Unexplainable - Who taught beavers to build dams?

Episode Date: July 21, 2025

How does any animal know what to do? A neuroscientist argues it's not “instinct.” Something bigger is going on. (First published in 2022) Guest: Mark Blumberg, behavioral neuroscientist at the University of Iowa For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠⁠⁠⁠[e-mail]⁠⁠⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠ Help us plan for the future of Unexplainable by filling out a brief survey: ⁠⁠⁠⁠⁠⁠⁠⁠⁠voxmedia.com/survey⁠⁠⁠⁠⁠⁠⁠⁠⁠. Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hey, I'm Matt Bouchelle, comedian, writer, and floating head you may or may not have seen on your FYP. And I'm starting a brand new podcast. Wait, don't swipe away. It's called, That Sounds Like a Lot. You know that feeling when you check your phone, read a few headlines and think, that sounds like a lot. I can't do this. Well, I can, and I'm going to get into it every Friday. You can watch on YouTube or listen wherever you get your podcast. I'm going to start by breaking down whatever insanity is happening in the world. And then I'll sit down with a comedian or actor or writer or, honestly, anyone who responds to my DMs. This is not the place to get the news, but it is a place to get the news.

to feel a little bit better about it. That sounds like a lot. Coming May 1st, part of the Vox Media Podcast Network. How does a spider know how to spin a web? How does a bird know how to fly? How does a beaver know how to build a dam? By instinct. For a long time, scientists have looked at fascinating, complex animal behaviors like spiders spinning a web, birds migrating, beavers building a dam, and used the term instinct, something that an animal seems to do without being taught, something it just knows. The term comes up a lot, from animal trainers. The animal is born with this instinct. To nature documentaries.

The instinct to have the right type of food is very powerful. To scientists. And then you might call it an instinct. The idea is that a lot of these behaviors are somehow genetically hard-coded. Each individual is born with built-in behavioral patterns. And it's a pretty complete. compelling idea. Like, how else would honeybees know how to honeybee? They are born with the ability and urge to do it.

But unexplainable listeners have some questions. Denise, Carlos, and Madeline all wrote in suggesting we look into instinct. And they ask things like, how does instinct work? Is it genetic or learned? And how can anything just know something? Well, turns out the idea of instinct is a lot less simple than those nature documentaries can make it seem. I talked to a scientist who can't stand this word. It's basically a covert expression of ignorance and lack of imagination. That's it. Mark Blumberg, behavioral neuroscientist, coming in hot. I can't tell you the number of articles, you know, for scientific journals that

I review where people just throw the word around. It drives me crazy. It's been bugging Mark ever since he was in grad school, and he felt like people were essentially using the idea of instinct as a shortcut. So as soon as you say it's genetic, it means like you can skisks. chip over all the things that actually get you from that amorphous blob of an embryo or a newborn and get right to the action. But Mark says it's nowhere near that simple. Every animal develops. It doesn't matter who you are.

All of us. We all develop. Mark wrote a whole book on this. It's called Basic Instinct, of course. Because he thinks relying on the idea of instinct gets away from everything he loves about science. Science is supposed to be asking the next question. And you just will never ask the next question. question, if you label it as instinct or innate or hardwired or programmed, all of those words

are basically designed to halt all further inquiry. And that's just not good for science. I'm Noah. I'm Hassanfeld, and this week on Unexplainable, we dive into an argument that made me question everything I thought I knew about instinct. So how real and how important is this idea of instinct? And if that's not where these incredible behaviors come from, how do animals know what to do? So, Mark, where does this idea of animal instinct and innate animal behavior come from? How far back does it go? It goes back a long, long way. But one of the interesting aspects of it is that it actually has its roots in a sort of a religious perspective. So it starts as a problem with free will and reason and good and evil. Really? Yeah, it's weird, right?

So imagine that you're, you know, in order to earn your way to heaven and heaven, You have to basically make choices. You have to have free will. You can't take an animal that cannot make choices about good and evil and put them in heaven or hell. That doesn't make sense. Humans are the only ones we have a soul, we have free will, we have rationality.

These are all ideas within the religious context. But we're not letting dogs into heaven or hell. So what you have to do is you have to deny them free will. But you have to explain what they're doing and you say, well, it's instinctive. So then how does this sort of religious idea make its way over to science? Well, that just creates the idea of instinct, really.

