Lynn margulis

Lynn Margulis, née Lynn Petra Alexander (Chicago, Illinois, March 5, 1938-Amherst, Massachusetts, November 22, 2011), was a prominent American biologist, considered one of the leading figures in the field of biological evolution, regarding the origin of eukaryotic cells. She has a BS from the University of Chicago, an MS from the University of Wisconsin-Madison, and a PhD from the University of California at Berkeley. she belonged to the National Academy of Sciences of the United States since 1983 and to the Russian Academy of Sciences. In 2008, she received the Darwin-Wallace Medal. In 2011, she was named a Distinguished Professor in the Department of Geosciences at the University of Massachusetts Amherst.

In 1999 he received the National Medal of Science from US President Bill Clinton. She was a mentor at Boston University and was named honorary doctorate by numerous universities; among others, by those of Valencia, Vigo, the Autonomous of Madrid and the Autonomous of Barcelona. In collaboration with the latter, she carried out work on evolutionary microbiology in the Ebro Delta.

Among his numerous works in the field of biology, he stood out for describing an important milestone in evolution, his theory on the appearance of eukaryotic cells as a consequence of the symbiotic incorporation of various prokaryotic cells (serial endosymbiosis)., also postulated the hypothesis according to which symbiogenesis would be the main source of novelty and biological diversity. If accepted, his hypothesis would put an end to a hundred years of prevalence of the current theory of modern evolutionary synthesis. His importance in evolution and the scope of his theories remain to be seen.

Biography

He was born in 1938 in the city of Chicago, where he began his secondary education studies at Hyde Park Public High School. When her parents transferred her to the elite University of Chicago Laboratory School, she returned on her own to the institute with her former friends, a place where she thought she belonged. From that time she fondly remembers her Spanish teacher, Mrs. Kniazza.

At the age of 16, she was accepted into the advanced program at the University of Chicago, graduating at the age of 20, acquiring "a degree, a husband (Carl Sagan) and a more enduring critical skepticism", according to her.^{[citation needed]} Margulis would say of her time at the University of Chicago:

There science facilitated the approach of the deep issues in which philosophy and science unite: What are we? What are we and the universe made of? Where do we come from? How do we work? I do not doubt that I owe the choice of a scientific career to the genius of this "idio-synchronic" education.

Margulis on its Natural Sciences Class II

In 1958, she continued her training at the University of Wisconsin as a master's student and assistant professor. She studied cell biology and genetics: general genetics and population genetics. Of his teacher of the latter two, James F. Crow, he would say:

He changed my life. When I left the University of Chicago I knew I wanted to study genetics, but after Crow's classes I knew I just wanted to study genetics.

Margulis, Symbiotic Planet

From the beginning, she felt attracted to the world of bacteria, which at that time were considered only in their dimension of germs of a pathogenic nature and without interest in the sphere of evolutionism. She read ignored and forgotten works in order to support her first insight into the importance of the microbial world in evolution. She herself recounts, in her different works, how she carried out her research and what were the background of her contributions. She always showed a special willingness to value this background: I remember her from Mrs. Kniazza, her Spanish teacher at the institute; that of her professors from her university and what they meant to her, and a wide reference to the works of those scientists that she rescued from her oblivion to support her evolutionary thinking. ^{[ quote required ]}

Investidura de Margulis as an honorary doctorate by the Universidad Autónoma de Madrid (UAM), together with Peter David Townsend (left), Rector Raúl Villar and Eugenio Morales Agacino.

He became interested in the work of Ruth Sager, Frank Ryan, and Gino Pontecorvo. These works led her to what she considers her masterpiece: The Cell in Development and Heredity (The cell in development and heredity), written by E. B. Wilson in 1928. All of this work on bacteria is also linked to the work of Ivan E. Wallin, Konstantin Mereschkowski, and A. S. Famintsyn, in which they hypothesized that the non-nucleated parts of eukaryotic cells were evolved forms of other bacteria of Free life. Since then, her work has focused on developing this hypothesis, which led her to formulate her theory of serial endosymbiosis, and later her vision of the role of symbiogenesis in evolution.^{[citation needed]}

His contributions to biology and evolutionism are multiple: he described step by step and concretely the origin of eukaryotic cells (the theory of serial endosymbiosis (SET), which he considers his best work); Together with K. V. Schwartz, he classified life on earth into five kingdoms, grouped into two large groups: bacteria and eukaryotes, formulated his theory of symbiogenesis and its importance in evolution; He supported from the outset the Gaia hypothesis of the chemist James E. Lovelock, contributing to it from biology and trying to make it acquire the status of a theory, and he carried out a number of specific works on bacterial organisms and symbiotic life forms, among others.

