We all know that dogs are smart, sensitive creatures, but interpreting their vocalizations and behaviors can still be a challenge. In this episode, animal behaviorist Daniel Mills reveals the true meanings behind dogs’ noises, actions, and body language. Then, author Pilley Bianchi tells the story of Chaser, the border collie who became known as “The Smartest Dog in the World” for the way that she learned language.

MUSIC FEATURED IN THIS EPISODE

Fabien Tell - Flower Market
Fabien Tell - You’re Like Me
Fabien Tell - Seven Daughters
Fabien Tell - Letter of Resignation
Fabien Tell - She, My Mirror
Fabien Tell - Onwards Upwards
Fabien Tell - Onwards Upwards
Fabien Tell - These Feelings
Fabien Tell - Fly Baby Fly
The Caravan - Crown of September
Thimble Rider - Organza
Fabien Tell - She, My Mirror
Fabien Tell - Treasure Map
Tres Leches - Alfajor
Fabien Tell - Under the Tuscan Sun
Megan Wofford - Reflection
Butterstone - Homin Brer
Butterstone - Don Germaine

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Learn about Daniel’s work with the Animal Behaviour, Cognition and Welfare Research Group.

Buy Pilley’s book, Animals Make Us Human.

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View Transcript ▶︎

You’re listening to Twenty Thousand Hertz. I’m Dallas Taylor.

[music in: Fabien Tell - Flower Market]

Dogs are truly man’s best friend. Around the world, almost a third of all households are home to a pet dog, which adds up to more than four hundred and seventy million canine companions. They protect our families, keep us active, and show us their love as soon as we walk in the door.

Leila VO: Now, we all know that dogs are smart, sensitive creatures.

That's Twenty Thousand Hertz producer Leila Battison.

Leila VO: But to communicate with dogs effectively, we have to understand how they're wired to think.

Daniel Mills: Dogs are going to see us through a dog's eye view of the world, and that is very different to a human one.

Leila VO: That’s doctor Daniel Mills, who's an expert in animal behavior.

Daniel Mills: Dogs are incredibly observant, and very good at predicting what will work, and what will get them what they need. So I think the starting point has to be to appreciate the fact that dogs want to fit in.

Leila VO: As in, they want to fit in with the people in their lives. And those social tendencies go way back to their wild wolf ancestors.

Leila VO: Wolves live and hunt in packs of about six or seven, roaming together over hundreds of square miles of territory. And when you rely on your pack for your next meal, it’s essential that you communicate well with them.

Daniel Mills: Vocalizations which you commonly find in the wild ancestors like whining [sfx: individual wolf whine] and howling, [sfx: individual wolf howl] are clearly social solicitation, and they've retained that function.

Daniel Mills: So if a dog howls, it basically says, “I want you to come to me.”

[SFX: husky howl]

Daniel Mills: And it's what wolves do before they go off hunting.

[group of wolves howling]

Daniel Mills: You know, they howl and they gather together as a pack and then they go off.

Leila VO: On the other hand, whining tells the rest of the pack that someone needs help.

Daniel Mills: Yeah, whining and whimpering, they're sort of care solicitation behaviors.

[SFX: wolf whine]

Leila VO: When humans and wolves first started hunting together tens of thousands of years ago, wolves learned that these whines were good at getting our attention.

Daniel Mills: The frequencies that they use, we find endearing and encourage us to care.

Leila VO: Like when a young baby whimpers and cries, a parent can't help but comfort it.

[SFX: baby softly crying in]

Daniel Mills: Certain sounds may intuitively encourage a more nurturing aspect to us. So they've piggybacked onto our own care of our own young, if you like.

Leila VO: Over time, the wolves that whined to us got our care, and passed that behavior on to their pups. And today, in dogs of every breed, that tendency remains. [sfx: whining dog in]

Daniel Mills: That's the way that evolution works. There's a niche there. What works?

[music in: Fabien Tell - You’re Like Me]

Leila VO: Of course, the sound that we most associate with dogs is the classic bark. [sfx: single bark] But it turns out, barking is not a very wolfy thing to do.

Daniel Mills: You will see it occasionally in certain sort of conflict situations that they may issue a bark. [SFX: wolf bark] But the wild ancestors of dogs, we don't think do much barking. And we think actually the bark is a behavior that humans may have selected for.

