Thomas N. Margulis, a crystallographer. They had a son named Zachary Margulis-Ohnuma, a New York City criminal defense lawyer, and a daughter Jennifer Margulis, teacher and author. They divorced in 1980. She commented, "I quit my job as a wife twice," and, "it's not humanly possible to be a good wife, a good mother, and a first-class scientist. No one can do it — something has to go." In the 2000s she had a relationship with fellow biologist Ricardo Guerrero. Her sister Joan Alexander married Nobel Laureate Sheldon Glashow; another sister, Sharon, married mathematician Daniel Kleitman. She was a religious agnostic, and a staunch evolutionist, but rejected the modern evolutionary synthesis, and said: "I remember waking up one day with an epiphanous revelation: I am not a neo-Darwinist! I recalled an earlier experience, when I realized that I wasn't a humanistic Jew. Although I greatly admire Darwin's contributions and agree with most of his theoretical analysis and I am a Darwinist, I am not a neo-Darwinist." She argued that "Natural selection eliminates and maybe maintains, but it doesn't create", and maintained that symbiosis was the major driver of evolutionary change. In 2013, Margulis was listed as having been a member of the Advisory Council of the National Center for Science Education. Margulis died on 22 November 2011 at home in Amherst, Massachusetts, five days after suffering a hemorrhagic stroke. As her wish, she was cremated and her ashes were scattered in her favorite research areas, near her home. Contributions Endosymbiosis theory In 1966, as a young faculty member at Boston University, Margulis wrote a theoretical paper titled "On the Origin of Mitosing Cells". The paper, however, was "rejected by about fifteen scientific journals," she recalled. It was finally accepted by Journal of Theoretical Biology and is considered today a landmark in modern endosymbiotic theory. Weathering constant criticism of her ideas for decades, Margulis was famous for her tenacity in pushing her theory forward, despite the opposition she faced at the time. The descent of mitochondria from bacteria and of chloroplasts from cyanobacteria was experimentally demonstrated in 1978 by Robert Schwartz and Margaret Dayhoff. This formed the first experimental evidence for the symbiogenesis theory. The endosymbiosis theory of organogenesis became widely accepted in the early 1980s, after the genetic material of mitochondria and chloroplasts had been found to be significantly different from that of the symbiont's nuclear DNA. In 1995, English