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

Summary

---

Short Wave – “What’s In A Kiss? 21 Million Years Of Evolution”

Podcast: Short Wave (NPR)
Hosts: Emily Kwong, Regina Barber (with Scott Detrow)
Date: November 28, 2025
Episode Length: ~10 minutes (excluding ads & credits)

Episode Overview

This episode of Short Wave dives into recent scientific discoveries spanning the origins of kissing in primates—including humans and Neanderthals—moss spores’ resilience in space, and the cosmic mystery of the Moon’s creation. Using their signature lighthearted tone, the hosts unpack truly ancient evolutionary histories, the science of astrobotany, and planetary detective work—with bursts of humor and palpable curiosity.

---

1. The Ancient Origins of Kissing

(Begins ~02:15)

Key Points:

• The episode opens with the quirky question: “How far back in evolutionary history does kissing go?”
• "Kissing" here means non-aggressive, mouth-to-mouth contact that isn’t about sharing food, but more about intimacy (02:33, Emily Kwong).
• Research led by Matilda Brindle (University of Oxford) mapped the trait of kissing across the evolutionary tree of primates (02:37, Regina Barber).
• Phylogenetic analysis suggests the ancestor of all large apes—21 million years ago—engaged in kissing (03:00, Regina Barber).
• Neanderthals likely kissed too. Since non-African humans have some Neanderthal DNA, this paints a new, more romantic picture of human–Neanderthal relations (03:33, Emily Kwong).

Notable Quotes:

• Emily Kwong (02:33):
  “And by kissing, scientists define that as non-aggressive mouth-to-mouth contact that does not involve passing food—that’s an important aspect.”
• Regina Barber (03:00):
  “Matilda’s team found that kissing was present in the ancestor of all large apes 21 million years ago.”
• Emily Kwong (04:08):
  “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.”

Memorable Moment:

• Scott Detrow jokes about prehistoric mistletoe and fossilized mid-kiss (02:20–03:12).

---

2. Space Moss: Life’s Survivors Aboard the ISS

(Begins ~04:20)

Key Points:

• Scientists are testing what plants can survive ‘the extremes’ of space to support possible long-term space travel (04:26, Emily Kwong).
• Moss (a bryophyte) was chosen because of its ancient adaptations for tough, fluctuating environments.
• Tomomichi Fujita (Hokkaido University) explains moss has outlasted even dinosaurs, colonizing land ~500 million years ago (05:10, Scott Detrow; 05:25, Emily Kwong).
• On Earth, moss spores inside “sporangia” are especially hardy, capable of surviving intense UV, heat, and cold (05:37, Regina Barber).
• Space experiment: After 9 months on the ISS, more than 80% of the moss spores germinated on return to Earth, suggesting viability for up to 15 years in space (05:54, Emily Kwong).
• Implication: Mosses could one day help terraform planets or support oxygen production on long journeys, though actual moss “growth” in space still needs to be tested (06:27–06:48).

Notable Quotes:

• Tomomichi Fujita (as quoted by Scott Detrow, 05:10):
  “We believe moss colonized on land about 500 million years ago. So they can survive for a long such period. Even dinosaur may be extinct, but still moss can survive.”
• Magdalena Bezania (cell biologist, commenting on results, 05:54):
  “I was really surprised. I mean, the spores just went out. They were just phenomenal.”

Memorable Moments:

• Regina Barber emphasizes the “aesthetics” of bringing plants on space voyages, not just for science (04:48).

---

3. Mystery of the Moon’s Origins: Meet Theia

(Begins ~06:48)

Key Points:

• The ancient story: After proto-Earth formed, a Mars-sized object dubbed Theia collided with it, resulting in debris that formed the Moon (07:07, Regina Barber).
• A new study (journal Science) analyzed lunar samples from Apollo missions and meteorites to trace Theia’s origins (07:19, Emily Kwong).
• Purdue geochemist Kelsey Preizl calls the study “a planetary whodunit” aimed at figuring out where Theia came from (07:37).
• The results: Theia likely originated closer to the Sun than Earth, in the inner solar system (07:48, Emily Kwong).
• This challenges the idea that Earth’s water was delivered by Theia (08:16, Regina Barber). If Theia came from a dryer, inner region, it probably didn’t carry much water.
• The study leaves open the big question: Where did Earth’s water come from? Potential answers include comets or earlier processes during Earth’s formation (08:52, Emily Kwong).

