How Do You Say ‘Danger’ in Sperm Whale Clicks? - Reasons to be Cheerful

Marina: Welcome to Deep Voices — I'm so glad you're here. I'm Marina, a marine biologist and science communicator who has spent the better part of my life completely, unapologetically obsessed with whales and dolphins. This show is where we dive into their songs, their secrets, their social lives, and the remarkable science working to understand what they're actually saying to each other. Marina: Before we go deep today, a warm thank you to our sponsors — Ada, who helps companies integrate A I into their workflows in ways that are actually useful and human-centered; Ago Consulting — that's "Ahh-Go" — silicon development experts working across everything from A I to full system-on-chip design; and Zen Semiconductor, an umbrella company with a whole portfolio of businesses across the silicon industry. These are the people helping build the tools that, honestly, are making some of today's cetacean science possible. So thank you all. Marina: And today — oh, today is a good one. We're going to talk about how sperm whales might encode something like the word "danger" in their clicks. We're going to explore a genuinely mind-bending question about where intelligent life has been hiding. And we're going to meet a population of humpback whales so isolated, so ancient in their separation, that scientists are making the case they deserve recognition as their own subspecies. Plus — a recording. The oldest known recording of a whale. Let's go. Marina: VOICES OF THE DEEP Marina: Okay, so I want you to picture this. You're hovering underwater somewhere in the Caribbean — let's say off the coast of Dominica — and the sea around you is not silent. It is anything but silent. The water is filled with this rapid-fire series of clicks, almost like someone dragging a stick along a picket fence but faster, more complex, layered. That's a sperm whale. And what you're hearing isn't random noise. Scientists are increasingly convinced it is structured communication of remarkable sophistication. Marina: Sperm whales produce what are called codas — these patterned sequences of clicks. A coda might be five clicks, or eight, arranged with specific rhythms and timing between them. And for decades, researchers noticed that different groups of sperm whales — what they call clans — seem to share particular codas. Like dialects. A whale born into one social group learns the clicks of that group, and those clicks mark them as belonging. Marina: But here's where things get genuinely exciting. Researchers working with sperm whale communication — including the team behind Project CETI, the Cetacean Translation Initiative — have been deploying underwater hydrophones, acoustic tags attached gently to the whales, AI-powered analysis tools, the works. And what they're starting to find is that sperm whale codas may have something like a combinatorial structure. Meaning the clicks aren't just labels — they might be combined in ways that generate different meanings, similar in principle to the way you and I combine sounds into words and words into sentences. Marina: One of the questions researchers are actively probing is exactly what a story from Reasons to be Cheerful framed so beautifully: how do you say "danger" in sperm whale clicks? Is there a coda for alarm? For "predator nearby"? For "come here now"? We don't have full answers yet. But the evidence is pointing toward something rich and intentional. Sperm whale brains are the largest of any animal on Earth — roughly five times the mass of a human brain. And they are extraordinarily social, living in tight matrilineal groups, caring for calves communally, mourning their dead. It would be genuinely strange if all of that complexity produced nothing worth saying. Marina: And then there's this — a story that stopped me in my tracks when I came across it. The oldest known recording of a whale. AP News recently covered the rediscovery of what may be the earliest audio ever captured of a whale call — recorded decades ago, before most people had any idea that whales even vocalized in ways that could be called songs or language. Researchers are treating this recording as a kind of acoustic fossil. It is a baseline — a window into what whales sounded like before the oceans filled with the noise of shipping lanes and sonar and engines. And why does that matter? Because if we're trying to understand whale communication, we need to understand not just what they say now, but what they might have been saying before we changed the acoustic landscape of their world almost beyond recognition. Marina: That recording — scratchy and imperfect as it may be — is a message in a bottle from another era. And it raises a question I find almost unbearably poignant: what conversations were happening in the deep ocean before we started listening? What did we miss? Marina: CULTURE AND DECODING Marina: Let me tell you about a project that I genuinely believe is one of the most ambitious scientific endeavors happening anywhere on Earth right now. Not in space. Not in a particle accelerator. In the ocean. Project CETI — the Cetacean Translation Initiative — is a collaboration of marine biologists, linguists, cryptographers, and A I researchers. And their goal is audacious: to use machine learning to decode sperm whale communication. Not to teach whales human words. To learn theirs. Marina: The approach is modeled, fascinatingly, on the same kind of work that's been done to decode ancient human languages and to search for patterns in deep space signals. Which brings me to a piece from Astrobiology Web about something called SETI/CETI Tricorder technology — and yes, that is a Star Trek reference, deliberately — where researchers are actually drawing on tools developed for the Search for Extraterrestrial Intelligence, SETI, and applying them to whale communication. Because when you strip it all back, decoding an alien language and decoding a whale language are, structurally, not that different a problem. Marina: You have a signal. You don't know the meaning. You look for patterns, repetitions, structure, context. You build up a corpus — a library of examples — and you use statistical tools to find regularities that a human ear or brain would never catch on its own. The A I doesn't know what a whale is. It doesn't know what "danger" means. But it can find that a certain click sequence appears reliably in certain contexts, and that is the beginning of understanding. Marina: And this connects so beautifully to a piece from Katie Couric Media that asked a question