Lynn Margulis

Lynn Margulis (born Lynn Petra Alexander;[2][3] March 5, 1938 – November 22, 2011)[4] was an American evolutionary theorist and biologist, science author, educator, and popularizer, 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."[5] 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"[6] – 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 (one grant application elicited the response, "Your research is crap, do not bother to apply again",[5]) and her formative paper, "On the Origin of Mitosing Cells", appeared in 1967 after being rejected by about fifteen journals.[7] 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.

Called "Science's Unruly Earth Mother",[8] a "vindicated heretic",[9] or a scientific "rebel",[10] Margulis was a strong critic of neo-Darwinism.[11] Her position sparked lifelong debate with leading neo-Darwinian biologists, including Richard Dawkins,[12] George C. Williams, and John Maynard Smith.[5]:30, 67, 74–78, 88–92 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 (1890-1957), and Ivan Wallin – and Margulis took the unusual step of not only trying to promote greater recognition for their contributions, but of personally overseeing 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.[13]

Lynn Margulis
Lynn Margulis
Margulis in 2005
Lynn Petra Alexander

March 5, 1938
DiedNovember 22, 2011 (aged 73)
Alma materUniversity of Chicago
University of Wisconsin–Madison
University of California, Berkeley
Known forSymbiogenesis
Gaia hypothesis
Carl Sagan
(m. 1957; div. 1965)

Thomas Margulis
(m. 1967; div. 1980)
ChildrenDorion Sagan (1959)
Jeremy Ethan Sagan (1960)
Zachary Margulis-Ohnuma
Jennifer Margulis di Properzio
AwardsNational Medal of Science (1999)
William Procter Prize for Scientific Achievement (1999)
Darwin-Wallace Medal (2008)
Scientific career
InstitutionsBrandeis University
Boston University
University of Massachusetts Amherst
ThesisAn Unusual Pattern of Thymidine Incorporation in Euglena' (1965)
Doctoral advisorMax Alfert
InfluencesIvan Wallin, Konstantin Mereschkowski[1]


Lynn Margulis was born in Chicago, to a Jewish, Zionist family.[14] 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.[15] She entered the Hyde Park Academy High School in 1952,[16] describing herself as a bad student who frequently had to stand in the corner.[3]

A precocious child, she was accepted at the University of Chicago Laboratory Schools[17] at the age of fifteen.[18][19][20] In 1957, at age 19, she earned a BA from the University of Chicago in Liberal Arts, and then completed a master's degree at the University of Chicago in genetics and zoology at age 22. 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 was with Plaut, on the genetics of Euglena, published in 1958 in the Journal of Protozoology.)[21] 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.[22] 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",[23] the post which she held until her death.[24]

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.[25][26] 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."[26] In the 2000s she had a relationship with fellow biologist Ricardo Guerrero.[16] Her sister Joan Alexander married Nobel Laureate Sheldon Lee Glashow; another sister, Sharon, married mathematician Daniel Kleitman.

She was a religious agnostic,[16] and a staunch evolutionist. But she totally rejected the modern evolutionary synthesis,[11] 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."[7] 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.[11]

Since 2013, Margulis has been listed on the Advisory Council of the National Center for Science Education.[27]

Margulis died on November 22, 2011 at home in Amherst, Massachusetts, five days after suffering a hemorrhagic stroke.[2][3][26][28] As her wish, she was cremated and her ashes were scattered in her favorite research areas, near her home.[29]


Endosymbiosis theory

Glaucocystis sp
The chloroplasts of glaucophytes like this Glaucocystis have a peptidoglycan layer, evidence of their endosymbiotic origin from cyanobacteria.[30]

In 1966, as a young faculty member at Boston University, Margulis wrote a theoretical paper titled "On the Origin of Mitosing Cells".[31] The paper, however, was "rejected by about fifteen scientific journals," she recalled.[7] 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.[3] The descent of mitochondria from bacteria and of chloroplasts from cyanobacteria was experimentally demonstrated in 1978 by Robert Schwartz and Margaret Dayhoff.[32] This formed the first experimental evidence for her theory.[3] The endosymbiosis theory of organogenesis became widely accepted in the 1980s, when the genetic material of mitochondria and chloroplasts was found to be different from that of the symbiont's nuclear DNA.[33]

In 1995, English evolutionary biologist Richard Dawkins had this to say about Lynn Margulis and her work:

I greatly admire Lynn Margulis's sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy. I'm referring to the theory that the eukaryotic cell is a symbiotic union of primitive prokaryotic cells. This is one of the great achievements of twentieth-century evolutionary biology, and I greatly admire her for it.[7]

Symbiosis as evolutionary force

Margulis opposed competition-oriented views of evolution, stressing the importance of symbiotic or cooperative relationships between species.[8]

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.[8] 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.[8]

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."[8] 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."[8]

Gaia hypothesis

Margulis initially sought out the advice of Lovelock for her own research: she explained that, "In the early seventies, I was trying to align bacteria by their metabolic pathways. I noticed that all kinds of bacteria produced gases. Oxygen, hydrogen sulfide, carbon dioxide, nitrogen, ammonia—more than thirty different gases are given off by the bacteria whose evolutionary history I was keen to reconstruct. Why did every scientist I asked believe that atmospheric oxygen was a biological product but the other atmospheric gases—nitrogen, methane, sulfur, and so on—were not? 'Go talk to Lovelock,' at least four different scientists suggested. Lovelock believed that the gases in the atmosphere were biological."[7]

Margulis met with Lovelock, who explained his Gaia hypothesis to her, and very soon they began an intense collaborative effort on the concept.[7] One of the earliest significant publications on Gaia was a 1974 paper co-authored by Lovelock and Margulis, 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.'"[34]

Like other early presentations of Lovelock's idea, 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.[35] When climatologist Stephen Schneider convened the 1989 American Geophysical Union Chapman Conference around the issue of Gaia, the idea of "strong Gaia" and "weak Gaia" was introduced by James Kirchner, after which Margulis was sometimes associated with the idea of "weak Gaia", incorrectly (her essay "Gaia is a Tough Bitch" dates from 1995 – and it stated her own distinction from Lovelock as she saw it, which was primarily that she did not like the metaphor of Earth as a single organism, because, she said, "No organism eats its own waste"[7]). In her 1998 book Symbiotic Planet, Margulis explored the relationship between Gaia and her work on symbiosis.[36]

Five kingdoms of life

Since 1969, life on earth was classified into five kingdoms, as introduced by Robert Whittaker.[37] Margulis became the most important supporter, as well as critic[38] – while supporting parts, she was the first to recognize the limitations of Whittaker's classification of microbes.[39] But later discoveries of new organisms, such as archaea, and emergence of molecular taxonomy challenged the concept.[40] By the mid-2000s, most scientists began to agree that there are more than five kingdoms.[41][42] 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 her 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).[40] Her concept is given in detail in her book Five Kingdoms, written with Karlene V. Schwartz.[43] It is mainly because of her that this five-kingdom system survives.[23]


It has been suggested that initial rejection of Margulis’ work on the endosymbiotic theory, and the controversial nature of it as well as Gaia theory, made her identify throughout her career with scientific mavericks, outsiders and unaccepted theories generally.[5] In the last decade of her life, while key components of her life's work began to be understood as fundamental to a modern scientific viewpoint – the widespread adoption of Earth System Science and the incorporation of key parts of endosymbiotic theory into biology curricula worldwide – Margulis if anything became more embroiled in controversy, not less. Journalist John Wilson explained this by saying that Lynn Margulis “defined herself by oppositional science,”[44] and in the commemorative collection of essays Lynn Margulis: The Life and Legacy of a Scientific Rebel, commentators again and again depict her as a modern embodiment of the "scientific rebel",[5] akin to Freeman Dyson's 1995 essay, The Scientist as Rebel, a tradition Dyson saw embodied in Benjamin Franklin, and which he believed to be essential to good science.[45] At times, Margulis could make highly provocative comments in interviews that appeared to support her most strident critics’ condemnation. The following describes two of these controversies.