Notable Quotes:

• Regina Barber (07:07):
  “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.”
• Kelsey Preizl (Purdue geochemist, paraphrased, 07:37):
  “This paper reads kind of like a planetary whodunit.”
• Regina Barber (08:07):
  “Scott, the call is coming from inside the house.”
• Timo Hopp (lead author, 08:43, paraphrased):
  If Theia didn’t bring the water, it “must have come from another type of material or process later or earlier—likely earlier.”

Memorable Moment:

• Scott Detrow and team joke about planetary hits and Theia as a Marvel villain (07:47).
• Regina highlighting the technical challenge of bringing back rock samples from Mercury or Venus:
  “Sadly, technology to withstand… the harsh surfaces of Mercury and Venus and actually travel there efficiently and back, our technology is just not totally there.” (09:06)

---

4. Banter and Closing Science Notes

(Throughout, e.g. 09:17)

• Scott delights in the episode’s “upping the weirdness”—the hosts agree to keep it coming.
• Playful, conversational wrap-up.

---

Timestamps for Key Segments

| Segment | Start Time | |-----------------------------------|------------| | Kissing Evolution | 02:15 | | Space Moss | 04:20 | | Moon & Theia Mystery | 06:48 | | Scientific Banter & Wrap | 09:17 |

---

Tone & Style

• Fun, informal, accessible even on complex topics.
• Regular humor: “apes making out,” “proto-Earth,” “planetary whodunit.”
• Affectionate teasing and pop-culture references (Marvel villains, mistletoe).

---

Summary Takeaways

• Kissing is a deep evolutionary trait, possibly 21 million years old, found in all great apes—including Neanderthals and, by extension, us.
• Moss spores can survive the gauntlet of space for years, hinting at their utility for future space colonization.
• The Moon-creating impactor, Theia, likely came from the inner solar system, making it an unlikely source for Earth’s water—a mystery still in search of an answer.

---

Notable Quote to Close (Emily Kwong, 04:08):

“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.”

---

Transcript

[Sponsor/Advertiser]

This message comes from US bank simplify how you do business with business essentials, a powerful combination of no monthly maintenance fee checking and card payment processing. Deposit products are offered by U.S. bank National association member FDIC.

[Emily Kwong]

You're listening to Short Wave from NPR.

[Regina Barber]

Hey, shortwavers, Regina Barber here and Emily Kwong with our biweekly science news roundup featuring the hosts of All Things Considered. And today we are back with special space case, Scott Detrow.

[Scott Detrow]

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.

[Emily Kwong]

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

[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.

[Scott Detrow]

You know, I think last time we talked about one of Jupiter's moons. So I'm glad we're closer to home this week.

[Regina Barber]

Yeah, moon, moon, you know, buy local.

[Emily Kwong]

Get excited for all of that on this episode of Shortwave, the science podcast from npr.

[Sponsor/Advertiser]

This message comes from Dell Technologies. It's time for Black Friday at Dell Technologies. Save big on PCs like the Dell 16 plus featuring Intel Core Ultra processors. Shop now at Dell.com deals. This message comes from BetterHelp. Most FSA dollars expire at the end of the year, so it's time to use em or lose em. With BetterHelp, you can invest those funds in taking care of your mind with online therapy. Join today and you can be matched with a licensed therapist in as little as 24 hours. Visit betterhelp.com NPR to get 10% off your first month support for this podcast and the following message come from Recorded Future. Every day, millions of cyber threats compete for attention, but only a few truly matter to your business as a leading threat intelligence company. Recorded Future cuts through the noise with precision intelligence. That's why top banks and governments trust them, because security leaders don't just react, they foresee, spotting the signals that others miss and acting before threats become setbacks. Recorded Future Know what matters. Act first.

[Scott Detrow]

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

[Emily Kwong]

It happened under some prehistoric mistletoe.

[Scott Detrow]

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

[Regina Barber]

Yeah, so many animals kiss. So birds, fish, insects, especially primates.

[Emily Kwong]

And by kissing, scientists define that as non aggressive mouth to mouth contact that does not involve passing food that's an important aspect. And Matilda Brindle at the University of Oxford wanted to know, how far back in evolutionary history does this go? 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.

[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.

[Scott Detrow]

How do you even begin to see if somebody was kissing somebody 21 million years ago? Like, like, was there a fossilized mid kiss? I don't know.

[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, which they.

[Emily Kwong]

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. 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.

[Scott Detrow]

Why does that matter?

[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.

