The hosts explain why Bornean orangutan mothers face a social dilemma: adult orangutans are largely solitary because fruit, their main food, is sparse and scattered, making group living costly, but infants are born alone roughly once every seven to eight years with no siblings to play with. They discuss why social play (non-aggressive tagging, wrestling, chasing) matters for development even in a mostly solitary species, citing a 2024 study by Julia Kunz that found play frequency was similar across sites once opportunity to play was controlled for. This sets up the new PNAS paper from the Max Planck Institute of Animal Behavior and University of Zurich, based on long-term data from the Tuanan research station in Borneo, which investigates whether mothers deliberately create those play opportunities for their infants.
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The Kunz 2024 study compared Bornean and Sumatran sites using 11,000 observation hours across 99 young orangutans, finding Sumatran infants played more often but at equal rates once opportunity was accounted for.
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The Tuanan research station data collection began in 2003 under Maria van Noordwijk, giving over a decade of mother-infant tracking before this analysis.
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The hosts use bear cubs as a contrast case, noting cubs play with littermates while orangutan infants have no siblings and depend entirely on chance mother-mother encounters.
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The species studied is specifically Pongo pygmaeus wurmbii, a Bornean orangutan subspecies living in central Kalimantan, Indonesia.
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2:40The headline here is irresistible. Orangutang mothers arrange playdates for their infants in order to invest in their social development. >> I mean, as soon as I saw this, I was like, we got to cover it. Okay. Because at first, I mean, it intrigues me in so many ways. As a new father, you know, I'm starting to think about the pros and cons of like putting my kid in daycare and like the social development that comes with it, but also the exposure to like, you know, just getting sick and like all sorts of like nonsense that comes with that. So, you know, um there's a lot hiding in that headline
3:21and when I was diving into the paper, there's a lot of rich science behind the methods and things like that that I thought would be perfect for this podcast. Um there's a fact that this seems to be a deliberate decision by the orangutang mothers. Like they're not just like casually meeting up with other mothers that have babies. this is a deliberate decision. Um there's a fact that they have to give up energy and time to do this. So there's a story where you know mothers are making sacrifices. It's so similar to how humans do things. Um and and the science underneath that headline is really
4:02interesting. Like the way they collected years of data, analyzed that data and then they can convincingly state that you know orangutang mothers are consciously or not consciously but deliberately trying to do this. I think it's really really cool. So >> careful with the consciousness word with all the AI stuff going on. Right. So so it's up for debate right now. >> Exactly. I mean, if you ask me personally, my personal opinion is that of course orangutang are conscious. Like just >> look at them and look at the way that they respond to their environment. They respond to each other. They respond to stress. I mean, it's it's obvious to me, but there's going to be people that like, you know, saying, "Yeah, you don't
4:43really know what consciousness is." Okay. Anyways, let's let's get into some history and background. Orangutans, they're the great apes. They're part of the great apes. That includes gorillas, chimpanzees, bonobos, and us. >> Mhm. >> The animals um that are in this study are particularly the Bornean orangutanks, specifically Pongo, Pyus, Wurumbai, another taxonomical name that I'm struggling with. But these are the guys that live in Tuanon in central Kalimantan in the Indonesian Borneo. So Borneo is a giant island and there's Indonesia has like a majority of that. And >> I'll just knowative uh for all of my Nickelodeon fans, the Wild Thorn Berries
5:24is the first time I ever heard of the location of Borneo because it's this >> family that traveled around as like wildlife videographers. Uh like that was kind of the it was like I think it's literally in the theme song uh that and and so it's it was really cool cuz they traveled the world, but that was the first time I understood where the location >> Well, they must have been looking for orangutans in Borneo because Borneo is very famous for being like sort of a native. So they the family had a a a a an ape Darwin that could speak to Eliza because Eliza could speak to >> animals. That's Oh, I see. >> That's the shtick of the show. >> And they had a you know Darwin was around >> as a good name for an ape. >> Yeah. >> And clearly was done with intent.
6:06>> Yeah. Yeah. Yeah. >> So orangutang are a bit different from other apes. Okay. Because they are not that social. Um they are solitary in the sense that adult females they occupy home regions that maybe overlap with neighbors but in a real sense like they're very solitary. Solitary here means that um the usual organization of travel and feeding like they don't they don't go in groups they don't assemble in packs you know um >> so like Americans very individualistic >> very individualistic in modern modern Americans very much so right um modern society very much so in some sense and
6:46um maybe that tells us something that we can gather from the study but we'll touch on that later on right um the idea is that rather than traveling every single day in a stable troop, they actually move as separate units. So, the mothers will be separate and if a mother has an offspring, they're going to move as separate units. Okay? They're going to have some kind of home range of like some section of the forest that they like explore, but those are going to be mostly disjoint. Now, there are good ecological reasons for that. It actually has to do with um the diet of these orangutans and like where they where they live. The diet is mostly like fruit, large fruit eaters.
