directly from that show.

Mongolia is a country in central Asia that’s mostly open steppes, which is a type of grassland. The soil isn’t right for most crops, but it’s great for horses. The people of Mongolia are traditionally nomadic, moving around from place to place to find grazing for their horses and other livestock, and about half of the current population still lives this way.

The Mongolian horse is a small, tough breed that probably hasn’t changed much in the last thousand years, possibly longer. It’s one of the oldest breeds of horse in the world and the ancestor of many other horse breeds. For a long time people assumed it was the domesticated descendant of the wild Przewalski’s horse, but genetic testing has determined that domestic horses developed from a different wild horse species that’s extinct now. Genetic testing also showed that the Mongolian horse has the highest genetic diversity of any horse breed tested. It’s incredibly strong for its size, can gallop for miles without tiring, has strong hooves that never need trimming or shoeing, and seldom needs or receives veterinary care.

The main reason for all these traits is that Mongolian horses live like wild horses in most ways. They live loose, grazing as they like, and if they get too far away from their humans, the owners will go out to find them. But they’re still domesticated. Mare’s milk is an important part of the Mongolian diet, so the mares are used to being milked, and people use their horses to ride, carry packs, and pull carts. The stallions are frequently raced. At the same time, though, they’re not really pets. Mongols don’t give their horses names, but instead refer to them with a detailed description. The Voice of Mongolia in English says the Mongolian language has over 300 words to describe horses, while Wikipedia says it’s over 500. Either way, the terminology is so precise that everyone knows exactly which horse someone’s talking about, which if you think about it is more useful than a name.

The Australian dingo is in a similar situation. It’s considered a feral dog breed, but it doesn’t need people to survive. Most feral dogs throughout the world barely scrape by, eating garbage and rats and often dying of starvation or disease. Dingos live like wild animals and do just fine. But at the same time, they’re happy to hang out with people from time to time, acting as hunting companions who are neither dependent on humans nor frightened of them.

The dingo is a strong, tough, lean dog that stands around 22 inches tall at the shoulder, or 56 cm. It has flexible joints like the Norwegian lundehund we talked about in episode 230, which allows it to climb cliffs and fences and otherwise navigate difficult terrain. It’s usually a yellowy or ginger color, sometimes with small white markings, although some dingoes are black and tan. It can survive on very little water. It often hunts in packs and will hunt animals larger than it is, like the red kangaroo.

The dingo was probably brought to Australia by humans, although we’re not sure when. Dingo fossils have been found dating to 3,500 years ago in western Australia, so it was at least that long ago. Genetic studies show that the modern dingo and the dingo of 3,500 years ago are pretty much identical. It also shows that it’s definitely a domestic dog, related to other dog breeds that were once common in Asia around 7,000 years ago, but which are rare now. It’s most closely related to the New Guinea singing dog, which makes sense since New Guinea is so close to Australia. Until somewhere between 6,500 and 8,000 years ago, New Guinea and Australia were connected when sea levels were low. Genetically the two dog breeds have been separated for about 8,300 years, which suggests that the dingo has been in Australia for at least that long.

Traditionally, Aboriginal Australians would take a dingo puppy from its den to keep as a pet, a hunting dog, or sometimes a herding animal. Sometimes the dingo would stick around when it was grown, but sometimes it would return to the wild. There’s a lot of controversy about breeding dingoes as pets, since it would be easy to breed the wild traits and behaviors out. Since the dingo has been killed as a livestock pest since white settlers arrived in Australia, in many places its numbers are in decline and there are worries that the wild dingo could go extinct. There are already problems with the dingo cross-breeding with other dog breeds. It’s a complicated topic, because while the dingo is a dog, it’s not precisely domesticated at this point but also not precisely a wild animal.

There used to be a domesticated canid in South America called the Fuegian dog, which was probably used as a hunting dog, especially to hunt otters. On cold nights, the dogs would wrap themselves around their people like living blankets so everyone stayed nice and warm.

The Fuegian dog wasn’t a dog, though. It was the domesticated form of the culpeo, also called the Andean fox. It’s actually not a fox although it looks a lot like one. It’s related to wolves and jackals, and it lives on the western slopes of the Andes Mountains all the way down to the southern tip of Patagonia. It eats small animals like rodents and introduced European rabbits. While the culpeo is sandy or tawny in color with gray on its back and a black tip to its tail, the Fuegian dog was sometimes brown and white or all white. Reportedly the Fuegian dog was not very tame in general and was an aggressive animal compared to actual dogs. It would hunt on its own and basically acted like a wild animal that just happened to hang out with humans a lot, like the dingo does today.

