Today you’ll learn about how fingerprints form, how quickly you can determine whether or not you like a song, and how ancient ancestors to homo sapiens were using tools way earlier than we thought!
Today you’ll learn about how fingerprints form, how quickly you can determine whether or not you like a song, and how ancient ancestors to homo sapiens were using tools way earlier than we thought!
Fingerprint Formation
I Love This Song
Ancient Tools
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Find episode transcripts here: https://curiosity-daily-4e53644e.simplecast.com/episodes/fingerprint-formation-i-love-this-song-ancient-tools
[SFX: INTRO MUSIC/WHOOSH]
NATE: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. Time flies when you’re learnin’ super cool stuff. I’m Nate.
CALLI: And I’m Calli. If you’re dropping in for the first time, welcome to Curiosity, where we aim to blow your mind by helping you to grow your mind. If you’re a loyal listener, welcome back!
NATE: Today you’ll learn about how fingerprints form, how quickly you can determine whether or not you like a song, and how ancient ancestors to homo sapiens were using tools way earlier than we thought!
CALLI: Without further ado, let’s satisfy some curiosity!
[SFX: WHOOSH]
NATE: It's pretty crazy that if you think about how many people there are on Earth, every one of them has their own unique set of fingerprints. And until quite recently, scientists didn't actually understand why that happens.
CALLI: So it's kind of crazy if you think about how many different types of unique fingerprints there are, but it kind of feels like a shower thought to me, like you just staring at your fingers, just like, Huh, there's a lot of these. Okay. But I do want to know more. Tell me more.
NATE: So fingerprints develop when we're in the womb, Little ridges pop out on our fingertips, and they begin expanding in waves from three different points on each fingertip in what's known as a Turing pattern. And these ridges all begin as downward growths in the skin, similar to little trenches before the cells quickly multiply and grow upward. But until recently, we haven't known exactly how they're forming in the womb or why.
CALLI: I was never actually freaked out about fingerprints. But now I am. But I do feel like I've heard a few of these theories before. For example, some scientists think it's the skin folding spontaneously, or there's that theory that the randomness of the ridge pattern is because it's following the arrangement of blood vessels.
NATE: So the researchers behind this study want to know for sure. And so they started with the observation that growing fingerprints begin as ridges, which is also how developing hair follicles grow. So they compared cells from both locations, hair and fingers, to see just how similar they are. And if they can compare the development of hair follicles to the development of fingerprints. And they discovered that the two share certain signaling molecules, which are basically messengers that transfer information between cells and these molecules are known as WNT, EDAR and BMP. And, you know, it's a lot of letters all strung together. But I think of WNT and EDAR as these two best pals that need each other to survive. And as they looked further, they discovered that WNT is the messenger that tells cells to multiply and to create ridges in the skin and to produce EDAR, whose sole purpose is to accelerate the production of WNT.
CALLI: Okay, but what about BMP? And I feel about it like you said, the other two are best pals and you left this one out.
NATE: All right. So that's what the researchers found. The most interesting is that BMP works as hard as it can to stop EDAR from forming, meaning it's a cell messenger that wants to stop other cells. And the researchers were curious about how these messengers works together to create fingerprints. So they manipulated the molecules levels in test mice.
CALLI: Why? Okay, I know we normally use mice, but why mice? They don't have fingerprints. Right?
NATE: That's true. But this study taught me that their toes do have striped ridges in the skin, similar to a human's fingerprints. And as the researchers adjusted each molecule, they were able to witness in real time how each mouse's toe pattern changed. An increase in EDAR resulted in thicker, more spaced out ridges across stripes decreasing EDAR led to the creation of spots instead of stripes, and if BMP was increased during either test, the patterns were thinner and more closely joined.
CALLI: That is so weird. Okay. Does the creation of stripes or spots have anything to do with the Turing reaction to fusion? I feel like it does just because you've been calling these Turing patterns.
NATE: Exactly. So yeah, the switcheroo that happened between the spots and the stripes is a key component of Turing reaction to fusion, which is a mathematical theory proposed back in the fifties by British mathematician Alan Turing. That theory describes the ways in which chemicals interact with each other and then spread to create the patterns we see in nature, like the patterns that wind can make on sand. Then to be clear, the Turing reaction diffusion only explains some patterns. But in the case of these fingerprints, it seemed to explain all of the patterns.
CALLI: Okay, Can I play devil's advocate here for a second? Because mouse toes are way too small to create the sort of complex shapes we see in human fingerprints. Right. So what did they do with that?
NATE: I'm glad you asked. The researchers knew the toes would be too small, so they had to move on to another phase using computer models. And these models simulated Turing patterns that spread from the ridge initiation spots on a fingertip, which are the center of the finger pad under the nail and at the joints crease nearest the fingertip. And in turn, the team were able to create each of the three most common fingerprint patterns arches. Loops and whorls, plus some rarer ones.
CALLI: So then how does each shape form?
