Lynn Margulis, a preeminent figure in modern biology, died suddenly at the age of 73. She was a good and an old friend of mine. When we were both living in Newton, Massachusetts, our spouses wanted nothing better than for us to take the kids out of the house on Sunday mornings. So, we went on countless walks together, the little ones running ahead of us. We talked about lots of topics, most of which I have forgotten. Now, I would dearly love to recall what they were. We have been friends ever since.
Her major contribution, as is widely known, was of cause the endosymbiotic theory of the origin of eukaryotic cells to become accepted as a central tenet in Biology. Although this idea had been proposed earlier, it laid fallow as a neglected and nearly forgotten notion that had little impact. Lynn broke through all the barriers explosively. I have mused about when this revolution would have happened had she not done this. Surely, in time, perhaps 10 or 20 years later, the bacteria-like properties of mitochondria and plastids would have compelled its acceptance. The clincher, of course, would have been the indisputable genomic homology between mitochondria and rickettsiae, and likewise between plastids and cyanobacteria.
What makes it hard to write about Lynn is not only the personal loss I feel. In addition to praising her, I feel obligated to point out that she repeatedly proclaimed views that were not only unorthodox but that seemed indefensible. As one example, she believed that AIDS is caused not by HIV but by some spirochete. Through the years, I've tried to explain this strange devotion to untenable beliefs. Was this the same tenacity that enabled her to fight the endosymbiotic theory battle so successfully? She was one of the most intelligent people I have ever known and therefore I cannot readily dismiss my puzzlement.
She was also one of the best informed biologists going. Her font of knowledge, especially of the protists (which, characteristically, she insisted in calling the Protoctista), was astounding. She knew the old 19th century literature inside and out, including hard-to-find Russian papers. This knowledge she put to use in the numerous books she wrote, some together with her son, Dorion Sagan. Most of these are well worth reading.
I cannot think of anyone more stimulating, more bewildering, more exasperating than Lynn. But, to me, what really matters is that she was a most caring person and a devoted friend. I will miss her.