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Lynn Margulis
Lynn Margulis.jpg
Margulis in 2005
Lynn Petra Alexander

(1938-03-05)March 5, 1938
Died November 22, 2011(2011-11-22) (aged 73)
Nationality American
Alma mater
Known for
  • (m. 1957; div. 1965)
  • Thomas Margulis
    (m. 1967; div. 1980)
  • Dorion Sagan
  • Jeremy Sagan
  • Zachary Margulis-Ohnuma
  • Jennifer Margulis
Scientific career
Fields Biology
Thesis An Unusual Pattern of Thymidine Incorporation in Euglena (1965)
Doctoral advisor Max Alfert
Influences Ivan Wallin, Konstantin Mereschkowski

Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American evolutionary biologist, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Margulis's name is as synonymous with symbiosis as Charles Darwin's is with evolution." In particular, Margulis transformed and fundamentally framed current understanding of the evolution of cells with nuclei – an event Ernst Mayr called "perhaps the most important and dramatic event in the history of life" – by proposing it to have been the result of symbiotic mergers of bacteria. Margulis was also the co-developer of the Gaia hypothesis with the British chemist James Lovelock, proposing that the Earth functions as a single self-regulating system, and was the principal defender and promulgator of the five kingdom classification of Robert Whittaker.

Throughout her career, Margulis' work could arouse intense objection. Her formative paper, "On the Origin of Mitosing Cells", appeared in 1967 after being rejected by about fifteen journals. Still a junior faculty member at Boston University at the time, her theory that cell organelles such as mitochondria and chloroplasts were once independent bacteria was largely ignored for another decade, becoming widely accepted only after it was powerfully substantiated through genetic evidence. Margulis was elected a member of the US National Academy of Sciences in 1983. 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.

Margulis was a strong critic of neo-Darwinism. Her position sparked lifelong debate with leading neo-Darwinian biologists, including Richard Dawkins, George C. Williams, and John Maynard Smith. Margulis' work on symbiosis and her endosymbiotic theory had important predecessors, going back to the mid-19th century – notably Andreas Franz Wilhelm Schimper, Konstantin Mereschkowski, Boris Kozo-Polyansky, and Ivan Wallin – and Margulis, not only promoted greater recognition for their contributions, but personally oversaw the first English translation of Kozo-Polyansky's Symbiogenesis: A New Principle of Evolution, which appeared the year before her death. Many of her major works, particularly those intended for a general readership, were collaboratively written with her son Dorion Sagan.

In 2002, Discover magazine recognized Margulis as one of the 50 most important women in science.


Lynn Margulis was born in Chicago, to a Jewish, Zionist family. Her parents were Morris Alexander and Leona Wise Alexander. She was the eldest of four daughters. Her father was an attorney who also ran a company that made road paints. Her mother operated a travel agency. She entered the Hyde Park Academy High School in 1952, describing herself as a bad student who frequently had to stand in the corner.

A precocious child, she was accepted at the University of Chicago Laboratory Schools at the age of fifteen. In 1957, at age 19, she earned a BA from the University of Chicago in Liberal Arts. She joined the University of Wisconsin to study biology under Hans Ris and Walter Plaut, her supervisor, and graduated in 1960 with an MS in genetics and zoology. (Her first publication, published with Plaut in 1958 in the Journal of Protozoology, was on the genetics of Euglena, flagellates which have features of both animals and plants.) She then pursued research at the University of California, Berkeley, under the zoologist Max Alfert. Before she could complete her dissertation, she was offered research associateship and then lectureship at Brandeis University in Massachusetts in 1964. It was while working there that she obtained her PhD from the University of California, Berkeley in 1965. Her thesis was An Unusual Pattern of Thymidine Incorporation in Euglena. In 1966 she moved to Boston University, where she taught biology for twenty-two years. She was initially an Adjunct Assistant Professor, then was appointed to Assistant Professor in 1967. She was promoted to Associate Professor in 1971, to full Professor in 1977, and to University Professor in 1986. In 1988 she was appointed Distinguished Professor of Botany at the University of Massachusetts at Amherst. She was Distinguished Professor of Biology in 1993. In 1997 she transferred to the Department of Geosciences at Amherst to become Distinguished Professor of Geosciences "with great delight", the post which she held until her death.

Personal life

Margulis married astronomer Carl Sagan in 1957 soon after she got her bachelor's degree. Sagan was then a graduate student in physics at the University of Chicago. Their marriage ended in 1964, just before she completed her PhD. They had two sons, Dorion Sagan, who later became a popular science writer and her collaborator, and Jeremy Sagan, software developer and founder of Sagan Technology. In 1967, she married 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. 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.


Endosymbiosis theory

Glaucocystis sp
The chloroplasts of glaucophytes like this Glaucocystis have a peptidoglycan layer, evidence of their endosymbiotic origin from cyanobacteria.

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.

Symbiosis as evolutionary force

Margulis opposed competition-oriented views of evolution, stressing the importance of symbiotic or cooperative relationships between species.

