Hey, Tumble fans. Marshall here.
It's been such a fun season so far, and we are hard at work on the rest of season 10.
We're so thankful for your support, and we're so excited to share more stories with you soon.
In the meantime, we have an amazing episode from season eight to share with you.
Was T. Rex smart? This episode really reminds me of our recent Dynotastic event in Brooklyn.
It was just such a blast and so great to see some of our awesome listeners like you.
Keep your eyes peeled for more live events in the new year, but for now, sit back and enjoy one of our favorite episodes.
Hello, I'm Lindsay.
And I'm Marshall. Welcome to Tumble, the show where we explore stories of science discovery.
Today we're asking, were T -Rexes smart?
Were they bloodthirsty carnivores or just hungry for knowledge?
Could they be both?
We're going to find out how the brains of extinct dinosaurs can help us understand what it means to be smart.
Our listener, Penny, sent us this question.
Hi, my name is Penny Jones and I'm seven years old.
My question is, how did smartness begin?
How did smartness begin?
Like, when could we call something smart?
It's a tricky question.
I'm going to guess sometime after rocks.
Penny has an idea of how scientists would find out.
I also think scientists will find out how smartness began by studying the time of the dinosaurs because dinosaurs were quite smart.
That's an interesting idea, but why does Penny think dinosaurs were smart?
I feel like the stereotype is that they're big dum -dums, except for velociraptors.
Why did velociraptors get all the credit for the brain?
You gotta be smart to hunt a, uh...
What did they hunt?
I have no idea. So no real reason you can think of of why velociraptors were smart, but it makes me wonder why we think of some animals as smart, like a wise owl, or a wily fox.
What makes an animal smart?
And, you know, what makes us humans smart?
Are we even smart? Let's ask our listeners what do you think smartness is?
And are dinosaurs smart?
How do you think scientists would find out?
Think about it, because we'll be back with the scientists who studied brains and smartness in all kinds of animals, including Tyrannosaurus Rex. Susana Herculano -Hüzel is a Brazilian -born neuroscientist. And she knows that most people don't think that T -Rex was very smart.
Susana Herculano -Hüzel Everybody has this image of the improbably gigantic creature with these person -sized teeth and everybody loves to debate whether they were just dumb reptiles.
I mean, t -rex is definitely a frequent topic of conversation in our house, especially among the younger members, like me.
The household consensus is that t -rex is very cool, no matter how smart they were.
I mean, person -sized teeth, those are cool.
But Susanna's a neuroscientist, which means she wants to go further beyond the teeth all the way up to the brains.
And while T -Rex is impressive in size, its brain is not.
I'll concede. It's true that when you look at the skull in that gigantic skull, the brain looks like an afterthought.
It's like a pair sitting in the trunk of a car really.
It's it's, it, it looks pathetic.
It looks meaningless.
Like a pair sitting in the trunk of a car?
That would rattle around a lot.
Well, that's hilarious!
So why was Susanna interested in studying T.
rex brains? It's not like they're gonna bring them back from extinction, right?
I hope not. But Susanna had an idea similar to pennies.
Looking at dinosaurs might be a good way to learn about smartness.
She wanted to question ideas about how smart different animals are, and to understand that, Susana says we have to answer this question.
First, what is this smartness thing that we're talking about.
Yeah. Like I mean, I guess smartness can mean a lot of things.
Susana agrees. I don't think intelligence is what we measure with exams at school.
So I had to come up with a working definition of intelligence, of smartness.
Susana's working definition wasn't something she could just go and look up in the dictionary.
And a working definition to a scientist is something that you can test. So she needed a definition that she could do experiments to see if it was correct or not.
Exactly. She wanted to define smartness so she could compare intelligence across species.
The definition needed to work for animals, not just humans.
So the definition that I came up with is that intelligence is flexibility, it's behavioral flexibility.
Behavioral flexibility?
What does that mean?
What that means is you're intelligent if you're capable of acting in different ways, in different circumstances, in different situations, after you've tried something and it worked or it work, can you change your behavior, can you do things differently." Okay so she's saying that intelligence is about being able to adapt your behavior to what you've learned.
Yes, and Susanna looked to what's inside the brain to test her ideas about smartness.
Neurons are the cells that form brains, and that move signals along different parts of the brain and actually across different parts of the body too.
Because neurons are what's responsible for our ability to think, Susana thought that how many neurons the brain has might determine how smart an animal is.
Then it follows that the more of these units that you have then the more capabilities you have of doing things with those signals.
So the more neurons you have the more things you can do with them like build houses, cook meals or circle, toys, and a catalog that you really hope you'll get for your birthday.
So, Susanna's next step was to find a way to count neurons in different types of brains.
So, maybe this sounds gross, maybe this actually sounds really cool, but however that sounds, the truth is, I count neurons by turning brains into soup.
She turns the brains into soup?
Like, is it good soup?
Does she season it with celery?
So are you coming down on the gross or cool side of the brain soup dilemma.
Um, I need to know more.
All right, let's be clear that brain soup is not for eating.
It's for science. It's science soup, and here's the recipe.
