Although Charles Darwin’s theory of evolution laid the foundations of modern biology, it did not tell the whole story. Most remarkably, The Origin of Species said very little about, of all things, the origins of species. Darwin and his modern successors have shown very convincingly how inherited variations are naturally selected, but they leave unanswered how variant organisms come to be in the first place.In Symbiotic Planet, renowned scientist Lynn Margulis shows that symbiosis, which simply means members of different species living in physical contact with each other, is crucial to the origins of evolutionary novelty. Ranging from bacteria, the smallest kinds of life, to the largest—the living Earth itself—Margulis explains the symbiotic origins of many of evolution’s most important innovations. The very cells we’re made of started as symbiotic unions of different kinds of bacteria. Sex—and its inevitable corollary, death—arose when failed attempts at cannibalism resulted in seasonally repeated mergers of some of our tiniest ancestors. Dry land became forested only after symbioses of algae and fungi evolved into plants. Since all living things are bathed by the same waters and atmosphere, all the inhabitants of Earth belong to a symbiotic union. Gaia, the finely tuned largest ecosystem of the Earth’s surface, is just symbiosis as seen from space. Along the way, Margulis describes her initiation into the world of science and the early steps in the present revolution in evolutionary biology; the importance of species classification for how we think about the living world; and the way “academic apartheid” can block scientific advancement. Written with enthusiasm and authority, this is a book that could change the way you view our living Earth.
Lynn Margulis (1938-2011) was a Professor of Geosciences at the University of Massachusetts, a member of the U.S. National Academy of Sciences and the Russian Academy of Natural Sciences.
If we care to, we can find symbiosis everywhere. Physical contact is a non-negotiable requisite for many differing kinds of life.
Symbiosis: interaction between two different organisms living in close physical association, typically to the advantage of both.
What this book is not: A straightforward account of the science of evolutionary biology in the late 20th century; nor is it a textbook approach; nor is it even a journalistic, popular science approach.
What this book is: An account of one woman’s journey through life, as she contributed to the science of evolutionary biology in the second half of the 20th century. (Admittedly there’s a bit more science in the narrative than that statement might imply. But really, the book could have been titled Evolution – A Personal View. It’s a scientific memoir.
These statements are not meant as criticisms at all. Just factual.
The author
Dr. Lynn Margulis (1938-2011) was an American evolutionary biologist and bacteriologist, with advanced degrees in zoology and genetics. She taught at Brandeis, Boston Univ., and the University of Massachusetts at Amherst, and was presented a National Medal of Science by President Clinton in 1999; among many other awards and honors (see https://en.wikipedia.org/wiki/Lynn_Ma...), she was elected a member of the US National Academy of Sciences in 1983, and the Linnean Society of London awarded her the Darwin-Wallace Medal in 2008. More biographical information can be found HERE
Instead of using the above sources any further, what I relate here is taken from the book’s second chapter, Against Orthodoxy. This chapter, the book’s longest, is basically a mini autobiography, a memoir of Margulis’ early years in science.
The chapter starts with her thirteenth year, and covers mainly the period from that time (1951) to the late 1960s. It has 24 pages of text. What I’ve summarized below would probably take about five of the book pages to print. So you see, it could be something of a spoiler.
This decade and a half saw Margulis earn a BA in Liberal Arts from Chicago at the age of nineteen (1957), the same year that she married an undergraduate astronomer named Carl Sagan (yes, that one); have two children (1959, 1960) while doing post-graduate work; complete her master’s degree at Wisconsin in genetics and zoology (1960); get divorced from Sagan (1964) and continue caring for her youngsters; obtain her PhD from Berkeley in 1965; start teaching at Boston University in 1966; and become married for a second time, to Thomas N. Margulis, a crystallographer, in 1967. Now, let’s backtrack to the beginning …
… my thirteenth year … In secret exercise of my perceived rights as a person of free will I snuck out of the University of Chicago eighth-grade laboratory school, with its vastly inferior pool of potential boyfriends, and returned to the huge public high school where I had decided I belonged. (p. 17)
This decision made in the fall. First deciding to run away from home, then realizing that without money and with winter coming on, this was impractical, she played things by ear. In the new year, in February, she leaves the lab school, and enrolls herself in the ninth grade at Hyde Park High School, concocting a story in the forms she fills out.
For some twelve weeks I simply went to all my assigned classes … My parents, of course, had no reason to think I was not in the lab school … on a daily basis and I had no reason to disabuse them. (18)
But sometime late in the spring the shit hits the fan. School officials have uncovered the fact that she did not finish eighth grade at the lab school, and hence “had no authority whatsoever to be attending Hyde Park.” It also comes out to officials that her parents have no idea what she’s doing. (19)
Many teary sessions followed in and out of school. Finally her dad, helping out, proposed that they request she be given the tests that a newly arrived foreign student would take for proper placement. She easily passes the ninth grade tests.
I won the battle. I was permitted to complete ninth grade at Hyde Park, where I enjoyed a far wider choice of boyfriends … But I lost the war. After two years of public high school my academic advisors told me, when, as an ‘early entrant’ college student, I reentered the University of Chicago, that I had declined in mathematical ability, that my vocabulary had diminished, and that, in general, I was a poorer student at the end of tenth grade than I had been halfway through eighth. When, in the spring of 1954, I finally left the urban racial misery of Hyde Park to attend The College (as the U of C was called, even though they accepted students at a very early age) I was primed, after a two-year lapse, to become a fine student again. Back where I belonged, according to my anxious parents, I was poised to meet the very best of handsome, smart, and eligible young men. The Sagan years followed. (19-20)
A page or two of her affair with and marriage to Sagan, who is almost five years older - many break ups, trips together, parental disapproval: My father hated his arrogance and my mother was always suspicious of his self-centered character. (21) They marry a week after she graduates from Chicago.