Leila VO: Selective breeding has radically changed the characteristics of many of our domesticated species, from dogs to cows, and even wheat and corn. And if you go back to those early days of hunter gatherers and their dogs, it makes sense that humans would have favored the barkier ones.

Daniel Mills: If you think about it from an evolutionary point of view, one of the early functions of dogs was to alert them and keep humans safe. And the bark is an alert, or “I'm here type vocalization.” [SFX: harsh husky type bark] But then we actually found that quite a useful thing.

Leila VO: So we favored the dogs that did a better job of alerting us to danger, and the bark became the sonic signature of dogs around the world.

[music out with quick montage of dark bogs from various breeds]

Leila VO: Barking is far from the only thing that humans have bred into dogs. Over the millenia, we've selected for all kinds of physical and personality traits. In time, we transformed the wolf into everything from the tiny chihuahua to the shaggy Tibetan mastiff. And of course, different sized dogs make different sounds.

[SFX: small dog yap]

Daniel Mills: If you're a small animal, you can't make deep sounds because you need a deep chest to do it.

[sfx: big dog bark]

Leila VO: But it turns out, selecting for size has also meant selecting for hearing. If you look up the hearing range of a dog, you get a standard figure of 40 hertz to 60 thousand hertz. But according to Daniel...

Daniel Mills: That's an oversimplification. The original work that was done was done on four dogs. And a number of years ago, one of my colleagues and myself decided that we'd bring dogs in, and start playing them different frequencies and see at what point they couldn't hear the sounds.

[SFX: frequency sweep begins]

Daniel Mills: And what we found was that, within dogs, size and hearing goes together.

[SFX: frequency sweep ends]

Leila VO: In other words, small dogs can hear higher frequencies than big dogs can.

Daniel Mills: So something like your Jack Russell will be able to hear mice scurrying around in your skirting boards, whereas your Great Dane can't.

Leila VO: This may be yet another trait that we've selected for in rat-catching dogs.

Daniel Mills: You look at the dogs that are ratters, they tend to be smaller dogs.

[terrier yap & rat squeak]

[music in: Fabien Tell - Seven Daughters]

Leila VO: As any dog owner can tell you, dogs bark for a wide range of reasons. And for Daniel, the common thread is frustration.

Daniel Mills: Frustration means you've lost control over the environment. Your predictions are no longer being met. So if you think about it, alerting barks, you know, "There's someone coming, and I'm not sure what I should do about it," so that's sort of a slightly frustrating situation. [SFX: frustrated sounding bark]

Leila VO: And a modern dog's life is filled with minor frustrations. Like simply being stuck in the house.

Daniel Mills: We keep dogs confined a lot so that would encourage barking over the other vocalizations.

Leila VO: But if a dog barks when it's home alone, there are some audible cues that can help explain why.

Daniel Mills: If it's like a deep bark, [SFX: deep bark] then it might suggest that the dog is reacting to something like another dog or potential threat.

Daniel Mills: However, if it's a much more high pitched bark, [SFX: higher bark - same breed] It might suggest that the animal is distressed by being left alone, and the separation from the owner a big problem for the dog.

Leila VO: After all the time that humans have spent with dogs, we've gotten pretty good at recognizing the emotion behind the sounds they make.

Daniel Mills: If you play people different types of bark, then you give them a list of circumstances in which those barks and growls might have happened, generally people are pretty good at matching them, even if they're not dog people.

Leila VO: To demonstrate, here are three recordings of dog growls. One was recorded while the dog was playing, one was in the presence of a threatening stranger, and one was while the dog was guarding a bone. See if you can guess which one’s which.

Leila VO: Here’s growl A…

[sfx: Growl: Guarding a Bone]

Leila VO: Here’s growl B…

[sfx: Growl: Playing]

Leila VO: And here’s growl C…

[sfx: Growl: Threatening Human]

Leila VO: Now, here are the answers: Growl A was guarding a bone.

[sfx: Growl: Guarding a Bone]

Leila VO: Growl B was the play growl.

[sfx: Growl: Playing]

Leila VO: And growl C was with a threatening stranger.

[sfx: Growl: Threatening Human]

Leila VO: But guessing the context of a sound is different from understanding its exact meaning. And sometimes when our dogs bark, it can be hard to tell precisely what they want.

