In many places, tree squirrels are extra busy these days. It’s time for them to collect nuts to prepare for winter! So we’re heading to a squirrel-themed adventure course and practicing a few of the skills they use to survive: gathering nuts, traveling in trees, and speaking like a squirrel. We’ll also learn about how squirrels evolved, and hear about some of their surprising relatives.

Plus, a mystery sound and a moment of um: what chemical in apples mixes with oxygen to turn brown?

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SARAH KATHERINE: You're listening to Brains On where we're serious about being curious.

SAM: Brains On is supported in part by a grant from the National Science Foundation.

MOLLY BLOOM: Fake fur? Check. Wire for structural support? Check. Kite string for controlling movements? Check. Feather boa for extra bussiness? Check. Sarah Katherine, we are all ready to make squirrel tails.

SARAH KATHERINE: Perfect. We're definitely going to need them for squirrelsperience.

MOLLY BLOOM: I was honestly so excited when I heard your question about squirrels.

SANDEN TOTTEN: Three months earlier.

MOLLY BLOOM: Oh, a new Brains On question. Let's hear it.

SARAH KATHERINE: Hi, I'm Sarah Katherine. And my question is, what are squirrels ancestors?

MOLLY BLOOM: Yes. There's only one way to answer this question. It's going to squirrelsperience. We're going to squirrelsperience. We're going to squirrelsperience. We're going to squirrelsperience. I am very excited could join in today to answer your question, we're headed to?

SARAH KATHERINE: Squirrelsperience.

MOLLY BLOOM: It's a special adventure course that celebrates all the spectacular skills that squirrels have.

SARAH KATHERINE: Yes, squirrelsperience. The theme park where you experience life as a squirrel.

MOLLY BLOOM: Because squirrels are so complex. To really know anything about squirrels, you really need to be ready to be a squirrel. Did you get your squirrelsperience handbook in the mail?

SARAH KATHERINE: Did I? I read it cover to cover. Call me Squirrel Katherine.

MOLLY BLOOM: I know. I've practically memorized my handbook. I've been so excited. In our squirrel experience, we'll learn three key squirrel skills. Eating and storing nuts.

SARAH KATHERINE: Moving through trees.

MOLLY BLOOM: And squirrel speak.

SARAH KATHERINE: I can't wait. Even just saying squirrelsperience is exciting. Squirrelsperience.

MOLLY BLOOM: It is. OK, let's finish up these tails. We've got to head out soon. OK, here's the fake fur.

SARAH KATHERINE: If you double it, that looks much more like a tail.

MOLLY BLOOM: Oh, yeah yeah. These are really coming together.



MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom, and my co-host today is Sarah Katherine from Columbia, South Carolina. Hi, Sarah Katherine.

SARAH KATHERINE: Hey, Molly. And a squirrel Katherine, remember.

MOLLY BLOOM: Oh, right. Sorry about that. Today, we're going nuts for squirrels. Squirrel Katherine, before we head to squirrelsperience, how would you describe a squirrel?

SARAH KATHERINE: It's like a little bushy brown animal with a huge tail that always eats from our bird feeders.

MOLLY BLOOM: What got you interested in squirrels?

SARAH KATHERINE: Well, we see them a lot around our house.

MOLLY BLOOM: How did the animals that you live with react to squirrels?

SARAH KATHERINE: Well, I have a dog but she just watches them. My cat likes to look out the window. So it same thing with him except he can't go outside.

MOLLY BLOOM: Your squirrels eat from your bird feeders?


MOLLY BLOOM: Is that OK or is that frustrating?

SARAH KATHERINE: Well, my dad is not happy about it but I don't really mind.

MOLLY BLOOM: The bird feed is there for everyone, including squirrels. Well, there are lots of kinds of squirrels, but squirrelsperience is based specifically on tree squirrels. They hang out in trees and eat nuts and acorns. In many parts of the world, these squirrels are everywhere.

SARAH KATHERINE: They're out and about a lot these days finding nuts and storing them for winter.

MOLLY BLOOM: And speaking of out and about, it is time for us to go. We've got to make our way to?

SARAH KATHERINE: Squirrelsperience.


I can't believe we're actually here.

MOLLY BLOOM: Wait, is that Menaka? Menaka?

MENAKA WILHELM: Molly? Sarah Katherine? What are you all doing here? I thought you were taping an episode today.

SARAH KATHERINE: That's Squirrel Katherine for today. And we're doing the same thing as everyone else. Learning all about squirrels by being squirrels.