Metamorphosis theory

In 2009, via a then-standard publication-process known as "communicated submission" (which bypassed traditional peer review), she was instrumental in getting the Proceedings of the National Academy of Sciences (PNAS) to publish a paper by Donald I. Williamson rejecting "the Darwinian assumption that larvae and their adults evolved from a single common ancestor."[46][47] Williamson's paper provoked immediate response from the scientific community, including a countering paper in PNAS.[46] Conrad Labandeira of the Smithsonian National Museum of Natural History said, "If I was reviewing [Williamson's paper] I would probably opt to reject it," he says, "but I'm not saying it's a bad thing that this is published. What it may do is broaden the discussion on how metamorphosis works and ... [on] ... the origin of these very radical life cycles." But Duke University insect developmental biologist Fred Nijhout said that the paper was better suited for the "National Enquirer than the National Academy."[48] In September it was announced that PNAS would eliminate communicated submissions in July 2010. PNAS stated that the decision had nothing to do with the Williamson controversy.[47]

AIDS/HIV theory

In 2009 Margulis and seven others authored a position paper concerning research on the viability of round body forms of some spirochetes, "Syphilis, Lyme disease, & AIDS: Resurgence of 'the great imitator'?",[49] which states that, "Detailed research that correlates life histories of symbiotic spirochetes to changes in the immune system of associated vertebrates is sorely needed," and urging the "reinvestigation of the natural history of mammalian, tick-borne, and venereal transmission of spirochetes in relation to impairment of the human immune system." The paper went on to suggest "that the possible direct causal involvement of spirochetes and their round bodies to symptoms of immune deficiency be carefully and vigorously investigated".[49]

In a Discover Magazine interview which was published less than six months before her death, Margulis explained to writer Dick Teresi her reason for interest in the topic of 2009 "AIDS" paper: "I'm interested in spirochetes only because of our ancestry. I'm not interested in the diseases," and stated that she had called them "symbionts" because both the spirochete which causes syphilis (Treponema) and the spirochete which causes Lyme disease (Borrelia) only retain about 20% of the genes they would need to live freely, outside of their human hosts.[11]

However, in the Discover Magazine interview Margulis said that "the set of symptoms, or syndrome, presented by syphilitics overlaps completely with another syndrome: AIDS," and also noted that Kary Mullis[a] said that "he went looking for a reference substantiating that HIV causes AIDS and discovered, 'There is no such document.' "[11]

This provoked a widespread supposition that Margulis had been an "AIDS denialist." Notably Jerry Coyne reacted on his Why Evolution is True blog against his interpretation that Margulis believed "that AIDS is really syphilis, not viral in origin at all."[50] Seth Kalichman, a social psychologist who studies behavioral and social aspects of AIDS, cited her 2009 paper as an example of AIDS denialism "flourishing",[51] and asserted that her "endorsement of HIV/AIDS denialism defies understanding."[52]

"9/11 Truth"

Margulis argued that the September 11 attacks were a "false-flag operation, which has been used to justify the wars in Afghanistan and Iraq as well as unprecedented assaults on ... civil liberties." She claimed that there was "overwhelming evidence that the three buildings [of the World Trade Center] collapsed by controlled demolition."[5]

