Lynn Margulis

5 March 1938, Chicago, Illinois, United States – 22 November 2011, Amherst, Massachusetts, United States (aged 73)

American biologist who showed that complex cells arose from the merger of simpler organisms (endosymbiosis), and who developed the Gaia hypothesis with James Lovelock.

Life

Margulis entered the University of Chicago at fifteen. There she met Carl Sagan, whom she married in 1957; their son Dorion Sagan later became her frequent co-author. She studied genetics and zoology in Wisconsin and took her PhD at Berkeley, then spent more than twenty years at Boston University before moving to the University of Massachusetts Amherst. She died at home in Amherst after a stroke.

Influences

Early twentieth-century biologists such as Konstantin Mereschkowski in Russia and Ivan Wallin in the United States had proposed that parts of cells were once free-living bacteria, but the idea had been dismissed. Margulis revived it with modern evidence. Her collaboration with James Lovelock from the early 1970s connected her microbial view of life to the planet as a whole.

Contributions

Her 1967 paper “On the Origin of Mitosing Cells” (published as Lynn Sagan) argued that mitochondria and chloroplasts descend from bacteria taken in by other cells. It was rejected by around fifteen journals before publication, and confirmed by genetic evidence over the following decade. It is now textbook biology. She argued more broadly for symbiogenesis, the creation of new organisms through long-term symbiosis, as a major source of evolutionary novelty.

With Lovelock she developed the Gaia hypothesis, contributing the knowledge of how microorganisms regulate the atmosphere and ocean chemistry. She rejected descriptions of Gaia as an organism or a goddess, describing it as an emergent property of interacting ecosystems. She also drew on Maturana and Varela’s autopoiesis to describe what makes cells, and the biosphere, self-maintaining.

Why it matters today

Margulis’s picture of life as networks of cooperation and merger, rather than only competition, has shaped microbiome research and Earth system science. Her view of Gaia as a planetary system of feedback loops is a reference point for climate science and for discussions of planetary boundaries.

Further reading

  • Lynn Margulis, Symbiotic Planet (1998)
  • Lynn Margulis and Dorion Sagan, Microcosmos (1986) and What Is Life? (1995)

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