I’m thinking of Lynn Margulis today, a brilliant pugnacious scientist who made one of the most important discoveries in biology, endosymbiosis, but did not receive her due. She also lived in her first husband Carl Sagan’s shadow although her work was more important.

Margulis discovered that mitochondria and chloroplasts evolved by the chance ingestion of blue-green algae and oxygen-consuming bacteria as symbiotic parasites. This explained the proliferation of multicellular life and it’s wonderful diversity.

Ultimately Margulis exemplified science at its best - she was a heretic, she stuck to her thesis tenaciously and weathered copious criticism (one proposal said, "Your research is crap, don't bother applying again") and her contributions are seminal. So why isn't she better known?

Several reasons: Her gender certainly played a role and she didn't fit traditional gender roles. But later she also became known for pushing fringe theories like HIV and syphilis having a common origin and supporting 9/11 "truthers". That didn't help her cause.

Margulis's marriage to Sagan was difficult and they divorced after eight years. Although she had her own flaws, her take on Sagan's self-important personality reveal his flaws like nothing I have read. Sagan was a great science communicator; she a great scientist.

Margulis faced widespread criticism, and her classic 1967 paper was rejected by 15 journals before finally appearing in the Journal of Theoretical Biology. The 56-page article remains eminently readable today and IMO is one of the most important papers of 20th century biology.

In some ways she reminds me of Fred Hoyle who made groundbreaking contributions to science but became infamous for supporting the steady state theory and panspermia. Both Margulis and Hoyle were undoubtedly brilliant, but perhaps at a disadvantage because of too much brilliance.