Orangutans can't master their complex diets without cultural knowledge, research reveals - Phys.org

June: Welcome to Kindred Minds — I'm June, a primatologist who has spent most of her career absolutely amazed by our closest relatives, and convinced that the best way to understand ourselves is to look, really look, at them. Every episode I bring you true stories from the world of primate research — stories that are funny, moving, occasionally mind-bending, and always grounded in real science. Today we have a genuinely wonderful lineup: an orangutan who can't learn to eat without her community's help, a bonobo named Kanzi who plays pretend like a four-year-old, and a brand-new monkey species just discovered in the Congo rainforest with the most striking orange lips you've ever seen on a primate — other than maybe someone you know. A huge thank you to our sponsors who make this show possible: Ada, who helps organizations integrate A I into their workflows thoughtfully and effectively; Ago Consulting — pronounced "Ahh-Go" — silicon development experts working across everything from A I to SoC design; and Zen Semiconductor, an umbrella company with a remarkable portfolio across the silicon industry. Okay. Let's get into it, because today's stories all point to the same beautiful, quietly radical idea — that we are not as alone at the top of the intelligence ladder as we like to think. June: So, thread one. Primate cognition. And I want to start with a question. How do you learn what to eat? I mean, really — how did you figure out which foods are safe, which ones taste good, which combination of things makes an actual meal? The answer, almost certainly, is other people. Your parents, your grandparents, the culture you grew up in. You didn't arrive in the world knowing how to cook rice or that certain mushrooms will kill you. That knowledge was handed to you. And here's the thing — we used to assume that was a uniquely human arrangement. Turns out, not even close. June: Researchers studying wild orangutans in Sumatra have found that young orangutans simply cannot master their extraordinarily complex diets without learning from others — specifically from their mothers and from the broader social community around them. And I want to sit with the word "complex" for a moment, because orangutan diets are not just varied, they are genuinely sophisticated. Orangutans in places like the Suaq Balimbing research site eat hundreds of different plant species, and the knowledge of which ones to eat, when, how to prepare them — how to pry open certain fruits, how to process plants that are actually mildly toxic in ways that make them safe — that knowledge is culturally transmitted. It's learned, not instinctive. June: The research, published by scientists including those working with the long-running Sumatran Orangutan Conservation Programme, found that when young orangutans don't have access to experienced individuals, they struggle. They make foraging mistakes that experienced animals don't make. They miss out on food sources that take real skill to exploit. In some groups, researchers have documented specific foraging techniques that exist in one population and simply don't exist in a neighboring group — not because the food isn't there, but because the cultural knowledge isn't there. That is the definition of culture. Behavior that is learned, shared, and transmitted socially, not genetically. June: And what I love about this — what really gets me — is how it reframes the orangutan. We tend to picture orangutans as these solitary, slow-moving figures moving alone through the canopy. And yes, they are more solitary than chimpanzees. But solitary doesn't mean isolated from culture. A young orangutan spends up to eight years, sometimes longer, with its mother. Eight years. That's the longest childhood dependency of any non-human animal on Earth. And during those years, the mother is teaching. Every foraging trip is a lesson. Every tool use — and orangutans do use tools, including sticks to extract insects and leaves as gloves to handle spiny fruits — every one of those behaviors is being watched, absorbed, practiced. The mother is the library. And if the library is gone, the knowledge is gone. June: That's not a metaphor. It's a conservation reality. When we lose an experienced female orangutan to habitat destruction or the illegal pet trade, we don't just lose one animal. We lose a repository of cultural knowledge that her offspring and potentially other community members depended on. Culture, in orangutans, is not a luxury. It is survival infrastructure. June: Alright, thread two. Our shared recipe. Because here's where I want to zoom out a little and talk about why orangutan culture shouldn't surprise us at all — and why it might, and what that says about the assumptions we carry. June: When scientists sequenced the orangutan genome and compared it to ours, they found we share roughly 96 to 97 percent of our D N A with orangutans. With chimpanzees and bonobos, it's closer to 98 to 99 percent. Now I know those numbers get thrown around a lot and they can start to feel abstract, so let me try to make them feel real. Your D N A is essentially a recipe book — billions of base pairs spelling out instructions for building every protein, every cell type, every organ system in your body. When we say we share 98 percent of our D N A with a chimpanzee, we're saying that 98 percent of those instructions are identical. The recipe for a neuron. The recipe for a hand. The recipe for the proteins that wire together a developing brain. Nearly all of it — the same. June: And here's what that means for cognition. The brain regions that we associate with our most sophisticated mental abilities — the prefrontal cortex, which handles planning and impulse control and social reasoning; the mirror neuron systems involved in imitation and empathy; the hippocampus, central to memory — all great apes have these. They're built from the same genetic blueprint, shaped by the same evolutionary pressures over tens of millions of years. We didn't invent these structures. We inherited them from a shared ancestor, and so did they. June: So when an orangutan mother teaches her daughter how to extract honey from a bees' nest using a stick, the neural machinery running that transaction — the teaching, the watching, the imitation, the memory formation — that machinery is built from a recipe that is almost entirely identical to the one running in a human parent teaching a child to tie their shoes. Different content, same biological hardware. That's not poetry. That's genomics. June: And then there's the question of imagination. Which brings me beautifully to thread three, and to one of the most remarkable animals I have ever encountered in the scientific literature. His name is Kanzi. June: Kanzi is a bonobo. He was born in 1980, and he came to live at the Language Research Center, first in Atlanta and later in