[ambiguous bark]

Leila VO: In recent years, scientists have been using AI to help understand what our dogs are saying to us. And maybe someday, we can develop a kind of dog translator, like in the Pixar movie Up!

[clip: Up!]

Dug the Dog: My master made me this collar. He is a good and smart master, and he made me this collar, so that I may talk. Squirrel!

Leila VO: In reality, it would probably be more like "This bark means 'I'm hungry.' This bark means 'I have to go potty.' And this bark means 'I heard a noise.’" That is, if those distinctions really do exist.

Daniel Mills: I think the technology is now there for AI, if we could harvest massive amounts of vocalization data, and the context in which they were gathered, then I think we can detect certain patterns, and may then be able to decode barks like that.

[bark + UI chime + AI voice]

Leila VO: Of course, dogs use much more than sound to communicate their feelings.

Daniel Mills: It could be things like facial expression, where the tail is…

Leila VO: There's the position of the ears, the stance or posture they're taking, bristling fur, and the list goes on. And just like with people, you can also glean a lot about their emotions from how they're behaving.

Daniel Mills: So, when you're frustrated, you become very narrow in your focus and very sharp in your actions. If you're scared, it's a quick response and we can see communication of fear.

[music in: Fabien Tell - Letter of Resignation]

Leila VO: To decode how a dog is feeling, you need to consider all of these factors.

Daniel Mills: You can't just use individual behaviors. You have to assess the whole animal. People say, "Oh, we had a waggy tail, but he bit me." Yeah, well, dogs wag their tails for lots of reasons. You have to understand the context in which that wag has occurred.

Leila VO: For dogs, the movement of their tails probably has to do with scent. For example, when a dog is scared, they often tuck their tail between their legs.

Daniel Mills: What we think is happening when a dog clamps his tail is he's putting the tail over the anal glands, which produce a certain scent. So by clamping his tail, he reduces the chemical signal, and so reduces the risk of antagonizing anyone.

Daniel Mills: Whereas if you raise your tail, you're exposing your anal glands. And if you wag your tail, you potentially create a bigger chemical cloud around you that signals much more about you.

Daniel Mills: So the wagging tail is, if it's up high, think about contexts in which an animal really wants to signal who I am… which could be in a play context. It could be in a threat context, though.

Leila VO: On top of that, the speed of the wagging tail can communicate different things.

Daniel Mills: It can be a very slow, deliberate wag, because I don't want to make it really fast because that could just provoke you and we could get involved in a fight that we don't really want.

Daniel Mills: So it's quite dangerous, I think, to say, "This is what this gesture means." You really need to understand the much wider context.

Leila VO: One area where it's really important to understand that wider context is with play.

Daniel Mills: Play is an interesting one because play can take any sort of behavioral element and mix it up with other ones so that it doesn't really make sense. So certainly we will see all sorts of vocalizations: barking, [SFX: happy bark] growling, [SFX: playful growl] even whining in the context of play. [SFX: playful whine]

Leila VO: But a dog's body language will usually tell you when it's growling for fun, and when it’s serious.

Daniel Mills: If a dog puts his chest down and his bum in the air, what we call a play bow, and then growls… [SFX: playful growl] what it means is, “I'm not actually threatening you.”

Leila VO: And there's one particular sound that you might hear when a dog’s playing, known as the play laugh.

Daniel Mills: It's a very breathy vocalization. You know, it sounds a little bit like a pant, but it's a sort of “Ha.” [SFX: play pant/laugh]

Leila VO: Dogs use this play laugh both with people and with each other. And for them, it seems to be an audible signal that everything is good.

[sound design: shelter environment, slamming gates, hard reverb]

Daniel Mills: Not only does it elicit play, but also if you played it in the background of dogs that were in shelters… [play laugh piped in] they seem to be more relaxed.

[play pant sounds piped in through speakers, whining/barking softens]

Leila VO: Unfortunately, this signal can also lead to a serious misunderstanding between people and dogs.

Daniel Mills: When a lot of children see a dog, they're really quite excited, and they often go…

[excited exhalation]

Daniel Mills: And if you blow on a dog, and I don't recommend anybody does this, because you could well get bitten by your dog, often your dog will bounce up at your face. They're responding to this vocalization that resembles the dog play laugh.