The culpeo is doing just fine, but the Fuegian dog is extinct. The Fuegian dog was tamed by a Patagonian people called the Selk’nam [shelknam], or ‘Ona, who were nomadic hunter-gatherers. They lived in such a remote part of South America that Europeans didn’t encounter them until the late 19th century when settlers showed up to raise sheep and rubber trees. We’ve talked about what happened to them in a previous episode, although I can’t remember which one. The Selk’nam didn’t understand the concept of livestock, so they figured those sheep were literally fair game. The sheep were living on their own hunting grounds, after all. The Selk’nam killed some of the sheep, and in retaliation, the European settlers murdered all the Selk’nam. I was going to tell you the name of the man who started the genocide, but I don’t think anyone should remember his name. It wasn’t just “oh, you killed my sheep, I’m going to shoot you because I’m mad,” either. There was a bounty on Selk’nam people, and that’s all I’m going to say because it’s just too awful and disturbing.

By 1930, only about 100 Selk’nam remained alive, and the very last member of the people, Ángela Loij, died in 1974. There’s a link in the show notes to a page with lots of information about her as a person.

In 1919 when Christian missionaries visited what was left of the Selk’nam, they discovered that all the dogs had been killed off by the people themselves because the dogs were too fierce and killed livestock. It sounds like a last, desperate attempt by the Selk’nam to stop the murder of their people by keeping their dogs from killing any sheep. But by then it was too late, and the genocide wasn’t really about the sheep in the end. It was racism and hatred. Remember that all people are equal, no matter what they look like or how they live. Don’t ever let anyone tell you otherwise.

Okay. Let’s finish with the story of another semi-domesticated animal, one that doesn’t involve people being terrible to each other. The kind of rat you can buy as a pet is considered semi-domesticated, and it hasn’t actually been domesticated for very long. The person mainly responsible for the pet rat is a man called Jack Black. Not the actor Jack Black; this was a different guy who lived in the mid-19th century.

Jack Black was a ratcatcher in London, England who said he was the Queen’s official rat-catcher even though he wasn’t. He was definitely an extravagant character who always wore what he called his uniform, which included a big leather sash over one shoulder decorated with rats made of iron, a crown, and the initials V.R. for Victoria Regina, or Queen Victoria. He told people the queen herself gave him the sash, but actually his wife made it for him. Black also carried a big domed cage with him to hold the rats he caught.

He mainly caught rats to sell to people who were training their dogs to kill rats, which was also a popular thing to watch. I mean, that doesn’t sound like any fun to me but this was before video games were invented. Occasionally, though, Black would catch a rat that had interesting markings or that was an unusual color. These rats he would keep, tame, and breed to produce more rats with different colors and patterns. He sold the tame, pretty young rats to people as pets. He especially liked white rats, which made popular pets then and are still popular today.

Pet rats, usually called fancy rats, are a subspecies of the brown rat, or Norway rat, which we talked about in episode 143. We also talked about Jack Black briefly in that episode, but at the time I didn’t realize he wasn’t really a royal rat catcher. By 1900 fancy rats were popular pets and remain so today, and are becoming more and more domesticated. If they’re not fully domesticated they’re well on their way, all thanks to a guy who thought rats were neat.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!

Episode 106: Domestication with and without foxes

Thanks to M Is for Awesome, who suggested the topic of domestication! This week we look mainly at foxes and how they relate to the domestication of dogs. Also, chickens.

Unlocked Patreon episode about chicken development and domestication: https://www.patreon.com/posts/21433845

A red fox:

Domestic foxes want pets and cuddles also coffee:

The fennec fox with toy I JUST DIED:

The raccoon dog is actually a species of fox:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Back in episode 80, about mystery dogs and other canids, I said I was going to leave foxes for another episode. And here it is! But as I researched, it turned out that while there are lots of interesting foxes, they’re all pretty similar overall. So while we will learn about some of the more unusual foxes this week, I’m mostly going to talk about how animals are domesticated by humans. This is a suggestion from M Is for Awesome, who suggested domestication “and how it changes domesticated creatures from their wild cousins.” You may not know how this relates to foxes, in which case, I’m about to blow your mind.

But first, we should learn about how scientists think other canids became domesticated. You know, how dogs became dogs instead of wolves.

Domestication of wolves took place possibly as much as 40,000 years ago, but certainly at least 14,000 years ago. Gray wolves are the closest living relative of the domestic dog, but the gray wolf isn’t the dog’s ancestor. Another species of wolf lived throughout Europe and Asia, possibly two species, and domestication of these wolves occurred at least four different times in different places, according to DNA studies of ancient dog remains.

One of the oldest dog remains ever found dates to 33,000 years ago, found in a cave in Russia. Researchers think it wasn’t fully domesticated, but was probably connected with the people who had been using the cave as shelter. A 2017 study concluded that it isn’t related to any modern dogs and apparently was related to a species of wolf that has since gone extinct.

