Lynn Margulis, who developed the endosymbiotic theory for the origins of some cellular organelles, has died, according to a note on the Web page of the University of Massachusetts, Amherst's geosciences department where she was a professor. Margulis was 73. She was also known for her contributions to James Lovelock's Gaia hypothesis that the living and non-living components of the Earth together comprise a self-regulating system. "She was smart, creative, and promoter of a lot of wild ideas … and to her credit, some of them were even right," writes PZ Myers at Pharyngula. "I think her greatest strength was her eagerness to step right out to the edge of science and push, push, push — sometimes futilely, but sometimes she really did succeed in pushing back the frontier a bit."