MENAKA WILHELM: Oh my gosh. Welcome. I had no idea you were coming today.

MOLLY BLOOM: How fun that you chose today of all days to visit squirrelsperience too?

MENAKA WILHELM: Oh, no. I'm not just visiting. I've been a volunteer squirrel structure for years. In fact, I'm about to lead the tour. Have a seat on any of the benches over there.


Squirrel lovers, squirrel curious, welcome. Who's ready to have a great squirrelsperience today?



MENAKA WILHELM: Well, before you can start living the life of a squirrel, you need a squirrel setup. We have a whole collection of accessories ready for you. Your squirrelcesories. First, reach underneath your chair, you get squirrel shades and you get squirrel shades and you get squirrel shades. We all get squirrel shades.

You see you need great distance vision to be a squirrel. Plus these will improve what you can see off the side of your head, your peripheral vision. So now, you can see far away and around your head just like a squirrel.

SARAH KATHERINE: I have always wished my eyes could be on the side of my head.

MENAKA WILHELM: Next, hanging on the back of your chair, you'll find a pair of fake squirrel teeth. Pop those babies on. Your human chompers are not strong enough to chomp nuts.

MOLLY BLOOM: Wow, these teeth are long and so sharp.

MENAKA WILHELM: Now, to the left of your chair, you'll find a pair of gloves and toe socks. Those will give you squirrel claws.

SARAH KATHERINE: Careful. These are sharp.

MENAKA WILHELM: And finally, I hope you all brought your homemade squirrel tails.

SARAH KATHERINE: We did and we added these tight strings so you can switch them around.

MENAKA WILHELM: Wonderful. Well, now that everyone is suited up for squirrel dome, you're ready for your next stop on the squirrelsperience tour.


SARAH KATHERINE: Squirrelsperience.

MENAKA WILHELM: OK, Molly and Sarah Katherine, your first stop today is the Nutty Valley. You've got a great squirrel structure for your tour. Although I've heard she can sometimes be a little tough.

LUCIA JACOBS: OK, squirrels, listen up. My name is Lucia Jacobs. I'm a professor of psychology at Berkeley. I've been studying squirrels for a long time and I know everything a squirrel needs to know to become a squirrel.

MENAKA WILHELM: And your first task in the Nutty Valley is, of course, cracking open nuts. Here are a bunch of acorns for you all.

LUCIA JACOBS: Everyone, grab a nut. Everyone, start chewing at the top of the nut.

MOLLY BLOOM: Oh, like at the top of the acorn.

MENAKA WILHELM: Yeah, squirrels front teeth keep growing for our whole lives so they stay sharp and strong for breaking nuts open.

LUCIA JACOBS: You've got 30 seconds to chew a hole in the top of the nut. Lock your lower teeth into that hole and break off a piece of the shell.


LUCIA JACOBS: Do it again. Do it again. Oh now, you've got a big hole in the shell. Now, start eating the nut.

MOLLY BLOOM: This acorn is terrible. The handbook never said anything about this.

MENAKA WILHELM: Oh, yeah. Don't actually eat that acorn. Humans can't eat acorns if they're cooked. But if they're raw, they can give you a stomachache. That's because they've got these chemicals inside called tannins. And when acorns are raw, the tannins make acorns taste super, super bitter. But that doesn't bother squirrels.

MOLLY BLOOM: Those little rodent geniuses even have special squirrel taste buds.

MENAKA WILHELM: I know. So now, you know how to open nuts.

SARAH KATHERINE: With our teeth one chomp at a time.

MENAKA WILHELM: But squirrels don't eat every nut they find. They hide most of them away for later, and that will be your next activity.

LUCIA JACOBS: OK, here's another nut. Everyone, pick up your nut. Everyone, weigh your nut.

MOLLY BLOOM: Lucia, are there scales we can use somewhere?

LUCIA JACOBS: What do you mean you don't know how to weigh your nut? That's the basic skill.

MENAKA WILHELM: The heavier the nut, the more food there is inside. So squirrels do this thing where they put a nut in their mouth and then shake their head.

SARAH KATHERINE: Oh, like if you hold something in your hand then you bob it up and down to see how heavy it is.


MOLLY BLOOM: I maxed out on acorn taste a minute ago so I'm just going to shake my acorn in my hand to weigh it.

MENAKA WILHELM: That's very reasonable.

MOLLY BLOOM: So this nut is pretty heavy. It's heavier than that one.

SARAH KATHERINE: Oh, that must mean it's good.