I mean, historically speaking, I mean, it has its derivation in this religious concept. And then Conrad Lawrence comes along, who was a very powerful Austrian scientist, who was one of the founders of ethology. What's etiology, exactly? Ethology is the study of animal behavior in its natural context. Okay. And so he was looking at different sorts of communication behaviors and birds. He's mostly known for his work on imprinting and, you know,

famous pictures of Conrad Lawrence and all these little ducklings following after him. So when a chick is hatched, we'll be able to be. basically create a visual connection to the first animal that sees in nature that's typically going to be the mother, and then they will follow the mother. And so the idea there is that they're sort of born with this computer program to imprint onto something, and then it gets turned on. Yes. And that's how they behave.

Well, one way you can think about imprinting. The way he did was it's like a switch. You know, you're born, and with the very limited time, you see your mother, or you see an Austrian ethologist, and you imprint on it, right? It's just a switch clicks, boom. But it turns out as a multi-step process, that it involves both a slight predisposition of bias to perceive the world in a certain way and the chick, and then a more typical learning process. But what happens a lot is that when you call it an instinct, it sort of throws a blanket over your inquiry.

I mean, if you just say it's instinctive and why is it instinctive, well, it's genetically encoded, or as you put it, it's a computer program. Well, then what's to understand about it? Like we would not have studied it further and learned the deeper, meaning of imprinting if we had simply accepted Lorenz's perspective on these things. Yeah, what kind of things have we figured out about imprinting since then? So one of the leaders in my field, Gilbert Gottlieb, was his name. He was interested in the auditory aspects of imprinting. So when chicks come out there, the mom makes what's called a maternal call

and it attracts the duckling. Well, he wanted to know where that came from. So he's somebody who did not do the Lorenzian thing and simply say, oh, it's instinctive. What he said was, how do they know to be attracted to the maternal call. So what he did was he looked at the eggs. And what he realized is that inside the egg, the chicks are vocalizing themselves. And he said, that's weird. Why would they be vocalizing inside the egg? And he wondered whether these vocalizations were creating an attraction somehow to the maternal call. So he figured out a way how to prevent the vocalizations from happening. So when these ducks normally, when they normally are hatched and you just play that chicken versus a duckling call, they go to the duckling call.

Right. But if they were devocalized and never heard their own vocalizations, they showed no species typical preference at all. So they were actually developing an attraction to the mom while they were still in the egg? Yeah. If Gilbert Gottlieb, if he was faced with this maternal call and he simply said, the newly hatched chicks have an instinct

to be attracted to their mother's call, would you ever go and do the experiments that he did? No. So these are some of the most famous experiments in my field that would never be done if you simply said it's instinctive. Right. But because he had doubts about the whole terminology, he was motivated to look deeper.

So are there other examples? I mean, let's say you move away from Lorenz a little bit. Are there other examples that show things that we might normally think of as innate animal instincts are actually developed through experience? Sure, let's take the writing reflex. So if anybody has a cat and likes to have fun with cats and you hold them upside down,

and you drop them, they'll land on their feet. Yeah, I grew up with a cat, and my brother once just tossed my cousin's tiny dog, thinking it'd be fine, and the dog just sort of landed on its back. I think it's more fun with cats. It's not great. So, okay, so here's the instinct part, perhaps. So you take a baby rat. You take a tank of warm water, and you put the rat on its back,

and then they flip over and they land on their legs. So the rats are, like, flipping themselves over in the water, just like the cats are doing in the air? As soon as they're born. Okay. It's instinctive, right? Well, how do you prove it's not? The way you prove that it's not

is that you have to do something that only we can do recently, which is you can gestate rats in space. Okay. Okay, because we were in a gravitational environment, and so you need to get them away from the gravitational environment. The way you do that is you send them up to space. So they did this. During the middle parts of gestation,

they fly these rats, and they had ground controls in this experiment. So the ground controls were just regular rats that were still on Earth. Just to make sure that they were still flip it. That was their control group, yeah. Okay. And then you have these rats that are just stated in space. And then the rats come back to Earth. And then the rats were born. And it turns out that a good chunk of these rats, when they dropped them on their back in the tank of water,

they just floated down and landed on their back. No writing reflex at all. And the ground controls flipped over and landed on their feet. And that's pretty cool because then that gets you thinking more broadly about what genes actually do. Genes evolved and function expecting a certain environment. And on our planet, you can expect that to be gravity. And it's because we take it for granted that we're able to say things like it's instinctive and it's in the genes because we're not thinking about the broader picture about the things that genes don't have to do.