The degree she has earned (at nineteen) is a BA with no major. Ever the iconoclast, Margulis applies for, and is accepted into a master’s program at Wisconsin (this is 1958 – Carl is working at Yerkes observatory near Milwaukee). Pregnant and sleepy in class. (22)
I was no more constitutionally inclined to focus monomaniacally on the cell nucleus than I was to be a satellite wife in a nuclear family; my attentions, like those of many women, were divided. … A woman must be almost octopoid in her attentions if she is to survive. Holding the infant in one arm … she stirs the pot with the other, while she watches the toddler. These multiple pressures were not then, nor are they now, wished away by political will and feminist rhetoric. (24)
I believe what Margulis is saying here is that political/feminist activism will not aid a woman trying to do these things. What this woman needs is more hours in the day.
She relates how she became interested in cytoplasmic (outside the cell nucleus) genetics, and comments on how times have changed. Symbiogenesis, now three decades later, is converting cytoplasmic genetics from a marginal subject to a central one in gene studies. (26)
Margulis realized, from her reading in old texts, long forgotten, that the genes controlling heredity of certain things “are not necessarily in the nucleus. In both plants and animals some cell genetic factors are dispersed.” (28) This was being pointed out by others - embryologists and botanists – though mainstream geneticists were concentrating on the nucleus of the cell.
Now let’s jump back in time several years, to her early classes in ‘The College’ of the University of Chicago. (29 ff) Margulis writes of the Natural Science 2 course as playing a crucial role in her outlook and methodology in pursuing science. This course required students to read “the writings of the great scientists themselves” – Mendel, Darwin, and many others: Hans Spemann, August Weismann, G.S. Hardy, J.B.S. Haldane, R.A. Fisher. As taught in Nat Sci 2, science was a liberal art, a way of knowing. We were taught how, through science, we could go about answering important philosophical questions.
Her fascination with biology and evolution began with the Nat Sci 2 syllabus, particularly with Theodosius Dhobzhansky, still active at Columbia University, who wrote “nothing in biology makes sense except in the light of evolution”. Margulis realized that Evolution is simply all of history.
Again, a jump back. Even as an undergraduate I sensed that something was too pat, too reductionistic, too limiting about the idea that genes in the nucleus determine all the characteristics of plants or animals. (32) By 1963, many papers on cytoplasmic factors of eggs showed mysterious genes outside the nucleus … T.H. Morgan’s advice to ignore the cytoplasm seemed to me, even then, simply denial.
In 1960, Margulis moves to Berkeley. Enrolled in the department of genetics for her PhD, 22 years old, mother of two (still married). She complains of the utter lack of mutual interest between the departments of paleontology, where evolution was studied, and genetics, where evolution was barely mentioned.
… at first I was shocked by the depth of the academic apartheid. Each department seemed oblivious of people and subject matter beyond its borders. (34)
Her reading outside the normal literature continued. What (Tracy) Sonneborn and his French colleague Jannine Beisson had discovered seemed grossly to contradict the ubiquitous dogma that induced characteristics cannot be inherited. (35) And experiments done at Indiana on Paramecium cilia (surgically reversing them on the cell’s surface) showed that “the cilia will appear in offspring cells, for many future generations, in this reversed position … Here was a laboratory example of the so-called inheritance of acquired characteristics that orthodoxy dismissed as Lamarckianism. (35-6)
A digression: on the political orientation of the 1960s, and more and more talk in academia about ‘relevance’. In this climate my interest in the patterns of cell inheritance was antisocial. What preoccupied me most was irrelevant to my instructors and most of my fellow students.
Many were beginning to look for “naked genes” outside the cell nucleus, to explain the supposed Lamarkian results. She pored over old but brilliant work of different researchers in various fields: H.J. Muller, Edouard Chatton, Lemuel Roscoe Cleveland, and Sonneborn.
These disparate sources of information substantiated my hunch: Bacteria, not naked genes, did reside outside the nucleus but inside the cells of many protists, yeasts, and even plants and animals … At least three classes of membrane-bounded organelles (plastids, mitochondria, cilia), all outside the nucleus, resembled bacteria in their behavior and metabolism. (37)
And a leap forward in time: My students and I still work on the central idea: the origin of cells with nuclei is exactly equal to the evolutionary integration of symbiotic bacterial communities. (38)
[Stepping outside the narrative for just a moment – 1963, Lynn moved to Massachusetts with her two sons to take up a biology lectureship at Brandeis; 1964, her marriage to Sagan ends; 1965, her Berkeley PhD is awarded at long distance.]
In 1966 her first paper is accepted, and published in the next year, after “fifteen or so” assorted rejections). It is called “Origin of Mitosing Cells”. What she proposed in the paper was dubbed SET (for Serial Endosymbiosis Theory) by another protist aficionado” Professor Max Taylor of the University of British Columbia, Vancouver.
Two years later, well into my second marriage and pregnant with my daughter Jennifer, obliged to stay home for extended periods, she is permitted uninterrupted thought. The 1967 paper has grown into a book length manuscript. I typed late into many nights … was given no compensation for the many illustrations I commissioned. Mailed off to Academic Press, the publisher who held the contract, the receipt of the box is not acknowledged; wait … wait … about five months later, my box, without explanation, sent by surface book rate, reappeared at my mail box. Much later I was informed, not even by the editor, that extremely negative peer review had led Academic Press to hold the manuscript for months. From the press finally I received a form letter of rejection. No explanation, in fact not even a personal letter. More than a year later, after far more painful and far longer labor than Jenny ever caused me, the book finally was nicely edited, produced, and published in 1971 by Yale University Press. (39) (The book is Origin of Eukaryotic Cells)
Throughout the 1970s and 1980s many scientists and graduate students contributed experimental data, which tended to confirm the once radical nineteenth-century idea that the cells of plants and of our animal bodies (as well as those of fungi and all other organisms composed of cells with nuclei) originated through a specific sequence of mergers of different types of bacteria. (40)
Most (not all) of the contentions in Margulis’ 1971 book are now accepted as true in the field of evolutionary biology.
What a story! In some sense it could even be paradigm-toppling?
The Book
Well, I’ve given a lot in info about the author here, and not said very much about what’s in the book. The reason, of course, is that it appears to me the book is really about Lynn Margulis, and I wanted to let her tell her own story.
Naturally there’s much here about evolution and cell biology. But it must be said, it’s very much her personal view. Much of this view is shared by the so-called mainstream biologists in the field; some of it isn’t. She goes out of her way at places, to say that many disagree with her, that she might be wrong. This is very unusual I would think. Nevertheless, it is hard, particularly if, like me, you are ignorant about biology, to know what parts are contentious, and what are not. Thus my judgement that it isn’t a good book to find out what current thinking is.
