Symbiotic Planet

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* Book: Symbiotic Planet: A New Look At Evolution. by Lynn Margulis. Basic Books, 1999



1. H.J. Spencer:

"This book summarizes the scientific evidence for three of the most radical theories that are changing our basic ideas about Life and Biology:

  • Symbiotic Evolution,
  • the Gaia Hypothesis and
  • the radical Five-Kingdom classification of all life forms.

Lynn Margulis is best qualified to discuss these topics as shewas either the originator or a major developer of these ideas."


2. From the publisher:

"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."




H.J. Spencer:

"In the course of her research, Margulis discovered that an American anatomist, I. E. Wallin proposed in the 1920s that several vital cell components, like mitochondria and chloroplasts, originated as symbiotic bacteria. When he was not being ignored, he was strongly condemned for daring to suggest that 'germs' could contribute anything positive to life forms that were rigidly believed to exist as only animals or plants. Additionally, in reading old biology books, Margulis did find links to the Symbiogenesis ideas of Merezhovsky. This stimulated her focus on the role of bacteria and her laboratory evidence that symbiotic associations between prokaryotic bacteria were absorbed into eukaryotic cells in the form of forerunners of distinct, independent organelles in a process that Margulis called Endosymbiosis (some symbionts living within a larger organism). Since Margulis proposed that this process had occurred several times over extended timeframes, she added the word 'serial' to emphasize its recurrence; so this is why she has described her theory as Serial Endosymbiosis Theory (or SET)."



H.J. Spencer:

"This final chapter may be the one with the widest appeal to the general reader, so I will expend quite some effort in summarizing its main points. Margulis was one of the first scientists to correspond with the originator of the GAIA theory, James Lovelock - a scientist as unusual (and independent) as her. She relates the little known origin of this revolutionary theory [that I accept]. Lovelock was consulting with NASA in the mid-1960s, helping to devise ways to detect life on Mars. He realized that life on any planet would have to use its fluids to recycle the elements required by life; on Earth this would be the atmosphere, oceans, lakes and rivers. Nutrients had to be supplied and wastes removed, making the chemistry of a living planet markedly different from that of a lifeless one. Lovelock was concerned about the amount of free methane in the Earth's atmosphere because oxygen reacts very strongly with this gas to produce CO2. He also knew that hydrogen and nitrogen react explosively in the presence of oxygen yet all co-exist on Earth; so these high levels must be being actively maintained. Lovelock asked Margulis about this mystery. She knew that most methane gas is produced by methanogenic bacteria that live in water-logged soil and cattle rumen, where it is released from the mouth (not by flatulence, as many believe). There is a further mystery about the Earth that it has become cooler in the past three billion years, while cosmologists theorize that the Sun, as a typical star, should have become hotter and warmed us up. So, Lovelock theorized that temperature and atmospheric regulation must occur on a global scale. These ideas led him to view our planetary environment had to be organically homeostatic: kept within a viable range for all the life forms here. This suggestion of 'optimization' generated the usual result from many intellectuals, like they resisted Maupertuis' Action-Optimization in 1744 (that predicted Newtonian physics) as this could only be achieved by intelligent humans, like themselves [for details see my Least-Action essay].The word Gaia was suggested by novelist, William Golding ( Lord of the Flies) who was a neighbor in the UK; this was related to the Greek word for 'Mother Earth' and forms the root of linked words, such as geology, geometry and Pangaea. Margulis thinks this was too good as it appealed to some religious people and feminists with its hint of a living goddess; however, it does also appeal to environmentalists. Margulis supports GAIA as a scientific theory but vacillates about whether this implies all life on Earth is a Super-Organism, evolving from the present ten million species. She denies this is a living organism because they all need energy (from the Sun?) and produce waste (plenty of that in the seas?). Although Margulis claims that GAIA is only an emergent property of Earth's life forms, she does admit that "GAIA is a tough bitch, not at all threatened by humans" as we are real Johnny-come-lately organisms that she dismisses as "upright, mammalian weeds". She regrets that the Goddess idea has encouraged anti-science movements and excoriates the Puritan-Feminists for the "rape" and destruction of the sunlit Earth. She diminishes its appeal by seeing it as only a convenient name for the regulation of temperature, acidity/alkalinity (pH) and gas mixtures - a purely scientific perspective. Margulis is betting on her favorite life-form: bacteria. These 'primitive' creatures first removed the huge quantities of hydrogen (H2) from Earth's atmosphere and then from the hydrogen sulfide (H2S)emitted by volcanoes. Later, they released oxygen from water (H2O). She even claims that bacteria survived the numerous extra-terrestrial impacts over their three billion year history whose energy vastly exceeds all our stock-piled nuclear weapons. I am not so sanguine as Lynn, nor do I think most people who first survived a nuclear war would be satisfied to know that bacteria are ready to repeat the Great Game of Life. Amusingly, Margulis reminds us of one our deeper senses, proprioception [see my essay SENSES, for details]. Animals use this sense for awareness of movement and spatial orientation. Lynn believes that the Earth (GAIA?) has enjoyed a proprioception system for millennia, long before humans appeared. She claims that this Sense-of-Self is as old as life itself - a nice thought."