Leila VO: And that response can take the form of a play bite, which dogs do to each other all the time.

Daniel Mills: Now the interesting thing is, when a dog does a play bite, it uses its incisors, the front teeth. Not the pointy teeth, not the canines. So it doesn't give a puncture wound, it often gives an arc of tooth marks.

Leila VO: And these are the patterns of bites that Daniel often sees on children's faces.

Daniel Mills: I think a number of the bites to children on the face in particular are these play bites. But the dog doesn't realize that the child hasn't got a hairy coat. And so when they put their teeth on it, they leave a mark, unlike when they do it to another dog.

[music in: Fabien Tell - She, My Mirror]

Leila VO: While misunderstandings are bound to happen, most of the time dogs are doing their best to figure out what their human is thinking or feeling.

Daniel Mills: Dogs live in a very emotional world. You know, we worry about paying the mortgage next month, and that sort of thing.

Daniel Mills: Dogs don't project themselves in time. They'll be more worried about, "Well, where's that bit of food gone that was in my bowl a minute ago?" An abstract thought is quite hard for them, if not impossible in many respects. But they are very, very in tune with emotion.

Leila VO: As humans, we communicate our emotions through the way that we speak. And fortunately, that's something that dogs are great at grasping.

Daniel Mills: They're very sensitive to tone of voice. And we know that across species, certain tones can convey certain meanings. So across the world, if you want to speed an animal up, you tend to use ascending tones…

Horse Rider: Yip, yip, yip! [SFX: horse hoofbeats speeding up]

Daniel Mills: And if you want to slow an animal down, you use descending low tones. So “Whoooo”.

[SFX: horse hoofbeats slowing down]

Daniel Mills: Likewise, if we get excited, then the dog will get excited, ’cause the change of the voice. You see how my voice has just changed. You know, it's going higher pitch. It's going faster.

Daniel Mills: Biologically, we tune into these things, and dogs are very tuned in on an emotional level.

Leila VO: While dogs are great at picking up on our tone of voice, there are some situations where the tone we choose can lead them astray.

[SFX: whistling and banging fireworks + dog whine]

Daniel Mills: A lot of people, if their dog gets scared by a firework, they'll try and console the dog and they'll crouch down, and they'll cuddle it and say, "Oh, everything's all right!"

Daniel Mills: Now, from a human point of view, what they're trying to do is reassure the dog. But from the dog's point of view, what they see is the bang goes off, and their human suddenly makes himself into a small ball, the pitch of their voice changes, and they cuddle up close to the dog, which actually means, "My human is scared as well!" So far from it being reassuring, it feeds into the problem.

Leila VO: So the next time your dog gets afraid of a loud noise, consider strutting around and acting confident and happy.

[SFX: another firework]

Dog Owner: Alright, it’s a firework! I love fireworks! Fireworks are the best! [SFX: happy bark]

[music in: Fabien Tell - Onwards Upwards]

Leila VO: To properly interpret the sounds our dogs make, and the behavior they display, we have to understand how they see the world. And once we do that, our dogs will understand us better, too.

Leila VO: But one remarkable dog has learned to understand human communication unlike any in recorded history.

Pilley: Chaser has been called “The scientifically most important dog in the last 100 years,” and that is because of the way that she learned language.

Leila VO: That's coming up, after the break.

MIDROLL

[music in: Fabien Tell - Onwards Upwards]

Leila VO: Just like proud parents, dog owners will often claim that their pooch is especially brilliant. And while dogs are highly impressive as a species, some individuals really do go above and beyond.

John: Chase, find Mongrel! Find Mongrel… Yeah, good girl! That’s Mongrel.

Leila VO: That’s a clip of Dr. John Pilley and his border collie, Chaser.

John: Chase, find Croc! Find Croc. There’s Croc. Shake Croc!

[music in: Fabien Tell - These Feelings]

Pilley: Chaser is known as the smartest dog in the world, having an understanding of the names of over a thousand objects.

Leila VO: That’s Pilley Bianchi, who managed and co-trained Chaser with her father John.

Pilley: My father was a very charismatic human being. He was a naturalist. He was very connected with nature. He was actually an expert whitewater paddler, great windsurfer, hiker...