Lynn Margulis – her life in science
What did Margulis contribute to evolutionary biology? Most would acknowledge that, as the New York Times noted in her obituary, “her work on the origin of cells helped transform the study of evolution”. Some point out that many of Margulis’ ideas are found in the work or much earlier scientists. Indeed it has been, and In many places in this book she specifically mentions earlier scientists whose forgotten research and theories inspired her.
I don’t think Margulis was a “laboratory scientist”, spending long periods of time designing and doing experiments. In the book she comments that she wants to give the reader “an idea of why I spend my life collecting evidence from all the dusty corners of biology”, and later notes that she reads much of the research from medical laboratories “whose scientists are unconcerned with evolution. Mainly I just monitor the findings.”
The Nat Sci 2 course at Chicago, mentioned above, had taught her that science could be an intellectual enterprise, one of reading and ruminating on problems, possible solutions, and the insights of other, often earlier, investigators. E.O. Wilson called her “one of the most successful synthetic thinkers in modern biology” - that is, someone who could combine the ideas of others into new insights not seen by any of those originators.
She gave up husbands twice, commenting, ”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.” The husband was the least important.
She had many long standing “feuds” (which may be too strong a term) with neo-Darwinists who would not recognize the role symbiosis played in evolution. She did not refrain from chiding, in a mostly good-humored way, evolutionists like Richard Dawkins and Stephen Gould, when she said that, because they come out of the “zoological tradition” in evolutionary biology, ”they deal with a data set some three billion years out of date.”
Her support for James Lovelock’s Gaia hypothesis disturbed some scientists, who, she thought, were put off by the anti-scientific thinking of many “new age” types who embraced the ridiculous “Earth Goddess” interpretation of Gaia.
On the other hand, even Dawkins has been quoted as saying, in 1995, “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 … the theory that the eukaryotic cell is a symbiotic union of primitive prokaryotic cells … is one of the great achievements of twentieth-century evolutionary biology.”
What was she like?
Persistent. Determined. Combative. Independent. Spirited. Courageous. Contrary. A rebel. And proud of it. “Some colleagues label me combative; others, unfair. Some say I only collect relevant work and unfairly ignore contradictory data. These accusations may be correct.”
The chapter Against Orthodoxy tells her story, and the title is Margulis’ view of how she is, and why she succeeded. She liked to shock people. A non-conformist female in a male’s world, who continued to push her views (ignored, discredited, at times ridiculed) until many were finally accepted, becoming part of the canon. To many, especially young women, she must have been inspirational.
Previous library review:LifeThe Science of Biology Next library review:Tigers in Red Weathera quest for the last wild tigers["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>["br"]>
To me, this book is a prime example of how science works in forming inferences from observable basic data and experimentation. Each inference has its champions and dissenters, and the discord between them over time prompts further scrutiny to either refine and increase our knowledge base, or invalidate an inference. That in stark contrast to the agenda based pseudo science of our materialistic culture that is intended to distract.
Herein is an inference championed by the author an others, that through the rigorous critical assessment of the scientific approach and further research will hopefully aid in the pursuit of understanding our being.
What, to me, distracted from the presentation are the author's focus on herself, a whole chapter about the shortcomings of taxonomic practices, and at times the tone and verboseness. However, I read this to get a better understanding of SET (serial endosymbiosis theory), where others might enjoy tangental meanderings if only for mental relief :-)
I think the writing is fair, and one can glean a basic understanding of SET from the material, along with a verbose clarification of the term Gaia in the final chapter.
I'm confused by a review that describes this book as concise, because I found it to be anything but. It seemed like the entire manuscript had been chopped up into paragraphs and rearranged, then never reworked for logical flow. It jumps from topic to topic in a not-at-all-charming way. It introduces terms 20 pages after the main discussion they were relevant to, if at all. It triggered far too many eye-rolls and sighs of exasperation in me, particularly at the awkwardly syrupy, sweeping, citation-needed passages that end many "chapters."
I also don't feel like I actually learned much new about evolution. "Hey, guess what? Organelles used to live outside! Wacky, right?" Yes, I've heard. That's why I'm here.
The science itself is scant and buried in answers to relevant, but less exciting questions: Historically, who has come to similar conclusions and been rejected by the larger scientific community? Which aspects of their ideas are wrong and right? Who disagrees with the author, and why are they wrong? What happened when she went through the halls that one time?
Oh, the anecdotes and autobiographical information! Yes, these are pivotal events in the journey to her eventual area of study, but I was not prepared for this! I wanted to read about symbiogenesis! RAAR!
*deep breaths*
Aside from those memoir bits, perhaps the book is an accurate reflection of how science is done. Occasionally you look through a microscope or something, but mostly you're wading through academic papers, dissecting their ideas, and responding to criticism.
That may excuse much of the content, but not the form. Not all scientists can write books for a general audience by themselves. That's fine! They shouldn't! The problem is she did.
P.S. You can't object to the personification of Gaia and then call her "a tough b*tch" on the next page where it suits you.
The work presents a concise explanation of the author's Serial Endosymbiosis Theory (SET), which she regards as the key to speciation. She's probably correct for the most part. I appreciated her explanation of the historical (taxonomical) development of the kingdoms among which the various forms of life are distributed, although said explanation would have been appreciated even more had it appeared earlier in the book. Her clarification of the Gaia hypothesis was skillful, but I take issue with her assertion that humans can do no real damage to nature. While it's probably true that humans lack the ability to destroy all life on Earth, we can certainly seriously reduce the diversity of life and go extinct ourselves in the process. I find somewhat less satisfaction than the author apparently does in the knowledge that some bacteria will survive the impending anthropogenic destruction of the biosphere and start the whole evolutionary process again. Her chapter on the origins of sex struck me as weaker than other parts of the book, but she has other works that focus on that particular aspect of evolution. I look forward to reading them. Her autobiographical detours were delightful, but that's a practice in which only senior scholars can safely indulge. The book is a quick but rewarding read for anyone interested in evolutionary biology.
