Pod Insights Short Wave What’s In A Kiss? 21 Million Years Of Evolution About this episode How far back in evolutionary history does kissing go? Through phylogenetic analysis, an international team of scientists found that kissing was likely present in the ancestor of all apes – which lived 21 million years ago. Not only that: They were definitely kissing Neanderthals. The study was published in the journal Evolution and Human Behavior http://linkinghub.elsevier.com/retrieve/pii/S1090513825001370. In this news roundup, we also talk about new clues about the collision that created our moon and a moss surviving the hardships of space.
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Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:00 Speaker 00 This message comes from Planet Visionaries. Host Alex Honnold sits down this season with extraordinary doers creating real climate solutions. Listen or watch wherever you get your podcasts. You're listening to Short Wave from NPR.
0:17 Speaker 01 Hey, Short Wavers. Regina Barber here.
0:18 Regina Barber? And Emily Kwong.
0:19 Speaker 01 With our biweekly Science News roundup, featuring the hosts of All Things Considered. And today, we are back with space case Scott Detrow.
0:27 Speaker 03 Listen, I like space, as you know, but I'm also a fan of apes making out. And that's, and that's why I'm here today. I heard that's a topic.
0:33 Speaker 01 Yes, we're going to pucker up to some weird research. We're also going to talk about space moss.
0:38 Regina Barber? Yes, and we are going to talk about another moon story, Scott, but this time it's ours and how it was made.
0:44 Speaker 03 You know, I think last time we talked about one of Jupiter's moons.
0:47 Speaker 01 Yeah.
0:47 Speaker 03 So I'm glad we're closer to home this week.
0:48 Speaker 01 Yeah, moon, moon.
0:49 Regina Barber? You know, bi-local.
0:50 Speaker 01 Get excited for all of that on this episode of Short Wave, the science podcast from NPR.
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2:22 Speaker 03 All right, we are back. And to start off, tell me about our ancestors making out with Neanderthals.
2:27 Regina Barber? It happened under some prehistoric mistletoe.
2:30 Speaker 03 How did science address this question? Like, I don't even know where to start with that.
2:34 Regina Barber? Yeah, so many animals kiss. So birds, fish, insects, especially primates. And by kissing, scientists define that as non-aggressive, mouth-to-mouth contact that does not involve passing food.
2:48 Speaker 03 That's an important aspect.
2:49 Regina Barber? And Matilda Brindle at the University of Oxford wanted to know, how far back in evolutionary history does this go?
2:56 Speaker 05 If you think about the fact that humans and our closest living relatives, chimpanzees and bonobos, all kiss, it makes sense that the common ancestor of those three species kisses as well.
3:07 Regina Barber? So tracking back through evolutionary time, Matilda's team found that kissing was present in the ancestor of all large apes 21 million years ago. And they published these results in the journal Evolution and Human Behavior.
3:19 Speaker 03 How do you even begin to see if somebody was kissing somebody 21 million years ago? Like, was there a fossilized mid-kiss? I don't know.
3:27 Regina Barber? That would be really cool, but no. This was all done through what's called phylogenetic analysis. Matilda and her colleagues basically treated kissing as a trait and mapped it onto like a tree of primates.
3:39 Speaker 01 Which they did by determining which primates kiss and which do not. So Matilda had to watch a lot of video footage of primates locking lips. And she compiled evidence of which of our primate cousins, canoodle, she built her family tree. And she discovered something else, which is that Neanderthals probably kissed too. And that is a big deal.
3:59 Speaker 03 Why did that matter?
4:00 Regina Barber? Well, most humans of non-African descent have a very small amount of Neanderthal DNA. And we know that Neanderthals and humans interbred after the two species split. And this kissing study gives us a little bit more insight into those relationships.
4:14 Speaker 05 Humans and Neanderthals were probably kissing each other, which is a way more romantic take on human-Neanderthal relationships than I think we might have thought of before.
4:24 Speaker 03 What a romantic image.
4:26 Speaker 01 I know.
4:27 Speaker 03 Equally romantic in my mind is moss spores in space.
4:29 Speaker 01 Right, yeah.
4:30 Speaker 03 How did this experiment come about?
4:32 Speaker 01 So, as humans contemplate long-term space travel, scientists want to know which plants may survive the extremes of space. Because space is cold, there is a lot of radiation, it's a vacuum. Scientists can simulate some of that on Earth. But to know how a plant will do in space, you got to put it there.
4:50 Speaker 03 And I assume that if you're going on a really long space travel at some point, you'd probably want some plants with you.
4:55 Speaker 01 Yeah, you want them for things like oxygen production, maybe to help terraform a planet, once that becomes possible. And for many people, aesthetics.
5:04 Speaker 03 Right, right, that's true. But why moss in particular?
5:07 Speaker 01 Well, because moss has some incredible survival strategies. Bryophytes, the group of plants that includes mosses, were the first plants to move from water to land.
5:17 Speaker 06 We believe moss colonized on land about 500 million years ago. So they can survive for a long such period. Even dinosaurs may be extinct, but still moss can survive.
