Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American biologist best known for her scientific theory on the origin of complex cells, called symbiogenesis. She obtained a bachelor degree from the University of Chicago at age 19, and married Carl Sagan, then a physics student. She graduated with master's degree in genetics and zoology from the University of Chicago at age 22. While working for a PhD at the University of California, Berkeley, she landed an appointment as lecturer at Brandeis University, where she worked during 1964-1966. She received her PhD in 1965. She joined the faculty of Boston University in 1966. In 1988 she became Distinguished Professor of Botany, and in 1997, Distinguished Professor of Geosciences at the University of Massachusetts at Amherst.
Margulis conceived her theory on endosymbiosis when she was a junior faculty at Boston University. Her landmark publication, "On the Origin of Mitosing Cells" came out in 1967, after it was rejected by about fifteen journals. Ignored for a decade, her theory that cell organelles such as mitochondria and chloroplasts were once independent bacteria became widely accepted after it was substantiated by genetic evidences. She expanded her idea that symbiosis is one of the major driving forces of evolution. Her theory also made her a proponent of Gaia hypothesis, based on an idea developed by the English environmental scientist James Lovelock. She was also the principal defender of the five kingdom classification of Robert Whittaker.
Variously branded as "Science's Unruly Earth Mother", a "vindicated heretic", or a scientific "rebel", Margulis was a strong critic of Charles Darwin's gradual selection theory and modern evolutionary theory. She explicitly stated that she was a Darwinist, but not a neo-Darwinist, a position that sparked a lifelong debate with leading Darwinian biologists, including Richard Dawkins, George C. Williams, and John Maynard Smith.
Margulis was member of the US National Academy of Sciences from 1983. For her scientific innovations, President Bill Clinton presented her the National Medal of Science in 1999. The Linnean Society of London awarded her the Darwin-Wallace Medal in 2008.
http://en.wikipedia.org/wiki/Lynn_Margulis
