17 Million-Year-Old Teeth Open Windows Into Early Ape and Human Evolution - Columbia University

June: Welcome to Kindred Minds — I'm June, a primatologist and science communicator, and this is the show where we tell true stories about our closest relatives on this planet: the primates. Stories that are fascinating, sometimes astonishing, and always — always — deeply human, even when the main character has fur. June: Before we dive in, a warm thank you to our sponsors today: Ada, who helps clients integrate A I into their workflows in smart, practical ways; Ago Consulting — pronounced "Ahh-Go" — silicon development consulting from A I all the way to SoC; and Zen Semiconductor, an umbrella company with a remarkable portfolio across the silicon industry. We are grateful for their support. June: Today's episode is a good one. We've got seventeen-million-year-old teeth that are rewriting what we know about our earliest ancestors. We've got a brand-new monkey species that science has only just met. We've got a ghost — a virus that lived in a chimpanzee's D N A and quietly changed everything. And we're going to take a moment to remember one of the greatest primate scientists who ever lived. The through-line in all of it? How alike we truly are. How much of the same recipe built all of us. Let's go. June: So — thread one. Primate cognition. And today I want to start somewhere you might not expect: with teeth. Specifically, with teeth that are seventeen million years old, dug out of the ground in Kenya, studied by researchers at Columbia University, and quietly rewriting the story of where we — and all the great apes — came from. June: Now, I know what you're thinking. Teeth? June, you said this was about intelligence. Bear with me. Because understanding how early apes were evolving, what they were eating, how they were living — that's actually the foundation for understanding how primate cognition developed in the first place. Intelligence doesn't appear out of nowhere. It grows from a lineage. June: These fossils belong to a group of early apes from the Miocene epoch — that's roughly five to twenty-three million years ago — a period that was absolutely explosive for primate evolution. There were dozens of ape species alive during the Miocene. Most of them went extinct. A precious few didn't. And we are the descendants of that precious few. June: What the Columbia researchers were able to do with these teeth is look at the microstructure — the growth patterns laid down in the enamel, almost like tree rings — and extract information about diet, about development, about how long these animals were growing before they reached maturity. And here's where it gets fascinating: the developmental patterns they found in these seventeen-million-year-old teeth look strikingly similar to those of modern great apes. Slow development. Extended childhood. A long time between birth and full maturity. June: That slow developmental pattern? It's one of the things that separates great apes — including us — from most other mammals. It's also, many researchers believe, deeply connected to intelligence. When you have a long childhood, you have a long window to learn. To watch. To practice. To make mistakes in a safe context. That extended juvenile period is essentially a long apprenticeship in being alive, and it appears to be ancient — baked into the ape lineage long before Homo sapiens ever walked the savanna. June: So when you look at a young chimpanzee spending years watching its mother crack nuts before it ever picks up a stone itself, or a young bonobo learning social nuance through play — that's not incidental. That slow, rich, observation-based childhood is something we inherited together, from ancestors whose teeth we are only now beginning to read. June: Seventeen million years old, and they're still telling us something true. I find that extraordinary. June: And speaking of finding something extraordinary — thread two. Our shared recipe. The biology that binds us. And today I want to bring in a story that sounds almost like science fiction, but is completely, verifiably real. A study published on Phys.org caught my eye this week, and I have been thinking about it ever since. June: Here's the setup. Researchers found that an ancient virus — and when I say ancient, I mean something that infected a primate ancestor potentially millions of years ago — left its genetic fingerprint inside chimpanzee D N A. This isn't unusual in a broad sense; our genomes, and the genomes of other primates, are littered with the remnants of old viral infections. Scientists call them endogenous retroviruses. They're essentially molecular fossils — pieces of viral D N A that got copied into the host's genome and then got passed down through generations. June: What makes this particular finding so striking is what that ancient viral remnant is doing. It appears to be switching off a gene in chimpanzees — a gene that, in humans, remains active. So here you have two species — chimpanzees and humans — who share somewhere in the neighborhood of ninety-eight to ninety-nine percent of their D N A. We share the same basic instruction manual for building a primate body. And yet, tucked inside that tiny fraction of difference, there's a viral ghost that turned a page of the chimp's instruction manual to silent. June: Think about what that means. The divergence between human and chimpanzee lineages happened roughly six to seven million years ago. And somewhere along the way, on the chimpanzee branch, an ancient infection left a mark that persisted — that became part of the genome, part of the inheritance, part of what it means to be a chimpanzee today. Evolution is not a clean story. It's a palimpsest. It's layer upon layer of events, some dramatic, some quiet, written into the very molecules of living creatures. June: And this is what I want you to sit with for a moment. When we talk about the D N A we share with chimpanzees — that ninety-eight-plus percent — we're not talking about a vague similarity. We're talking about the same genes, doing the same jobs, building the same proteins, running the same cellular machinery. The same recipe, copied faithfully for millions of years. The differences are real and they matter — this viral silencing is a perfect example — but they are variations on a theme, not a completely different song. June: What this research also opens up is a medical window. If a gene is active in humans but silenced in chimpanzees, and if that gene is connected to health or disease, understanding why and how it was silenced could teach us something profound about our own biology. The research on what distinguishes us from our