D (2:33)

Interesting. Okay, so how did scientists test this?

B (2:36)

In a study out this week in PLOS Biology, scientists played piano music by Bach to sleeping newborn babies. And the babies were hooked up to these EEG machines to see how well their little brains predicted rhythm or the melody.

D (2:51)

Love this. So what did they find?

C (2:53)

They were looking for brain signals that show the babies were predicting the Next note. In adults, our brains predict both the rhythm and the melody of the next note. But they found that the babies tracked the rhythm, even though it could get pretty complicated.

B (3:05)

But the babies didn't track the melody.

D (3:08)

Interesting. So does that mean that babies have rhythm at birth, but not melody?

B (3:12)

Seemingly. Possibly.

D (3:14)

Hmm. And do they have an idea as to why we might have this sort of innate sense of rhythm really early in life?

C (3:20)

Yeah. We also talked to Laurel Trainor about that. She's a developmental neuroscientist at McMaster University. She studies music perception, and she said it's likely because rhythm is everywhere.

F (3:30)

Babies crawl rhythmically. They flail their arms rhythmically. Their heartbeats are rhythmically rhythmic. So in biological systems, rhythms are just fundamental to everything from movement to proceeding, things like speech or music to thinking.

C (3:46)

So she says it makes sense that predicting rhythm is an ancient trait after all. She points out that babies are exposed to rhythm in the womb through the mother's heartbeat and walking.

B (3:55)

But melody, on the other hand, isn't present at birth, at least not in the part of the brain where the scientists were looking. But just because the scientists didn't see it doesn't mean it's not there. And we should note that this study only looks at Western classical music.

D (4:08)

Interesting. Okay, let's go to our next topic. And there's a clue about snakes and hunger. I understand. I am not the biggest fan of snakes, but I'm willing to go on this journey with you.

C (4:18)

Snakes freak me out, but they are extraordinary when it comes to their feeding patterns. Some can go without food for months or even a year.

D (4:25)

Right. And then they'll eat a huge meal, right?

C (4:27)

Yeah, exactly. My brother honestly does this, so I call it his snake meal. But researchers haven't understood if there's a genetic piece to why snakes and some other reptiles do this. But now they might have a clue. Researchers looked at the genomes of over 100 reptile species and found some snakes and chameleons have lost the genes that produce the hunger hormone ghrelin.

D (4:47)

And humans have that, too. Right. That's why I'm hungry right now.

C (4:50)

Yeah.

B (4:51)

Yeah, we do. It's all part of this hormonal system of appetite in humans. As ghrelin levels rise in our bodies, we get hungry. I just satisfied mine. I just had a sandwich. It's also involved in how much we eat and body weight regulation. And you've probably heard of another appetite hormone, GLP1, right? Yeah. It's sort of like ghrelin's counterpart. It tells us when we're full.

D (5:13)

So what does this mean for snakes if they don't produce this hunger hormone?

C (5:17)

The researchers think this finding could tell us more about why snakes are able to fast for months. And the study was published this week by the Royal Society. I talked to another evolutionary biologist who wasn't involved in the study. His name's Alex Pyron. And he told me studying these kinds of metabolic pathways in reptiles could tell us more about humans in the future.

B (5:36)

With more research bonus trivia. Juana, did you know that GLP1 drugs like Ozempic were inspired in part by research on Gila monster venom?

D (5:45)

I did not know that.

B (5:46)

Yeah, it's super cool. So sometimes animal studies can have surprising payoffs.

D (5:50)

All right, let's move on to our third topic, and this one I'm excited about because I love sleep, and I have a lot of problems that need solving. And I hear that sleep might help.

B (5:59)

Yeah, I mean, when I was in college, I would dream about difficult quantum mechanics problems, and it turns out it might have helped me.

E (6:06)

We learn during the day very effectively, but to really make it stick, we need something additional, and some of that's happening during sleep.

C (6:13)

That's Ken Pallor, a cognitive neuroscientist at Northwestern University. And he and his team studied this by working with 20 Lucid Dreamers. So people who are sometimes aware that they're dreaming, which I'm very jealous of, and they ask them to solve brain teaser puzzles or riddles. Like, here's one of them. Juana, can you find a meaning or a cute way to interpret this set of letters?

D (6:35)

G, E, S, G. I literally have no ideas. Please help me.

C (6:41)

We're gonna let that one simmer.

D (6:43)

It will marinate.

C (6:43)

We'll marinate for a while. Yeah. And in the meantime, I'll tell you more about the study. So the scientists only gave the volunteers three minutes to solve puzzles like this, which usually wasn't enough time. And then they also played a unique soundtrack while people were solving each puzzle.

B (6:58)

And, Juana, as you stare at these letters, like G, E, S, G in confusion, imagine, like, also hearing this song. The idea was to help people's brain, like, link the puzzle to a sound or a song. And then the participants were told to go to sleep.

D (7:15)

Huh. And then what happened when they went to sleep?

C (7:17)

So the scientists monitored the sleepers, and once they entered REM sleep, the researchers would play that unique soundtrack cue to do a little inception. They wanted to encourage dreaming about that specific puzzle that they hadn't been able to solve when they were awake.

D (7:31)

So what did they find? Can you solve puzzles in your sleep, like Gina?

C (7:34)

Well, after the volunteers woke up, they were more than twice as likely to solve puzzles they dreamt about compared to puzzles they didn't remember dreaming about. So, yeah. The results are published in the journal Neuroscience of Consciousness.

B (7:46)

Speaking of which, Juana, did you have an answer for a riddle from earlier? Like looking at these letters G, E, S, G?

D (7:53)

No, I didn't have time to sleep on it and I'm just really bad at these.

C (7:57)

Do you want the answer?

B (7:58)

I do.

C (7:59)

Okay, the answer's scrambled eggs.

D (8:02)

Well, now I'm just hungry again. How do you get scrambled eggs out of gesg?

B (8:06)

Because it smells eggs.

C (8:08)

It smells eggs, but they're mixed up. I didn't get it either, honestly.

B (8:11)

Okay, but the bigger point isn't the answer to this one puzzle that stumped all of us. It's that these scientists are one step closer to answering that age old question, like, why do we dream? Like, what is it for? And according to Robert Stickgold, another dream research work on the study, dreams aren't just entertainment. They're a catalyst for processing information and inducing creativity.

D (8:32)

Very interesting. You've given me something to think about when I doze off later tonight.

B (8:35)

Yeah, hopefully it's not work.

D (8:36)

Hopefully not.

B (8:37)

Juana, thank you so much for coming on our show and having so much fun with us solving puzzles.

C (8:41)

Yeah, next time we'll have more puzzles.

D (8:43)

Oh, no, I'm still not going to be good at them. But I will bring my best game.

B (8:51)

You can hear more of Juana on consider this and PR's afternoon podcast about what the news means for you.

C (8:56)

And for more science stories just like this one, follow Short Wave on whatever app you're listening to. I produced this episode alongside Jordan Marie Smith and Burleigh McCoy. It was edited by Christopher Intagliotta and Rebecca Ramirez.

B (9:09)

Hannah Glovna and Jimmy Keeley were the audio engineers. I'm Regina Barber.

C (9:14)

And I'm Rachel Carlson. Thanks for listening to Short Wave, the science podcast from npr.

A (9:37)

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