LUCIA JACOBS: Everyone know how much their nut weighs? All right. Cache the nut.

MENAKA WILHELM: Now, this isn't cash like cash money. It's cache like C-A-C-H-E.

MOLLY BLOOM: Oh, I remember reading about this.

SARAH KATHERINE: When you see C-A-C-H-E something, you hide it away.

MENAKA WILHELM: Plus there's a squirrelly system for caching nuts.

LUCIA JACOBS: The more it weighs, the further you carry it. You know that. That's the rule.

MOLLY BLOOM: Right, because heavier nuts are more valuable. So we want to store them in an extra safe space farther away from the tree where we found them.

LUCIA JACOBS: Dig a hole. Put the nut in the hole. Pound the nut in with your teeth. Cover it with your paws. Walk away carefully so no one's seen you do it.

MENAKA WILHELM: You're going to be expert nut hiders.

MOLLY BLOOM: I get that hiding nuts is what squirrels do, but there are so many acorns on the ground. Isn't hiding them so carefully overkill?

LUCIA JACOBS: Remember, we're not going to give you any food for nine months. Everything you cache from September and October is your complete winter food supply. If you don't cache enough nuts and you run out in January, tough luck.

MOLLY BLOOM: Oh, my. Menaka, hand me that nut. I feel like I'm behind on my caching already.

MENAKA WILHELM: Technically, Molly, you might be able to find some early tree snacks around like March, but it's definitely good to stash more nuts rather than less.

SARAH KATHERINE: And from what I remember, we're going to need a lot of nuts. How many is it each year, Lucia?

LUCIA JACOBS: You may need to cache, as an adult, over 3,000 nuts.

SARAH KATHERINE: Plus we need to remember where our nuts are and what kinds of nuts we've had in different places.

LUCIA JACOBS: So you're going to be making this map using your eyes and your nose and your brain. Every nut is one trip. Up the tree, down the tree, out to the cache site, bury it and back. Up the tree, down the tree, out to a cache site, bury it then back.

MENAKA WILHELM: That might sound like a lot of running around in trees, and it is. But don't worry, learning tree traversing is the next squirrel skill on your tour. But first, you've all been working hard. Go get a squirrel sip. It's very important to stay hydrated at squirrelsperience. We'll meet back on the Oak Knoll in a bit.



RUBY GUTHRIE: Oh, Hiya, squirrel friends.

MOLLY BLOOM: Hey, it's our pal Ruby Guthrie. Wait a minute, what are you doing here?

RUBY GUTHRIE: Menaka hooked me up with this sweet job at the squirrel sip stand. Want a drink? We've got everything. Hazelnut latte, walnut tea, and almond milk on top. Ice cold, of course.

SARAH KATHERINE: That sounds refreshing. I'll take one please.


RUBY GUTHRIE: Two icy almond milks coming right up. And voila. Tell me, how's your squirrelsperience going so far?

MOLLY BLOOM: Oh, it's really something else. I am starting to feel one with the squirrels.

SARAH KATHERINE: Agreed. But I'm still curious about the squirrels of the past. In a nutshell, I just want to know where these beady-eyed, bushy-tailed creatures came from.

RUBY GUTHRIE: Oh, well, I could help you there. You see I've been squirrel-educating myself ever since I started working here. Did you know squirrels are a type of rodent?

SARAH KATHERINE: Like mice or rats?

RUBY GUTHRIE: Correct a mundo Squirrel Katherine. You see squirrels evolved from ancient rodents between 30 and 40 million years ago. These rodents evolved into squirrels, chipmunks, prairie dogs and marmots.

Oh, hey. It's my fellow squirrel sip tender, Ornella Bertrand. Hey Ornella, didn't you research rodents at the University of Edinburgh? Oh, you got to tell them that story about how squirrels are related to the mountain beaver. That one is nuts. What even is that?

ORNELLA BERTRAND: They look nothing like squirrels. From the outside, they're very small and they dig a lot. So they spend most of their lives underground. They're solitary. If you look at it, you wouldn't say like, Oh, wow, that's a very close relative to squirrels.

SARAH KATHERINE: What the nuts? A beaver?

RUBY GUTHRIE: I know. The name is actually soup's misleading. Even though mountain beavers look like a classic beaver just without the big paddle tail, they're not technically beavers. But just like squirrels, they evolved from the same ancient rodents. And researchers like Ornella here think mountain beavers and squirrels actually live together millions and millions of years ago.