I want to sit with for a second: we've been searching the cosmos for intelligent life — but has it been in the ocean all along? That's not a rhetorical flourish. It's a serious scientific provocation. Dolphins pass on tool use — some populations in Shark Bay, Australia, carry marine sponges on their rostrums to protect themselves while foraging on the seafloor. That behavior is taught, mother to daughter, generation after generation. That is culture. Humpback whales have songs that evolve. A new phrase appears in one population in the Pacific, and within a few years it has spread — whale to whale, ocean to ocean — like a hit song going viral. That is culture. Orcas have been documented teaching their young to hunt by intentionally beaching themselves on shores, a terrifying and technically demanding skill that young whales practice under supervision. That is culture. Marina: We have spent billions of dollars and decades of scientific effort pointing telescopes at distant stars hoping to find a mind out there in the dark. And all the while, in the deep ocean — which covers more than seventy percent of our planet's surface — there have been beings with large brains, complex social structures, rich communication systems, and multi-generational traditions. We just didn't know how to listen. Marina: What Project CETI and the researchers working on sperm whale codas are betting is that A I might be the tool that finally lets us bridge that gap. Not translate perfectly — not yet, maybe not ever in the way we translate French into English. But enough to start to understand the shape of what's being communicated. And I think that is one of the most profound things happening in science right now. Marina: A CETACEAN AND PEOPLE STORY Marina: I want to take you somewhere very specific now. The Arabian Sea. Picture a wedge of warm, ancient water bounded by the Indian subcontinent to the east, the Arabian Peninsula to the west, and opening into the Indian Ocean to the south. It is one of the most biologically and culturally rich ocean regions on Earth. And living within it — isolated for what genetic evidence suggests may be tens of thousands of years — is a population of humpback whales unlike any other on the planet. Marina: The Arabian Sea humpback whales do not migrate. Almost every other humpback population on Earth follows a grand annual rhythm — feeding in cold polar waters in summer, traveling thousands of miles to warm tropical breeding grounds in winter. But the Arabian Sea humpbacks stay put. They live year-round in one of the hottest, most hypoxic — that means low-oxygen — seas on Earth. They have adapted to conditions that would be extreme for any other humpback. Marina: And now, genetic research from the Wildlife Conservation Society and their partners has strengthened the case that these whales are not just an unusual population — they may deserve recognition as a distinct subspecies. The genetic data suggests their isolation from other humpback populations is deep and ancient. They have been going their own way for a very long time. And there are not many of them. Estimates put the population at just a few hundred individuals — potentially the most endangered population of humpback whales in the world. Marina: Here's what makes this a story about people as much as whales. These animals have lived alongside human communities around the Arabian Sea for centuries — fishermen in Oman and Pakistan and India have known them, have stories about them, have watched them. But because they weren't formally recognized, because the science was still catching up, they fell through the cracks of international conservation frameworks. You can't protect what you haven't named. Marina: The push to recognize them as a distinct subspecies is not just a taxonomic debate — it is a conservation argument. If they are recognized, they gain a stronger legal and advocacy standing. Protections that might apply generally to humpbacks could be specifically designed for this population and its unique habitat, its unique pressures — the shipping traffic, the fishing nets, the noise and disturbance of one of the world's busiest ocean corridors. Marina: There's something deeply moving to me about this story. These whales have been out there in the Arabian Sea, singing their songs — and humpback whale songs are among the most complex and beautiful acoustic phenomena in the natural world — singing their songs in isolation for potentially tens of thousands of years. Developing, perhaps, their own dialect, their own culture, their own way of being a humpback whale that no other humpback whale shares. And only now, with genetic tools and international scientific collaboration and the patient work of researchers and conservationists, are we beginning to understand what and who they are. Marina: That is what science and care together look like. It's slow, and it's painstaking, and sometimes it takes decades. But when it works — when a population that might have been overlooked is finally seen, finally named, finally protected — it matters enormously. For the whales. And honestly, I think, for us too. Marina: Before I let you go, I want to come back to where we started. Clicks in the dark. An ancient recording crackling with the voice of a world we nearly missed. Humpbacks singing alone in a warm sea for thousands of years. A machine learning model finding patterns in sounds our ears can't parse. There is so much intelligence in the ocean — so much conversation, so much culture, so much life — and we are only just beginning to learn how to listen. Marina: These animals don't need us to find them remarkable. They have been remarkable, quietly and magnificently, for millions of years. But I do think something shifts — something important shifts — when we actually start to hear them. When we bring the tools and the attention and the wonder that this moment in science makes possible. That shift matters. I believe that with everything I've got. Marina: Deep Voices, brought to you by Ada, Ago Consulting, and Zen Semiconductor — three teams helping build the future, and making shows like this one possible. Marina: If today's episode moved you or made you curious, please subscribe wherever you listen, leave a review if you're feeling generous, and share it with someone who loves the ocean — or someone who doesn't know yet that they should. All the research and links behind today's stories are in the show notes — the link in show notes will take you right there. Until next time, stay curious, keep listening, and remember — the deep has so much left to say.