An icebreaker
A biologist argued that mitochondria and chloroplasts, the parts that power and feed a cell, began as separate free-living bacteria swallowed billions of years ago. Dismissed for years as fringe, the idea was later confirmed by genetic evidence.
She argued in a 1967 paper, rejected by roughly fifteen journals before publication, that mitochondria and chloroplasts began as free-living bacteria absorbed by early cells. She later extended the same logic to claim that whip-like cell tails also had a bacterial origin, a claim that did not hold up.
In 1905 he proposed that the chloroplasts in plant cells began as free-living cyanobacteria taken into a larger cell, and a few years later coined the word symbiogenesis. His idea was largely forgotten for decades before it was revived and tested.
In the 1920s he argued mitochondria arose from symbiotic bacteria living inside cells, publishing his case in a 1927 book. His claims were dismissed as contamination by his peers, and his work was largely forgotten for decades.
In the 1970s he argued that mitochondria and the nucleus grew from within a single cell rather than by merger. Within a decade he had come round, and built much of his later work on endosymbiosis — while still rejecting her claim that cell tails came from bacteria.
In the mid-1970s he and colleagues compared genetic sequences from chloroplasts and free-living cyanobacteria using a new sequencing method, and found them closely related. That molecular evidence turned a disputed idea into an accepted one.