Leila VO: John was also a professor of psychology at Wofford College in South Carolina. He was especially interested in animal cognition, and he closely followed researchers who were attempting to teach human language to animals like dolphins, apes, and parrots.

Pilley: These things inspired him to want to teach his dog human language.

Leila VO: At that time, John’s dog was a mixed breed border collie called Yasha.

Pilley: We got Yasha in the late 80s, and he was really truly my father's heart dog. He went everywhere with my dad. He was a very assertive dog, and had a lot of confidence.

Pilley: And Yasha was so smart, he learned behavior so quickly that my dad decided it would be infinitely more fun to use dogs in the classroom than rats and pigeons. So Yasha became his research partner, and he brought him into the class every day.

[music in: Fabien Tell - Fly Baby Fly]

Leila VO: In class, John and his students explored canine understanding as they taught their dogs to do complex behaviors. But teaching the building blocks of language proved more of a challenge.

Pilley: When we speak to our pets, we usually talk in phrases, so they don't know, "Fetch the paper" is three words. They just understand "Oh, yeah, I get to run outside and grab that thing on the lawn and run back in the house!"

Pilley: So when my father tried to teach proper noun names like "paper," Yasha was understandably confused when the paper was back in the house, because it had no value to him. The fun part was racing out the door, grabbing this thing. But this thing, he was not allowed to play with. He couldn't chase it, chew it, or bounce it. So once it was in the house, it had no value.

Pilley: So sadly, he concluded that dogs were not able to learn language the way that most children do.

Leila VO: Having come to this conclusion, John backed off from trying to teach language to dogs. In his mid seventies, he retired from teaching, and settled into a quiet life with his wife Sally.

Leila VO: In retirement, John started going to Border Collie trials, where dogs showcase their skills in herding sheep according to the farmers' whistles and instructions.

[sheepdog trial scene]

[crossfade into fireside scene]

Leila VO: One night after one of these trials, John was sitting around a campfire with some of the farmers...

Pilley: He had the audacity to say, "You know, your dogs are incredible. The nuance that they can understand with sounds and whistles and their relationship with the sheep is really remarkable, but science tells us they don't really understand proper nouns. They don't even understand their own name. It's just a label, and it's just a cue to look."

Pilley: So, one crusty farmer said to him, "Wow, is that, that's what science tells us? Well, you tell me why I can call Jeb out of four other dogs and ask him to get Millie and Tilly, two different sheep out of a hundred sheep, he will do it every time. You tell me what science has to say about that."

Pilley: This severely humbled my father. And he realized that he needed to go back to the drawing board, and pay attention to the people that were actually using dogs in day to day life.

Leila VO: By that time, John sadly no longer had Yasha in his life.

Pilley: He had gone ten years without a dog after Yasha passed away because it really threw him more than he realized.

Leila VO: But as John explained in a video, his wife Sally got tired of him moping around the house in retirement. And she knew exactly what would cure him.

[music in: The Caravan - Crown of September]

John: Sally, my wife, knows me better than I know myself. She knew that I needed some new challenge. She knew that I loved dogs. So Sally told me one day just before Christmas, “You’re going to have a new dog.” And that made me happy.

Leila VO: So they went out to the border collie breeder and looked at the litter. And one particular puppy stood out.

Pilley: To be honest, she chose them. She came up to them and went and sat in his lap.

[sfx: puppy yap]

Leila VO: They named her Chaser, and from that moment, Pilley could see that they were going to be an unstoppable team.

Pilley: He was so charismatic and Chaser was adorable. She was very social. And I knew she was going to sparkle on camera and they were both going to be famous.

Leila VO: Pilley still remembers when she saw that greatness for the first time.

Pilley: When I came home for Christmas, she was about 8 months old at this time and he had this huge pile of toys. I believe at this time there were about two hundred toys. And they looked like they had been slobbered over one too many times. And I'm watching as he asked her to find specific toys out of this huge pile, and she did it flawlessly.

[music out with 2 clips of John requesting toys by name]

John: Chaser, find Paws! Go get Paws! Yeah, there’s Paws!

John: Peppermint! Find Peppermint! Find Peppermint… Yeah, there’s Peppermint!