NATE: They didn't say how each shape was formed, but as an example, the arch shape we see on many fingerprints comes about whenever finger pad ridges get a slow start to their production. This allows for ridges that originate from the fingers joint crease and from under the nail to take up more space on the finger. Their work is further supported by another recent study that showed that people with gene mutations that affect WNT and EDAR have skin abnormalities. So basically it's as if the very concept of how fingerprints are formed affects other parts of their skin instead. So I talked a little about wind and sand and how it can makes patterns. If you go back to that, it's all about how these molecules mix together. If there's more wind, the sand takes on a different pattern than if there's less.
CALLI: This is very interesting. So what's next for this team? It's kind of rare for us to actually talk about a study that actually seems to have some sort of closure to it.
NATE: Well, this may be the end of the fingerprint study, but it's only the beginning of this team's dive into the world of skin. Because now they want to find out if they can figure out ways to manipulate the creation of skin structures such as sweat glands whenever they're not forming properly in the womb. In the broadest terms, the team want to understand how the skin matures, why the skin matures, and most importantly, what can be done to make sure the skin matures properly.
CALLI: Cool. Or just one of my cats. I want to see if they've got fingerprints.
NATE: Koalas have fingerprints that are apparently so similar to humans they can cause confusion in crime labs. That's the story I've heard.
CALLI: That's my favorite thing I have ever heard.
NATE: I don't know what the situation was in which there was both a crime and koala fingerprints to confuse someone. But just apparently they are similar enough.
CALLI: Well, okay, but who was fingerprinting koalas?
NATE: I think the idea is just like if there were a crime scene and you lifted a print, you'd be like, okay, we have a print here, but it could be from a koala.
CALLI: Okay.
NATE: You're like, Size might be a key.
CALLI: It's really tiny.
NATE: Well, is that the size of a man's fingerprint or is it the size of a three year old child's fingerprint?
CALLI: Okay, Now I have to know in what situation there was a crime that a child committed that we needed to fingerprint them. Gee, I wonder how much of that is getting cut.
NATE: If anyone if anyone has actually been fooled by this in a crime lab, I'm very disappointed in them.
[SFX: WHOOSH]
CALLI: Okay. So, you know, sometimes a friend will come to you and we'll be like, hey, you've got to listen to this new song. It's fantastic. And just within the first couple of seconds, you hate it. And then and then they're like, No, wait, wait until it gets to the good part. Well, the next time that happens, just tell your friend: psychology has proven there is no good part. This isn't just a bias. It is supported by science.
NATE: Okay. I'm trying to think right now if I've ever had someone try and share a song with me, like I didn't like it first, but then I started liking it, you know, if it got to the good part or if I all listened to his song or listened to it a couple of times, it grows on you like, I don't know, I'd have to really think about it and maybe keep notes. I don't think that happens to me all that often. But okay, I want to hear more about how the science supports this weird bias.
CALLI: All right. So a researcher named Pascal Wallisch noticed that leading music industry platforms like iTunes or Amazon provide very short 30 second or less long snippets of songs when promoting an album for sale. But he wondered if 30 seconds or less is even enough time for a consumer to figure out whether they like that song or not. Even more, why that sample of the song. So some snippets are probably chosen ahead of time by the artist or their record label, but others are automatically just plucked by an algorithm. And Pascal wanted to know if the portion chosen made a difference on the consumer.
NATE: Okay. Yeah, I see what you mean. So, you know, we got Taylor Swift's people. She might be more excited if one of the dynamic and catchier parts of the song is played as compared to, say, a slow, maybe a spoken word introduction to a song or something like that.
CALLI: Exactly. And to figure out whether that ultimately matters as well as the answers to his other questions, Pascal got a research team together to conduct an experiment on 650 or so university undergrad students and other New York City residents. In this experiment, the participants listened to 250 complete songs in a variety of genres, ranging from country to hip hop, as well as excerpts from the same songs that lasted five, ten or 15 seconds. Now, each excerpt was pulled from a different part of the song to either the intro, outro, chorus or verse. The participants were then asked to rate how much they liked a song or a clip, then rate their familiarity with the song.
NATE: I like listening to music. I know a lot of other people do. It seems to me that a study of listening to 250 songs like that seems like it would sound fun at first, but he would get old pretty quick. Like, that's a lot of listening to music.
CALLI: Yeah, I'm pretty sure that's just my Spotify weekend, so, you know. But to be clear, they didn't make 650 people each listen to 250 songs. The pool was randomized from the 250 songs. Okay. Yeah, there you go. But what the researchers discovered was that the participants preferences for a certain song, whether they first heard it as a clip or as an entire song, completely aligned, meaning that the choice of the clip on a streaming service didn't matter. People liked or disliked songs regardless of how they heard it. Even more interesting, the length of the clip didn't matter. Some were just as likely to hate a song after 5 seconds as they were after 5 minutes.
NATE: To me, it seems that one's pretty easy to explain, though. Like if you change the order that people listened to the songs, you'd get different results, wouldn't you?
CALLI: Oh, that's what the researchers thought, too. And they found that the correlation for song preference was actually higher if somebody heard the complete song first rather than the second. On the other hand, they acknowledged that there was also a correlation showing that people had a preference for an excerpt over an entire song. Recognition of the song admittedly could contribute to any of these results, except less than a fifth of the songs were recognized by the participants. So they had no choice but to conclude that although the unrecognized clips that were presented before the song were the least predictive of a song preference rating, those clips are still far more predictive than one would expect from random chance.