Margulis died on November 22, 2011 at her home in Amherst, Massachusetts, five days after suffering a hemorrhagic stroke. She was further studying different spirochetes and their possible role in symbiogenetic processes.

She brings a spectacular influence because it brings the mix of biology with humanities. She is the lineage of these scientists: Galileo Galilei, Copernicus and Newton. It is a scientist who brings radical ideas, but that time and history show that they are correct.

Dimaris Acosta Mercado, Professor of Biology at the University of Puerto Rico.

Research and scientific contributions

Theory of Serial Endosymbiosis

Variety arising from eukaryotic cells.

The theory of serial endosymbiosis describes the origin of eukaryotic cells as a consequence of successive symbiogenetic incorporations of different prokaryotic cells. Margulis considered this currently accepted theory, in which he defines that process as a series of symbiotic interactions, to be his best work.

In 1966, after fifteen unsuccessful attempts to publish his work on the origin of eukaryotic cells, he managed to get the Journal of Theoretical Biology to accept and publish his article at the end of 1967 Origin of Mitosing Cells (thanks, he says, to the special interest of his former editor James F. DaNelly). Max Taylor, a professor at the University of British Columbia specializing in protists, was the one who named it with the acronym SET (Serial Endosymbiosis Theory).

Margulis continued to work on his theory of the origin of eukaryotic cells, and what was initially an article became the size of a book. He again failed in his attempts to publish. His then-publisher, Academic Press, after holding the manuscript for five months, sent him a letter announcing their rejection without further explanation. After more than a year of trying, the book was published by Yale University Press.

The transition from prokaryotes to eukaryotes meant the great leap in complexity of life and one of the most important in its evolution. Without this step, without the complexity that eukaryotic cells acquired, without the division of labor between membranes and organelles present in these cells, further steps such as the appearance of multicellular organisms would not have been possible. Life probably would have limited itself to conglomerate bacteria. In fact, the four remaining kingdoms come from that qualitative leap. The success of these eukaryotic cells made possible the subsequent adaptive radiations of life that have led to the great variety of species that exist today.

The fundamental idea is that the additional genes that appear in the cytoplasm of animal cells, vegetables and other nucleated cells are not "naked genes", but rather have their origin in bacterial genes. These genes are the palpable legacy of a violent, competitive and truce-forming past. The bacteria that long ago were partially devoured, and were trapped inside the bodies of others, became oreganols. The green bacteria that photosintetize and produce oxygen, the so-called cyanobacteria, still exist in the ponds and streams, in the muds and on the beaches. Their relatives cohabit with countless larger organisms: all plants and all algae. [...] I like to assume that we, my students, my colleagues and I, have won three of the four battles of the theory of serious endosymbiosis (SET). We can now identify three of the four partners that underlie the origin of cellular individuality. Scientists interested in this matter now agree that the underlying substance of the cells, nucleocytoplasm, descended from archobacteria; in particular, most of the metabolism of protein builders comes from the thermoaccidophilous bacteria (“appeared to those of the genus Thermoplasma”). The oxygen-breathing mitochondria of our cells and other nucleated cells evolved from bacterial symbionts now called "purple bacteria" or "proteobacteria". The chloroplasts and other seedlings of algae and plants were in their time photosynthetic pictures of free life.

Margulis, A revolution in the Evolution, cap.: Individuality by incorporation.

In the 1960s this step was not a problem of understanding, the theory of modern evolutionary synthesis had already been consolidated and from this paradigm, this step would have been taken through small adaptive changes resulting from random mutations (errors in replication of DNA) that natural selection would have been responsible for fixing. Also, at that time, evolutionism, led mainly by zoologists, placed special emphasis on the animal kingdom. Bacteria went unnoticed by this field of science and were treated almost exclusively as pathogens, studied from the field of medicine.

Before Margulis, mainly at the end of the 19th century, beginning of the 20th, different scientists intuited and came to propose that the transition from prokaryotes to eukaryotes was the result of symbiotic interactions. Proposals that were rejected, even ridiculed, and that cost their proponents to lose professional prestige. These works remained forgotten until Margulis, also intuiting the symbiotic origin of eukaryotes, rescued them and relied on them to formulate his symbiogenetic theory.

Margulis's symbiogenetic proposal clashed and still clashes on several points with the neo-Darwinian paradigm, although its role in the appearance of eukaryotic cells has already been accepted as a specific fact. The fusion of organisms and the expression of that fusion in the DNA of the resulting individual contradict the neo-Darwinian thesis present in the modern evolutionary synthesis theory, that the evolution of organisms and the appearance of new species is mainly caused by errors in DNA replication (random mutations). Margulis's proposal, with bacteria as active agents in such an important step in evolution, was also exotic for evolutionism at the time, for which bacteria had gone unnoticed. To support his hypothesis, Margulis gathered "a large number of morphological, biochemical, and paleontological facts" of his own and other scientists.