Fascinating concept, irritatingly chatty and discursive execution. Much as I enjoy hearing what it was like to be married to Carl Sagan, the incessant name-dropping of colleagues and family members detracts from a clear narrative arc.
The Symbiotic Planet is a new look at evolution by Lynn Margulis. Some of the issues which Margulis is hoping to address, clarify and interpret in the language of biology - within a framework of a broadly understood concept and philosophy of Gaia - are far reaching and transcend our common human-orientated species specific arrogance: 'The planet takes care of us, not we of it. Our self-inflated moral imperative to guide a wayward Earth or heal our sick planet is evidence of our immense capacity for self-delusion. Rather, we need to protect us from ourselves'. The author proposes a Serial Endosymbiosis Theory as the mechanism behind the process of biogenesis and evolutionary diversity of life. Highly recommended for anyone interested in biology, deep ecology, evolution and the history of life.
Life is a planetary level phenomenon and the Earth has been alive for at least 3000 million years. To me the human move to take responsibility for the living Earth is laughable - the rhetoric of the powerless. The planet takes care of us, not we of it. Our self inflated moral imperative to guide a wayward Earth or heal a sick planet is evidence of our immense capacity for self-delusion. Rather, we need to protect us from ourselves.
*
So far the only way in which we humans prove our dominance is by expansion. We remain brazen, crass, and recent, even as we become more numerous. Our toughness is a delusion. Have we the intelligence and discipline to resist our tendency to grow without limit?
Margulis presents her theory of evolution -- it happens through symbiosis between and within organisms. We do not just evolve from bacteria but we incorporate more bacteria and other simple life forms into our system. Protoplasmic genes do matter and are important components of our genetic inheritance. She labels her theory "Serial Endosymbiosis Theory." It is a worthy read.
En Planeta Simbiótico la brillante biologa Lynn Margulis nos habla de la teoria endosimbionte que la haría estar en todos los libros de biologia de bachillerato, aunque nunca se la mencionara mas alla de "eh, niños, ¿recordáis esas gominolas naranjas y verdes de la celula eucariota? Si, si, esas con nombres tan simpáticos, la mitocondria y los cloroplastos. Pues que sepáis que esas células son bacterias que una célula mas grande se comió y se fusionaron". Eso, amigos míos, es capacidad de síntesis.
La teoría endosimbiotica pertenece a esa reducidisima categoría de teorías que asombran por su brillantez y lógica; sorprende que nunca nadie hubiera pensado en ello -que ocurrió, ojo, Margulis lo cuenta en su libro-. Es una teoría brillante, de la que me hubiera gustado saber mucho mas de lo que se cuenta en el libro, que no deja de ser un resumen accesible pero glorificado de la teoría y de como se puede extrapolar a la ecología planetaria y exoplanetaria: Gaia, y las ideas de Lovelock. Pero Gaia científica, ojo, Gaia como conjunto de sistemas imbricados, no la interpretación new age de la tierra injuriada y vengadora. Es un buen libro para adentrarse en el pensamiento de Margulis y sus ideas científicas, y conocer un poco mejor una teoría que permite comprender, de una forma diferente, el origen de la vida y su significado: una nueva dosis de humildad para el ser humano y su ombliguismo. Desgraciadamente, no me ha podido explicar mucho mas de lo que ya sabia. Por lo demás, un buen libro.
A lovely concept. Endosymbiosis as a means of creating new species and higher order organisms. Serial endosymbiotic theory (SET) aims to account for the differentiation of five major kingdoms of life through the composition of multiple types of microbes to allow higher order life to emerge.
It's a broad survey of SET tracing its origins and highlighting challenges, victories, and social response, peppered with personal anecdote and reflection. It feels a bit scattered and difficult to follow without rich prior knowledge, and the thread jumps around a bit... but the core idea of SET is so interesting, so it's forgiven.
"We need to be freed of our species-specific arrogance. No evidence exists that we are "chosen," the unique species for which all others were made. Nor are we the most important one because we are so numerous, powerful, and dangerous. Our tenacious illusion of special dispensation belies our true status as upright mammalian weeds."
I appreciate this mindset because I share it. This book was by turns interesting and skimmable. If all the autobiographical banter had been pared out I would have rated it higher. Still a good book though.
Maravilla. He leído estas páginas con mucho asombro de lo que me fueron revelando. Aunque me perdí en los específicos, química y biología demasiado avanzada para mí, pero me quedo con la visión de un mundo de procesos, de conexiones, de preguntas. Un mundo invisible del cual dependemos, el cual también somos. Y una mirada llena de curiosidad y valentía.
I'm a sucker for popular science books. As a minor member of one of C P Snow's Two Cultures, I am respectful of but in no way conversant with the scientific mind (and even less so of technology), so popular science writings are my way of consuming regurgitated scientific principles without too much indigestion.
Lynn Margulis is a celebrated microbiologist who has, by all accounts, done sterling work on the relationships between bacteria, fungi, plants and animals. Her main contribution to science is her endosymbiotic theory, which postulates that over millions of years organisms have often absorbed or been absorbed by others, developing and evolving into new organisms (I think I have that right). For example, human cells have long been known to include bacterial relics such as mitochondria, which among other attributes process oxygen and provide the energy that keeps us going, and without which we would certainly not have evolved to be here.
The Symbiotic Planet goes further than that, however, and suggests links with James Lovelock's Gaia hypothesis. Gaia, so beloved by some mystics, feminists and romantics, is actually the name currently given to the processes that help to regulate the planetary eco-systems that sustain life in its myriad forms, not some anthropomorphised goddess that needs worshipping (as would have happened in the classical period).
There are lots of exciting ideas here, the distillation of many years of work, collaboration and stamina, and I certainly am in no position to criticise the science behind them. Her writing at times exhibits passion and poetry, and you can see that this is a real powerhouse of a woman who converses and argues with other scientists (inter alia, she was married to Carl Sagan for nearly a decade) to expand horizons and perpectives.