Many researchers think that wolves actually started the domestication process. Wolves hunt but they also scavenge, so they may have gotten into the habit of following bands of humans around to find scraps of food. Back in the hunter-gatherer days before we started growing crops, humans were nomadic, moving from place to place to find food. Wolves would have been attracted to the bones and other parts of dead animals humans left behind. If a wolf got too close to a campfire where humans were sitting around eating, two things might happen. If it was an aggressive wolf, the humans would chase it away or even kill it. But if it wasn’t aggressive, maybe because it was scared or young, a human might have tossed it a little bit of meat or a bone. That wolf would definitely hang around more, hoping for more food. If the humans grew used to it, it might even have started to consider itself part of the human’s pack. And if another predator approached, the wolf might growl at it and warn the humans, who would reward the wolf with more food. Over the generations, the wolves who got along best with humans would receive the most food and therefore be more likely to have babies that also got along with humans. It’s a lot easier to act as a camp guard and be given food and pets than it is to go out and try to kill ice age megafauna with your teeth.

Remains of a puppy dated to 14,000 years ago was found recently in a prehistoric grave in Germany. A test of its DNA indicates that it is related to modern dogs. The puppy was fully domesticated, well cared for, and had been buried with a man and a woman. Researchers can even tell that the puppy died of distemper, which leaves telltale marks on the teeth. The puppy had survived until the disease was well advanced, and it could only have done so with special care from humans. Even today distemper is a terrible disease among dogs. I had a puppy that died of it when I was little. Obviously, even 14,000 years ago dogs were already more than working animals or camp scavengers. Someone loved that puppy and tried to help it get better.

An interesting thing happens with domestication. Certain physical traits come along with the behavioral traits of reduced aggression and willingness to treat humans as surrogate parents. In the case of dogs, these often include a puppy-like appearance, including floppy ears, curled tail, smaller adult size, and a rounder head with smaller jaws. This isn’t the case with all dog breeds, of course, but the changes seem to be genetically linked to behavior. It’s called domestication syndrome.

So this is interesting, but how does it apply to foxes? Foxes are canids, but they aren’t all that closely related to dogs.

Well, in 1959 a Russian zoologist named Dmitry Belyaev decided to see if he could domesticate foxes. Taming and domestication are different things. A wild animal that has become used to certain humans can be considered tame, but a domesticated animal is one that is genetically predisposed to treat humans as caregivers. Belyaev didn’t just want to tame a few foxes, he wanted to try actually domesticating them.

He started his project by going to a fur farm that bred foxes to kill for their furs, which were then made into coats and other clothing. These were red foxes, which are common throughout much of the world, but because they were bred for their fur, they weren’t red. They were a darker color called silver, a color mutation, but other than that they were regular foxes. Belyaev chose foxes by how well they tolerated people, the ones that were less likely to bite.

He bred these foxes and when the babies grew up, he chose the least aggressive ones to breed. Then he chose the least aggressive babies from those parents, and so on. And after only six generations, he started to see results. Some of the foxes in the sixth generation actively sought out humans. They licked their hands, whined for attention, and even wagged their tails.

Something else happened too. The foxes started showing physical differences. Some had fur with white patches or various other color variations, some had floppy ears, some carried their tails so that the tip pointed up. All these traits are common in dogs, but pretty much never seen in wild foxes. Recent research shows that the changes are genetic and linked to lower adrenaline production. One color of fox, called Georgian white, has never been seen except in Belyaev’s domesticated foxes. It’s a lovely white all over with black ears and black or gray markings on the face and paws.

In case you’re wondering how much of the behavioral differences are due to increased human contact, the study also breeds the least tame foxes. They continue to look and act like wild foxes.

The breeding project has continued even though Belyaev died in 1985. These days almost all the foxes are as tame as dogs. Belyaev also conducted domestication projects with rats and American mink, both of which succeeded as well as the fox project. But if you want a pet fox, you’re out of luck. The foxes are occasionally for sale, but they’re extremely expensive and some parts of the world don’t allow foxes to be kept as pets at all, even these domesticated foxes. Occasionally someone will pop up online claiming to have some of the domesticated foxes for sale, but they always disappear after taking people’s money and never deliver any foxes.

Besides, even though Belyaev’s foxes are domesticated, they aren’t dogs. They don’t always behave in ways that make sense to humans. Humans and dogs have been buddies for untold thousands of years and we’ve basically evolved together, while foxes have only been domesticated for basically one human lifetime. One zoologist whose institute has several of the domesticated foxes for study and outreach says that she has to watch her coffee cup because if she doesn’t, one of the foxes might pee in her coffee. As soon as I read that, my desire to own a pet fox diminished. They’re really cute, but so are dogs, and while I have had a dog that would steal and eat sticks of butter off the counter, I never had to worry about him peeing in my coffee. Besides, the domestic foxes are also hard to house-train and still retain a wild fox’s musky odor.