ORNELLA BERTRAND: First of all, the oldest mountain beaver and the squirrels, they probably lived in trees very early on. What happened is squirrels stayed in trees while the mountain beaver group chose another trajectory. They become more terrestrial and also lived more underground progressively throughout the million years that followed.

RUBY GUTHRIE: Over millions of years, the squirrel and the mountain beavers evolved in different environments. And one of the most interesting things Ornella told me is this change in the environment made squirrel brains grow bigger and bigger.



RUBY GUTHRIE: Nuts, right? I'll tell you more about it. But first, there's something else for you to chomp into. It's the--

MOLLY BLOOM: Hey, that's my line.

RUBY GUTHRIE: Oh, right. Take it away, Molly.

MOLLY BLOOM: It's the--

SARAH KATHERINE: Mystery sound.

MOLLY BLOOM: Here it is.


It's pretty short so let's hear it again.


Sarah Katherine, what is your guess?

SARAH KATHERINE: That sounds like dumping something like nuts. Just thinking it might be related to this episode. Like dumping nuts onto a hard surface.

MOLLY BLOOM: Really good guess.

SARAH KATHERINE: Or maybe like pouring birdseed into a bird feeder.

MOLLY BLOOM: I like the brainstorming. OK, so either some nuts or some birdseed. Well, we're going to hear it again and give you another chance to guess in just a bit.


We're working on an episode all about superstitions and we want to hear from you.

SARAH KATHERINE: Superstitions are beliefs about things that are lucky or unlucky.

MOLLY BLOOM: Like some people think it's bad luck to break a mirror or good luck to find a four leaf clover.

SARAH KATHERINE: We want to hear what you think. Are there things that you do to bring good luck? Maybe things that you avoid because you think they're bad luck?

MOLLY BLOOM: What about you, Sarah Katherine? Do you have any good luck charms?

SARAH KATHERINE: Not really. Even though sometimes there are rainbows and I think those are lucky.

MOLLY BLOOM: Are there any bad luck things you avoid?

SARAH KATHERINE: Not really. My father thinks opening an umbrella inside is seven years of bad luck though.

MOLLY BLOOM: He probably does not like when you do that. I'm guessing. Well, listeners, send us your answer at And while you're there, you can also send us mystery sounds, drawings or questions.

SARAH KATHERINE: Like this one.

Hi, I'm Alexandra from Kansas City, Missouri. I'm eight years old and my question is, what chemical in apples mixes with oxygen to make the Apple turn brown?

MOLLY BLOOM: We'll answer that during our Moment of Uhm after the credits, and then we'll read the most recent listeners to be added to the Brains Honor Roll.

SARAH KATHERINE: So keep listening.


You're listening to Brains On from American Public Media. I'm Squirrel Katherine.

MOLLY BLOOM: And I'm Molly.

RUBY GUTHRIE: And I'm Ruby. And this is my pal Ornella Bertrand. We work at the squirrel sip stand. Where were we? Oh, that's right, squirrel brains. This discovery started when Ornella here was studying lots of different squirrel skulls, comparing old ones to the squirrels of today. That's when she noticed there was a part of the brain that was getting bigger.

ORNELLA BERTRAND: Yeah, exactly. We thought that living in trees required good vision and also good control of your eye movement. When you jump onto a branch, make sure your eyes are like well-fixed on the branch and that you know how far you need to go. You can't really close your eyes at that point because you need to catch that branch. What we found actually was that the early squirrels showed an expansion of the neocortex.

RUBY GUTHRIE: The neocortex is the part of the brain that helps with lots of things, including vision, listening, and memory. All things you would use way more often being up in a tree.

ORNELLA BERTRAND: We hypothesized that was in response to that change of environment going into the trees because the closest relatives didn't have it.

RUBY GUTHRIE: Like the mountain beaver. In fact, over time the neocortex in the mountain beaver got smaller.

ORNELLA BERTRAND: We hypothesized simply that when you live underground, you don't need as much vision and you don't need to make big jumps because you're in your little tunnel. It really shows you how much the animal is adapted to the environment.

RUBY GUTHRIE: And squirrels are a prime example of how to co-evolve with your environment, especially with trees. You see about 20 million years ago, the trees started growing harder and harder nuts. Animals would have a harder time eating them, and more of those nuts would grow into trees. But over time, squirrels jaws also developed to be bigger and stronger.

SARAH KATHERINE: All the better to chomp with.