7:29Now fruit is something that is kind of rare in the forest and it's sporadic. It's not like you know at a regular cadence you can be like that tree is definitely going to have fruit and then this tree is definitely going to have fruit. So group living has its advantages right because you can like share information, you can share protection. But the disadvantages are that there's a limited amount of food and you're going to be competing for that limited amount of food, right? In a space where this density of food is very low. >> So that's why orangutans I mean from a biohysical perspective there's a lot of um theories out there for why they are solitary. It's actually has to do with
8:11the the physics of the environment itself. There's a resource constraint that they are conscious not consciously but actively >> uh operating around. >> Exactly. Um this is very different from other great apes. Chimpanzees very famously they are in troops right there's a lot of resource abundance in the place that chimpanzees live right. So they can they can actually administer in that. So now in this space of solitary confinement of these orangutang individuals the adults who are solitary in the forest now let's consider the infant. Okay orangutangs usually have one baby at a time and um
8:56usually that baby happens once every 7 to 8 years. >> Oh wow. >> So they don't have siblings. >> Yeah. >> In the traditional sense, right? It's not like a a litter of kittens or puppies where like they they have a bunch of people their same age that they can play around with. These are single babies to a single to to a single mother effectively cuz the dad >> went to go get the milk. >> Yeah. Yeah. Yeah. Let's you know the dad is not involved. Let's say let's say that. Um so so these this is a single mom with a single baby no siblings and you've got to introduce some bit of social >> you know
9:36>> interaction >> interaction yes you have to introduce some bit of that you don't have group living so what do you do that's the challenge right >> that's the challenge um and that creates a developmental problem inside of the ecological problem >> that's interesting yeah there's there's layers Right. The ecological problem is well because of the forest that I'm living in and because of the constraints that I have depending on the fruit and all of the choices that I have for food, I need to stay independent. But if I have a kid, I need the kid to socialize in order to like actually grow up and be sort of functionally accurate, right?
10:17Like play is a very very important part of upbringing. So play is actually very important. It's been studied for a very long time. Play is difficult science-wise because it's easy to recognize, but it's hard to like quantify. >> Yeah. >> Like this is a a a photo of two bear cubs playing. Now, here they're probably siblings, which is why they're close to one another, right? And they're playing amongst one another. I don't think bear cubs really mess with other bear cubs because mama bears are very, very cautious of other bears when they are nursing and when they're bringing up their kids, right? So, so bears have
10:58this advantage of having siblings. Orangutang do not. Now, in orangutang research, social play means that you have non-aggressive interactions such as tagging, wrestling, chasing. It's the stuff that like humans are are pretty are pretty used to. And there's a long history behind why play evolved. I mean, one idea is that it rehearses adult skills. Mhm. >> So even if the adult is not meant to be in a social setting, play can still be important. If the adult is meant to be in a social setting, then of course play is important, right? Because you're getting used to socializing. But you could have the argument that like, well, orangutans, they're they're asocial. Why
11:41do you need to play? Well, play gives you a kind of emotional regulation and it gives you the ability to respond to something that is unexpected, right? >> Right. If you're doing selfplay, then it's kind of a self feedback. >> You know what's coming. >> You know what's coming. When you're when you're playing with someone else, you don't know what the other person is going to do. And that ability to respond to an environment or to a stimulus that is unpredictable, that can have a lasting effect. It's beneficial to your own survival ultimately because you want to be able to react to unknown stimuli in a way that is beneficial to your own survival but that is not also an overreaction. >> Yes. >> Unnecessarily.
12:22>> Exactly. Yeah. So, so, so there is there is a benefit to play even if the population itself is asocial. That was the first thing that when I was reading the paper I was like that's actually interesting to think about, right? because it's trivial that play is important for social animals because you need to be social but even for asocial animals that's an interesting >> there is a there is a component of play that is important for your development >> um any case do orangutang youngsters play well in 2024 Julia Kun who is a co-author on the current study that we're going to be talking about in depth she published this article that um showed 11,000
13:02um observation hours from 99 young orangutans at two sites, one in Borneo and one in Somatra. And she showed that social play was more frequent in the Somatan site versus the Borneo site. But actually, if you controlled for >> the amount of times that >> um play was presented, >> ah >> it was the same. >> So if they're given the opportunity to play, youngster or rangutang will play. So now let's try to hone in on the other part which is how many times are they given the opportunity to play? >> That's what this paper is about >> because there's a difference. >> Right? It's like it's like if I'm not given the opportunity then I can't do
13:42it. Right? And the new paper builds on that groundwork. This is the paper that came out in the proceedings of the National Academy of Sciences in October 2026. >> I see you've avoided the acronym >> PEAS. That's what it is. That's what everyone says. Okay. Everyone says stop saying the the acronym and that's >> no no that's a joke everyone says it um this is from Maxplank Institute of Animal Behavior and there's a few authors from the University of Zurich so the earlier work established that orangutang youngsters play >> and that the opportunities for that play varies right and here what we're saying is that the maternal association could
14:25provide for that opportunity and the moms actually make a concerted effort in providing that opportunity. Okay, that's what's so cool about this. Um, the methods are incredible, I would I would say. Okay, >> so since 2003, Van Nordwick and her team have been following mother infant pairs at Tuan Research Station on the island of Borneo since 2003. Over a decade of research, they've observed encounters between mothers that are rare, but when they do happen, the mothers are very cautious, but the kids, as soon as they
15:06see each other, >> they just like run at each other and start blast. Yeah, they're having a blast. The mothers are very cautious. They've, you know, developed the whole adult thing of being solitary. The kids,
Animal BehaviorArtificial IntelligenceNeuroscienceProtein Engineering