And normally, they do not have to do anything about providing a gravitational environment. That comes for free. Right. So if we just said, you know, rats flipping is instinctive, we would miss the idea that gravity shapes the entire way we develop. Yeah. And you could take this even far. rather now talk about so gravity hits all animals the same way, but now you move into different

species. These are things that we inherit as well. So think about a beaver. Think about building a dam. How does a beaver know how to build a... Well, where do beavers grow up? They grow up around trees around water. When you're born as a beaver, your environment comes for free. When you develop in that sort of environment, then developing the capacity to build a dam is going to emerge out of your interactions with the environment. If a beaver family were put in the desert, they're not going to build a dam. There's no water. There are no trees.

Right. So the environment enables and shapes the sorts of behaviors that we call species typical because the environment is part of the inheritance of every species. It can be a large environment like water and trees. It can be a microenvironment like dew on a bottom of a leaf or, you know, all the sorts of small little aspects that we aren't even aware of because of our size that are vitally shaping the way animals develop and behave. I read a study, just in preparing to speak with you,

I read a study that said something like, if you isolate squirrels, raise them away from other squirrels, you raise them maybe in like a cage with a hard floor, they still kind of do these like digging and burying motions. Why would they be trying to dig dirt if they've never seen dirt? Isn't that sort of a hard-coded instinct? Yeah, I think that's a fascinating thing.

phenomenon. I've heard a similar thing about like burrowing rodents that are put in hard cages on its surface that does feel like a very strong argument for things that emerge without any sort of rationale in the external environment. They just do it, right? But when you see an animal do that, when you see a rodent in a cage digging, the tendency is to say, look, they've never countered dirt before. They're digging in a cage. It makes no sense. Therefore, it must be instinctive. That is dangerous because we don't know very much about the developmental experiences that got them to doing that behavior. Now, I do believe that it is fascinating and should be studied, but I don't know anybody who has studied it in a careful way. Yeah, so you're basically saying there could have been, you know, other less obvious things besides seeing actual dirt that might have led squirrels to try to dig.

Yeah, let me give you a great example. So, you know, there are these animals, cuckoos and cowbirds, where a mom will lay its eggs in the nest of another species. Okay, that's a really interesting problem because now you've got an egg from one species being raised with a bunch of eggs from another species of bird, and then at some point they grow up and they find their mates because they keep reproducing. They must find their mates somehow. And so a very famous, you know, evolutionary biologist and ornithologist named Dernsmeyer, he said that the ability of a cowbird to find, you know, identify its own species is encoded in the zygote, right? He just assumed he was basically calling it an instinct with no data, no investigation, just like,

this is what's happening. I cannot imagine any other way than this can happen. And it turns out there are ways that it can happen. One way that's been shown into slightly different situations in other birds, birds is that when a young bird is out and about, the adults of its own species will identify it and literally bully it. And so through that bullying process, the young bird figures out who are the members of its own species. Not that the young bird is going out searching for its own species and goes, oh, my instinct button just went off and oh my God, you know, the lights

went off and now I say like, oh, you're my people. Now it's the identification goes the other way. It's the adults who see the young bird and then bring them into the fold through this process of engaging with them aggressively. That turns the whole process on its head. It almost feels like for some of these scientists, if there's no obvious connection of like A leads to B,

the default is it must just be hard-coded. Exactly. And so even with like the squirrel example, I don't know, it seems plausible that there are other reasons it could be digging besides having a gene for digging. Absolutely. Understanding the development

of complex behavior is a really, really tough problem. And it should be treated as a tough problem in a way that does justice to the problem and doesn't just put a lot of things under the rug. Fighting words. Well, I'm calling this the way I see it because I've been, you know, a lot of us who care about these issues have been saying this for a very long time. I mean, want to hear fighting words? Yeah, please.

It's no different than being a creationist. I mean, what is a creationist? You're confronted with the complexity of the external world, and you cannot imagine how it could have evolved. And so you have to resort to a creator to try to capture the complexity and to give it some explanation when you can't provide one that makes sense.

Coming up next, this whole instinct argument can have some pretty serious implications. Lawrence was promoting eugenics, trying to stop the breeding of inferior peoples in his scientific works. More with Mark after the break. It's all about you.

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Every week I'm sitting down with trailblazing women at the top of their game to discuss ambition, work ethic, and the ups and downs that come on the path to achieving greatness. We'll dive into their stories and get valuable insights from top executives, actors, entrepreneurs, and other individuals who have inspired me so much in my own journey. Follow pretty tough wherever you get your podcasts. Instinct. So this idea that animal behavior is hard-coded, is this still an argument that lots of scientists are making? Yeah, it's everywhere. They use the word like, I'm studying an innate behavior.