[Emily Kwong]

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.

[Scott Detrow]

What a romantic image.

[Regina Barber]

I know.

[Scott Detrow]

Equally romantic in my mind is moss spores in space.

[Regina Barber]

Right? Yeah.

[Scott Detrow]

How did this experiment come about?

[Emily Kwong]

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.

[Scott Detrow]

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.

[Regina Barber]

Yeah. You want them for things like oxygen production, maybe to help terraform a planet once that becomes possible. And for many people, aesthetics.

[Scott Detrow]

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

[Regina Barber]

Well, because moss has some, like, incredible survival strategies. Bryophytes, the group of plants that includes mosses, were the first plants to move from water to land.

[Scott Detrow]

We believe moss colonized on land about 500 million years ago. So they can survive for a long such period. Even dinosaur may be extinct, but still moss can survive.

[Emily Kwong]

This is plant biologist Tomomichi Fujita at Hokkairu 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.

[Regina Barber]

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.

[Scott Detrow]

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

[Emily Kwong]

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 MO. 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 Eye Science.

[Scott Detrow]

So are we going to terraform with them?

[Regina Barber]

Well, the paper points out that moss and other biophytes 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.

[Emily Kwong]

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.

[Scott Detrow]

Finally, we're gonna talk about a moon. This week. It's our moon. A close to home moon. Yes, Gina, I'm always pro moon stories. Tell me about this week's.

[Regina Barber]

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

[Scott Detrow]

True.

[Regina Barber]

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

[Scott Detrow]

No moon.

[Regina Barber]

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.

[Emily Kwong]

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 Preizl put it. She's a geochemist from Purdue University who didn't work on this study. For me, this paper reads kind of like a planetary whodunit, where we're trying.

[Scott Detrow]

To figure out how do we form.

[Emily Kwong]

The Earth moon system.

[Scott Detrow]

All right, so where Did Theia, the Earth Smasher, it's like a mythological phrase.

[Regina Barber]

It's like a Marvel villain.

[Scott Detrow]

Yeah.

[Emily Kwong]

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 Ear. So Theia was born in the inner solar system.

[Regina Barber]

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.

[Scott Detrow]

Water? How so?

[Regina Barber]

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.

[Scott Detrow]

But now I'm curious. Where did Earth's water come from?

[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.

[Scott Detrow]

Say I could not have brought a lot of water to the Earth. That means the water must have come from another type of material or process later or earlier. Likely earlier.

[Emily Kwong]

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 Theia did indeed come from closer to the sun, we would need samples from Venus or Mercury to prove it.

[Regina Barber]

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.

[Scott Detrow]

Just seems like it's too hot.

[Regina Barber]

Yes, it is too hot.

[Scott Detrow]

That's my scientific analysis right now.

[Regina Barber]

Scott, it is always super fun to have you. We love talking about space with you.

[Emily Kwong]

Yep.

[Scott Detrow]

Thanks. As long as you keep upping the weirdness of the stories each week, I'll be right.

[Emily Kwong]

I try every time.

[Regina Barber]

We'll try.

[Emily Kwong]

Yeah.

[Scott Detrow]

Thank you both.

[Sponsor/Advertiser]

Thank you.

[Regina Barber]

You can hear more of Scott Detrow on consider this NPR's afternoon podcast about what the news means for your. This episode was Produced by Burly McCoy and Kai McNamee. It was edited by Rebecca Ramirez and Christopher Intagliota.

[Emily Kwong]

Tyler Jones checked the facts. Zimon, Laszlo Janssen and Damien Herring were the audio engineers. Hi, I'm Emily Kwong.

[Regina Barber]

And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from npr. We have too much fun this message.

[Sponsor/Advertiser]

Comes from Capital One. With the Capital One Savor card, earn unlimited 3% cash back on dining and entertainment. Capital One. What's in your wallet? Terms apply [e-mail] this message comes from Mint Mobile. At Mint Mobile, their favorite word is no. No contracts, no monthly bills, no hidden fees. Plans start at $15 a month. Make the [e-mail] Switch that's mintmobile.com Switch Upfront payment of $45 for 3 month 5GB plan required equivalent to $15 a month New customer offer for first 3 months only, then full price plan options available, taxes and fees extra. See Mint Mobile for details. This message comes from NPR sponsor Capella University. With Capella's flexpath Learning format, you can set your own deadlines and learn on your schedule. A different future is closer than you think with Capella University. Learn more at Capella. Eduardo.