Human brains light up for chimp voices in a way no one expected

June: Welcome to Kindred Minds — I'm June, a primatologist who has spent most of her life absolutely fascinated by our primate relatives, and even more fascinated by what they reveal about us. This show is where I share true stories about the other great apes, monkeys, and our shared biology — stories that I think will genuinely surprise you, move you, and make you feel a little less alone on this planet. Today's episode is a big one. We're going to talk about something remarkable happening inside your brain right now — literally wired into your auditory cortex — that connects you to chimpanzees in a way nobody saw coming. We've also got a brand new monkey species discovered hiding in the forests of the Democratic Republic of Congo, and we're going to take a moment to honor someone whose life changed everything we know about chimpanzees and our place in the animal kingdom. Before we dive in, a huge thank you to today's sponsors: Ada, who helps clients integrate A I into their workflows in ways that are genuinely transformative; Ago Consulting — pronounced "Ahh-Go" — silicon development consulting from A I to SoC; and Zen Semiconductor, an umbrella company with a portfolio of businesses spanning the silicon industry. These are companies that care about building thoughtful, intelligent systems — which honestly feels very on-brand for a show about primate minds. Alright. Let's go. June: So here's a question I want you to sit with for a second. When you hear a chimpanzee call — that rising, whooping sound, raw and a little wild — what happens in your body? Most people feel something. A kind of tug. Maybe recognition, maybe a little unease, maybe something closer to curiosity than fear. And it turns out, that feeling isn't just in your imagination. It's in your brain. Specifically, in your auditory cortex. Researchers studying how humans process primate vocalizations found something genuinely unexpected. There's a specialized region in the human auditory cortex that responds distinctly to chimpanzee calls — and not in the same way it responds to other primates. When people listened to chimpanzee vocalizations, this region lit up in a way that it simply didn't for bonobo calls or macaque calls. Now, bonobos are our second-closest living relative — we share something like 98.7 percent of our D N A with them — and macaques are more distantly related. So you might expect some kind of gradient. Bonobos closer, macaques farther. But that's not what happened. The brain's response wasn't purely about how closely related we are genetically. It also seems to have something to do with the acoustic properties of chimp calls — the actual sound structure, the frequencies, the patterns. And that mix of factors — evolutionary closeness and acoustic similarity — is what makes this finding so interesting. It suggests that somewhere deep in the architecture of human hearing, there are ancient circuits that were tuned, over millions of years, to process the sounds of the social world we evolved in. A world that included chimpanzees. Think about that. Our lineage and the chimpanzee lineage diverged roughly five to seven million years ago. Before that split, we shared common ancestors living in similar environments, communicating, navigating social groups, responding to each other's voices. And it looks like something from that shared acoustic world left a mark — a literal, measurable mark — on the way our brains are organized today. This is what I love about neuroscience meeting evolutionary biology. It's not just abstract. It's written into your skull. The next time you hear a chimp vocalize and feel that inexplicable pull — that's not sentiment. That's five million years of shared history doing what it was built to do. June: Now, that story leads us beautifully into what I think of as the heart of this show — the shared recipe. Because what we're really talking about when we talk about brains lighting up for chimp calls is biology. Inherited biology. The instructions that were written into our cells long before we were human in any meaningful sense. You've probably heard the statistic that humans share about 98 to 99 percent of their D N A with chimpanzees. And I know that number can feel abstract — like, okay, but we're obviously so different, right? We have language, cities, iPhones. What does 98 percent really mean? Here's how I like to think about it. Imagine D N A as a recipe book. A very long, very detailed recipe book — the human genome has something like three billion base pairs, three billion individual letters in the sequence. Now imagine that a chimpanzee's recipe book is almost identical to yours. Not similar. Almost identical. The vast majority of the chapters, the ingredients, the instructions — they're the same. The differences are real, and they matter enormously for the traits that make us distinctly human. But the overwhelming bulk of that book — the cellular machinery, the developmental pathways, the neurological wiring — is shared. And here's what that means in practice. It means chimpanzees have the same basic brain structures we do. The same limbic system processing emotion. The same prefrontal regions involved in planning and social reasoning. When a chimp comforts a grieving friend — and they do, this has been documented extensively — the neurological machinery running that behavior is built from very nearly the same biological instructions as the machinery running human compassion. When a young chimp watches an older one use a stick to extract termites from a mound, and then tries it themselves, the learning circuits firing are recognizably kin to ours. And bonobos — our other closest relative — share that