Awards and recognitions



  • Margulis, Lynn (1970). Origin of Eukaryotic Cells, Yale University Press, ISBN 0-300-01353-1
  • Margulis, Lynn (1982). Early Life, Science Books International, ISBN 0-86720-005-7
  • Margulis, Lynn, and Dorion Sagan (1986). Origins of Sex : Three Billion Years of Genetic Recombination, Yale University Press, ISBN 0-300-03340-0
  • Margulis, Lynn, and Dorion Sagan (1987). Microcosmos: Four Billion Years of Evolution from Our Microbial Ancestors, HarperCollins, ISBN 0-04-570015-X
  • Margulis, Lynn, and Dorion Sagan (1991). Mystery Dance: On the Evolution of Human Sexuality, Summit Books, ISBN 0-671-63341-4
  • Margulis, Lynn, ed. (1991). Symbiosis as a Source of Evolutionary Innovation: Speciation and Morphogenesis, The MIT Press, ISBN 0-262-13269-9
  • Margulis, Lynn (1991). "Symbiosis in Evolution: Origins of Cell Motility". In Osawa, Syozo; Honzo, Tasuku (eds.). Evolution of Life: Fossils, Molecules and Culture. Japan: Springer. pp. 305–324. doi:10.1007/978-4-431-68302-5_19. ISBN 978-4-431-68304-9.
  • Margulis, Lynn (1992). Symbiosis in Cell Evolution: Microbial Communities in the Archean and Proterozoic Eons, W.H. Freeman, ISBN 0-7167-7028-8
  • Sagan, Dorion, and Margulis, Lynn (1993). The Garden of Microbial Delights: A Practical Guide to the Subvisible World, Kendall/Hunt, ISBN 0-8403-8529-3
  • Margulis, Lynn, Dorion Sagan and Niles Eldredge (1995) What Is Life?, Simon and Schuster, ISBN 978-0684810874
  • Margulis, Lynn, and Dorion Sagan (1997). Slanted Truths: Essays on Gaia, Symbiosis, and Evolution, Copernicus Books, ISBN 0-387-94927-5
  • Margulis, Lynn, and Dorion Sagan (1997). What Is Sex?, Simon and Schuster, ISBN 0-684-82691-7
  • Margulis, Lynn, and Karlene V. Schwartz (1997). Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth, W.H. Freeman & Company, ISBN 0-613-92338-3
  • Margulis, Lynn (1998). Symbiotic Planet : A New Look at Evolution, Basic Books, ISBN 0-465-07271-2
  • Margulis, Lynn, et al. (2002). The Ice Chronicles: The Quest to Understand Global Climate Change, University of New Hampshire, ISBN 1-58465-062-1
  • Margulis, Lynn, and Dorion Sagan (2002). Acquiring Genomes: A Theory of the Origins of Species, Perseus Books Group, ISBN 0-465-04391-7
  • Margulis, Lynn (2007). Luminous Fish: Tales of Science and Love, Sciencewriters Books, ISBN 978-1-933392-33-2
  • Margulis, Lynn, and Eduardo Punset, eds. (2007). Mind, Life and Universe: Conversations with Great Scientists of Our Time, Sciencewriters Books, ISBN 978-1-933392-61-5
  • Margulis, Lynn, and Dorion Sagan (2007). Dazzle Gradually: Reflections on the Nature of Nature, Sciencewriters Books, ISBN 978-1-933392-31-8
  • Margulis, Lynn (2009). "Genome acquisition in horizontal gene transfer: symbiogenesis and macromolecular sequence analysis". In Gogarten, Maria Boekels; Gogarten, Johann Peter; Olendzenski, Lorraine C. (eds.). Horizontal Gene Transfer:Genomes in Flux. Methods in Molecular Biology. 532. Humana Press. pp. 181–191. doi:10.1007/978-1-60327-853-9_10. ISBN 978-1-60327-852-2. PMID 19271185.



  1. ^ Kary Mullis won the 1993 Nobel Prize for the polymerase chain reaction, and is known for his unconventional scientific views.


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  49. ^ a b Margulis, Lynn; Maniotis, Andrew; MacAllister, James; Scythes, John; Brorson, Oystein; Hall, John; Krumbein, Wolfgang E.; Chapman, Michael J. (2009). "Syphilis, Lyme disease & AIDS: Resurgence of "the great imitator"?" (PDF). Symbiosis. 47 (1): 51–58. doi:10.1007/BF03179970.
  50. ^ Jerry Coyne (2011-04-12). "Lynn Margulis disses evolution in Discover Magazine – Embarrasses both herself and the field". Why Evolution is True.
  51. ^ Kalichman, S. C.; Eaton, L.; Cherry, C. (2010). ""There is no Proof that HIV Causes AIDS": AIDS denialism beliefs among people living with HIV/AIDS". Journal of Behavioral Medicine. 33 (6): 432–440. doi:10.1007/s10865-010-9275-7. PMC 3015095. PMID 20571892.
  52. ^ Seth C. Kalichman (16 January 2009). Denying AIDS: Conspiracy Theories, Pseudoscience, and Human Tragedy. Springer Science & Business Media. pp. 181–82. ISBN 978-0-387-79476-1.
  53. ^ Guest Lecturers
  54. ^ a b c d Margulis, Lynn. "Curriculum Vitae" (PDF). Retrieved 19 December 2014.
  55. ^ "Lynn Margulis | World Academy of Art & Science". 2011-11-18. Archived from the original on 2012-03-30. Retrieved 2011-11-23.
  56. ^ "Biologist Lynn Margulis of UMass Amherst Elected Fellow of American Academy of Arts & Sciences" (Press release). Amherst, Massachusetts: University of Massachusetts Amherst. 1998-05-05. Retrieved 2016-01-29.
  57. ^ "Launches Sciencewriters Imprint". Chelsea Green. 2006-07-22. Retrieved 2011-11-23.
  58. ^ "Lynn Margulis". University of Advancing Technology. Archived from the original on 28 July 2014. Retrieved 25 July 2014.
  59. ^ "The Code Online". International Council of Zoological Nomenclature.