The initial skepticism and rejection of the possibility that eukaryotic cells had evolved by symbiogenesis had to be modified, giving way to partial acceptance of the theory (proven in three of the four steps), since even today Among us are the descendants of those primordial bacteria that led these symbioses.

Margulis was pleasantly surprised when, during the 1970s, her theory, baptized with the acronym SET, began to arouse interest in the academic world, appearing papers by researchers and doctoral students developing aspects of her theory. theory. Serial endosymbiosis was supported by Rayen, Schnepf & Brown and Taylor; but highly attacked by other authors, especially by Alsopp, Raff & Mahler and by Bogorad.

Since then, the SET has been making its way until today, when the incorporation of three of the four symbionts is considered proven, or if you like, two of the three steps proposed by Margulis (the hypothesis of the incorporation of the spirochetes is not considered proven).

Fortunately, thanks to the great American biologist Lynn Margulis, today we have the solution to this disconcerting riddle: a much more sensible, lucid and creative scientific explanation than the one that has been determined to support the neodarwinist orthodoxy for the last 35 years, despite having the solution, published by Margulis in 1967, literally in front of its noses. Orthodoxy has resisted with nails and teeth—to a large extent it continues to resist—to accept Margulis' theory by the simple fact that it does not fit with its Darwinist prejudices. But if you manage to get rid of that irrational and anti-scientific ballast, you will immediately see that the idea of Margulis is not only the right one, but it is endowed with a luminous explanatory power. The Margulis model on the origin of the eukaryotic cell is not gradual, but it does not require it to be feasible. It implies a sudden and highly creative event, but also entirely materialistic, blind and mechanical.

Javier Sampedro, Deconstructing Darwin.

In 2010, Lynn Margulis published a scientific article in Biological Bulletin with her latest discoveries about the cilia of eukaryotic cells that would provide possible evidence of the symbiotic origin of these structures, and their relationship with the origin of mitosis: «There are intermediate forms in which it is not possible to see if they are cilia or spirochetes (helical bacteria). Now we've gotten every step, and that's news."

Now we have every step and there are no missing links in this type of symbiogenesis in the formation of cylios. We form relationships with spirochetes but each step is analyzed. To understand this scheme, you have to choose each element and put it in order because in nature this order does not exist. We begin with a theoretical scheme and in life we already have exactly what we have predicted and everything goes in the same direction.

Interview with Lynn Márgulis, Many of the things that no one knows about Darwin have happened in Chile, SINC, 27/11/2009

Symbiogenetic theory

Evolutionary biology has focused, since its inception, on the study of animals and plants, which are considered actors in the innovations that have led to the highest levels of complexity and specialization. For Margulis, these higher complexity organisms are communities of less complex individuals capable of survival.

Margulis formulated the hypothesis that bacteria would be the architects of this complexity and of the current refinements of the different organisms. To a vision of animals, plants and, in general, of all multicellular beings as individual beings, he opposes the vision of self-organized cell communities, giving these cells the maximum evolutionary potential. He considered them the engine of evolution.

In addition, this line of thought on the importance of symbiosis has served to lead the idea that much of the evolutionary progress is due to consortium between organisms with different genomes. Dr. Margulis is convinced that, although most scientists seem to not want to realize this, science has been documenting the evolution in action in the form of fragmented literature and even in a disorganized way, but that it collects cases for the study of its evolution. The agents of evolutionary change therefore tend to be fully living organisms -microbes- and not just random mutations.

Nuria Anadón, University of Oviedo

Margulis, when searching for and assessing the antecedents of his works, instead of diluting this antecedents by coining new terms, tried to use those of previous authors. This is the case of the term «symbiogenesis» (Konstantin Mereschkowski, 1855-1921), which he rescues and with which he defines the core of his proposal for evolutionary biology.

He considered that, just as eukaryotic cells (origin of protists, animals, fungi and plants) have their origin in symbiogenesis, most of the acquisitions of multicellular characters would be the product of the symbiotic incorporation of, mainly, free-living bacteria. He downplayed random mutations, considering them overvalued by current evolutionary biology, and raised a new vision of evolution by genetic incorporation; in which organisms would tend to organize themselves in consortia:

Symbiogenesis brings together different individuals to create larger and more complex entities. Symbiogenetic life forms are even more improbable than their inverossimiles "progenitors". The "individues" permanently merge and regulate their reproduction. They generate new populations that become new multi-unit symbiotic individuals, which become "new individuals" at broader and inclusive levels of integration.