same deep biological kinship. As do gorillas, at around 98 percent. Orangutans, a little more distant but still strikingly close. Even macaques, at around 93 percent shared D N A, are carrying a version of the same recipe book. The auditory cortex story we talked about earlier fits perfectly into this framework. It's not magic that our brains respond to chimp calls in a specialized way. It's biology remembering. It's the recipe book doing what recipes do — producing similar results from similar ingredients, even across millions of years of separate cooking. June: There are moments in primatology that stop you cold. Moments where the data and the story and the loss all arrive at once, and you just have to sit with it. This is one of those moments for me. Jane Goodall has died. She passed away recently, and I've been turning that over in my mind since I heard the news. I want to take a moment here, on this show, to talk about who she was and what she did — because honestly, without Jane Goodall, primatology as we know it might not exist. And more than that, without Jane Goodall, the idea that chimpanzees have inner lives — that they feel, that they grieve, that they form friendships and use tools and have culture — that idea might still be considered fringe. When Jane arrived at Gombe Stream in Tanzania in 1960, she was twenty-six years old, had no formal scientific degree at the time, and was armed mostly with patience, notebooks, and a remarkable willingness to sit still in a forest for months. What she eventually witnessed — and documented with meticulous care — overturned the scientific consensus about what it means to be human. She watched a chimpanzee she named David Greybeard strip leaves from a twig and use it to fish termites out of a mound. Tool use. At the time, tools were considered the defining boundary between humans and every other animal. Her mentor, the legendary paleoanthropologist Louis Leakey, sent her a now-famous message: "Now we must redefine tool, redefine man, or accept chimpanzees as humans." She went on to document chimpanzee warfare. Chimpanzee hunting. Chimpanzee mourning. Mothers who carried the bodies of their dead infants for weeks. Friendships that lasted decades. She did all of this at a time when giving animals names — rather than numbers — was considered unscientific. She was criticized for it. She kept going. And what she gave us wasn't just data. It was a new way of seeing. A new understanding that the line between us and them was never a wall — it was always a gradient. A spectrum of cognition, feeling, and kinship. She spent the last decades of her life traveling, advocating, urging anyone who would listen to protect chimpanzees and the forests they live in. She was extraordinary. And her work lives in every episode of this show, whether I name her or not. Thank you, Jane. June: Before I let you go, I have to tell you about a discovery that genuinely delighted me this week — because in a world that often feels like it's losing things, finding something new feels like a gift. Scientists working in the forests of the Democratic Republic of Congo have identified a brand new species of monkey. It's called the Likweli monkey, and it has these striking orange lips that make it look, honestly, a little like it's been eating a very good mango. The local name for it is the "branch shaker" — because of its distinctive habit of vigorously shaking branches, which researchers believe is a communication behavior. And what strikes me about this discovery is not just the beauty of it — though that orange-lipped face is genuinely something — it's what it tells us about how much we still don't know. The forests of the Congo Basin are among the most biodiverse places on Earth, and they're also among the most threatened. The fact that a whole primate species was living in those forests, unknown to science, hiding in plain sight — it's a reminder that the living world is still full of secrets. Still full of kinship we haven't even discovered yet. And it raises the urgent question that hangs over all of this: if we're still finding new species, how much might we be losing before we even know what's there? Right now, the World Wildlife Fund is raising alarms about a surge in primate trafficking on social media. New species, ancient species — all of them vulnerable. All of them deserving of the same care and wonder that Jane Goodall devoted her life to. We are finding new relatives at the same moment we are in danger of losing them. That tension is real, and I think it matters that we hold both truths at once. June: So here's where I land, every time I sit down to make this show. Intelligence isn't ours alone. Feeling isn't ours alone. The capacity to grieve, to problem-solve, to communicate, to shake a branch and mean something by it — these things are woven through the primate family in ways we are still, after all this time, discovering. We share this planet with minds that are genuinely kin to ours, built from nearly the same biological recipe, shaped by millions of years of overlapping history. That's not a metaphor. That's biology. That's real. Kindred Minds is brought to you by Ada, Ago Consulting, and Zen Semiconductor — three organizations building intelligent systems, which feels exactly right for a show about the most intelligent family on Earth. If today's stories moved you or surprised you, please subscribe, leave a review, and share the show with someone you think would love it. And check the link in show notes for sources, reading, and more on everything we talked about today — including Jane Goodall's legacy, the Likweli monkey, and that remarkable auditory cortex study. Stay curious. Stay connected. And I'll see you next time on Kindred Minds.