And they're doing it in part because they think that by calling it innate, they're making their work sound more important, you know, more universal. You know, I'm not just studying behavior X. I'm studying innate behavior X. therefore anything I learn about it must be super important. Must have been evolved and ancient and universal. Use the words of choice. So it's partly a strategy and partly its ignorance about what the words actually mean.

That feels like you're calling it laziness. I am absolutely calling it laziness. Do you make enemies out of this? Do you call people out and people who are talking about innate behaviors? Are they like, ah, Mark? No, I mean, yeah, I don't know. I like to think I'm not making enemies. I actually, I try to do it more subtly.

Sounds like you're making enemies. Well, you know, look, it's science. It's supposed to be, you know, if we can't be honest about what we think, then we shouldn't be doing the business. And there is really a lot of confusion out there. I mean, it's really hard to think developmentally about how certain things come about, especially when it's not obvious, especially when the developmental processes are subtle and complex and circuitous.

It's not easy. Even like the most basic necessary behaviors, those are still hard to figure out? Yeah. The classic experiment was from 1910 or 12. It involved a scientist who was looking at ring doves in basically a tank of water. It was a shallow tank of water, I believe. And on the bottom were some seeds. Now, these birds were young and they had never actually drunk water before.

But as the person was observing the behavior, they saw that the first time they actually got water into their bill was when they were pecking at the same. seeds at the bottom of the water. They peck at it and they accidentally get water into their mouth. So, you know, it's over a hundred-year-old anecdote now. Hasn't really been followed up to my understanding, but it was followed up in rats to some extent. And they found that if they raised the rats from, you know, early in development, as soon as they start weaning off their mother, you know, when they start to eat food, if they gave them a wet mash so that it contained liquid and food, then when they gave them dry food at a water bottle, they could not figure out how to drink. But if they raised them from early on with dry food, they immediately learned

how to drink. So, you know, when we learn to drink, it's because we get dehydrated because we eat dry food and we feel a dry mouth and we feel dehydrated. That's the stimulus to drink, but you need to learn. You need to come into contact with water. And that often happens by accident. That is so even, it's hard to imagine anything more instinctive, sorry to use the word, than drinking. Yeah. It seems like that's like something that we all need to do. And you're saying that, you know, there's examples where if animals are not learning how to drink early on, they don't know how to drink. Yeah.

What I love about this paper was the author had a lovely turn of phrase. He referred to an acquired nature. An acquired nature, interesting. An acquired nature because that's what defeats dichotomies as you bring these ideas together. we all have this ability to drink. It's essential. If we don't drink, we die, but we acquire it. So it's not a nature thing.

It's not a nurture thing. It's the combination. And that's why those of us who don't use phrase words like nature, you know, innate and instinct and so on, we don't because it's a false dichotomy, that these things are inextricably linked. It doesn't make sense to pull them apart. You need both of them together to make us work.

But I also think, you know, there's another trap here, which is we're always sort of looking at animals that go through a typical developmental process. But for me, I'm fascinated also by when animals are born with atypical bodies for their species, and yet they figure a lot of stuff out. What do you mean? Every human that I'm aware of that's born with a condition which involves the shortening of the legs, they all discover the ability to walk on their arms. Within the body that they have, they're graceful, and they engage in lots of very complex behaviors. So they did, like, just walking around on their hands?

Go on YouTube and look for Johnny Eck, who was an actor, whose legs were not functional. Still the human species, same genome, but they all become handwalkers. That is not species typical for us. And yet, we still find the solution. And the point that I think is so important is that all of us learn to move our bodies like Johnny Eck, right? Same process. It's just if you have legs, you stand.

upright and you walk. And if you don't, you use your arms to walk around. It's not instinctive to walk on your legs or on your arms. It's just that you learn to use the body that you have. And it's not like you're saying genetics plays no role here, right? I mean, I don't think you're saying this, but it's not like a fox in a different environment is going to learn how to be a bird. I gave a talk once about this very topic at the Howard Hughes Institute in in Northern Virginia, and it was a room filled with a lot of really excellent scientists. And I gave my whole talk, basically saying these things. And a very sort of pushy guy, and the front row said, so what you're trying to tell me is

is that genes don't do anything. And I went, that is absolutely the opposite. You know, from what did you get? So for that per, for this one individual, if genes are not doing everything, if I'm saying that genes don't do everything, then I must be saying they do not. And that's dichotomous thinking at its core. Of course, I'm a biologist. Without genes, there's no us.