Margulis, Symbiotic Planet

The hypothesis of symbiogenesis as the main evolutionary force, as postulated by Margulis, far from complementing the current paradigm of modern evolutionary synthesis, openly contradicts it. It also implies criticism of different Darwin's postulates that are part of the modern evolutionary synthesis theory, such as gradualism (also contested by punctuated equilibrium). He postulated that, if Darwinism is a gradual process, symbiogenetic processes are abrupt, with short time lapses compared to the magnitudes that are considered in the evolutionary process of life. If Darwin postulated that gradualism despite the absence of evidence in the fossil record (arguing its incompleteness) when he postulated his theory; Margulis (like Niles Eldredge and Stephen Jay Gould) considered that the absence of some of the stages of that gradualism in the fossil record was not due to imperfection (it should be noted that in the fossil record, this process has been completing since Darwin's times), but because the speciation processes are punctual, which would coincide with what has been recorded. Nevertheless, he stresses that "the insights of much of science beyond his century, amplified by molecular biology and paleontology, are fully consistent with Darwin's insight."

It also contradicted Darwin's vision of a static nature with limited resources in which species and individuals struggle to find a place. This is explained from Darwinism through the wedges metaphor, where nature is represented as a limited surface that, when it is complete, by inserting a wedge (a new species or a new individual) displaces other. Margulis emphasizes the ability of life itself to modify the environment and generate new resources.

Thus, his hypothesis confronts the current theory of modern evolutionary synthesis, currently supported by the scientific community. It poses a head-on clash, since it maintains that biological novelty comes from random mutations (genetic errors) and symbiogenesis proposes that a large part of the characteristics of organisms come mainly from the interaction of these organisms, mainly with bacteria.

Let's take as an example of the two models (modern evolutionary synthesis and symbiogenesis) the evolution of the eye, so hyped and carried by those who have wanted to discredit evolution or defend it. We extract the explanation of the modern evolutionary synthesis from Dawkins: a genetic error occurred that provided the individual with the slightest selective advantage, natural selection would give priority to that individual and his lineage would proliferate. Later, there would be another small improvement in the same sense as the previous one, the product of another genetic error, which would provide the individual with another small advantage and so on until reaching the current state of the organ of sight.

We can “walk” a great distance through “animal space”, and our movements will be credible as long as we take small steps. [...] Two or three features of a "well-designed" eye could have developed in a single fortuitous accident. It is the number of intertwined parts, all well suited to the vision and well adapted to each other, which requires a special type of explanation, beyond just chance. The Darwinist explanation, of course, also implies random, in the form of mutations. [...] We all know, by personal experience, that, in the dark nights, there is an insensitively continuous series of gradations ranging from a total blindness to a perfect vision, and that each step along this series gives significant benefits. A vision of the world through binoculars focused and progressively defocused, can quickly convince us that there is a gradual series of qualities in the approach, each step of this series being an improvement over the previous one.

Richard Dawkins, The blind watcher.

In contrast to this random explanation with gradual changes for the evolution of the eye, symbiogenesis suggests that many of the characteristics of the organ of vision would be related to the acquisition of genomes, with the interaction of organisms with different bacteria and with the subsequent incorporation of their genomes into the individual's own DNA. Relationships that at first could be parasitic became mutualistic. It postulates that different bacteria with photosensitive capacity, present and detectable in nature, could initiate a parasitic relationship with the infected individual and, over time, this individual would be able to take advantage of this specialty of his parasite. Natural selection would have been responsible for fine-tuning the entire process.

Contrary to the neo-Darwinian orthodoxy that supports the current theory of modern evolutionary synthesis, Margulis indicated that mutations are 99% harmful to the organism, not considering them as the main origin of evolutionary novelties.

Most of the academic world does not accept symbiogenesis as valid. Currently, the theory of modern evolutionary synthesis is accepted as valid and most biologists defend their paradigm: that biological novelty also comes from genetic errors and is fixed by natural selection. In this regard, Ernst Mayr, in the prologue to Margulis's book Capturing genomes, highlighting the importance of symbiotic processes, denies that symbiotic processes are the actors in speciations, noting that "there is no indication whatsoever that none of the 10,000 species of birds or 4,500 species of mammals arose by means of symbiogenesis" (nor is it proven that any species arose as a result of genetic error). He also rejects Margulis's assessment according to which such symbiotic processes can be described as Lamarckian. Also, Maynard Smith, in his book Eight milestones of evolution confronts the symbiogenetic vision of Margulis:

Lynn Margulis, who presented the evidence that persuaded the biologists that mitochondria and chloroplasts were once symbiont, has sometimes claimed that symbiosis is the main source of evolutionary novelty, and that natural selection has been of minor importance. This is unacceptable. [...] Symbiosis is not an alternative to natural selection; rather it is backwards: we need a Darwinian explanation of symbiosis.