What I am less happy about in this book, though, is its poor editing and occasional lack of clarity and direction. Many of her other books are co-authored (often with one of her sons) and I feel that this publication could have done with more imput from other minds. We have a whole chapter on her early career which, while interesting, diverts from the main thrust of her arguments. There are fine diagrams, but they are often placed arbitrarily amongst the pages and labelled inconsistently when compared one with another. There is an index, but us non-scientists, at whom the book must largely be aimed, would have welcomed a glossary when new terms are introduced (though to be fair these are sometimes partly explained a few pages on, but sometimes not at all). And there are occasional misspellings (an obvious one is 'archaebacteria', appearing twice on one page as 'archeabacteria', which raises concerns about those I must have missed).
Most of these faults must be laid at the door of an editor (was there one?), because there is no doubting the enthusiasm, expertise and creativity of the author. In fact, one of the plus-points of this book for me, as a non-scientist, was the analogy I can see with the creative arts (not to mention technology). I've often suspected that it's hard to create new art-forms de novo, and that most artistic innovation is the symbiosis of two or more distinctly different genres; The Symbiotic Planet's arguments provide the perfect parallel in describing the evolution of life-forms.
Wowa, scientists really love talking shit about politics without having read a single work in that field, eh? Even when I was a dumb wee genetics kid I knew there was something worth hearing from the counterculture. Seems Lynn Margulis just lumps all cultures together into one big monomyth of ignorance, which her scientific mind cuts through like a prismatic spray.
So the good points.
Lynn Margulis radically challenges Neo-Darwinism with her theory of endosymbiosis. Essentially, Darwinists (though perhaps not Darwin himself) saw competition as the sole driving force of evolution. There is interspecies competition (between species) and intraspecies competition (within species). An example of interspecies competition: two different species have overlapping niches. Mutations in either of the species' gene pools that enable greater exploitation of the environment (absorption, utilisation, expansion, etc), will lead to more successful future populations. An ongoing arms race ensues, and both species change over evolutionary time. An example of intraspecies competition: two animals of the same species are courting a mate of the opposite sex. They're being judged on their ability to build a comfy nest. The one who is selected and the one who does the selecting will pass on their genes. The population will shift towards comfph city, with both the desire for comfy nests and the capacity for building comfph surviving.
As any humanities student will notice, this understanding of a natural law is suspiciously aligned with capitalist ideology which arose concurrently during the Enlightenment and Western imperialism . . . we'll come back to this later.
Lynn Margulis argues that endosymbiosis is a far more important driver for evolution than competition. Her theory of endosymbiosis can be understood as the merging of two previously distinct species. If Darwinian selection branches the tree of life, endosymbiosis merges branches into rhizomal networks. Visualise two branches of the tree of life coming together and then splitting off into three. Two of these lines are the original ancestors (who keep trucking along) and the third is the new progeny (who has novel capacities and will likely colonise an uninhabited niche). This theory was proposed in the 60's and ridiculed for decades. It is now taught in high schools.
Even though Lynn is against "politics" and implicitly posits "science" as the cure for . . . well everything (scientists love doing this and it's arrogant and boring as heck), her theory fundamentally challenges Darwinian and capitalist ontologies. In other words, her theory is political. She suggests a world whose development came about not through competition and the slow accruement of beneficial mutations, but through the wholesale merging of separate beings with all their genetic matter. Species proliferate from their interspecies ruptures into one another's lifeworlds, through failed ingestions that lead to indelible biological alliances. Out of two comes one. This is an ontological reversal of the most extreme case.
Out of this understanding, comes a political revelation that life innovates through mutualism. In other words, Lynn Margulis reproduces Peter Kropotkin's Mutual Aid argument, at the level of biogenesis. This is the biological equivalent of the discovery of quantum physics. It's profound, strange and exuberant.
Later on, she connects endosymbiosis to the Gaia theory. Gaia theory is the idea that earth itself is living, in the sense that it has a metabolism. A metabolism is simply something that regularly transforms matter (one chemical compound into another chemical compound) through the use of energy (solar, sugar, protein, etc). A homeostatic environment is created. This is not a static (still) environment, but a regulated (flowing) environment. Things transform, but in a predictable manner. In other words, constant change creates stability. Gaia, like endosymbiosis, is the merging of all ecosystems into a greater emergent totality — it is the Tao of Earth.
So the bad points.
The book kinda ends with Lynn saying heyo, we got no control over anything, Gaia will just do its thing, dumb scientists are dumb and environmentalists succ.
Like, she spends all this time, literally undoing the ontology of genetics, and then just doesn't go into its implications. She makes fun of spiritualist understandings of Gaia, but her own understanding is cynical detachment. She fails to understand that being apolitical is the political stance of the status quo.
It's like she has absolutely no understanding of how Darwin's theories of evolution have reinforced capitalist ideologies, leading to the massive exploitation of Earth's resources towards a state that will, (of course) right itself in due time, but after the death of many, many beings. I'm pretty nihilistic, but Lynn's detached cynicism is disgusting. She doesn't seem to understand that the beings on the margins of society will suffer far fucking more than those in the centre driving catastrophic climate change (yes, I'm talking about capitalists). Like yeah whoopie! Gaia will never die, but we will. I don't think life is precious, but I think freedom is, and that freedom is the freedom to live or die however I want. In such a way, freedom has to be understood as a network of effects that intersect at both micro- and macro-social levels. It is never individual, but mutually constituted by our environment and our kin (yiff). Lynn seem to understand that on a biological level but not on a political one. She doesn't seem to understand that catastrophic climate change is a tyrannical end determined by the few towards the many. It is the destruction of freedom through the theft of the future.
Her ignorance of politics is most evident in Chapter 2 where she outlines the resistance to her ideas in the 60's-onwards from the scientific community. While she is right that there are dogmatic scientists who cling to their theories as Platonic ideals, she doesn't understand why this is; and while I appreciate her stress in materialist practices, hers is a materialism of naivety. Universities organised along capitalist principles of competition lead to neurotic dogmatism, because to be scientifically contested is to be economically undermined. Competition becomes a threat to one's material existence. Furthermore, once an institution has gained widespread legitimacy, the critical thought that founded it becomes secondary to its own reproduction. The effect of institutionalised power in a competitive and hierarchical social field is ignorance, arrogance and gate-keeping.
