Sep 23, 2026 · 30 min
Giant insects expose the limits of the oxygen theory
What happened to the giant bugs?
The mystery of prehistoric insect gigantism reveals how much remains unknown about both ancient ecosystems and today’s insect declines.
- 1High Carboniferous oxygen may have enabled giant insects, but new physiology experiments weaken a simple oxygen-size explanation.
- 2Locust flight experiments suggest insects can deliver oxygen efficiently, even during intense activity and recovery.
- 3Climate, dryness, ecological competition, and biological constraints may explain the giants’ disappearance—and illuminate modern insect losses.
Don't miss
Ned Snelling’s locust flight-chamber experiments show insects recovering from intense flight immediately, challenging assumptions about oxygen delivery.
The brief
The Carboniferous was a swampy, pre-dinosaur world where dragonfly-like insects and millipede-like creatures reached extraordinary sizes. Their disappearance remains the central mystery.
The classic explanation points to unusually high atmospheric oxygen, but Ned Snelling’s research examines whether insect bodies actually struggle to deliver oxygen to their tissues.
In locust flight-chamber experiments, Snelling finds that insects recover from intense flight immediately, suggesting their oxygen-delivery systems may be more efficient than expected.
Across 44 insect species, larger bodies require only slightly more oxygen-tube space in their flight muscles, weakening oxygen as a complete explanation for giant size.
Climate change, heat, dryness, ecological competition, and the rarity of large animals may all have contributed to the giants’ decline, with lessons for modern insect losses.
Featuring
Carboniferous
University of Pretoria
NatureListen to the full episode and explore every guest, topic, and moment on PodLume.