External links


BioSystems is a monthly peer-reviewed scientific journal covering experimental, computational, and theoretical research that links biology, evolution, and the information processing sciences. It was established in 1967 as Currents in Modern Biology by Robert G. Grenell. In 1972 the journal was renamed Currents in Modern Biology: Bio Systems, which was shortened to BioSystems in 1974. Previous editors include J.P. Schadé, Alan W. Schwartz, Sidney W. Fox, Michael Conrad, Lynn Margulis, David B. Fogel, Gary B. Fogel, George Kampis, Francisco Lara-Ochoa, Koichiro Matsuno, Ray Paton, and W. Mike L. Holcombe.

Carl Sagan Medal

The Carl Sagan Medal for Excellence in Public Communication in Planetary Science is an award established by the Division for Planetary Sciences of the American Astronomical Society to recognize and honor outstanding communication by an active planetary scientist to the general public. It is awarded to scientists whose efforts have significantly contributed to a public understanding of, and enthusiasm for planetary science.

Carl Sagan Memorial Award

The Carl Sagan Memorial Award is an award presented jointly by the American Astronautical Society and The Planetary Society to an individual or group "who has demonstrated leadership in research or policies advancing exploration of the Cosmos." The annual award, first presented in 1997, was created in honor of American astronomer, astrobiologist and science popularizer, Carl Sagan (1934–1996).

Dorion Sagan

Dorion Sagan (born 1959) is an American author, essayist, fiction writer, and theorist from Madison, Wisconsin. He has written and co-authored books on culture, evolution, and the history and philosophy of science, including Cosmic Apprentice, Cracking the Aging Code, and Lynn Margulis: The Life and Legacy of a Scientific Rebel. His book Into the Cool, co-authored with Eric D. Schneider, is about the relationship between non-equilibrium thermodynamics and life.


Echinostelium is a genus of slime mould, and the only genus in the family Echinosteliaceae, or Echinosteliidae. It was discovered by Heinrich Anton de Bary in 1855, apparently near Frankfurt am Main. Some species of Echinostelium have a sexual life cycle; others have been shown to be asexual. The plasmodium can divide vegetatively, in a process called plasmotomy, to distinguish it from true cell division.


Eumetazoa (Greek: εὖ [eu], well + μετά [metá], after + ζῷον [zóon], animal) or Diploblasts, or Epitheliozoa, or Histozoa are a proposed basal animal clade as a sister group of the Porifera.The basal Eumetazoan clades are the Ctenophora and the ParaHoxozoa. Placozoa is now also seen as an Eumetazoan in the Parahoxozoa.

Several other extinct or obscure life forms, such as Iotuba and Thectardis appear to have emerged in the group. Characteristics of eumetazoans include true tissues organized into germ layers, the presence of neurons, and an embryo that goes through a gastrula stage.

Some phylogenists have speculated the sponges and eumetazoans evolved separately from single-celled organisms, which would mean that the animal kingdom does not form a clade (a complete grouping of all organisms descended from a common ancestor). However, genetic studies and some morphological characteristics, like the common presence of choanocytes, support a common origin.Traditionally, Eumetazoans are a major group of animals in the Five Kingdoms classification of Lynn Margulis and K. V. Schwartz, comprising the Radiata and Bilateria — all animals except the sponges. When treated as a formal taxon Eumetazoa is typically ranked as a subkingdom. The name Metazoa has also been used to refer to this group, but more often refers to the Animalia as a whole. Many classification schemes do not include a subkingdom Eumetazoa.

Gaia hypothesis

The Gaia hypothesis (, , ), also known as the Gaia theory or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.

The hypothesis was formulated by the chemist James Lovelock and co-developed by the microbiologist Lynn Margulis in the 1970s. Lovelock named the idea after Gaia, the primordial goddess who personified the Earth in Greek mythology. In 2006, the Geological Society of London awarded Lovelock the Wollaston Medal in part for his work on the Gaia hypothesis.Topics related to the hypothesis include how the biosphere and the evolution of organisms affect the stability of global temperature, salinity of seawater, atmospheric oxygen levels, the maintenance of a hydrosphere of liquid water and other environmental variables that affect the habitability of Earth.