Take your brain of interest, cut out the part that you want to study, cut it up, dice it.
You're going to turn it into mush with detergent.
Turn it into a soup.
Sounds like detergent would really cut out the eating element of the soup.
Yeah, I don't like eating soap and other non -food ingredients with my soup.
Pretty much ruins things.
It's like, man, this is some great brain soup, except for the detergent part.
Could you maybe cut that out?
Replace it with carrots?
So anyhow, after the brain soup is blended up, it's ready to study.
Yum. Then, collect some of your soup and go to the microscope, count how many cells you have. It's basically just counting the little noodles in your bowl of chicken noodle soup.
Yes, make that a microscopic bowl of brain soup.
So after Susanna counts the cells, she does some math to multiply the number of neurons found in different parts of the brain.
And doing that, she discovered something really important, which is that a bigger brain doesn't necessarily mean more neurons.
Neurons are maybe the only cell in the body that exists in different sizes.
We have tiny little neurons and we also have gigantic neurons inside the brain.
So neurons are the only cells that come in different sizes?
Yeah! Which means that you can pack more neurons into a smaller brain if the neurons are smaller.
And to see how that's true, you only have to take the fact that elephants have much bigger brains than us.
We study elephants and not the other way around.
So, yeah, it would be weird if elephants were trying to sign us up in their research study.
Right. And that's because it's not one -size -fits -all when it comes to brains.
Susana found that each type of animal has a different equation behind their number of neurons.
Once you realize that a primate brain is made in a completely different way from, in terms of numbers from a cat brain or a dog brain, then you really cannot compare one to the other." So it's kind of like trying to compare apples to oranges.
It just doesn't work unless you're trying to decide which is the better fruit.
You know, I've done that and it is very hard. I'm sure.
So Susanna had to blend a lot of brains to get a good understanding of the animal kingdom, And she made a lot of interesting discoveries about living animals along the way.
But you might be wondering, how does this all work with a T.
rex? I've gotten so into the brain soup part that I've kind of forgotten all about the T.
rex. But now that you mention it, I am wondering, what does this have to do with a T.
rex? Can you make T.
rex brain soup? We'll find out after this short break.
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Okay, we're back. When we left off, Susana had blended a bunch of brains to figure out how many neurons are in the brains of each type of animal, but what does she do when the brain she wants to know about doesn't exist anymore?
So this is where science really turns into detective work.
When we try to understand the forms of life that existed before us— Susanna had to find a different way to crack the case of the T.
rex smarts. Yeah, if this is a detective story, where's the evidence?
Because it really doesn't seem like brains could fossilize.
That's exactly right.
There are no T. rex brains just lying around.
Instead of turning into stone that is preserved over millions of years like bones are, their brains just dissolve away.
So, Susanna turned to the next best thing – the dinosaurs that are still alive.
One really interesting thing about dinosaurs that not everybody realizes is that there are still some living dinosaurs amongst us.
And that's the birds, right?
Fortunately, Susanna had a list of neuron estimates for all different birds.
So she's looking at birdbrains, which come to think of it, birdbrain is sort of an insult for being not smart, so how's that going to go?
You might be surprised.
Actually, the non -flying birds, they are the ones that are the closest cousins to dinosaurs like T.
rex and that was exactly my starting point.
So Susana had a different kind of evidence than brain soup.
She had her neuron estimates for living birds and she had an estimate for the size of a t -rex brain.
So, what can she do with that?
She can make some assumptions and then do some math.
I could just presume that well, if they have the brain size that you would expect for their bodies, if they also had their brains made in the same way that other birds, the remaining dinosaurs are still made to this day, then if I know how large their brain was, I can actually calculate very quickly with very simple math how many neurons that brain must have had.
Okay, so what did she find?
She found something that kind of frightened her.
Even though I'm never gonna have a real dinosaur brain to study, there's very good reason to believe that with a brain that big and it being a close cousin to living birds, then it probably had something in the order of two to three billion neurons, which makes T -Rex horribly, horribly scary.
Those 2 to 3 billion neurons are in the cerebral cortex, the part of the brain that scientists believe plays the biggest role in thinking.
So is like 2 to 3 billion neurons a lot of neurons?
It seems like a lot.
When you're a fearsome giant carnivore, it is.
So let me put this into context.
the vast majority of animals have fewer than 1 billion neurons that's 1 with 9 zeros.
Very few animals have 2 or more billion neurons.
Wow, so t -rex could be on an elite level of intelligence, like doing math with its tiny little arms. Why do you need arms to do math, though?
How are you going to hold the chalk?
Well, let's just say that for the animal kingdom, T.
rex was pretty smart.
The most neurons you'll find in a living bird is in a macaw, with about two to three billion neurons, which is exactly how many I could estimate that T.
rex would have had.
Two to three billion neurons.
Some people say macaws are about as smart as a human toddler.
Okay I'm starting to get the scary thing because I can only imagine the mind of a toddler in a giant carnivore that could knock over a building.
Yeah, so you really have to get their meals into the right color bowl or the consequences are going to be very very harsh.
But Susana realized that T -Rexes would have something else in common with macaws.
