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Microcosmos: Four Billion Years of Microbial Evolution

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If you're one of those who has felt worried that the earth might not survive what we're doing to it, then worry no longer! We, as a species which has brought 'wholesale ecological carnage' to the planet may not survive, but the earth surely will! What soon emerges from this insightful book is that humankind is a relatively young species, still 'vulnerable, error-prone.' Humans are not seen as the dominant species - the pinnacle of evolution - but as one of the still immature species. The real players are the species that have been here the longest, the bacteria. 'Even nuclear war would not be total apocalypse, since the hardy bacteria underlying life on the planetary scale would doubtless survive it.'

Margulis and Sagan relegate Darwin to a secondary place within the order of things: the most powerful and important changes in evolution happen not through mutation - as Darwin would have it - but through symbiosis, '...the merging of organisms into new collectives, proves to be a major power of change on Earth.' In particular oxygen-breathing bacteria merged with other organisms to enable oxygen-based life on the once alien surface of this hydrogen filled planet. 'The symbiotic process goes on unceasingly.' 'Fully ten percent of our own dry body weight consists of bacteria - some of which.... we cannot live without.' That's an estimation of ten thousand billion bacteria each!

Imagine a droplet of water with a membrane holding the water in place and allowing certain nutrients in. This is a simplified description of how it is imagined the first becteria came into being. The book offers a fascinating history of the evolution of life on our planet. This is a wonderful story full of fantastic developments spanning thousands of millions of years. Every now and then we are reminded by the authors that none of it could have taken place or could be happening now were it not for the metabolic abilities of bacteria. It gives a really eye-opening account of bacterial sex with the insight that all bacteria, all over the planet, are really part of one organism because they are all able to exchange genetic information. For instance it's thought that bacteria obtained their now well-known resistence to penicillen from their bacterial cousins in the soil. But also, you begin to get the impression that perhaps it's the bacteria which have used every means possible and are now using us too to spread onto the land and all over the planet and beyond from their original wet home in the ocean. Humans are defintely relegated to a secondary place within something much, much bigger that is (consciously?) evolving.

This is a fascinating book which has radically changed the way I perceive life and the universe. I read it with great excitement and completed it with a new awe for those minute beings, the bacteria, which have, until now, had a very bad press. The best non-fiction book I've read this year.

Microcosmos is a natural history of the unseen beings upon whom we depend every moment for survival: the microbes. Margulis, who is currently Distinguished University Professor in the Department of Geology at the University of Massachusetts, did undergraduate work in biology and received her PhD in Genetics. She worked with James Lovelock on developing the Gaia theory, which posits that the earth can be regarded as a sort of super-organism. In Microcosmos we see all aspects of her education and sensibilities -- a close attention to scientific detail and a "big picture" approach to how living entities coexist.

In the introduction she lays out her philosophy about life on earth, for which she was roundly criticized by many reductionist scientists. In the past, she writes, all life on Earth was traditionally studied as being merely a prelude to the appearance of humans. Now, overwhelming evidence suggests that microbes (one-celled organisms) not only inhabit every known living thing on earth, they are also indispensable to the survival of all living things. They, not human beings, are the most important beings on the planet.

Furthermore, in opposition to one of the most accepted tenets of Neo-Darwinism, Margulis states that life did not colonize the planet by competition so much as by networking. Cooperation between one-celled creatures led, over billions of years, to the evolution of beings such as ourselves, who possess the capability for self-conscious awareness. Our human consciousness, of which we are so proud, "may have been born of the concerted capacities of millions of microbes that evolved symbiotically to become the human brain."

Strong words! Yet, Margulis sets forth compelling evidence in the remainder of her book to support her bio-philosophical ideas. Along the way, we learn many amazing things. For instance, we get a perspective on what upstart newcomers we are: the continents we inhabit now appeared in their present locations only in the last tenth of a percent of Earth's history. We learn that bacteria invented genetic engineering. Thus, when ultraviolet light damaged early microbes' DNA, the creatures produced repair enzymes to remove the damaged portions and copy new replacement DNA. This is a natural form of gene splicing.

Sometimes, the DNA used in gene splicing was borrowed from neighboring bacteria of different strains, thus affording these critters a prodigious adaptability. This borrowing still goes on today. Through intermediaries, two very different bacteria can share genetic information. Why is this important? Because it allows the distribution of genetic information in the microcosm with a speed "approaching that of modern telecommunications--if the complexity and biological value of the information being transferred is factored in." This speed makes bacteria the biosphere's first responders in dealing with planetary changes.

