What’s In A Kiss? 21 Million Years Of Evolution

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. Interested in stories about human evolution? Email us your question at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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  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.

• 0:17Speaker 01

  Hey, Short Wavers. Regina Barber here.

• 0:18Regina Barber?

  And Emily Kwong.

• 0:19Speaker 01

  With our biweekly Science News roundup, featuring the hosts of All Things Considered. And today, we are back with space case Scott Detrow.

• 0:27Speaker 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.

• 0:33Speaker 01

  Yes, we're going to pucker up to some weird research. We're also going to talk about space moss.

• 0:38Regina Barber?

  Yes, and we are going to talk about another moon story, Scott, but this time it's ours and how it was made.

• 0:44Speaker 03

  You know, I think last time we talked about one of Jupiter's moons.

• 0:47Speaker 01

  Yeah.

• 0:47Speaker 03

  So I'm glad we're closer to home this week.

• 0:48Speaker 01

  Yeah, moon, moon.

• 0:49Regina Barber?

  You know, bi-local.

• 0:50Speaker 01

  Get excited for all of that on this episode of Short Wave, the science podcast from NPR.

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  This message comes from Planet Visionaries. If you're looking for a dose of optimism, Planet Visionaries is the podcast you need. Host Alex Honnold sits down this season with extraordinary doers creating real climate action. It's a lineup that proves hope isn't naive, it's fuel for change. In partnership with the Rolex Perpetual Planet Initiative, this is Planet Visionaries. Listen or watch wherever you get your podcasts.

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• 2:22Speaker 03

  All right, we are back. And to start off, tell me about our ancestors making out with Neanderthals.

• 2:27Regina Barber?

  It happened under some prehistoric mistletoe.

• 2:30Speaker 03

  How did science address this question? Like, I don't even know where to start with that.

• 2:34Regina 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.

• 2:48Speaker 03

  That's an important aspect.

• 2:49Regina Barber?

  And Matilda Brindle at the University of Oxford wanted to know, how far back in evolutionary history does this go?

• 2:56Speaker 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.

• 3:07Regina 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.

• 3:19Speaker 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.

• 3:27Regina 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.

• 3:39Speaker 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.

• 3:59Speaker 03

  Why did that matter?

• 4:00Regina 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.

• 4:14Speaker 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.

• 4:24Speaker 03

  What a romantic image.

• 4:26Speaker 01

  I know.

• 4:27Speaker 03

  Equally romantic in my mind is moss spores in space.

• 4:29Speaker 01

  Right, yeah.

• 4:30Speaker 03

  How did this experiment come about?

• 4:32Speaker 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.

• 4:50Speaker 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.

• 4:55Speaker 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.

• 5:04Speaker 03

  Right, right, that's true. But why moss in particular?

• 5:07Speaker 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.

• 5:17Speaker 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.

• 5:31Speaker 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.

• 5:56Speaker 03

  So the moss spores passed the UV test on Earth. How did they do in space?

• 6:01Speaker 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.

• 6:31Speaker 03

  So are we gonna, are we gonna terraform with them?

• 6:33Speaker 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.

• 6:55Speaker 03

  Finally, we're gonna talk about a moon. This week, it's our moon, a close to home moon.

• 7:00Speaker 01

  Yes.

• 7:01Speaker 03

  Gina, I'm always pro moon stories. Tell me about this week's.

• 7:05Speaker 01

  Yes, Scott. Okay, right now, in the sky, there's a moon.

• 7:08Speaker 03

  True.

• 7:08Speaker 01

  Okay. And then in the beginning, when the solar system was forming, there was a proto-Earth and no moon.

• 7:13Speaker 03

  No moon.

• 7:14Speaker 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.

• 7:39Speaker 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?

• 7:48Speaker 03

  All right, so where did Theia, the Earth-smasher? It's like a mythological phrase.

• 7:53Speaker 01

  It's like a Marvel villain.

• 7:54Speaker 03

  Yeah.

• 7:55Speaker 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.

• 8:21Speaker 03

  Water, how's that?

• 8:22Speaker 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.

• 8:41Speaker 03

  But now I'm curious, where did Earth's water come from?

• 8:44Regina 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.

• 8:50Speaker 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.

• 8:59Regina 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.

• 9:23Speaker 03

  Just seems like it's too hot.

• 9:25Regina Barber?

  Yes, it is too hot.

• 9:26Speaker 03

  It's my scientific analysis.

• 9:28Regina Barber?

  Right now. Scott, it is always super fun to have you.

• 9:32Speaker 01

  It's true.

• 9:33Regina Barber?

  We love talking about space with you.

• 9:34Speaker 01

  Yep.

• 9:35Speaker 03

  Thanks. As long as you keep upping the weirdness of the stories each week.

• 9:38Speaker 01

  I try every time.

• 9:39Regina Barber?

  We'll try.

• 9:39Speaker 01

  Yeah.

• 9:40Speaker 03

  Thank you both.

• 9:41Speaker 01

  Bye.

• 9:41Regina 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.

• 9:54Speaker 01

  Tyler Jones checked the facts. Simon Laszlo Janssen and Damian Herring were the audio engineers. I'm Emily Kwong.

• 10:00Regina Barber?

  And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.

• 10:09Regina Barber?

  We have too much fun.

• 10:11Speaker 04

  Stay tuned for the following announcements and messages from our sponsors.