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.”