The Gaia hypothesis was initially criticized for being teleological and against the principles of natural selection, but later refinements aligned the Gaia hypothesis with ideas from fields such as Earth system science, biogeochemistry and systems ecology. Lovelock also once described the "geophysiology" of the Earth. Even so, the Gaia hypothesis continues to attract criticism, and today some scientists consider it to be only weakly supported by, or at odds with, the available evidence.

Hans Ris

Hans Ris (June 15, 1914 – November 19, 2004) was an American cytologist and pioneer electron microscopist. His studies of chromosome structure revealed the importance of non-histone proteins, and along with evolutionary biologist Lynn Margulis, he was one of the first to recognize that blue-green algae were a special type of bacteria. He coined the term genophore for prokaryote DNA to highlight its differences from the eukaryal chromosome. Ris was a founding member of the American Society for Cell Biology and received the Distinguished Scientist Award by the Microscopy Society of America in 1983.


Holobionts are assemblages of different species that form ecological units. Lynn Margulis proposed that any physical association between individuals of different species for significant portions of their life history is a symbiosis. All participants in the symbiosis are bionts, and therefore the resulting assemblage was first coined a holobiont by Lynn Margulis in 1991 in the book Symbiosis as a Source of Evolutionary Innovation. Holo is derived from the Ancient Greek word ὅλος (hólos) for “whole”. The entire assemblage of genomes in the holobiont is termed a hologenome.


Kinetoplastida (or Kinetoplastea, as a class) is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of an organelle with a large massed DNA called kinetoplast (hence the name). The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts" The group includes a number of parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments. Their distinguishing feature, the presence of a kinetoplast, is an unusual DNA-containing granule located within the single mitochondrion associated with the base of the cell's flagella (the basal body). The kinetoplast contains many copies of the mitochondrial genome.

The kinetoplastids were first defined by Bronislaw M. Honigberg in 1963 as the members of the flagellated protozoans. They are traditionally divided into the biflagellate Bodonidae and uniflagellate Trypanosomatidae; the former appears to be paraphyletic to the latter. One family of kinetoplastids, the trypanosomatids, is notable as it includes several genera which are exclusively parasitic. Bodo is a typical genus within kinetoplastida and including various common free-living species which feed on bacteria. Others include Cryptobia and the parasitic Leishmania.


Margulis is a surname that, like its variants shown below, is derived from the Ashkenazi Hebrew pronunciation of the Hebrew word מרגלית (Israeli Hebrew /maʁɡaˈlit/), meaning 'pearl,' and may refer to:

Berl Broder (born Margulis), Broder singer

Dan Margulis, author

Evgeny Margulis, musician

Grigory Margulis (born 1946), mathematician

Margulis lemma

Lynn Margulis, biologist

Margulis, a villain from the game series Xenosaga


Radiata or Radiates is a historical taxonomic rank that was used to classify animals with radially symmetric body plans. The term Radiata is no longer accepted, as it united several different groupings of animals that do not form a monophyletic group under current views of animal phylogeny. The similarities once offered in justification of the taxon, such as radial symmetry, are now taken to be the result of either incorrect evaluations by early researchers or convergent evolution, rather than an indication of a common ancestor. Because of this, the term is used mostly in a historical context.In the early 19th century, Georges Cuvier united Ctenophora and Cnidaria in the Radiata (Zoophytes). Thomas Cavalier-Smith, in 1983, redefined Radiata as a subkingdom consisting of Myxozoa, Placozoa, Cnidaria and Ctenophora. Lynn Margulis and K. V. Schwartz later redefined Radiata in their Five Kingdom classification, this time including only Cnidaria and Ctenophora. This definition is similar to the historical descriptor Coelenterata, which has also been proposed as a group encompassing Cnidaria and Ctenophora.

Although radial symmetry is usually given as a defining characteristic in animals that have been classified in this group, there are clear exceptions and qualifications. Echinoderms, for example, exhibit unmistakable bilateral symmetry as larvae, and are now in the Bilateria. Ctenophores exhibit biradial or rotational symmetry, defined by tentacular and pharyngeal axes, on which two anal canals are located in two diametrically opposed quadrants. Some species within the cnidarian class Anthozoa are bilaterally symmetric (For example, Nematostella vectensis). It has been suggested that bilateral symmetry may have evolved before the split between Cnidaria and Bilateria, and that the radially symmetrical cnidarians have secondarily evolved radial symmetry, meaning the bilaterality in cnidarian species like N. vectensis has a primary origin. The differing definitions assigned by zoologists are listed in the table.