Leila VO: John had followed the example of those farmers who taught their dogs the names of every sheep in the flock. And Chaser was rapidly becoming the world’s best toy herding dog. But it turns out, teaching dogs the names of things isn’t easy.

[music in: Thimble Rider - Organza]

Daniel Mills: Generally, dogs struggle with object labels.

Leila VO: Again, that's doctor Daniel Mills.

Daniel Mills: If I teach you that a thing about three or four inches in diameter a ball, and I then give you a choice between a cube that is about 3 or 4 inches in diameter, and a spherical object that is 10 inches in diameter, and I say, "Which of these is a ball?" you'll go for the large sphere.

Leila VO: That's because humans have a shape bias, meaning we primarily recognize objects based on their shape. On the other hand...

Daniel Mills: If you're a dog, you'll go for the cube, because dogs don't have a shape bias. They have a size bias when it comes to labels like that.

Daniel Mills: Intrinsically, it makes sense, because we're hunter gatherers. And so shape is important for identifying different berries. "That red berry is poisonous. That red berry is a raspberry."

Leila VO: On top of that, we're also tool users.

Daniel Mills: The shape of something affects what you can do with it. So, a screwdriver is for putting screws in, not nails, into a wall. So shape is very important to us. Why would shape be important to a dog? Size is important to a dog ‘cause, "If you're really big I need two of my mates to bring you down and eat you."

Daniel Mills: So to a dog, a ball is not actually a spherical object. It's probably "a fetchy thing." And a stick and a ball are both fetchy things as far as the dog's concerned. You could call them both balls, and the dog wouldn't mind.

Leila VO: In order to teach Chaser the difference between two fetchy things, John Pilley worked with her for five hours a day.

Pilley: When people hear that he taught her five hours a day, they usually misinterpret this, because he played with her for five hours a day.

Daniel Mills: Chaser was taught stuff in the context of play. So play is important because it's very highly motivating and it's self-reinforcing. It's good that people use click and treat, but actually I don't want to be seen as a food dispenser by my dog. I want to be seen by my dog as my friend, and play is one of the ways that you build friendships.

Leila VO: And like any good friend, Chaser was eager to learn the rules of the games that John wanted to play.

Daniel Mills: So, using play, you encourage the animal, this is a cooperative activity, and the label that I put to this object becomes important for that game.

[music in: Fabien Tell - She, My Mirror]

Leila VO: With play as the foundation for Chaser’s learning, the objects that became important to her were those ragged, slobbered-over toys. In the end, she had a thousand of them.

Pilley: She liked toys. That was her happy place. And she needed a vocabulary. So these thousand objects were the start of her vocabulary.

Leila VO: So how do you teach a dog the names of a thousand objects?

Pilley: He set her up to succeed by using a method called "Errorless Learning." So Errorless Learning is hosting a situation where she could not make a mistake.

Pilley: So the first object she learned was a blue ball and he would show it to her and say, "Chaser, this is Blue." And he would roll it to her and he would say, "Take Blue." So, of course she was motivated, she took the ball in her mouth. And then he let her play with it for a while.

Pilley: Then, he would ask her to "Find Blue" and he would hide it in plain sight. So she would find Blue, and pick up Blue. And then he’d end up putting it on the couch, "Find Blue." Constantly repeating the name of the object with the object.

Pilley: And after about three days when she could find this toy in another room, he would move on to another object. And then to keep these objects in her long term memory, he would rehearse them a couple of times each day. But always just through two or three minute sessions of play.

Leila VO: John had started this training when Chaser was just a few weeks old, so it was central to all of their interactions.

Pilley: So in her fifth month, she had that "Aha" moment that, "Ahhh, objects have names! When he says 'This is...' he's pairing the object." And she began learning incredibly fast on one trial alone.

Leila VO: After named objects, the next challenge for Chaser was the verbs, the doing words. Now, most of us teach our dogs verbs, like "Sit," or "Lie down." But John wanted to combine verbs with the proper nouns she already knew. And just like he had done with the objects...

Pilley: He also kept it very simple. So he was pairing behavior with the ball. So she understood it's not just "Fetch the ball." She could "Take the ball." She could "Find the ball." She could "Toss the ball." So she was pairing the name of these objects with a verb.

