- Born:
- March 5, 1938, Chicago, Illinois, U.S.
- Died:
- November 22, 2011, Amherst, Massachusetts (aged 73)
- Awards And Honors:
- National Medal of Science (1999)
- Subjects Of Study:
- Gaia hypothesis
- cell
- eukaryote
- evolution
- symbiosis
Lynn Margulis
-
Who was Lynn Margulis?
Lynn Margulis (1938-2011) was an American biologist renowned for her serial endosymbiotic theory (SET) regarding eukaryotic cell development. This revolutionary concept posits that eukaryotic cells evolved through the symbiotic merger of nonnucleated bacteria.
Margulis's SET suggests that mitochondria and chloroplasts, key organelles in eukaryotic cells, originated from once free-living bacterial species. Initially met with skepticism, her ideas gained widespread acceptance over time. Margulis also collaborated with James Lovelock on the Gaia hypothesis, viewing Earth as a self-regulating organism.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What is Lynn Margulis known for in biology?
Lynn Margulis (1938–2011) was an American biologist best known for her serial endosymbiotic theory (SET) of eukaryotic cell development. This revolutionary theory posits that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of nonnucleated bacteria that had previously existed independently.
In her theory, mitochondria and chloroplasts, major organelles of eukaryotic cells, are descendants of once free-living bacterial species.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What is the endosymbiotic theory that Margulis proposed?
Lynn Margulis, an American biologist, transformed how we understand the origin of life on Earth with her serial endosymbiotic theory. This theory explains that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of nonnucleated bacteria.
According to SET, organelles like mitochondria and chloroplasts in eukaryotic cells are descendants of once free-living bacterial species. Margulis also proposed additional symbiotic mergers led to the internal transportation system of the nucleated cell and that eukaryotic cilia were originally spirochetes. Though initially met with skepticism, her theory is now widely accepted.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How did Lynn Margulis's ideas change the way scientists think about the origins of complex cells?
Lynn Margulis's serial endosymbiotic theory (SET) dramatically shifted views on the origins of complex cells. SET posits that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of non-nucleated bacteria.
Initially met with skepticism, her theory suggested that mitochondria and chloroplasts, key organelles in eukaryotic cells, descended from once free-living bacterial species. Margulis proposed that another symbiotic merger of cells with bacteria developed into the nucleated cell's internal transportation system and that cytoplasm evolved from a symbiotic relationship between eubacteria and archaebacteria. Though radical at the time, Margulis's ideas are now widely accepted, revolutionizing the understanding of how life arose on Earth.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What evidence did Margulis use to support her endosymbiotic theory?
Lynn Margulis's serial endosymbiotic theory (SET) posits that eukaryotic cells evolved from symbiotic mergers of non-nucleated bacteria. In this theory, organelles within eukaryotic cells, like mitochondria and chloroplasts, descended from once free-living bacterial species.
Margulis's theory was initially met with skepticism but gained acceptance over time. Evidence supporting the endosymbiotic origin of organelles includes:
* Self-division of mitochondria and chloroplasts
* The presence of their own DNA and protein-synthesizing machinery, similar to prokaryotes
* The ability of chloroplasts to produce ATP and trap photons using mechanisms similar to certain prokaryotes
* UCYN-A and B. bigelowii maintain a consistent size ratio, which allows efficient exchange of nitrogen and photosynthetically fixed carbon between the host and UCYN-A, thereby optimizing their synchronized growth
* Synchronized replication and division of UCYN-A with its host
* The presence of host-derived proteins within UCYN-A, essential for its function, mirroring the dependence of mitochondria and chloroplasts on host proteins4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How has Lynn Margulis's work influenced modern biology and our understanding of evolution?
Lynn Margulis (1938–2011) transformed biology with her serial endosymbiotic theory (SET). SET posits that eukaryotic cells evolved from symbiotic mergers of nonnucleated bacteria. In this theory, organelles within eukaryotic cells, like mitochondria and chloroplasts, are descendants of once free-living bacterial species.