Rhodomicrobium is a microaerobic to anaerobic, purple non-sulfur, cluster-building genus of bacteria. Rhodomicrobium uses bacteriochlorophyll a and bacteriochlorophyll b for photosynthesis and occurs in fresh- and sea-water and in soil

Sputnik Observatory

Sputnik Observatory (SPTNK) is an educational non-profit organization that specializes in the study of contemporary culture. SPTNK documents, archives and disseminates ideas that are shaping modern thought. SPTNK has a website designed by Jonathan Harris that interconnects ideas in fields as diverse as quantum physics, mathematics, neuroscience, biology, economics, architecture, digital art, video games, computer science and music. Conversations include such people as physicist Freeman Dyson, game designer Will Wright, venture capitalist Jacques Vallée, biologist Lynn Margulis, aerospace entrepreneur Robert Bigelow, architect Lars Spuybroek and computer scientist Vint Cerf..

Sputnik Observatory was established and funded in New York City in 2003 by the principals of Sputnik Inc. Its goal is to encourage lifelong learning within a democratic space where people can listen and engage with ideas that inform contemporary history. Board Members include John Perry Barlow, Hiro Yamagata, Bruce Odland and Dorion Sagan.


Symbiogenesis, or endosymbiotic theory, is an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967. It holds that the organelles distinguishing eukaryote cells evolved through symbiosis of individual single-celled prokaryotes (bacteria and archaea).

The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells represent formerly free-living prokaryotes taken one inside the other in endosymbiosis. In more detail, mitochondria appear to be related to Rickettsiales proteobacteria, and chloroplasts to nitrogen-fixing filamentous cyanobacteria.

Among the many lines of evidence supporting symbiogenesis are that new mitochondria and plastids are formed only through binary fission, and that cells cannot create new ones otherwise; that the transport proteins called porins are found in the outer membranes of mitochondria, chloroplasts and bacterial cell membranes; that cardiolipin is found only in the inner mitochondrial membrane and bacterial cell membranes; and that some mitochondria and plastids contain single circular DNA molecules similar to the chromosomes of bacteria.


Tychoplankton (Greek, "tycho", accident, chance) are organisms, such as free-living or attached benthic organisms and other non-planktonic organisms, that are carried into the plankton through a disturbance of their benthic habitat, or by winds and currents. This can occur by direct turbulence or by disruption of the substrate and subsequent entrainment in the water column. Tychoplankton are, therefore, a primary subdivision for sorting planktonic organisms by duration of lifecycle spent in the plankton, as neither their entire lives nor particular reproductive portions are confined to planktonic existence.They are also known as accidental plankton or pseudo-plankton (compare: pseudoplankton), although "pseudoplankton" also defines organisms that do not themselves float but, rather, are attached to other organisms that float.


An undulipodium (a Greek word meaning "swinging foot") or a 9+2 organelle is a motile filamentous extracellular projection of eukaryotic cells. It is basically synonymous to flagella and cilia which are differing terms for similar molecular structures used on different types of cells.

The name was coined to differentiate from the analogous structures present in prokaryotic cells. It is structurally a complex of microtubules along with motor proteins.The usage of the term was early supported by Lynn Margulis, especially in support of endosymbiotic theory. The eukaryotic cilia are structurally identical to eukaryotic flagella, although distinctions are sometimes made according to function and/or length.

World Summit on Evolution

The World Summit on Evolution is an evolutionary biology meeting hosted at the Galapagos Islands by Universidad San Francisco de Quito (USFQ), an Ecuadorian private liberal arts university. Its focus is on recent research and new advances in our understanding of evolution and the diversity of life.The summit hosts more than 150 participants presenting invited and submitted talks, poster sessions and scientific-outreach talks. It has been called "The Woodstock of Evolution" bringing together experts and students from widely different areas of evolutionary biology that rarely meet. It has attracted researchers working on evolution from over 15 different countries, including Peter and Rosemary Grant, Niles Eldredge, Antonio Lazcano, Douglas Futuyma, Lynn Margulis, Ada Yonath, William H. Calvin and Daniel Dennett.

Scientific career
Science books
Sagan Prizes

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