The Idea That Was Rejected Fifteen Times

In 1967, Lynn Margulis argued that the mitochondria in our cells were once free-living bacteria, and about fifteen journals turned her paper down. 🦠

The clues were real: mitochondria are bacteria-sized, divide by splitting, and carry their own ring of DNA, and her idea is now in every biology textbook.

3D models are simplified illustrations and may not be exact. "Human Cell" by Shihab, "Mitochondria" by CAPTAAINRO and "Bacterium" by andrewfrueh (Sketchfab, CC BY 4.0). Sources: Sagan (Margulis) 1967, Journal of Theoretical Biology.