closest relatives isn't just philosophical — it's potentially clinical. It matters for medicine. It matters for understanding who we are as a species. June: And here is the part that always moves me: every time we look closely at our differences from chimpanzees, we end up learning something about ourselves. That's what shared ancestry does. It makes us each other's mirrors. June: Okay. Thread three. A meaningful primate-and-people story. And today I have two things to bring to you — one that is a celebration, and one that is a farewell that deserves to be said out loud. June: First, the celebration. There is a new monkey in the world — or rather, a monkey that has always been in the world, living its life in the trees, entirely unbothered by our ignorance of its existence, until now. The BBC reported this week on a newly discovered monkey species, and every time I hear a story like this, I feel two things simultaneously: pure joy, and a kind of humility. June: Pure joy, because the world is still surprising us. In an age when it sometimes feels like every corner of the planet has been mapped and catalogued and documented, a previously unknown primate species can still emerge from the forest and say, hello, we've been here all along. That is wonderful. June: And humility, because it's a reminder of how much we still don't know — how many creatures share this planet with us whose inner lives, whose social structures, whose intelligence, whose communication, we have not even begun to study. Every newly discovered primate is a new window. A new chance to learn something about what intelligence looks like, what society looks like, what being a mammal with a complex brain looks like, when evolution has been running its experiment in a different direction from ours. June: The discovery also matters for conservation. You cannot protect what you don't know exists. Naming a species, describing it scientifically, giving it a formal identity in the record of life on Earth — that is the first step toward giving it legal standing, toward making the case that its habitat deserves protection. A new species discovery isn't just a biological event. It's the beginning of a conservation story. June: And Cleveland is writing its own conservation story this week, with the opening of the new Primate Forest experience at Cleveland Metroparks Zoo. Now, I know that some people have complicated feelings about zoos, and I think that's worth acknowledging — those conversations are real and important. But modern accredited zoos, at their best, do something genuinely significant. They bring people face to face with animals they would never otherwise encounter. They fund field conservation. They participate in breeding programs for endangered species. And they change people. June: Because here's what I know from years of working with primates and watching people encounter them up close for the first time: something shifts. You look into the face of a gorilla or a chimpanzee or an orangutan, and the philosophical distance collapses. Whatever story you told yourself about the separation between humans and animals — it becomes very hard to hold onto. And that moment of recognition? That's not nothing. That's the beginning of caring. And caring is the beginning of everything. June: Which brings me to the farewell I mentioned. This week I want to take a moment to honor Frans de Waal, the legendary Dutch primatologist who passed away in 2024, and whose memorial tribute was published in the Proceedings of the National Academy of Sciences. If you have ever read a book about chimpanzee politics, or empathy in animals, or whether animals have morality — there is a good chance Frans de Waal was the scientist who brought you that idea, or the one who proved it, or the one who spent decades fighting to have it taken seriously. June: Frans de Waal spent his career at the intersection of primatology and what you might call moral philosophy — he was fascinated by the question of where human morality came from, and his answer, supported by decades of careful observation, was: it didn't appear from nowhere. The roots of empathy, of fairness, of consolation, of reconciliation after conflict — he found all of these in great apes, in monkeys, in elephants, in other social animals. He argued, patiently and brilliantly, that we did not invent kindness. We inherited it. June: His work changed the field. It changed the conversation. And for many people — scientists and non-scientists alike — it changed how they saw themselves in relation to the rest of life on Earth. He had a phrase I love: he called it "bottom-up morality." The idea that our ethical lives didn't descend from religion or reason alone, but grew upward from ancient social instincts — instincts we share with our primate cousins, instincts that are millions of years old. June: We lost a great voice when we lost Frans de Waal. But the work continues. The observations he made, the framework he built, the questions he asked — they live on in every researcher who looks at a chimpanzee comforting a grieving companion and asks, seriously, what is happening there? What does that animal know? What does that animal feel? June: The answer, increasingly, is: more than we thought. Almost always, more than we thought. June: And that brings us home. To the point that this show keeps coming back to, week after week, because it keeps being true. Intelligence and feeling are not ours alone. The capacity for learning, for empathy, for social complexity, for grief and play and curiosity — these are not human inventions. They are primate inheritances. They are mammalian inheritances. We didn't build them from scratch. We received them, refined them, and live inside them alongside millions of other creatures who received the same ancient gift. June: Seventeen-million-year-old teeth. A viral ghost in chimpanzee D N A. A monkey the world is only now beginning to know. A scientist who spent his life insisting that kindness has deep roots. These stories are connected. They're all saying the same thing: we are not separate. We never were. June: This is Kindred Minds, brought to you by Ada, Ago Consulting, and Zen Semiconductor. Thank you so much for listening, and thank you to our sponsors for making this show possible. June: If this episode moved you or surprised you, please share it — with a friend, a kid, a parent, a colleague, anyone who might need reminding that we belong to something bigger than ourselves. Subscribe wherever you get your podcasts, and check the link in show notes for sources, further reading, and everything we talked about today. June: Stay curious. Stay kind. And I'll see you next time.