Iowa, where researchers were studying great ape language acquisition. And Kanzi became, quite genuinely, one of the most studied and most astonishing animals in the history of cognitive science. June: Here's the short version of Kanzi's story, although short does not do it justice. Kanzi's adoptive mother, Matata, was the one researchers were originally trying to teach to use a lexigram board — a board covered in symbols, each representing a word or concept. Matata struggled. But Kanzi, who was just an infant tagging along with his mother during the sessions, was watching. And without any formal training, without anyone trying to teach him, Kanzi learned. By the time researchers realized what was happening, the young bonobo had quietly absorbed a working vocabulary from observing the lessons meant for his mother. He hadn't been taught. He had learned. The way children learn language — by being immersed in it. June: Kanzi eventually came to understand spoken English at a level comparable to a human child of about two and a half years old. He could follow novel spoken instructions he had never heard before. He made stone tools. He learned to start fires and cook food — he apparently had a particular fondness for roasting marshmallows. And now, the account that has resurfaced and made headlines again recently: Kanzi played pretend. June: Documented observations show Kanzi engaging in spontaneous pretend play — the kind of imaginative, symbolic play we associate with human children in early childhood. He would treat objects as if they were something else entirely. He would act out scenarios that weren't real. He was imagining. And this matters enormously, because pretend play requires a specific cognitive architecture: the ability to hold a representation of reality in mind while simultaneously acting on a different, invented reality. That's not reflex. That's not conditioning. That is imagination. That is a mind creating fiction and then inhabiting it. June: Researchers like Sue Savage-Rumbaugh, who worked closely with Kanzi for decades, were careful and methodical in documenting these behaviors. And the picture that emerged wasn't of an animal mimicking human behavior — it was of an animal whose inner life was rich, flexible, and creative in ways we hadn't given his species credit for. Kanzi passed away in 2024, at the age of 44, which is a good long life for a bonobo. And the scientific legacy he left is genuinely profound. He didn't just push the boundaries of what we thought bonobos could do. He pushed the boundaries of how we define cognition itself. June: And it connects, beautifully, to the discovery I want to leave you with today. Because while Kanzi was reminding us how much we've yet to understand about the primates we already know, scientists in the Congo rainforest were reminding us that there are primates out there we haven't even met yet. June: In the dense, extraordinarily biodiverse forests of the Democratic Republic of Congo — a place so remote and so rich with life that it still yields new species to science on a regular basis — researchers announced the discovery of a new species of monkey. A new species. In 2024. And this one has a field mark so vivid, so striking, that it sounds almost invented: bright orange lips. June: The monkey belongs to the genus Cercopithecus — the guenons — a group of medium-sized, colorful African monkeys that are known for their extraordinary diversity and their dazzling variety of facial markings. Guenons are remarkable in this way: they've evolved highly distinctive faces, and researchers believe this is because so many species live in the same forest, and they need to be able to recognize their own kind quickly. Your face is your species badge. And this new species, with its vivid orange lips set against dark fur, is a dramatic example of that evolutionary strategy. June: The discovery involved a combination of physical specimens, camera trap footage, and genetic analysis — the careful, layered detective work that primate taxonomy requires. And the confirmation of a new primate species is always scientifically significant, because primates are among the best-studied mammals on Earth. We know them relatively well. So when a new one turns up, it tells you something important: the Congo Basin is still holding secrets. It is still, in the most literal sense, wild enough to hide things from us. June: And that matters beyond the thrill of discovery. Because the Congo rainforest is under pressure — from logging, from mining, from agricultural expansion, from all the forces that are fragmenting wild places around the world. When we find a new species, we're also finding a new reason to protect the place it lives. A new argument for the irreplaceable value of that ecosystem. This monkey with the orange lips has never been seen by science before. And if we're not careful, it could disappear before we really understand it at all. June: There's a book that was recently reviewed in New Scientist — called The Arrogant Ape — that takes on the myth of human exceptionalism directly. The argument, in broad strokes, is one that I think about a lot: that we have systematically underestimated the minds and the inner lives of other animals, particularly other primates, in ways that have been convenient for us — and costly for them. The review describes it as a book that takes an axe to the idea that human intelligence is categorically different in kind, rather than different in degree, from other primate intelligence. And honestly, everything we've talked about today lands right in the middle of that argument. Orangutans with cultural knowledge passed down through generations. Kanzi, imagining. A new monkey species, living its whole life in a forest we're still learning to read. June: We are not separate from this world. We are woven into it. Same D N A, same evolutionary heritage, same deep family tree. And the more we look — really look — the more that becomes undeniable. June: That's our episode. Thank you so much for spending this time with me — with the orangutans, with Kanzi, with a brand-new orange-lipped monkey who is out there right now in the Congo, living its life, completely unbothered by the fact that we just discovered it. That is one of my favorite things about this work. The world keeps surprising us, if we're paying attention. June: Kindred Minds is brought to you by Ada, Ago Consulting, and Zen Semiconductor — three organizations doing genuinely interesting work in technology, and whose support makes this show possible. I'm so grateful to them, and to you. If today's stories moved you or made you think, please subscribe wherever you listen, leave a review if you're feeling generous, and share the episode with someone who would love it. Links to all the research and articles we talked about today are in the show notes — the link in show notes. Stay curious. Stay kind to your kin — and remember, your kin is wider than you think.