Pilley: So at that point, she started understanding. "Ahhh, verbs! These are different from these objects." So she could "Catch Snowflake." She could "Paw Snowflake." She could "Nose Snowflake." She could combine these independently. [clip of John & Chaser]

John: Chase, nose Lifesaver. There it is. Paw Lifesaver. Yes, good girl!

Leila VO: With all of these elements of human language in her repertoire, the world really became Chaser's oyster.

[music in: Fabien Tell - Treasure Map]

Pilley: This really accelerated her learning because learning builds upon learning. She was able to learn the qualifying words, like "fast" and "slow" and adjectives like "bigger," "smaller," as well as abstract concepts like "again," "repeat," "another."

[clip of John & Chaser]

John: Reverse! Look up. Look up, look up. That’s it, good girl.

Leila VO: Time and time again, Chaser proved her remarkable understanding of language. She knew the names of places around her property, like "Road," "Grass" and "Front Porch." She knew her individual balls by name, but she also knew that they were all balls, which was different from a toy. And if John asked for a toy that she had never seen or heard of before...

John: Chase c’mere. Find Charcoal. Popop wants Charcoal.

[music pause with sniffing/clinking]

Leila VO: Chaser would look through her toys, and deduce that it must be the one she didn't recognize.

John: There’s Charcoal! Good girl.

Pilley: What Chaser was able to do was not rote behavior. It was an understanding that words had independent meaning.

Leila VO: Most importantly, she understood how these meanings worked together. For instance, John could give her a command like "To Santa Clause, take Flip Flop."

Pilley: Those are four independent words. And she could execute these flawlessly. And what that demonstrates is that dogs do have conceptual understanding, they’re very intelligent animals, and communication with them is certainly possible and so important.

Leila VO: Once Chaser understood that everything around her had a name, she started picking up words on her own, and even expressing opinions about things. For instance, Pilley's mom Sally would often go on walks with a group of other seniors and their dogs.

Pilley: She had this group called the "Ya-Ya Winos." They were a bunch of really crusty, saucy seniors that shared their love of bourbon and dogs. So they would all go walking in the evening with their dogs, there were about five of them.

Leila VO: One of those dogs was named Casey.

[music in: Tres Leches - Alfajor]

Pilley: We were sitting around a table one night at dinner And my mom said, "I'm not going to go on the walk tonight, because Casey's visiting, and Chaser doesn't really like Casey." So out of nowhere, Chaser came up to the table and she gave a little growl. [sfx: growl]

Pilley: And I was like, "What? What's going on with Casey?" And mom said, "Well, Chaser doesn't like her because she's always up in Chaser's butt, and in her grill. You know, Chaser tolerated this because she's a lover, not a fighter, but she didn't care for Casey." So when we said Casey's name again, Chaser gave a bigger growl. "Rawr." [sfx: bigger growl]

Pilley: And so I was like, "Wow, Chaser, you don't like Casey?" And then she started to get very animated and started barking out loud. [sfx]

Pilley: She had learned this dog's name simply by listening when they're on walks. So at this point, I decided want to ask Chaser about the other dogs. So I asked about Fafnir. She just wagged her tail. Then I asked her about Dixie. Dixie was nice, she liked Dixie too. Then asked about Slick and she started growling. [sfx] She didn't too much care for Slick. And then, there was another dog named Holly and she didn't like Holly either. She gave a little growl… [sfx] But then we asked about Casey again and she just started full-fledged barking.

Leila VO: John put Chaser through rigorous testing, and published two scientific papers documenting her achievements.

Pilley: Chaser has been called, "the scientifically most important dog in the last 100 years," and that is because of the way that she learned language.

Leila VO: And beyond the realm of academia, Chaser made headlines all around the world. She was featured in news reports and magazine articles, and showed off her skills to Anderson Cooper and Neil DeGrasse Tyson.

[music in: Fabien Tell - Under the Tuscan Sun]

News Clip 1: Chaser the border collie lives with Dr. John Pilley.

News Clip 2: Chaser the canine knows the names of over over thousand toys.

News Clip 3: She’s been trained intensively for three years.

Anderson Cooper: She may be the smartest dog in the world.

Neil DeGrasse Tyson: And I’ve come to check out what she can do.

Leila VO: But Pilley thinks the focus is in the wrong place.