Initially met with skepticism, Margulis's ideas, which focused on symbiosis, have gained wide acceptance and revolutionized our understanding of how life arose on Earth. Her work also included the five-kingdom system of classifying life and collaboration on the Gaia hypothesis, which views Earth as a self-regulating organism.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Lynn Margulis (born March 5, 1938, Chicago, Illinois, U.S.—died November 22, 2011, Amherst, Massachusetts) was an American biologist whose serial endosymbiotic theory of eukaryotic cell development revolutionized the modern concept of how life arose on Earth.
Margulis was raised in Chicago. Intellectually precocious, she graduated with a bachelor’s degree from the University of Chicago in 1957. Soon after, she married American astronomer Carl Sagan, with whom she had two children; one, Dorion, would become her frequent collaborator. The couple divorced in 1964. Margulis earned a master’s degree in zoology and genetics from the University of Wisconsin at Madison in 1960 and a Ph.D. in genetics from the University of California, Berkeley, in 1965. She joined the biology department of Boston University in 1966 and taught there until 1988, when she was named distinguished university professor in the department of botany at the University of Massachusetts at Amherst. She retained that title when her affiliation at the university changed to the department of biology in 1993 and then to the department of geosciences in 1997.
Throughout most of her career, Margulis was considered a radical by peers who pursued traditional Darwinian “survival of the fittest” approaches to biology. Her ideas, which focused on symbiosis—a living arrangement of two different organisms in an association that can be either beneficial or unfavourable—were frequently greeted with skepticism and even hostility. Among her most important work was the development of the serial endosymbiotic theory (SET) of the origin of cells, which posits that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of nonnucleated bacteria that had previously existed independently. In this theory, mitochondria and chloroplasts, two major organelles of eukaryotic cells, are descendants of once free-living bacterial species. She explained the concept in her first book, Origin of Eukaryotic Cells (1970). At the time, her theory was regarded as far-fetched, but it has since been widely accepted. She elaborated in her 1981 classic, Symbiosis in Cell Evolution, proposing that another symbiotic merger of cells with bacteria—this time spirochetes, a type of bacterium that undulates rapidly—developed into the internal transportation system of the nucleated cell. Margulis further postulated that eukaryotic cilia were also originally spirochetes and that cytoplasm evolved from a symbiotic relationship between eubacteria and archaebacteria (see archaea).
Her 1982 book Five Kingdoms, written with American biologist Karlene V. Schwartz, articulates a five-kingdom system of classifying life on Earth—animals, plants, bacteria (prokaryotes), fungi, and protoctists. The protist kingdom, which comprises most unicellular organisms (and multicellular algae) in other systems, is rejected as too general. Many of the organisms usually categorized as protists are placed in one of the other four kingdoms; protoctists make up the remaining organisms, which are all aquatic, and include algae and slime molds. Margulis edited portions of the compendium Handbook of Protoctista (1990).
Another area of interest for Margulis was her long collaboration with British scientist James Lovelock on the controversial Gaia hypothesis. This proposes that the Earth can be viewed as a single self-regulating organism—that is, a complex entity whose living and inorganic elements are interdependent and whose life-forms actively modify the environment to maintain hospitable conditions.
In addition to Margulis’s scholarly publications, she wrote numerous books interpreting scientific concepts and quandaries for a popular audience. Among them were Mystery Dance: On the Evolution of Human Sexuality (1991), What Is Life? (1995), What Is Sex? (1997), and Dazzle Gradually: Reflections on Nature in Nature (2007), all cowritten with her son. She also wrote a book of stories, Luminous Fish (2007). Her later efforts were published under the Sciencewriters Books imprint of Chelsea Green Publishing, which she cofounded with Dorion in 2006.
Margulis was elected to the National Academy of Sciences in 1983 and was one of three American members of the Russian Academy of Natural Sciences. She was awarded the William Procter Prize of Sigma Xi, an international research society, and the U.S. National Medal of Science in 1999. In 2008 she received the Darwin-Wallace Medal of the Linnean Society of London. She was a coauthor, with Dorion, of Encyclopædia Britannica’s article on life.
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