5:31 Speaker 01 This is plant biologist Tomomiichi Fujita at Hokkaido University, who led the work. And he says land is a lot harsher than the ocean, with larger temperature fluctuations, higher risk of drying out, and more UV. In ground studies before the team sent moss to space, they found that moss spores, which were enclosed in this protective coating called a sporangium, did much better with exposure to extreme heat and cold, and importantly, to UV.
5:56 Speaker 03 So the moss spores passed the UV test on Earth. How did they do in space?
6:01 Speaker 01 They did shockingly well, says Magdalena Bezania, a cell biologist at Dartmouth, who is not involved in this work. Her lab just happens to study the same moss. I was really surprised. I mean, the spores just went out. They were just... Phenomenal. After nine months in space, more than 80% of these spores germinated once they were back on Earth. From this, scientists calculate the spores could go about 15 years in space conditions and still germinate. The team published their results in the journal iScience.
6:31 Speaker 03 So are we gonna, are we gonna terraform with them?
6:33 Speaker 01 Well, the paper points out that moss and other biophites can survive low light. They're great at making oxygen and fixing carbon, and they could be good at transforming other planets' surfaces into fertile soil. But the scientists have only shown that the spores can survive, you know? They haven't shown that the moss, the green fuzzy stuff that you see on Earth, can grow in space under this extreme radiation.
6:55 Speaker 03 Finally, we're gonna talk about a moon. This week, it's our moon, a close to home moon.
7:00 Speaker 01 Yes.
7:01 Speaker 03 Gina, I'm always pro moon stories. Tell me about this week's.
7:05 Speaker 01 Yes, Scott. Okay, right now, in the sky, there's a moon.
7:08 Speaker 03 True.
7:08 Speaker 01 Okay. And then in the beginning, when the solar system was forming, there was a proto-Earth and no moon.
7:13 Speaker 03 No moon.
7:14 Speaker 01 Then something maybe the size of Mars came and smashed into proto-Earth, and that debris from that giant crash made the moon. And the name of this, like, planet-smashing object was Theia. Now, a new paper in the journal Science is attempting to figure out what this object, Theia, was made out of and where in the solar system it came from. Here's how Kelsey Prizel put it. She's a geochemist from Purdue University who didn't work on this study.
7:39 Speaker 07 For me, this paper reads kind of like a planetary whodunit, where we're trying to figure out, how do we form the Earth-Moon system?
7:48 Speaker 03 All right, so where did Theia, the Earth-smasher? It's like a mythological phrase.
7:53 Speaker 01 It's like a Marvel villain.
7:54 Speaker 03 Yeah.
7:55 Speaker 01 Well, they looked at lunar samples brought back from NASA's Apollo missions and other meteorites from our solar system, and comparing those samples to rock samples from Earth. They found that Theia, the Earth-smasher, could have been born even closer to the Sun than Earth. So Theia was born in the inner solar system. Scott, the call is coming from inside the house, okay? And this also gives us a clue about maybe the origins of water on Earth.
8:21 Speaker 03 Water, how's that?
8:22 Speaker 01 If Theia had formed in the outer solar system, so past Jupiter, where it's colder, there's ice, some scientists thought that Theia could have delivered water to Earth during that collision. But with this study, we now know that Theia came from the inner solar system, which is drier, and that means that Theia was probably not the source of water on Earth.
8:41 Speaker 03 But now I'm curious, where did Earth's water come from?
8:44 Regina Barber? So I asked that to the lead author of the study. His name is Timo Hopp, and he's from the Max Planck Institute in Germany.
8:50 Speaker 08 They could not have brought a lot of water to the Earth. That means that water must have come from another type of material or process later or earlier, likely earlier.
8:59 Regina Barber? Now, water could have come from comets. It could have formed when the Earth did, though to truly solve the debate, we're just going to need to gather more space rocks. Because if they did indeed come from closer to the Sun, we would need samples from Venus or Mercury to prove it. But sadly, technology to withstand like the harsh surfaces of Mercury and Venus and actually travel there efficiently and back, our technology is just not totally there.
9:23 Speaker 03 Just seems like it's too hot.
9:25 Regina Barber? Yes, it is too hot.
9:26 Speaker 03 It's my scientific analysis.
9:28 Regina Barber? Right now. Scott, it is always super fun to have you.
9:32 Speaker 01 It's true.
9:33 Regina Barber? We love talking about space with you.
9:34 Speaker 01 Yep.
9:35 Speaker 03 Thanks. As long as you keep upping the weirdness of the stories each week.
9:38 Speaker 01 I try every time.
9:39 Regina Barber? We'll try.
9:39 Speaker 01 Yeah.
9:40 Speaker 03 Thank you both.
9:41 Speaker 01 Bye.
9:41 Regina Barber? Thank you. You can hear more of Scott Detrow on Consider This, NPR's afternoon podcast about what the news means for you. This episode was produced by Barilla McCoy and Kai McNamee. It was edited by Rebecca Ramirez and Christopher Intagliata.
9:54 Speaker 01 Tyler Jones checked the facts. Simon Laszlo Janssen and Damian Herring were the audio engineers. I'm Emily Kwong.
10:00 Regina Barber? And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.
10:09 Regina Barber? We have too much fun.
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