John Maynard Smith, Eight milestones of evolution

It should be noted that Margulis has never questioned natural selection (only the important role he gives to mutations). On the contrary, he considers it necessary to establish symbiotic relationships.

It is difficult to find published criticisms of his symbiogenetic hypothesis within the scientific community, but numerous specialists in the field of evolution reject it and consider the modern evolutionary synthesis theory satisfactory. If the symbiogenetic theory were corroborated and accepted, it would spell the end of neo-Darwinism after nearly a hundred years of prevalence.

Gaia Hypothesis

Lovelock postulates that both the chemical composition of the atmosphere, and its global temperature, the salinity of its oceans and the alkalinity of their surface (pH 8,2), are not random parameters, but are presumably regulated by the metabolism of the sum of life on Earth. This kind of global modulation does not mean that the surface of our planet is the equivalent of an organism, because, unlike the biosphere, it cannot survive its own waste or breathe its own gaseous excretions. However, the surface of the Earth does have some characteristics of organisms. It is constructed largely from cells that reproduce, takes its nutrients from the water and produces incessantly residues. Both enter into ecological associations, sometimes symbiotic, absolutely necessary for waste recycling, which determines that the cell kingdom expands. The result is that, over time, the environment becomes increasingly organized, differentiated and specialized.

Margulis, Captando genomas.

From the moment Lovelock formulated the Gaia hypothesis, Margulis supported it and tried to extend it, contributing his vision according to which bacteria are the main responsible for the chemical transformations of the biosphere.

Especially interesting [...] the intense collaboration he has maintained with the scientist James Lovelock, author of the Gaia hypothesis, which considers the Earth as a superorganism capable of self-regulating and which regulates its surface in a way very different from how a similar planet would do in size and relative position regarding the Sun, but lacking in life.

Isabel Esteve, UAB.

The ecological Gaia hypothesis postulates that the conditions of the Earth have been modified by life itself. Before it was formulated, it was accepted that life had arisen and evolved because the Earth had the optimal conditions for this to occur. The Earth would have evolved independently of the presence of living beings, and they would have adapted to these changing conditions. Gaia proposes that once the conditions were given for life to arise on Earth, the community of living beings itself has been the main person responsible for the changes that have taken place on the planet and for the radical differences that exist between Earth and the rest of the planets. Of the solar system.

Gaia proposes that life and the environment interact, behaving as a whole, diluting the differences between organic and inorganic matter, configuring a system in which one and the other nourish each other. Margulis exposes that the chemistry of the atmosphere, the salinity of the oceans, are not fortuitous, they are related to the respiration of trillions of microorganisms that modify it. The action of organic matter with its transformations and reuses has been modifying the Earth, turning it into a more "habitable" planet, expanding the possibility of containing more life.

The formulation of the Gaia hypothesis included three aspects of the biosphere: temperature, composition of the atmosphere, and salinity of the oceans. Currently, its proponents are working on expanding it to other aspects. They wonder if life has been responsible for the retention of water on Earth, as far as the biosphere reaches in depth, or if salinity is the exclusive responsibility of life's interactions: «Other questions also come to mind, as if granite is or is not a Gaian rock, or if the distribution in time and space of the great iron formations is or is not directly related to the genesis and development of life".

Margulis, and the study of evolution

Lamarck, Darwin and Margulis

Lynn Margulis at the international symposium held at the Ramón Areces Foundation in Madrid (November 2009).

Margulis avoided calling himself directly a Lamarckist or a neo-Lamarckist, a theory reviled since evolutionism. However, valuing Darwin's contribution to evolutionism, he also rescued and valued the figure and theory of Lamarck. Margulis considered that Darwin himself would have become a Lamarckian, referring to his evidently Lamarckian theory of acquired characters that he called "pangenesis."

Darwin admitted that, on its own, that process of natural selection did not seem to be able to create newness, simply to eliminate, from the immense catalogue of different organisms present in Nature, those individuals unable to reproduce. But where did this intrinsic and inherited variation originate, postulated by Darwin?

It would seem as if Darwin wanted to make us believe that the whole concept of evolution begins with him. Consistently stops honoring his vital paternal grandfather, Erasmus Darwin, doctor and progressive poet whose contribution Zoonomia (1794-1796) about natural selection, it does not seem to have been taken too seriously by your grandson. Jean-Baptiste Lamarck (1774-1829) was the first modern naturalist to publish a great corpus of bibliography, arguing the evolution of all modern forms of life from ancestral predecessors. In the Anglophone circles, Lamarck is spoken of as the Frenchman responsible for a negative contribution to science, with his erroneous claim that the characteristics acquired by an animal or plant can be inherited by the descendants of the acquirer.

