Nature Podcast Why insects aren't huge: a new challenge to a decades-old idea
9 snips
Mar 25, 2026 Justin Aikin, a UCSF researcher advancing in vivo CRISPR CAR‑T approaches, and Ned Snelling, a comparative physiologist probing insect respiratory limits. They discuss why insects do not grow huge, measurements of tracheole scaling, debates over air sacs and convection, and the implications for ancient versus modern insect sizes. They also cover in vivo CAR‑T engineering strategies and early mouse results.
AI Snips
Chapters
Transcript
Episode notes
Oxygen Dogma On Insect Size Is Being Challenged
- Insect respiratory limits via oxygen diffusion have long been blamed for small modern insect size.
- Snelling challenges this dogma by measuring tracheal structures and finding alternative explanations for past giant insects.
Locust Recovery Suggests Oxygen Supply Is Ample
- Rapid post-flight recovery in locusts suggested oxygen supply isn't a limiting factor for activity.
- Electron microscopy showed tracheoles occupy very little flight muscle despite high metabolic demand.
Tracheoles Scale Minimally Across Huge Size Range
- Tracheole volume in insect flight muscle increases with body size but remains extremely small across a 10,000-fold mass range.
- Measured values rose only from ~0.5% in tiny insects to ~0.8% in 5 g insects, undermining a diffusion limit argument.