RUBY GUTHRIE: Right. These nuts were far too hard to crack for other animals like mice or birds. Only this squirrel would rain squirrel preen. But the squirrels didn't just crack and eat the nuts. They also took some far, far away from the tree, weighed them, just like how you learned with Menaka and Lucia, and then they cached them in the ground, essentially planting them, which meant more trees and more nuts.

MOLLY BLOOM: Johnny Appleseed. More like squirreling nut cache.

RUBY GUTHRIE: Oh, good one Molly. The trees helped feed the squirrels, and in turn the squirrels helped to build up the forests. Without the help of squirrels, we wouldn't have nearly as many hickory trees, walnuts, or pecans as we do today.

SARAH KATHERINE: Wow. Thanks squirrels.

RUBY GUTHRIE: Speaking of, it's almost my lunch break and I could really go for some pecan pie.

MOLLY BLOOM: You better go now before they run out.

RUBY GUTHRIE: You're so right. Good luck with the rest of your squirrelsperience.

SARAH KATHERINE: Thanks for the squirrel tips. Bye Ruby and Ornella.

ORNELLA BERTRAND: Yeah, of course.

RUBY GUTHRIE: Think nut-thing of it.


MOLLY BLOOM: Squirrel Katherine, are you ready for that mystery sound again?


MOLLY BLOOM: All right, here it is one more time.


OK, any new thoughts?

SARAH KATHERINE: Not really. I definitely think it's pouring something onto a hard surface. I'm just going to say acorns or something.

MOLLY BLOOM: I love that guess. Ready for the answer?


MOLLY BLOOM: Here it is.

SAM: Hi, I'm Sam.

GISELLE: Hi, I'm Giselle.

SAM: Our mystery sound was acorns rolling down a park slide.

MOLLY BLOOM: You are totally right.


MOLLY BLOOM: Acorns on a hard surface rolling down a park slide.



MENAKA WILHELM: Heys, girlfriends. Welcome back to your tour. Earlier, we covered eating acorns and hiding nuts. Are you ready to learn how to make your way through the trees?

SARAH KATHERINE: Totally ready.

MENAKA WILHELM: Excellent, because your squirrels director Lucia Jacobs is back to tell you about her top tree tips. Lucia, to start off this tree training, can you remind us for anyone who didn't get to chapter 6 in their handbook, where do we actually find the nuts in the first place?

LUCIA JACOBS: You find the nuts in the trees. And that's why you're a tree squirrel and that's why it's so important that you can climb and leap and jump.

MENAKA WILHELM: Right. Let's all internalize that with an affirmation. I can climb.






MOLLY BLOOM: Are you sure about that jumping? I'm afraid of heights.

LUCIA JACOBS: Now, remember, you've been practicing. Since you came out of the nest, you were born in a tree.

MENAKA WILHELM: Yeah. Don't forget about where you came from, my squirrel friends.

LUCIA JACOBS: You've got really good vision and particularly for things that are moving. You can judge the distance between branches, but some of this is just going to be trial and error. And you're going to have to rely on your very sharp claws and your big bushy tail and everything you've learned.

SARAH KATHERINE: So we've got to see where to jump, grip the tree bark with our sharp claws, and balance with our fluffy tails. Shout out to all our squirrelcessories for making this possible.

MENAKA WILHELM: You got it. Amazing work everyone. Now, your final skill will be squirrel speak. For this one, we're running through a scenario.

SARAH KATHERINE: I've been waiting for this skill all day.

LUCIA JACOBS: You're in a tree and suddenly out of nowhere, a hawk dive bombs you. Ha! You know that red tailed hawk has incredible vision, and you're looking at the hawk and the hawk is looking at you.

SARAH KATHERINE: You don't scare me, hawk.

LUCIA JACOBS: You give it lots of signals that you tell the hawk "I've seen you. You can't catch me so what do you do?" Come on. What's the first thing you do? Squirrel 101, you tail flag.

MENAKA WILHELM: A tail flag is when you flick your tails so they wave in a big S shape.

SARAH KATHERINE: Like this, right?

MENAKA WILHELM: That looks great.

MOLLY BLOOM: Thank goodness we made these tails movable.

LUCIA JACOBS: So you do your big beautiful S-shaped tail flag, at the same time you tell everyone else, "Hey, there's a hawk."

MENAKA WILHELM: For that, you need your squirrel alarm call.


LUCIA JACOBS: You can make it to. Practice it.

MENAKA WILHELM: Three, 2, 1.


We might have to keep practicing a little bit. We flag, flag, flag, and we quack quack, quack. Whenever we see a hawk and if you see a predator on the ground like a dog or a fox, you want to do the same thing.

