Are dolphins the only animals that call each other by name? - Science | AAAS

Marina: Welcome to Deep Voices — I'm so glad you're here. I'm Marina, a marine biologist and science communicator, and this podcast is my love letter to the most extraordinary communicators on the planet: whales and dolphins. Marina: Before we dive in, a huge thank you to our sponsors — Ada, who helps businesses integrate A I into their workflows in smart, practical ways; Ago Consulting, pronounced "Ahh-Go," your go-to for silicon development consulting from A I all the way to SoC; and Zen Semiconductor, an umbrella company with a remarkable portfolio spanning the silicon industry. We genuinely appreciate their support. Marina: Today's episode is a good one. We're going to talk about dolphins who literally call each other by name, we're going to look at the surprising mathematical laws hiding inside whale song and birdsong, and we're going to explore how scientists — and A I — are working to actually decode what these animals are saying. Stay with me. This one will stay with you. Marina: Okay, let's start with something that I think is genuinely one of the most remarkable discoveries in animal behavior research. It's the kind of thing where, when I first encountered it, I just sat back and thought — of course. Of course they do this. Marina: Bottlenose dolphins have signature whistles. Every dolphin develops one — usually in the first few months of life — a unique, individualized whistle that functions, for all intents and purposes, like a name. Not a label given to them by humans. A name they choose for themselves. A name that other dolphins in their community learn, remember, and use to address them directly. Marina: Now, researchers have known about signature whistles for decades. But what's more recent, and more astonishing, is the evidence for how dolphins actively use them socially. When dolphins call out a signature whistle that belongs to another individual — not their own — the animal being named responds. They answer to their name. And the caller isn't just making a general noise into the water. They're specifically reaching out to a specific individual, the way you or I would call across a room. Marina: Scientists writing in journals like Science have been digging into just how sophisticated this gets. Are dolphins the only animals that do this? The honest answer is: we're not sure about "only," because the more we look, the more complexity we find across the animal kingdom. Some parrot species do something similar. Elephants appear to have individualized calls. But dolphins remain the clearest, best-documented case of one animal learning another's self-generated name and using it in context. Marina: What makes this so moving to me is what it implies about their inner social world. To use someone's name, you have to have a concept of that individual as a distinct entity. You have to hold them in mind. You have to want to reach them specifically. That is not a simple cognitive trick. That is a form of social awareness that most people — until very recently — assumed was unique to us. Marina: And when you're underwater with dolphins, listening through a hydrophone, hearing these whistles ripple through the blue — it's almost impossible not to feel like you're eavesdropping on a conversation. Because you probably are. Marina: Let's stay in the world of animal voices for a moment, because there's a study that has been making waves — pun fully intended — in the scientific community, and it connects whale song and birdsong in a way that I find almost philosophically beautiful. Marina: Researchers have been applying a concept called Zipf's Law to animal vocalizations. Now, Zipf's Law is a pattern that shows up in human language, almost universally. The basic idea is this: in any language, a small number of words get used very, very frequently, and a long tail of words get used rarely. The word "the" in English. The word "de" in Spanish. A tiny handful of units carry enormous communicative weight, and then frequency drops off in a very predictable mathematical way. Marina: And here's the thing — when scientists analyzed birdsong, and when they analyzed whale song, they found the same pattern. The same mathematical structure. The same relationship between how often certain units appear and how they're organized. This was published and reported widely, including through Yahoo News, drawing on underlying linguistics and bioacoustics research. Marina: Now, does that mean whale song is a language in the way that English is a language? Scientists are careful here, and I want to be careful too. Zipf's Law appearing in a system doesn't automatically mean that system has the full structure of human language — grammar, displacement, arbitrary symbols. But what it does suggest is that these communication systems share deep organizational principles with human language. They're not random. They're not chaotic. They follow rules, and those rules look surprisingly familiar. Marina: And when you layer that finding onto what we know about the complexity of humpback whale song — these epic, evolving, culturally transmitted compositions that can last for hours and change across populations like musical trends — the picture that emerges is of a communicative world that we are only just beginning to map. Marina: There's also beautiful work happening right now with bowhead whales, those extraordinary Arctic giants who can live for over two hundred years — there are bowhead whales alive today who were born before the American Civil War. Researchers at places like Whitman College have been analyzing bowhead whale songs to track their migration patterns, using the whales' own voices as a kind of acoustic GPS. Different song types, heard at different times and in different places, become a way of reading where these whales are, where they're going, and how their journeys change season by season. It's science that is as elegant as it is useful for conservation. Marina: Which brings me to what I find one of the most exciting scientific frontiers of our time — the genuine, serious, well-funded effort to use A I to decode cetacean communication. Marina: Let me tell you