Lynn laments the lack of critical thinking in the scientific community but she fails to understand its material origins. Anyone who's worked at a university will have experienced the threat of departmental cuts from lowered student numbers (leading to wasteful spending in PR campaigns and petty interdepartmental squabbles) and the auditing of teaching staff performances in relation to student grades (leading to simplified lecture content). It's because of such pressures that critical thinking is less and less taught and instead students are taught diagrams, names and dates. The scientific method comes second place to the reified concept, an infobyte that perfectly resembles the capitalist commodity form. Lecturers and students begin to resemble the dead facts they hollowly recite. This is preferable for the university, for critical may lead to the development of not just scientific critique, but also, social critique. Perhaps Lynn should have paid more attention to the counterculture, instead of denigrating it, because such movements can help us build more grassroots and emancipatory scientific and pedagogical frameworks, that nourish life as a living relation and a mutually-constituted freedom.
As someone who is currently studying evolution for my PhD, symbiotic theory of the mitochondria was my favorite thing I learned about in grade school. Furthermore, I'm from the same area as Lynn Margulis (which meant I was also a sucker for her perfectly selected Dickinson quotes at the start of each chapter), so I was really excited to finally read one of her books. I had heard before hand that some of her ideas were more extreme and controversial and I was pleasantly surprised by how clearly and with what great self awareness she wrote about which of her ideas are accepted and which are more debated. Of course, as the book is from 1998, there are some ideas she puts forward that have been disproved, or are slightly different than she anticipated. But even for her time, she will often reference specific people and articles that contradicted her ideas. While she is clearly biased towards her own hunches, she has no problem giving people easy means to hunt down other ideas and to develop their own opinions.
A few places felt particularly out of date, reading the book 20 years later. The chapter 'Sex Legacy' uses very mammal focused language, unlike the rest of her book, which puts emphasis on diversity of life forms. It almost felt like she was trying to take advantage of the frankly 'sexy' nature of sex, and tried to make this chapter more accessible for non-scientists. I am not sure if this was the intended effect or if it would succeed, but it felt weird to suddenly be using such human mindsets when the rest of the book is so microbial language-centric. This is not to say that this section was without insight, it included many fascinating ways of understanding the evolution of life, but the language occasionally felt out of place.
Her last chapter 'Gaia' ends with her contribution to thoughts on human impact on the planet. She reminds us that we are just another species, and that we are not a separate thing from nature, and therefore cannot really destroy it, we can only make it unlivable for ourselves. This is true, however she also claims that basically all other animals will be fine despite our actions, but really we are destroying the planet for us and other organisms like us. She is right that yes, bacteria will survive, humans are not going to stamp out all life on Earth, but the effect that humans are having on our fellow animals, we now know is more substantial than her final passages may lead us to believe.
Margulis is the type of scientist who was able to describe major theories that changed the way we view life and evolution because she was unafraid to begin exploration of ideas that were currently lacking in data. It is visible in this book, the same traits that made her controversial, are what drove her admirable knack for the formation of new hypotheses.
Lynn Margulis' Serial Endosymbiosis Theory (SET) proposes that advanced life started with the combination of bacteria that were living symbiotically. There were three steps:
1. Heat and acid tolerant archaebacteria merged with spirochetes, the later forming undulipodia and giving movement. The archaebacteria became the nuclei.
2. The swimming anaerobes merged with oxygen breathing bacteria, becoming the mitochondria that allow the product to cope with increasing levels of oxygen. These are the ancestors of animals and fungi.
3. These bacteria then merged with photosynthetic cyanobacteria, to form the ancestors of plants - the cyanobacteria becoming chloroplasts.
The DNA retained in mitochondria closely resembles that of oxygen breathing bacteria. The DNA retained in chloroplasts resembles that of cyanobacteria.
The book is somewhat autobiographical and details earlier thinkers that led her to SET. Margulis describes her efforts to reshape taxonomy of lower life to reflect the evolution of life.
Wally Gilbert proposed that RNA formed in a non-living "biochemical evolution", and that RNA acting as a replicating ribosome became the kernel of the first cell.
A chapter on sex includes a great description of life in the Proterozoic Era. It is suggested that sex originated as abortive cannibalism, where one protoctist tried to consume another, failed but allowed the two nuclei to merge.
Margulis describes an eco-system as the smallest unit that recycles the biologically important elements.
The term Gaia was suggested to James Lovelock by William Golding ("The Lord of the Flies"). As opposed to popular culture, Lovelock proposed Gaia not as an organism but as the aggregate of systems present on earth.
Margulis strives in this short book to connect the idea of Gaia with her symbiotic theory of evolution and does so quite convincingly to my mind. I appreciate her scientific explication of the Gaia Hypothesis, as opposed to the widespread, pop-spirituality one of a personified uber-organism. In Margulis's words, "Gaia itself is not an organism directly selected among many. It is an emergent property of interaction among organisms, the spherical planet on which they reside, and an energy source, the sun."
Lynn Margulis explica la Teoría de la Endosimbiosis conectándolo con temas como Origen de la Vida, Evolución e Hipótesis de Gaia de una manera entusiasta, amena y hasta graciosa; pero siempre utilizando argumentos científicos.
Cada capítulo comienza con un poema de Emily Dickinson y se desarrolla entre anécdotas (personales o de investigadores clave), ejemplos, dibujos y referencias a artículos o libros. Aunque se publicó en 1998 (y existe información más actualizada) este libro es un buen punto de partida para cualquiera que se interese en el tema.
The ideas were fantastically interesting and thought-provoking (as with Margulis's last book I read, Microcosmos, which was cowritten with her son Dorion Sagan).
The actual writing style and execution, though, were not great. Repetitive, incohesive structure, sometimes unclear. Margulis is not much of a long-form writer. Still, I was definitely interested enough to read the whole book. The writing wasn't bad, just not great.
Interesting in that it explained how cells were formed by symbiotic relationships between bacteria, but failing to explain how symbiotic relationships in general speed evolution forward.
