Short Wave

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

November 28, 2025

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  • Phylogenetic analysis suggests that kissing, defined as non-aggressive, mouth-to-mouth contact not involving food transfer, was present in the common ancestor of all apes 21 million years ago, and likely occurred between humans and Neanderthals. 
  • Moss spores demonstrated remarkable resilience, with over 80% germinating after nine months in space, suggesting they could survive up to 15 years in space conditions and potentially aid in future terraforming efforts. 
  • New analysis of lunar samples suggests the impactor that formed the Moon, Theia, originated in the inner solar system, implying it was likely not the source of Earth's water, which may have arrived from other sources earlier or later. 

Segments

Intro to Science News Roundup
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(00:00:21)
  • Key Takeaway: Regina Barber and Emily Kwong introduce Scott Detro for the science news roundup.
  • Summary: The hosts welcome Scott Detro and preview the topics: kissing research, space moss, and the moon’s formation.
Evolutionary History of Kissing
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(00:02:14)
  • Key Takeaway: Kissing, defined as non-aggressive mouth-to-mouth contact, dates back 21 million years to the common ancestor of large apes.
  • Summary: The discussion covers Matilda Brindle’s research using phylogenetic analysis to trace kissing behavior, including the finding that Neanderthals likely kissed.
Moss Spores Survive Space
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(00:04:18)
  • Key Takeaway: Moss spores survived nine months in space, with over 80% germinating upon return, suggesting long-term viability for space travel.
  • Summary: Scientists tested moss spores due to their historical survival strategies. The experiment, led by Tomomichi Fujita, showed high germination rates after exposure to space extremes.
Origin of Earth’s Moon
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(00:06:46)
  • Key Takeaway: New research suggests the impactor Theia originated in the inner solar system, making it an unlikely source of Earth’s water.
  • Summary: The segment details the Giant Impact Hypothesis, focusing on a new study published in Science that analyzed lunar samples to pinpoint Theia’s birthplace and its implications for Earth’s water origins.
Wrap-up and Credits
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(00:09:20)
  • Key Takeaway: The hosts thank Scott Detro and transition to credits and sponsor messages.
  • Summary: The hosts conclude their discussion, thank Scott Detro, and the segment moves through production credits and sponsor reads.