She later formulated a theory that proposed symbiotic relationships between organisms of different phyla, or kingdoms, as the driving force of evolution, and explained genetic variation as occurring mainly through transfer of nuclear information between bacterial cells or viruses and eukaryotic cells. Her organelle genesis ideas are now widely accepted, but the proposal that symbiotic relationships explain most genetic variation is still something of a fringe idea.

Margulis also held a negative view of certain interpretations of Neo-Darwinism that she felt were excessively focused on competition between organisms, as she believed that history will ultimately judge them as comprising "a minor twentieth-century religious sect within the sprawling religious persuasion of Anglo-Saxon Biology." She wrote that proponents of the standard theory "wallow in their zoological, capitalistic, competitive, cost-benefit interpretation of Darwin – having mistaken him ... Neo-Darwinism, which insists on [the slow accrual of mutations by gene-level natural selection], is in a complete funk."

Gaia hypothesis

One of the earliest significant publications on Gaia was a 1974 paper co-authored by Margulis and James Lovelock, which succinctly defined the hypothesis as follows: "The notion of the biosphere as an active adaptive control system able to maintain the Earth in homeostasis we are calling the 'Gaia hypothesis.'"

The Lovelock-Margulis 1974 paper seemed to give living organisms complete agency in creating planetary self-regulation, whereas later, as the idea matured, this planetary-scale self-regulation was recognized as an emergent property of the Earth system, life and its physical environment taken together. In her 1998 book Symbiotic Planet, Margulis explored the relationship between Gaia and her work on symbiosis.

Five kingdoms of life

In 1969, life on earth was classified into five kingdoms, as introduced by Robert Whittaker. Margulis became the most important supporter, as well as critic – while supporting parts, she was the first to recognize the limitations of Whittaker's classification of microbes. But later discoveries of new organisms, such as archaea, and emergence of molecular taxonomy challenged the concept. By the mid-2000s, most scientists began to agree that there are more than five kingdoms. Margulis became the most important defender of the five kingdom classification. She rejected the three-domain system introduced by Carl Woese in 1990, which gained wide acceptance. She introduced a modified classification by which all life forms, including the newly discovered, could be integrated into the classical five kingdoms. According to Margulis, the main problem, archaea, falls under the kingdom Prokaryotae alongside bacteria (in contrast to the three-domain system, which treats archaea as a higher taxon than kingdom, or the six-kingdom system, which holds that it is a separate kingdom). Margulis' concept is given in detail in her book Five Kingdoms, written with Karlene V. Schwartz. It has been suggested that it is mainly because of Margulis that the five-kingdom system survives.

Awards and recognitions

  • Elected Fellow of the American Association for the Advancement of Science in 1975.
  • Guggenheim Fellowship in 1978.
  • Elected to the National Academy of Sciences in 1983.
  • Guest Hagey Lecturer, University of Waterloo, 1985
  • Miescher-Ishida Prize in 1986.
  • 1989, conferred the Commandeur de l’Ordre des Palmes Académiques de France.
  • Has her papers permanently archived in the Library of Congress, Washington, DC.
  • 1992, recipient of Chancellor's Medal for Distinguished Faculty of the University of Massachusetts at Amherst.
  • 1995, elected Fellow of the World Academy of Art and Science.
  • 1997, elected to the Russian Academy of Natural Sciences.
  • 1998, recipient of the Distinguished Service Award of the American Institute of Biological Sciences.
  • 1998, elected Fellow of the American Academy of Arts and Sciences.
  • 1999, recipient of the William Procter Prize for Scientific Achievement.
  • 1999, recipient of the National Medal of Science, awarded by President William J. Clinton.
  • 2001, Golden Plate Award of the American Academy of Achievement
  • 2002–05, Alexander von Humboldt Prize.
  • 2005, elected President of Sigma Xi, The Scientific Research Society.
  • Profiled in Visionaries: The 20th Century's 100 Most Important Inspirational Leaders, published in 2007.
  • Founded Sciencewriters Books in 2006 with her son Dorion.
  • Was one of thirteen recipients in 2008 of the Darwin-Wallace Medal, heretofore bestowed every 50 years, by the Linnean Society of London.
  • 2009, speaker at the Biological Evolution Facts and Theories Conference, held at the Pontifical Gregorian University, Rome aimed at promoting dialogue between evolutionary biology and Christianity.
  • 2010, inductee into the Leonardo da Vinci Society of Thinking at the University of Advancing Technology in Tempe, Arizona.
  • 2010, NASA Public Service Award for Astrobiology.
  • 2012, Lynn Margulis Symposium: Celebrating a Life in Science, University of Massachusetts, Amherst, March 23–25, 2012
  • 2017, the Journal of Theoretical Biology 434, 1–114 commemorated the 50th anniversary of "The origin of mitosing cells" with a special issue
  • Honorary doctorate from 15 universities.

See also

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