Wer sich für Wissenschaftsgeschichte interessiert, kann hier auf seine Kosten kommen. Lynn Margulis, Ex-Frau von Carl Sagan und Mutter von Dorion Sagan, außerdem - und wichtiger - die "Mutter" der Endosymbiontentheorie, plaudert nämlich hier auch ein bißchen aus der Schule, sprich: aus ihrem Leben. Obwohl das Buch primär eine historische Übersicht der Entwicklung der Endosymbiontentheorie bietet, enthält es auch einiges Privates, so über jugendliche Eskapaden. "In secret exercise of my perceived rights as a person of free will I snuck out of the University of Chicago eight-grade laboratory school, with its vastly inferior pool of potential boyfriends, and returned to the huge public high school where I had decided I belonged. I refused to stay another day in that lab school, where everything was so familiar and algebra was so hard. I was living in my parents' lovely South Shore Drive apartment and decided that running away was the only solution. Of course, I had no money, nowhere to go, and a rigid schedule of classes and duties." Es kam wie es kommen mußte. "Fury hit the fan when the high school administrators realized that my parents had no idea that I was not in the lab school; when I had told them that I was leaving I hadn't admitted that my parents didn't know. Of course my parents had not noticed the missing tuition bill. - Many teary sessions followed in and out of school." Man bekommt aber einen Endruck, warum sich der charismatische Carl Sagan von dieser dickköpfigen jungen Dame angezogen gefühlt haben mag. "At age fourteen I was lucky indeed to be accepted into the University of Chicago's special early entry program. Although three and a half years later I graduated with many acquisitions, including a liberal arts degree and a husband [Sagan], by far the most lasting was a thoroughgoing, finely nurtured critical scepticism. I cherish my University of Chicago education for its central teaching: one must always strive to distinguish bullshit from authenticity."
Obwohl das Buch nun schon ein paar Jahre alt ist (1998) bietet es einen immer noch aktuellen, allgemeinverständlichen, aber knapp gehaltenen (146 S.) Überblick sowohl über die Endosymbiontentheorie als auch über die Gaia-Hypothese. Ein klein wenig Grundwissen über beide Themen sollte man allerdings mitbringen. Der einzige Wermutstropfen ist die spärliche Ausstattung mit nur wenigen und durchgehend schwarzweißen Abbildungen. Beide, die serielle Endosymbiontentheorie (SET à la Margulis) und die Gaia-Hypothese, werden im Kontext ihrer historischen Entwicklung dargestellt. Insofern ist dies nicht nur ein Lehrbuch, sondern vielmehr ein Geschichtsbuch aus individueller Sicht – aber wie gesagt: man sollte sich wirklich für Biologiegeschichte interessieren.
Margulis ist von Grund auf Optimistin. Sie meint, die Erde wird auch mit so schädlichen Organismen wie Homo sapiens fertigwerden: "Gaia, a tough bitch, is not at all threatened by humans".
In my recent reading of Merlin Sheldrakes’ book; Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures, I was introduced to how important symbiotic relationships are to many of earth’s living creatures. Sheldrake referenced Lynn Margulis several times in his book so I put her book, Symbiotic Planet, on my reading list.
I found this to be a very educational and fascinating book. Basically, Margulis puts forth the theory that living creatures evolved even more through symbiotic relationships that they did via the steps articulated by Darwin.
Now don’t panic - I am not an anti-darwin, flat earth, earth was created in seven days type of guy. Rather I do think that Margulis makes an excellent case for the importance of symbiotic relationships and that their importance has been overlooked by the scientific community.
Symbiosis is a convenient shortcut when a species wants to survive in a new or changing environment. For example, rather evolving an entirely new digestive system one organism can pair with another one that already knows how to digest the new food. In a way, I picture this a bit like the process of pre-mastication where mothers of some creatures pre-chew food to produce baby food capable of being consumed by their offspring during the weaning process.
Margulis points out that Darwin said very little about the actual origin of species in his book of the same name. What he focused on was how a species adapted to a change in their environment, such as a bird developing a longer beak in order to feed, but not where the species came from in the first place. Margulis focuses on the actual origin of the species and suggests that entirely new organisms came about by the merging together of two or more existing ones. As cited in both this and Sheldrake’s book, lichen is an organism that emerges from algae living among the filaments of fungi in a mutually beneficial symbiotic relationship. This relationship is so successful that lichen has the ability to breakdown solid rock into soil and thus opened the earth’s surface to every variety of plant and animal we see today.
This book was published twenty-four years ago so I am sure there are more current books by other authors. However, I found Margulis writing and presentation of her theories engaging and very easy to follow. The traditional presentation of “the tree of life” looks very different after Margulis redraws it and this has prompted me to rethink what I thought I knew about evolution. As the bumper sticker on my car says, “I think, therefore I am dangerous”. I hope that reading this book will go a long way toward prompting thinking in others as it certainly did with me.
This is my first introduction to Margulis as an author, though as someone that tries to follow as much of current research in Biology as possible, I was very much aware of her work involving SET theory, without knowing who she was. Having said that though, I do have to say I was a little disappointed in this book overall. My general impression is that Margulis is the type of person that is much smarter than the average Biologist, and has a better grasp of viewing these kinds of concepts in a “big-picture” type mentality than the average scientist. But I just don’t quite feel like that came through in this book very well.
I don’t think very many Biologists think of natural selection as a great source of innovation any more. It seems to hold better explanatory power for why populations tend to remain stable. So the quest is try to now explain where and how the innovation of traits comes from. I was hoping that this book would give me a little better insight into this issue. It did not. Certainly Margulis made a good case as to how and why symbiosis is a powerful force in how life evolved on this planet when we are talking about microbes. But apart from hinting at the fact that there might be more to the story when we move to multi-cellular animals, it kind of fell short. It seems that the best she could do was to try to relate this idea of symbiosis to the rather unpopular Gaia Theory.
The frustrating thing about this book, is that I’m left with this distinct feeling that Margulis knows much more about these topics than she presented in this book. I’m left feeling like if I could go have a cup of coffee with her for the afternoon, and have a chance to grill her about why she holds some of these particular views--what she feels is the real evidence for holding these views, I might feel more satisfied with her thesis.
This book spurned my interest enough into Margulis’ work that it has made me add a couple of her books to my to-read list. But overall, I just wish it could have been a little bit more in-depth and coherent.