Pilley: A lot of researchers confidently proclaim from their high horses in their office that she was an outlier, she was an innate genius. But that's not true. She wasn't born as some animal phenom.

Leila VO: As Pilley sees it, all dogs could be capable of what Chaser achieved... if they had access to the innovative training that her father pioneered.

Pilley: People don't recognize it was the man who was so smart. He was her sensei, and she was his grasshopper.

Leila VO: Together, John and Chaser showed the world how to unlock their dogs’ potential. But it was a golden partnership destined not to last.

Pilley: We all know that dogs live short, beautiful lives. They’re never here long enough. So we knew that Chaser wasn't going to live forever. And my dad was in his 80s when he had his success with Chaser. So, who knew who was going to go first? Because they were both up in their years.

Leila VO: In the end, it was John.

[music in - Megan Wofford - Reflections]

Pilley: He got sick with a rare form of leukemia when he was 89 and was six weeks later he was gone.

Leila VO: In those final weeks, it seemed like it was tough for Chaser to be in the room with John, and to see him in that condition.

[hospital scene in]

Pilley: But then the last day, Chaser positioned herself right at the foot of his bed and she pulled her shoulders really close together, her tail was tucked, her ear was back, she's staring at my father with that border collie eye… And out of nowhere she gave one loud, sharp bark. [SFX: sharp bark]

Pilley: And it stunned us all into silence, you know, we felt goosebumps creeping up our arms and down our neck, and realized that she was not commanding him to wake up, she was bidding him goodbye. And he passed away eight hours later, he was gone. So Chaser knew, and she was okay with it.

Leila VO: Without her sensei, the aging Chaser started to decline in the year after John’s death.

Pilley: She started going downhill pretty fast a year later. She was really not doing well. She couldn't stand up any longer, her breathing was labored, and we determined it was time.

Leila VO: When the day came, the vet came out to their house, so Chaser could pass in the place that she was most comfortable.

Pilley: And it was just, it was devastating. We just sobbed and sobbed and sobbed. We ended up burying her in the backyard with our other family pets, with Yasha and Grendel.

Leila VO: Chaser’s passing was felt around the world.

Pilley: When it was announced in the Times, it went globally viral, and just thousands of papers across the world, internationally and other languages. So she was mourned. She was mourned.

[music in: Butterstone - Homin Brer]

Leila VO: Today, Pilley is carrying on her father's legacy with a nonprofit called the Chaser Initiative, which aims to educate children about the power of play-based learning.

Pilley: We're going into classrooms and teaching them about empathy, and learning through play with dogs. The other arm of the Chaser initiative is canine welfare research. So again, it's carrying Chaser's legacy forward, encouraging conversations, and thoughtful ways that we can really find a way to give back to dogs.

Leila VO: To many, Chaser is simply the famous dog who learned a thousand words. But John and Chaser's story is about more than just a clever dog and an innovative researcher. It's about what's really possible when a dog and its human understand each other better.

Pilley: Communication is very important in all species. And if you can crack that code working with your dog, this greatly enlarges their world. And it's also fast tracking our relationship and our bond with animals.

Daniel Mills: Any relationship, if it's going to be successful, depends on good communication. It's really important that we learn to communicate better with our dogs because that's the basis on which we have a peaceful relationship. We don't want to be misunderstood, and we don't want to misunderstand our dogs. So we should be putting the effort in to make sure that what we want from our dogs is both fair but also clear.

Pilley: Dogs are constantly listening. So why wouldn't we channel a language with them? A lot of times, people don't pay attention to what their dog is really saying to them. But dogs teach us so much, and if we just pay attention, we're going to be better humans because of it.

[music out into music in: Butterstone - Don Germaine]

Twenty Thousand Hertz is produced out of the sound design studios of Defacto Sound. Hear more at Defacto Sound dot com.

Leila VO: This episode was written and produced by Leila Battison

Other Voices: And Casey Emmerling, with help from Grace East. It was sound designed and mixed by Jesus Arteaga.

Thanks to our guests Pilley Bianchi and Daniel Mills. Pilley's new book, For the Love of Dog is a beautifully illustrated guide to forging a better relationship with your dog. You can find it wherever books are sold. To learn more about the Chaser Initiative, as well as Daniel's animal research, just follow the links in the show notes.

I'm Dallas Taylor, thanks for listening.