The fennec fox is the smallest canid, and it’s sometimes kept as a pet, but it’s not domesticated. If the babies are taken from their mother very early, they grow up fairly tame, but they’re still wild animals and can be aggressive.

I have seen a fennec fox at the Helsinki Zoo! It was adorable. I definitely can see why people want one as a pet, but honestly, cats are about the same size and shape but are a lot less likely to bite. Also, cats purr. The fennec fox lives in northern Africa and parts of Asia and its fur is a pale sandy color with a black tip to the tail. Its eyes are dark and its ears are large. It stands only about 8 inches tall at the shoulder, or 20 cm, but its ears can be six inches long, or 15 cm. It eats rodents, birds and their eggs, insects, and other small animals, as well as fruit. It can jump really far, some four feet in one bound, or 120 cm. Because it lives in desert areas, it rarely needs to drink water. It gets most of its water through the food it eats, and researchers think it may also lap dew that gathers in the burrow where it spends the day.

The most common species of fox is the red fox. Foxes are canids related to dogs and wolves, and just to be confusing, male foxes are sometimes called dogs. Female foxes are vixens and baby foxes are cubs or kits. But the red fox isn’t the only species out there, not by a long shot.

For instance, the grey fox lives throughout North and Central America. It can look a lot like a red fox but its legs are always reddish or tan, unlike the red fox, which always has black legs. Instead of a white tip to its tail like red foxes have, the grey fox has a black tipped tail. It’s also not that closely related to the red fox or any other foxes, for that matter. Its pupils are rounded like a dog’s instead of slit like other foxes, which have eyes that resemble cats’ eyes.

The grey fox also has hooked claws that allow it to climb trees. That’s right. I said it can and does climb trees just like a cat. It’s nocturnal and omnivorous, which means it eats pretty much anything. It especially likes rabbits and rodents, but it also eats lots of fruit and insects.

The only other canid that can climb trees is the raccoon dog, which is neither a raccoon nor a dog. It’s actually a type of fox, but it does look a lot like a raccoon at first glance. It has grizzled brown-gray fur, a black mask over the eyes and cheeks, and a short muzzle and rounded ears. And, of course, it also climbs trees like a raccoon. But it’s larger and bulkier than a raccoon with much longer legs, and its tail isn’t ringed like a raccoon’s tail.

The raccoon dog is native to parts of Asia, but it was introduced to parts of western Russia in the early 20th century as a fur animal and is now widespread throughout much of Europe. It’s an omnivore too; pretty much all foxes are omnivores. It eats rodents, frogs and toads, birds, fish, fruit and plant bulbs, some grains, and insects. You know, pretty much anything. It even eats toads that are toxic to other animals, diluting the toxins with massive amounts of saliva. And in cold areas, the raccoon dog hibernates. It’s the only canid that does.

Several months ago, I released a Patreon episode about chicken teeth that also talked about the domestication of chickens. It wasn’t my best episode but it’s relevant here so I went ahead and unlocked it for anyone to listen to. There’s a link in the show notes so you can click through and listen in your browser without needing a Patreon login or anything. Anyway, let’s finish up today with some information I just learned about the domestication of chickens. Specifically, a breeding project similar to the Belyaev foxes but with the wild birds that are the ancestors of domesticated chickens.

The bird is called the red jungle fowl, which lives in Asia and looks like a chicken, but is smaller than domesticated chickens. It was domesticated as long as 8,000 years ago but the wild bird still exists. A Swedish research team tried replicating Belyaev’s domesticated fox experiment with some of the wild birds. Like the foxes, the researchers bred a population of birds that were just ordinary wild jungle fowl and not selected for tameness, and a population of birds that were chosen because they tolerated humans a little more than usual. As each of the baby birds grew up, they were tested by having a human walk into the pen and try to touch it. The human wasn’t told whether the bird was from the tame group or the wild group. But after a couple of generations, it was obvious which was which. The tame birds became so tame that they didn’t mind the human at all.

And like the foxes, although the only trait the researchers selected for was tameness, the chickens began to change in other ways too. They became bigger and the hens laid more and larger eggs. This happened within only a few generations, which suggests that domestication is a much faster process than researchers once assumed.

And thanks to recent study, we’re pretty sure we know why these physical changes happen along with the behavioral changes. Selecting for tameness alters the genes that controls what are called the neural crest cells. When the embryo is developing, the neural crest cells migrate to different parts of the body. They affect the coat or feather coloring and some other physical developments, but they also affect the development of many other traits, including the fight-or-flight response. In other words, if you select for an animal that tends to be calm instead of fighty or flighty, you’re also accidentally selecting for differences in physical traits. Follow-up studies confirm that neural crest cells migrate differently in domestic animals than they do in their wild counterparts.

Research into domestication is a hot area of study right now, now that DNA and molecular genetics studies are more sophisticated. You know, in case anyone out there is considering a career in science.

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