about Project CETI. CETI stands for Cetacean Translation Initiative, and it's a collaboration involving marine biologists, linguists, cryptographers, and A I researchers who are focused initially on sperm whales. Sperm whales communicate in clicks called codas — short, patterned bursts of sound that they exchange with each other in their social groups. These codas vary between individuals and between clans. They appear to carry information. But what information? That's the question. Marina: Project CETI's plan is to record an enormous number of these coda exchanges — potentially billions of clicks — tag individual whales, understand the social context of each exchange, and then feed all of that into machine learning models trained on human language. The hope is that patterns will emerge. That the A I will find structure that human ears and human analysis have missed. Marina: And David Gruber, one of the scientists involved in this space and featured in a University of Chicago Big Brains podcast episode, frames it in a way I love. He talks about not just decoding what whales say, but potentially finding a way to speak back. To create a genuine two-way communication. He's clear that we're not there yet — this is a long-horizon scientific goal — but the seriousness with which that question is now being pursued, with real tools and real resources, is extraordinary. Marina: What moves me about this is that for most of human history, the ocean has been essentially silent to us. We could see these animals. We could wonder about them. But their voices — the rich, complex, structured acoustic world they inhabit — was invisible to us. And now, slowly, painstakingly, with hydrophones and algorithms and the kind of patient scientific dedication that takes years and decades, we're starting to hear it. Really hear it. Marina: Imagine the day — maybe in our lifetimes — when we understand even a fragment of what a sperm whale is saying to her calf. What a bowhead sings across the Arctic ice. What a dolphin means when she calls her friend's name in the dark water. Marina: Now I want to tell you a story about whales and people. A true one. And I want to start it not with a rescue or a dramatic moment, but with something quieter — the story of a whale named J35, also known as Tahlequah, and a vigil that shook the world. Marina: In the summer of 2018, a female orca in the Southern Resident population of the Pacific Northwest gave birth to a calf. The calf died within half an hour. And Tahlequah carried her dead baby at the surface of the water for seventeen days and over a thousand miles. Marina: Scientists and researchers who study these whales — and these Southern Resident orcas are among the most intensively studied cetaceans on Earth — watched in near-silence. What they were witnessing had been documented in other cetacean species: this behavior called "grief carrying," where mothers refuse to let go of their dead young. It happens in dolphins. It happens in pilot whales. And it happened here, for seventeen days, in full view of the world. Marina: The Southern Residents are a critically endangered population. At the time of Tahlequah's vigil, there were only seventy-five individuals. The population is in crisis, largely because their primary prey — Chinook salmon — has collapsed due to dam construction and habitat loss. These whales are, in a very real sense, starving. Marina: What Tahlequah's vigil did — and I've spoken with researchers who were moved to tears by this — was translate a statistical conservation crisis into something undeniably emotional and human. People who had never thought about orca populations suddenly understood, viscerally, that there was a mother who had lost her baby and would not let her go. Marina: The conservation response was real. Advocacy for salmon recovery, for dam removal, for protecting critical habitat — it gained renewed urgency. Scientists pointed to Tahlequah and said: this is what is at stake. Not an abstract species. Not a number on a spreadsheet. A mother. A family. A culture. Marina: Because Southern Resident orcas do have culture. Their dialects — the specific patterns of calls their pods use — are distinct from other orca populations and are passed down through generations, matriarch to calf, year after year. When you lose an individual, you lose a piece of that culture. When you lose a population, you lose something irreplaceable. Marina: Tahlequah eventually released her calf. And in 2020, she gave birth again — to a healthy calf who survived. Researchers named him Phoenix. The community of people who follow these whales celebrated like it was a birth in their own family. Because in a way, it was. Marina: That's what happens when science and story come together. When we stop seeing animals as specimens and start seeing them as the complex, feeling, communicating beings that the evidence increasingly tells us they are. Marina: And I think that's actually the throughline of everything we've talked about today — from signature whistles to Zipf's Law to A I and sperm whale codas to Tahlequah's vigil. All of it is pointing toward the same thing. The ocean is not silent. It never was. We just didn't know how to listen. Marina: The more we learn about how whales and dolphins communicate, the more it becomes clear that we share something fundamental with them — a drive to connect, to be known, to reach across the dark water toward each other and say: I'm here. Do you hear me? Marina: And I think learning to hear them back might be one of the most important things we ever do. Marina: Deep Voices, brought to you by Ada, Ago Consulting, and Zen Semiconductor — three companies helping to build the intelligent technologies that are changing what's possible, in the ocean and beyond. Marina: If today's stories moved you, or made you curious, or made you want to look up bowhead whales or Project CETI or Tahlequah at midnight — good. Stay curious. That's the whole point. Subscribe wherever you listen, share this episode with someone who loves the sea, and check out the link in show notes for more on everything we talked about today. Marina: I'm Marina. Thank you for diving deep with me. I'll see you next time.