Hay un vicio que Lynn Margulis que comparte junto con su ex-esposo Carl Sagan y Richard Dawkins, y es el irse por las ramas en su ensayo, criticar a otros científicos, e incluso dedicar capítulos enteros a sucesos de su vida (por ejemplo, el divorcio de Carl Sagan), que francamente no aportan absolutamente nada a la obra ni a los temas a tratar; además, y lo más repetido, por no decir lo más estereotipado, es que prácticamente se pelean con otros científicos con los que no están de acuerdo, dando una imagen de que un buen científico es aquel que se niega a todo y tiene una actitud pedante y llena de superioridad moral, cuando todos estamos en el mismo barco de estar muy lejos de comprenderlo todo en nuestra realidad.
Este libro no es la excepción y me parece que pudo haber sido, sin problemas, un buen ensayo de 40 páginas si las ideas hubieran sido bien hiladas y concretadas. De hecho, el libro parece más bien una recopilación de datos al azar para justificar la teoría endosimbiótica. De repente Lynn da por sentado que sabemos la evolución de los hongos y otros taxones y no se detiene a explicar con más paciencia lo que está pasando con su teoría.
Hay capítulos enteros donde se pelea con científicos con los que no está de acuerdo y el capítulo final, dedicado a la teoría Gaia, es una sarta de alegatos y refutaciones tan numerosas que resulta en un dolor de cabeza.
Un libro que técnicamente está muy mal ejecutado, resulta caótico y deja en segundo plano el objetivo de divulgar y hacer llegar de una manera más accesible el conocimiento científico.
Una prueba más de que la divulgación científica tiene serios problemas de comunicación y de procesos de edición en cuanto a corrección de estilo.
Explora el concepto de la simbiosis como factor fundamental de la evolución y como generador de novedad. Desde las interacciones entre arqueas y bacterias que desembocan en los diferentes tipos de células eucariotas mediante endosimbiosis pasando por la idea de que las simbiosis entre organismos forman organismos novedosos actualmente hasta llegar a la concepción de que todo el sistema de la Tierra es una simbiosis de organismos llamada Gaia. A través de los diferentes capítulos se expone que las simbiosis han prevalecido y prevalecen ante la individualidad, se explica la Teoría Endosimbiótica Serial de Lynn Margulis (SET), la dificultad a la que se enfrentó para obtener aceptación por parte de la comunidad científica de la versión “solo tres de cuatro de la SET” y la controversia respecto al paso 2 de la SET en el que las espiroquetas serían el organismo previo a la endosimbiosis que desembocaría en los ondulipodios, también habla de como la taxonomía pasa superficialmente por las interacciones y endosimbiosis entre organismos y critica la noción de las bacterias como gérmenes a eliminar cuando la mayoría son beneficiosas para los sistemas, en cuanto al origen de la primera célula repasa los diferentes enfoques y apoya el inicio en las microesferas generadas espontáneamente y similares a membranas celulares. Explica el origen de la reproducción sexual meiótica desde la simbiosis entre organismos bajo condiciones de estrés y como canibalismo fallido y termina con la idea de Gaia como una gran simbiosis entre todos los sistemas de la Tierra que se autorregula, recicla la materia y la distribuye mediante los fluidos del planeta, atmosfera e hidrosfera. Me ha interesado y adormecido a partes iguales
I found this book lacking most logical continuity or narrative chronology, but I also found it rather insightful. It's a shame, the structure. Margulis is on top of her game and her Serial Endosymbiotic Theory is rich, as is the explanation of scientific Gaia Theory. However, it seems like a tendency to leave it all to hindsight and explain everything really makes The Symbiotic Planet inaccessible. Her prose is, at times, accessible--however, she gives no forewarning before launching into a scientific explanation and rattling off the top researchers in the subject area she is speaking on.
Basic essay structure would have done this book wonders.
In other news, this is the first science I've read in a long time. I am eager to see if other scientists have a better grasp on the human language, no hate intended, heehoo.
"We can group life into three or five or a million categories, but life itself will elude us."
Wowza. This was a read. It wasn't overly long (about 130 pages not including the notes and index sections) which was great for me, because if it was an longer I may not have made it. There were parts I found interesting and even poetic from Margulis, but on the whole I found this to be rather dry and unapproachable for someone who doesn't come from an extensive scientific background.
Definitely not a book to take on lightly of you don't regularly ingest some form of scientific content. There was a lot of heavy jargon and name dropping of various scientists and their work.
I read this for a college course and can see the value in it from an academic perspective, but I definitely wouldn't have read it casually.
Escrito poco más de una década antes de su muerte, se puede considerar un manifiesto científico sobre el origen de la vida compleja multicelular y sobre la Teoría de Gaia, en la que se reconoce a los seres vivos como reguladores activos de las condiciones climáticas y químicas para que el planeta Tierra prevalezca benevolente hacia la vida. No hacia una especie en particular, mucho menos la insignificante pero muy arrogante especie humana. Como ya tiene poco más de 20 años, algunos conceptos no están actualizados, como el actual "árbol de la vida", la relación y clasificación de todas las especies vivas, pero muchas ideas son muy importantes para entender la vida, la biodiversidad, la importancia de la simbiosis en la evolución, etc.
Scattered but illuminating: for its articulation of symbiogenesis and its centrality to life’s development, for Margulis’s passionate microbe-level view of the world, and for its clearing of the air around Gaia.
The memoirish bits, to my mind, actually add a lot, helping locate these concepts amid networks of scientists, discourses, attitudes at a particular moment. She mentions that one thing she valued in her university training was an emphasis on reading the original writings of pivotal researchers alongside the more typical, updated textbook syntheses of their ideas. That’s what we get here, and I think it’s invaluable for understanding late-20th-c biology.
Un libro de lectura obligada para comprender la evolución y cómo surgió la vida compleja. Lynn Margulis con un estilo sencillo hace un recorrido que permite entender cómo se dio el proceso por el cual las células eucariotas llegaron a serlo (camino evolutivo del cual descendemos), haciendo un repaso a su propia vida y cómo dio con la Teoría de Endosimbiosis Seriada (SET, en inglés), así como explica la forma en que el planeta es un sistema que permite sostener la vida, la teoría de James Lovelock (Gaia).