I mean, they're an essential part of the mechanism. But that is just an ounce of the complexity that's going on inside of a developing organism. So this whole time you've been making the case that avoiding the term instinct allows us to ask, you know, more and better questions. And I'm just wondering if we flip this around. Would using the term instinct open up any new questions? Are there questions about innateness that we wouldn't be able to ask? I've never, in my 30 years of doing this and thinking about it and being a developmentalist, I've never seen a single instance where calling something instinctive or innate had any benefit

that was actually tangible. So we're not just like throwing Conrad Lorenz under the bus here? Well, look, he focused attention on natural behavior that was a very positive thing. I'm just talking here about the conceptual level, about what you can infer from those types of observations. Yeah, I mean. And he was a Nazi. Oh, God.

So, yeah, I think you can throw somebody like that under the bus. I'm okay with that. Is it too much of a stretch to connect the idea of, like, instinctive things are the way they are, things behave the way they do with, like, a Nazi type of ideology? Funny you should say that. So one of my scientific heroes is a guy by the name of Danny Lerman, and in a really wonderful paper in 1953, he went after the much more senior Conrad Lawrence over the issue of instinct.

And Lawrence was promoting eugenics, trying to stop the breeding of inferior peoples in his scientific works throughout the war period. Most people don't know about that, and it was in German, and it's never been – those papers, as far as I know, have not been translated. But Lerman did translate it, and he wrote about it in his 1953 paper very, very briefly because he was told by his senior colleagues to cut out all the stuff he had originally put in there about it. Yeah, is that why you would say that this debate is important? I mean, it seems like on the surface someone could see it as a semantic debate. Because it really influences the way science is done. It influences which scientists

get the resources to do their work. It elevates scientists who are not so great, and it makes it harder for scientists that are doing the hard work to get the notoriety and the attention they deserve. I see this in conferences all the time, you know, where very prominent people simply throw out the innate word

or the instinct word, and they get away with it because they aren't being challenged. And that offends me as a scientist. So let me give you an example of where these assumptions get in the way. So I study a phenomenon called twitches, which was what animals do in their sleep. The old idea about twitches was that these were simply behaviors that were emitted when we're dreaming. So it's like, you know, a dog is chasing rabbits in its sleep. That assumption basically led to there being no studies about what twitching is.

Now, all animals twitch in their sleep, human infants are twitching. tens of thousands of times per day. Now, if it's just a byproduct of dreams, well, then why study it? But it turns out that when you dive in and you look at it, you find that these twitches are among the most powerful activators of brain activity

in early development that we see. If I had simply accepted the assumption that these were byproducts of dreams, all the work I've been doing for the last 15 years on this would not have happened, and the work of others as well. And so these assumptions are damaging. They close our minds to possibilities.

And I think that that's what words like an instinct and innate do. They close our minds to possibilities. You just have to continue to be inquisitive and not search for simple answers to complex problems. You know, this is biology. Nothing is more complex than how animals come to do the things that they do, whatever the cause. And we should be trying to understand the diversity of life

and all the different mechanisms that are available. And we probably still don't understand it all that well. No, now we were scratching the surface, big time. Okay, hey, I like to just do a hey everyone, like I'm talking to someone. Hey, everyone. This week's episode was produced by Noam Hassanfeld. Editing from Catherine Wells, Meredith Haudenot, and me, Brian Resick. Mixing and sound design from Christian Ayala, music from Noam, and fact-checky.

Fact-checky. Speaking can be hard sometimes. Fact-checking from Zoe Mullock. Mandy Nguyen is wondering how small plants... Oh, small plants are. Sorry, this is getting bad. I said how small plants are. She's got a really big magnifying glass.

Mandy Nguyen is wondering how smart plants are. Neil Danehia is counting armadillos. And Bird Pinkerton, she woke up and found herself in a long featureless hallway, lit with flickering fluorescent lights. She could just barely hear a low rumble in the distance. If you want to read more about animal behavior from Mark, he's got a couple of great books you can check out. One's called Basic Instinct, the other is called Freaks of Nature.

For a shorter read, he's got a fascinating paper called Development Evolving, the origins and meanings of Instinct. If you have thoughts about this episode or ideas for the show, please send us an email. We're at Unexplanable at Vox.com.