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What happened to the giant bugs?

Unexplainable

Hosted by Noam Hassenfeld

27m
Transcript

Original podcast

Summary

Written by a model from the transcript; not yet reviewed.

The episode explores the prehistoric Carboniferous period, when Earth was dominated by giant insects like suitcase-sized dragonflies and two-meter-long millipedes, and investigates the long-standing mystery of why these massive bugs eventually died out. The guest and host examine the classic scientific hypothesis that higher atmospheric oxygen levels allowed ancient insects to grow so large, contrasting it with new experimental physiology research questioning whether oxygen availability actually limits insect body size. Listeners are guided through wind tunnel experiments on locusts, muscle dissections across dozens of insect species, and alternative theories involving predation by flying dinosaurs and climate change, revealing that insect biology remains surprisingly mysterious.

  • The Carboniferous period featured massive prehistoric insects, including carnivorous dragonflies with 70-centimeter wingspans and two-meter-long millipede-like bugs. 2:00
  • The traditional scientific explanation attributes giant prehistoric insect sizes to atmospheric oxygen levels reaching up to 35 percent. 5:02
  • Experimental physiologist Ned Snelling discovered that locusts recover from intense flight exercise immediately without showing signs of being winded. 14:15
  • Dissections of 44 different insect species revealed that a bug can be 10,000 times larger while requiring only a tiny fraction more oxygen tube space. 21:35

Chapters

  1. 0:01
    Sonos Promotion

    The host promotes Sonos, describing its sound system and app features.

  2. 0:36
    Google Gemini Sponsorship

    A brief ad for Google Gemini, highlighting its image recognition and AI capabilities.

  3. 1:21
    Carboniferous Overview

    The hosts explain the Carboniferous period, its timing, and its swampy, fern-filled environment.

  4. 2:42
    Giant Bugs of the Carboniferous

    Discussion of the massive dragonfly-like insects and millipede-like bugs that existed during this era.

  5. 4:36
    Oxygen Hypothesis Introduction

    The hypothesis that higher atmospheric oxygen allowed insects to grow larger is introduced.

  6. 5:21
    Ned Snelling’s Research

    Ned Snelling’s work on insect metabolism and oxygen delivery is described, challenging the oxygen hypothesis.

  7. 6:46
    Insect Respiratory System Explained

    Explanation of how insects breathe through spiracles and tracheal tubes, contrasting with human respiration.

  8. 8:35
    Oxygen Diffusion and Size Limits

    Exploration of how oxygen diffusion limits insect size and the debate over whether higher oxygen levels enabled giant bugs.

  9. 13:51
    Current Insect Decline Context

    Hosts connect past bug size trends to modern insect population declines and the need for further research.

  10. 18:42
    Scaling of Oxygen Tubes in Bugs

    Study of how oxygen tube space scales with bug size, revealing only modest increases for much larger insects.

  11. 24:30
    Alternative Explanations for Bug Decline

    Discussion of environmental changes, predation, and other factors that may have caused the disappearance of giant bugs.

  12. 27:39
    Closing and Credits

    The episode ends with acknowledgments, sponsor messages, and a call for listener feedback.

Highlights

Quotes

  • “So I want an amazing sound system. But I also want something that's easy. It just works.”
    Noam Hassenfeld · 0:05
  • “They think the Carboniferous was more like 30% to 35% oxygen.”
    Unnamed speaker · 5:02
  • “But if in this experiment, the insect had no issues getting oxygen to its cells, right?”
    Unnamed speaker · 16:57
  • “A bug could actually be 10,000 times bigger than another bug and only need sort of a tiny bit more oxygen tube space in its flight muscles.”
    Unnamed speaker · 22:22
  • Sonos 0:12–0:30
  • Google Gemini 0:36–1:07
  • Sonos 11:54–12:21

About this episode

Once upon a time (around 300 million years ago), Earth was home to massive dragonfly-like insects and two meter long millipede-like creatures. Why did they die off? Guests: Ned Snelling, professor of experimental physiology at the University of Pretoria; Jon Harrison, professor of environmental physiology at Arizona State University For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠ ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠ ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠And please email us! ⁠⁠⁠⁠[email protected]⁠⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠ Learn more about your ad choices. Visit podcastchoices.com/adchoices

Transcript

0:00
27:15

4,423 words · 10 speakers

Speaker names marked are inferred from speaking time and the show’s known hosts — they are not voice-verified.

Topics

  • Carboniferous
  • Permian
  • University of Pretoria
  • Mesozoic Era
  • Valentino Beauty
  • Anthropic

Page updated · transcript and summary are machine-generated