The "herence of acquired characteristics", an inseparable expression already of Lamarck's name, is known as Lamarckism and mistakenly. However, and like Lamarck, Darwin himself discussed with the problem of the first source of heredable variation, also reaching erroneous conclusions. It seems to be preferable to forget that, as Mayr points out in his book (1982), Darwin ended up inventing a Lamarckian explanation — his hypothesis Pangenetic— to explain the origin of hereditary variations. According to this theory, Glues, supposed particles of which all living would be endowed and subject to experience during the life of their carriers, send representatives to the next generation. Darwin's point of view, which is difficult to differentiate from Lamarck's, is a formal statement in favour of the "herence of acquired characteristics".

Margulis, Captando genomas.

Margulis understood natural selection as a consequence of the evolution of organisms: «What Darwin called “natural selection” is simply this fact of elimination. Never 100% of the offspring manage to survive and reproduce. The biotic potential is not reached, except for very short periods of time under extremely permissive environmental conditions»; thus denying it a creative character. For Margulis, natural selection continues without giving an answer to the source of evolutionary novelty, defending symbiogenesis: «For more than forty years I have repeatedly heard of genetic errors. Genetic errors exist, but they generate diseases. No species is known to have arisen through genetic errors. However, I observe numerous cases of symbiogenesis."

After 150 years, it can be said with certainty that Darwin was right, that there is a process of evolution and natural selection. This has been demonstrated by biochemical experiments that did not exist at the time. We now know that all living beings have a common past and that we come from a lineage, but it has not yet been established which is the source of that innovation that gives rise to new species.

Lynn Margulis, interview: In the US, if you don't believe in God, you're a murderer, Marta del Amo, Public, 6/11/2009.

Margulis defended the inheritance of acquired characters postulated by Lamarck. But unlike this, he considered that it is not traits (phenotypes) that are inherited, but genomes or sets of genomes "acquired in life"; by individuals.

Margulis and the modern evolutionary synthesis

Margulis considers that the modern evolutionary synthesis (neo-Darwinism) gives the genome the quality of a fundamental entity in evolution, with the errors produced in its replication as the main origin of the changes that lead to said evolution. Margulis denies such capacity to the genome and gives prominence to organisms. While for the theory of modern evolutionary synthesis the genome is the director of the process, and the organisms are limited to following its dictates indicated in the genetic code, for Margulis it is the organisms, the living beings, that evolve and stamp the result of that evolution in the genome. According to her, the organisms are the true actors in the process and the genome is a record that these organisms are in charge of filling out and modifying.

The general idea among neodarwinists, basically zoologists who currently call themselves "evolutionary biologists", is that the inherited variation derives from random changes in the chemistry of genes. The hereditary variations are caused by mutations, and these are random. Unpredictable and independent of behavior, social conditions, food or any other element, mutations are permanent genetic changes. As these random genetic changes are accumulated over time, they determine the course of evolution. Such is the vision presented by most of the evolutionary literature.

We certainly agree that hereditary random changes, or genetic mutations, occur. We also agree that these random mutations are expressed in the body's chemistry. The existence of altered proteins, whose origin can be traced back to genetic mutations in living organisms, has been widely demonstrated. The main difference between our point of view and the current official neo-Darwinist doctrine deals with the importance of random mutation in evolution. We believe that the transcendence of random mutation as a source of hereditary variation is being enormously exaggerated. Mutations, genetic changes in living organisms can be induced; it is something that can be done with x-rays or by adding mutagenic chemical compounds in the body's food. Numerous forms of mutation are known, but none of them leads to the emergence of new organisms. The accumulation of mutations does not lead to the emergence of new species, not even new organs or new tissues. If the egg or sperm of a mammal are subject to mutation, hereditary changes will actually occur, but, as Hermann J. Muller (1890-1967) said earlier, the Nobel Prize that demonstrated on the fruit fly the mutagenic capacity of X-rays, 99.9 percent of mutations are harmful. Even professional evolutionary biologists have serious difficulties in finding mutations, whether experimentally or spontaneously induced, which contribute positively to evolutionary change.

We will show here that the main source of hereditary variation is not random mutation, but that the significant variation transmitted, which leads to evolutionary novelty, comes from the acquisition of genomes. Integer sets of genes, and even complete organisms with their own genome, are assimilated and incorporated by others. Moreover, we will also demonstrate that the process known as symbiogenesis is the main path for the acquisition of genomes.