They're the ones that are pretty crafty.
They're flexible, so they're smart and intelligent in that way that I like to define it.
So basically T -Rexes are going to be eating us for dinner if they want, or you know, whatever they wanted to eat at the time when they were alive, like a triceratops or something.
They really had their pick of snacks.
Anything they could catch. Well, so Penny, who asked our original question, thought that looking back to the time of the dinosaurs would help us find when smartness started, so does it?
Well, Susana wanted to study T.
rexes to get a new perspective on how ancient animals may have lived, and there was another good reason to study them.
Come on, how could I not?
Totally understandable.
Maybe T -Rexes were smarter than we give them credit for.
But Susanna says that dinosaurs definitely weren't the first smart creatures on earth.
To come back to her question, when did smartness appear?
We can say that capability of doing things differently, of being flexible, that capability has been there for a long, long, long time.
And it's a capability that we find in every single bony creature.
So anything with a bone in its body probably has some level of intelligence.
Right. By Susana's definition.
The first bony animals were also pretty small creatures, and they increased over time and they also gained neurons over time.
So you don't need to have a big brain or lots of neurons to be considered smart.
Yeah. we all make the best of what we've got to work with.
Certainly I try. And T -Rex's probably would have kept on doing pretty well if that meddling asteroid hadn't shown up.
Which you can learn all about in our episode, the dinosaur asteroid.
But even though Susana's made a pretty convincing case for how smart T -Rex's were, is it ever really possible to know the truth?
Susana says there's only one way to know for sure.
Well we would love to have a machine of course, right?
That would be the only way to really settle any of these questions.
I guess those questions and like a lot other questions.
Well I think that's Susana's way of saying it's impossible to know for sure but science is a tool we have to get as close as we can to knowing and to keep questioning what we think we know.
I think science is made of these assumptions, things that we believe are true, and then somebody gets curious and goes there and asks, do we really understand this?
Do we really know how this works?
So we never have to stop asking questions, even if it seems like someone has the answer now.
Yes, and as long as, like Susana, you do the work of getting good evidence, however you can.
That's the nature of science.
It's great, it's actually very comforting and refreshing in a way to realize that everybody can ask these questions and everybody can challenge an idea and have this very healthy the custom of just hearing something the first time, stated as a fact, and going, hm, I wonder if we really, really know that.
You know, I think that's a pretty good thing to do whenever somebody tells you that they know something.
It's a pretty smart thing to do after all.
Ha ha! So, you've learned that Susanna defines smartness as being flexible in your behavior.
Think of how you're smart in this way, and then think about animals.
Observe the animals you see in your own life, in your home or around your house.
What kind of decisions are they making and how could they be smart about them?
Maybe it's your dog figuring out how to get you to take it for a walk, or a bird hanging around where they know humans leave their food.
Try drawing a picture of the smart behaviors you see and send it to us at tumblepodcastatgmail .com.
We'd love to see what you find.
Thanks to Dr. Susanna Herculano -Houzil, associate professor at Vanderbilt University.
Also thanks to our listener, Penny and Ian, for sending in their questions about smartness.
You can hear more about Susanna's research on brains in our bonus interview episode on Patreon.
Just support our show at the one dollar level or higher at patreon .com slash tumble podcast. It will have more free resources to learn about neuroscience available on the blog on our website sciencepodcastforkids .com.
Sarah Roberson -Lentz edited this show and designed the episode art.
Elliot Hajjaj is our production assistant and Gary Calhoun James engineered and mixed this episode.
I'm Lindsay Patterson and I wrote this episode and I'm Marshall Escamilla and I made all the music and sound design for this episode.
Tumble is a production of Tumble Media.
Thanks for listening and stay tuned for more stories of science discovery.
Here we are at the end of the episode, and we all know what that means.
It is time for the birthday shout outs!
Whoo! So, here we go.
On December 13th, a happy birthday to Pierre.
I hope it is a good one.
Kafa and mama love you.
And Milo, have an awesome 8th birthday on December 13th.
Happy birthday to Olivia on December 13th, mama y papate quiere mucho!
Graham, welcome to your ninth orbit around the sun on December 13th as well!
Mom and Dad love you and your gentle and curious soul so much, here's to many more orbits together.
To Max, happy birthday on December 15th, mommy, mama and Lane love you so much!
And on December 16th, happy birthday to Spencer, lots of love for our Science Guy from Mom, Dad, Emily, and Henry!
And to Camillo, another happy birthday on December 16th, keep being the talented, kind, and brave person you are.
Everyone is so proud of you.
Happy birthday. Desmond, happy eighth birthday on December 16th.
Always stay curious.
Your imagination will take you to millions of worlds in your mind and worlds beyond Earth.
And a happy birthday on December 18th to Ash.
Mom and Dad love your curiosity and interest in the world around you.
Thanks to all of you and to everyone who supports Tumble and Patreon.
We couldn't do it without you guys.
If you want to get a birthday shout -out of your own, like these fine folks, Support Tumble on Patreon at the $5 level or higher by going to patreon .com slash tumble podcast Once again, that's patreon .com slash tumble podcast