NATE: Interesting. All right. So what does all of this mean about music, then?
CALLI: Okay. It means that if you present somebody with new music, there is a very, very high chance that they're going to decide how they feel about that song, no matter how much of it is shown to them. They believe this result could have deeper implications into the links between the properties of music that creates emotion in people. Because all it takes is a few seconds of music to strike emotion in people. That suggests that it's not so much whether a song is good, bad, well-constructed, simple or complex. It's all about the vibe the song presents to the listener, which is exactly what the researchers hope to explore in further studies. What exactly is a vibe and don't tell you.
NATE: Taylor Swift.
CALLI: It's Taylor Swift. She's a vibe.
[SFX: WHOOSH]
NATE: Some researchers in East Africa have found something 2.9 million years old, a tool that did not belong to a human.
CALLI: Okay. So that's going to be like really, really rare. Tell me more.
NATE: Let me introduce you to The Nutcracker man. This was a hominin, which is an ancient relative of humans. So The Nutcracker Man was a small-brained hominin whose nickname came from his powerful jaw and big old teeth. Researchers found two large molars at an archeology site, and when they did an analysis of these teeth, they discovered that he had a very heavy grass based diet.
CALLI: Okay, awesome. So were these tools used to help harvest or cut grass or eat it?
NATE: Not exactly, but I'll get there. So Thomas Plummer from Queens College City University in New York, started excavating at a western Kenya dig site known as Nyayanga back in 2015 after he heard stories of fossils, bones and tools eroding out of the hillsides. And Thomas and his team found more than 1000 fossil remains of different creatures, from extinct horses to giant crocodiles.
CALLI: Interesting. And this is where they found the teeth.
NATE: Exactly. So they also found around 300 stone hammers and a lot of other tools. And after dating the site, using an assortment of methods, they discovered that all of these relics were roughly 2.9 million years old.
CALLI: And that's what you said before, which is fascinating, because humans didn't exist then. So that's really cool.
NATE: Exactly. Yes. Homo sapiens only began existing 300,000 years ago, which means these tools were used about 2.5 million years before we evolved into modern humans. And even more impressive, there's archeological evidence to suggest that these tools were used to slaughter a hippopotamus.
CALLI: Oh, my gosh. Okay, So definitely not used for cutting grass. Kinda sad for the hippo, though.
NATE: Well, yeah, I suppose. But this this totally changes what we think we know about evolution because it indicates that humans might not have been the first ones to use stone tools. And these tools were relatively sophisticated. They're known as Oldowan style tools. And what makes them so impressive is that instead of a more rudimentary style of making these objects, you know, smashing one rock into another, sharpen it. Whoever made the Oldowan tools had a specialized hammerstone that chipped away at similar rocks that they rotated in their other hand. And these tools were precise. So they were used to cut through plants and animal flesh, which is also interesting because these tools also predate the first known scientific evidence of intentional fire, meaning that the Nutcracker man either ate raw flesh or pounded it into a fine mush.
CALLI: GROSS okay.
NATE: Oh, you eat steak tartare.
CALLI: That is different. That is not different.
NATE: It's not HIPPO.
CALLI: It seems different. It's not Hippo. So is this the oldest tool ever found at a dig site?
NATE: It is, yeah. So we now know that The Nutcracker Man was a much smarter, more creative creature than science originally gave him credit for. Plus, this means that a lot of what we've theorized about early hominin behavior is really incomplete and probably always will be. Still, we've been digging around in East Africa since the 1930s, and every year we find something new.
CALLI: That is really cool. And now I just want steak tartare.
[SFX: WHOOSH]
NATE: Let’s recap what we learned today to wrap up. Why do fingerprints exist? That was the question at the heart of a recent study that discovered that fingerprints are the results of a sort of molecular battle being raised from the moment you’re conceived till birth. Due to the random levels of certain molecules being deposited at any given time, our fingerprints are all so unique! Now that this mystery’s been put to bed, the team is looking into other abnormalities in our skin - such as why some fetuses don’t develop sweat glands properly! Maybe we’ll even talk about that in a future episode when that study drops, too!
CALLI: Have you ever heard the first few seconds of a song and realized instantly it was the worst thing you’d ever heard? Turns out that’s science, baby! A new study out of New York City has revealed that no matter if people are presented with five seconds or five minutes of a song, no matter which order the recordings are presented in, their feelings were ultimately mostly predictive when they were shown a short sample. Meaning that no matter how much your friend insists a song you hate “gets better,” all you need to do is trust your gut!
NATE: Tools are something humans invented one day, right? According to a recent study out of east Africa - nope! Stone tools dated back 2.9 million years have been discovered in Kenya alongside bones of The Nutcracker Man, an ancestor predating Homo sapiens by nearly 2 and a half million years! This is a massive discovery in the scientific community - and one that changes the context completely of what we know about our ancient ancestors.