Margulis and Dorion Sagan, Captando genomas

He considered the vision of evolution given by the modern evolutionary synthesis theory to be simplistic, considered as a “red nature of teeth and claws”, understanding that the different interactions of organisms should be valued, especially unicellular organisms. Margulis's idea did not deviate excessively from Darwin's, but he considered the interactions between individuals very important and supported the idea that organisms do not simply compete, they seek to survive and on numerous occasions they need each other to achieve it.

Margulis was radically opposed to neo-Darwinism, considering it a doctrinaire and reductionist scientific paradigm. She defended that the origin of the species is found in symbiogenesis and not in genetic mutation, understood as errors produced in DNA; and that there would really be no evidence, neither by observation of nature, nor by laboratory work, by which it can be thought that the accumulations of random genetic mutations have been responsible for the hatching of a single species.

I once asked the eloquent and affable paleontologist Niles Eldredge if he knew of any case in which the formation of a new species had been documented. I told him I'd settle for his example being taken from the lab, field work, or fossil record observation. He could only have a good example: Theodosius Dobzhansky's experiments with Drosophila, the fruit fly. In this fascinating experiment, fruit fly populations grew at progressively growing temperatures, spreading genetically. After about two years, the warm-up maids could no longer produce fertile prole with their cold-bred sisters. “But,” Eldredge quickly added—this turned out to be related to a parasite!” In fact, it was subsequently discovered that hot-breeding flies lacked an intracellular symbiotic bacteria that appeared in which they were cold. Eldredge dismissed this case as an observation of spice because it involved microbial symbiosis. They had taught him, like all of us, that microbes are germs and that when you have germs you suffer a disease, you do not become a new species. They had also taught him that evolution through natural selection takes place by the gradual accumulation, along eons, of simple genetic mutations.

Margulis, Symbiotic Planet

His criticisms of the modern evolutionary synthesis theory, of those considered by it to be its doctrinal methods they are ignored from neo-Darwinism, which is limited to incorporating SET into its paradigm, once it has been considered partially demonstrated.

That animal and plant cells originated through symbiosis is no longer a matter of controversy. Molecular biology, including genetic sequencing, has claimed this aspect of my cell symbiosis theory. The permanent incorporation of bacteria within animal and plant cells in the form of plates and mitochondria is the part of my theory of serial endosymbiosis that now appears even in the textbooks of the institutes. But the full impact of the symbiotic vision of evolution has not yet been felt; and the idea that new species appear from symbiotic mergers between members of the ancients has not yet deserved even discussion by respectable scientific society.

Margulis, Symbiotic Planet

Other contributions

HIV/AIDS Hypothesis

Margulis also argued that "there is no evidence that HIV is an infectious virus," and that the symptoms of AIDS "overlap... completely" with those of syphilis Seth Kalichman cited his 2009 paper as an example of HIV/AIDS denialism.

Support for independent investigations into the attacks of September 11 and the fall of WTC 7

In 2011 Lynn Margulis supported a new independent investigation into the events of 9/11 in the US, into how the 7 World Trade Center (the third building) collapsed on the day of the attacks. He affirms that the explanations given so far by the Government, the Government Investigation Commission, NIST, FEMA and other bodies related to the investigations carried out, show that they were responding to the US government, and it would not really be an independent scientific analysis (see: Theory of the controlled demolition of the World Trade Center).

Lynn Margulis hypothesizes that WTC 7 collapsed in on itself at 5:45 p.m. on September 11 without being hit by aircraft. She indicates that her investigations would have detected the presence of microscopic red-gray crystals present in the rubble of the buildings that establish a very strong suspicion of the presence of high-powered explosives used on the day of the attacks.

As stated above, Margulis joined the “Architects and Engineers for 911 truth” movement, in which more than 1,400 scientifically educated professionals came together to demand a new investigation into the facts regarding the fall of WTC7.

Work

Main work

Margulis also stood out for his dissemination skills. His books written alone, in collaboration with Dorion Sagan (his son) and other distinguished scientists were adding in number to this work. His prose is entertaining and the content of his works is available to everyone.

In addition, Lynn Margulis's work is one of those who do not lose validity and his books can be read and read over and over again, because there is always "small letra" that can at first go unnoticed. They are publications that, in addition to informing us, encourage us to reflect on the knowledge of the biological and planetary world.

Marisa Castro, Vigo University.

• 1970, Origin of Eukaryotic CellsYale University Press.

• 1982, Early LifeScience Books International.

• 1986, in collaboration with Dorion Sagan, Origins of Sex: Three Billion Years of Genetic RecombinationYale University Press.

• 1987, in collaboration with Dorion Sagan, Microcosmos: Four Billion Years of Evolution from Our Microbial AncestorsHarperCollins. Trad. Microcosmos. Tusquets Editores (1995).