LUCIA JACOBS: You want to go up the tree and find where you're right over the dog's head or the fox or the coyote, and you're looking right down at them and you're making your tail flags and you're making your quack sounds. And you're saying "I can see you. I'm right up here. I see you. You see me. Just go away. Forget it. You're not going to eat me today."

MENAKA WILHELM: Or tomorrow or the next day. Before I came to squirrelsperience, I always thought squirrels were taunting dogs and cats when they did this. But they're really just sounding the alarm so that other squirrels know what's up and also to tell the predator to back off.

MOLLY BLOOM: For all of squirrel's amazing talents, I don't think they're very good at communicating with other species.

SARAH KATHERINE: That's true. In dog language, their alarm call seems like it means "Bark at me as loud as you can."


MENAKA WILHELM: One more round of quack, quack, quack for good measure. Quack. Quack. Quack.

Molly and Squirrel Katherine, congratulations. You have made it to the end of your tour. We're sending you home with a certificate and a temporary tattoo commemorating your new squirrelly skills. But before you go, it's time for your squirrel send off.

LUCIA JACOBS: OK, everyone, flag your tail. Flag it again. All right. Off you go.


SARAH KATHERINE: Squirrelsperience.

MENAKA WILHELM: We really hope you've had a wonderful time and learned a lot about squirrels. And please come back soon. I'm here every Thursday and Saturday.

MOLLY BLOOM: It really has been quite a squirrelsperience. Squirrels have some amazing skills.

SARAH KATHERINE: Yeah. I'm ready to store acorns. I know how to get around the trees. I think with just a bit more practice, my alarm call will be spot on. It might not make sense to dogs but other squirrels will get it for sure.

MOLLY BLOOM: Squirrels are part of the rodent family and they're a super diverse species.

SARAH KATHERINE: Tree squirrels are expert acorn openers, but they don't always eat the nuts they find.

MOLLY BLOOM: They stockpile lots and lots of nuts for later. It's called caching.

SARAH KATHERINE: Their vision and their sharp claws help them climb and leap around trees. They communicate with sounds and big tail movements.

MOLLY BLOOM: And over millions of years, squirrels co-evolved with their environment to better survive. That wraps up our squirrel saga. We're about to hear an answer to the question, what makes apples turn brown during the Moment of Uhm. But first, some super duper quick credits.

SARAH KATHERINE: Brains On is produced by Molly Bloom, Ruby Guthrie, Marc Sanchez, Sanden Totten and Menaka Wilhelm.

MOLLY BLOOM: We had engineering help from Alex Simpson, Johnny Vince Evans, George Kurtz and Sean Burch. And our intern is Katherine Sundqvist. Special thanks to Miranda and Andrew Ritter and Dan Latu. Our executive producer is Beth Perlman and the executives in charge of APM Studios are Lilly Kim, Alex Shaffer and Joanne Griffith.

SARAH KATHERINE: Brains On is a nonprofit public radio program.

MOLLY BLOOM: You can support the show and help us keep making new episodes by heading to While you're there, you can donate, join our free fan club or check out our merch.

SARAH KATHERINE: There are face masks, T-shirts, and hats.

MOLLY BLOOM: And you can buy the Brains On book there too. It's

SARAH KATHERINE: Now, before we go, it's time for a Moment of Uhm. What chemical an apples mixes with oxygen to make the apple turn brown?

ANDREA TORGERSON: There are actually two chemicals in apples that contribute to it turning brown. Hi, I'm Andrea Torgerson and I am a scientist who studies taste in food. When apples turn brown, it's actually a chemical reaction that needs three parts. Oxygen from the air, the phenolic that's in the apple, and another enzyme that's in the apple too. Phenolic are a plant chemical.

When oxygen comes into contact with the damaged tissue of an apple when you cut an apple, oxygen comes into contact with those phenolic then the phenolic start to turn brown because of an enzyme that is also in the apple. And an enzyme is a helper that helps the oxygen and the phenolic interact.

Once the phenolic and the oxygen come together, phenolic changes a little bit and turns brown. Different amounts of enzyme and different amounts of phenolic in the apple can make this apple turn brown at different rates.


MOLLY BLOOM: This list is better than a hot apple pie on a cool fall day. It's the Brains Honor Roll. These are the incredible listeners who share their questions, ideas, mystery sounds and drawings with us.



We'll be back soon with more answers to your questions.

SARAH KATHERINE: Thanks for listening.

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