• 1987 in collaboration with J. Lovelock, G. Bateson, H. Atlan, F. Varela, H. Maturana and others. Gaia. A way of knowing. Bring Spanish: Gaia. Implications of the new biology. Editorial Kairós (1989)

• 1991 in collaboration with Dorion Sagan, Mystery Dance: On the Evolution of Human SexualitySummit Books.

• 1991, Symbiosis as a Source of Evolutionary Innovation: Speciation and MorphogenesisThe MIT Press.

• 1992, Symbiosis in Cell Evolution: Microbial Communities in the Archean and Proterozoic EonsW.H. Freeman.

• 1997 In collaboration with Dorion Sagan, Slanted Truths: Essays on Gaia, Symbiosis, and EvolutionCopernicus Books.

• 1997 in collaboration with Karlene V. Schwartz, Five Kingdoms: An Illustrated Guide to the Phyla of Life on EarthW.H. Freeman & Co. ISBN 0-613-92338-3 Five kingdoms. Illustrated Guide phyla of Life on Earth. Editorial Labor, S.A. 335 p. Barcelona, 1985 ISBN 84-335-5217-1

• 1998, Symbiotic Planet: A New Look at EvolutionBasic Books. Trad. Simbiotic Planet: A New View on Evolution. Ed. Discussion (2002)

• 2002 Dorion Sagan, Acquiring Genomes: A Theory of the Origins of SpeciesPerseus Books Group. ISBN 0-465-04391-7 trad. Capturing genomes. A theory on the origin of species. Ed. Kairos.

• 2002 The Ice Chronicles: The Quest to Understand Global Climate Change. University of New Hampshire.

• 2007. Margulis, Lynn, Dorion Sagan. Dazzle Gradually: Reflections on the Nature of Nature, Sciencewriters Books, ISBN 978-1-933392-31-8

• 2007. Margulis, Lynn, Eduardo Punset, eds. Mind, Life and Universe: Conversations with Great Scientists of Our Time, Sciencewriters Books, ISBN 978-1-933392-61-5

• 2007. Margulis, Lynn. Luminous Fish: Tales of Science and Love, Sciencewriters Books, ISBN 978-1-933392-33-2

• Margulis, Lynn (2009). «Genome acquisition in horizontal gene transfer: symbiogenesis and macromolecular sequence analysis». In Gogarten, Maria Boekels; Gogarten, Johann Peter; Olendzenski, Lorraine C., ed. Horizontal Gene Transfer:Genomes in Flux 532. Humana Press. pp. 181-191. ISBN 978-1-60327-852-2. PMID 19271185. doi:10.1007/978-1-60327-853-9_10.

Work in Spanish

• Margulis, Lynn; Olendzenski, Lorraine (1996). Environmental developments: effects of the origin and evolution of life on planet Earth. Sole Rojo, Monica (trad.) (1st edition). Editorial Alliance. pp. 416 p. ISBN 978-84-206-2841-7. The reference uses the obsolete parameter |coautores= (help)
• Margulis, Lynn (2003). A revolution in evolution: Selected writings. Honoris Causa Collection. Valencia (Spain): Universitat de Valencia. pp. 374 p. ISBN 978-84-370-5494-0.
• Margulis, Lynn (2002). Light fish: History of love and science. Vicente Campos (trad.). Tusquets Editors. ISBN 9788483108437.
• Margulis, Lynn; Dorion Sagan (1995). Microcosm: Four billion years of evolution from our microbial ancestors. Lewis Thomas, Ricard Guerrero (trad.) (2nd ed. edition). Tusquets Editors. pp. 317 p. ISBN 9788472238428. The reference uses the obsolete parameter |coautores= (help)
• Margulis, Lynn; Dorion Sagan (1996). What is life?. Tusquets Editors. The reference uses the obsolete parameter |coautores= (help)
• Margulis, Lynn; Dorion Sagan. What's sex?. Tusquets Editors. The reference uses the obsolete parameter |coautores= (help)
• Margulis, Lynn (2002). Symbolic planet. Editorial Debate. p. 161. ISBN 84-8306-998-9.
• Margulis, Lynn; Dorion Sagan (2003). Capturing Genomas. A theory on the origin of species. Editorial Kairos. p. 285. ISBN 84-7245-551-3. The reference uses the obsolete parameter |coautores= (help)
• Margulis, Lynn; Michael F. Dolan (2009). The beginnings of life. Evolution on Earth precámbrica. Valencia (Spain): Professor of Science, Publicacions Universitat de Valencia (PUV). p. 225. ISBN 978-84-370-7378-1. The reference uses the obsolete parameter |coautores= (help)