In responding to change, bacteria end up altering and shaping their environments. Few people realize that the entire earth's atmosphere, which we depend on for our life's breath, was created, and is maintained, by microbes. This is a good thing to remember next time you feel like spraying down your bathroom or kitchen with anti-microbial spray. Our fear of bacteria is misplaced. Yes, some are harmful to us, but most are beneficial. Indeed they are a lot more helpful to us than we are to the rest of the planet!

This book isn't an easy read, but it will broaden one's outlook on our place in the natural world. Even if bacteria are not in the end responsible for the intricacies of our human brain and consciousness, we still owe them many debts. This book unveils the smallness of humans before the vast and minute workings of nature, and encourages a sense of humility before the greater Life that surrounds us.

Margulis and Sagan return us to the days of life's inception. It's a journey in time and scope, travelling far back and down in size. Looking at the microbial world might seem unrewarding, but they escort us through a rich trove of information. The knowledge contributes to our understanding of how we work. Although mysteries remain hidden in that distant time, the authors clearly demonstrate the logic of how early life has developed into ourselves and our animal and plant neighbours on this planet. The title suggests that the journey must necessarily occur at high speed, but they demonstrate that if we don't appreciate the beginning the remainder of the trip will be undertaken in obscurity. A better knowledge of the origins, they suggest, will also give us better insight into what the future heralds.

After some preliminary discussion of how life started, the authors move into the realm of cellular organisms. The various ideas of life's origins are fascinating, but not until it achieved the level of individual micro-organisms does life take on meaning. The authors describe the events occurring during the long reign of the prokaryotes. These simple organisms were little more than a bag containing some genetic information. Yet, their emergence was the start of true life. While it's easy to think this "primitive" organism has faded into oblivion with the passage of time, the authors remind us that all our bacterial neighbours [and some inhabiting us!] are of that distant family.

When conditions varied in certain localities, these simple creatures performed some amazing tricks. One of these resulted in a devastating event the authors term The Oxygen Holocaust. The original prokaryotes thrived on hydrogen, making useful compounds of it and other elements. Since the best available source was water, the resultant waste product was oxygen. As this pollutant entered the atmosphere many organisms were forced to change their lifestyle or die out. The massive changes resulting increased the complexity of many organisms that began adding new protective devices to their structures. According to the authors, some cells had already initiated a new survival technique - the merging of various prokaryotic cells resulting in a new type. The new cell packaged its genetic material in a nucleus, creating the form known as the eukaryotes. Eukaryotic cell structure led down the long evolutionary track to complex creatures like ourselves.

There is a goal behind their descriptions of life's evolution. They remind us that textbook illustrations of individual bacteria are misleading. All Bacteria "clump" in some form or another as part of their survival strategy. Because these tiny organisms encounter so many environments and because their genetic makeup allows astonishing variation, many bacteria form communities with various groups performing specific tasks. These roles may include shielding the rest of the community from environmental hazards, processing food and waste or mobility. This revelation also points up a major theme of this book - cooperation has played a greater role in evolution than has competition. Cooperation is a survival strategy whereas competition may leave too few winners to ensure perpetuation of the species. How far can the cooperation extend in a planet of highly varying environments?

That question is answered in their concluding chapter. In it, they extend their previous narrative to reinforce the case for James Lovelock's Gaia thesis. In their view, Gaia is a "superorganism" extending throughout the entire biosphere. It is self correcting and self-regulating - indeed, the role of evolution is but the "operating system" of this global organism. Since the oxygen we breathe came from waste-expelling microbes, more than lifeforms are contained within Gaia. The atmosphere and oceans aren't habitats and support systems for life, but an integral part of a grander structure, one thoroughly integrated. One can only wonder what Darwin might have thought of this extrapolation of his idea of evolution by natural selection. This is not the place to debate Lovelock's thesis. While Gaia has been strenuously challenged by other commentators, Margulis and Sagan weave a tightly knit support for the idea. They do it earnestly and with clarity, and their view should be given some consideration. Strangely, however, while they have no qualms about describing certain theories about life's evolutionary progress as "still a mystery" or "controversial," this aspect of the book is presented as a given. The inconsistency is glaring, but shouldn't detract from the worth of the book as a whole.

This is a useful and interesting book. It has a major flaw because Margulis does not appreciate just how different the Archaea are from regular eubacteria. This leads to her picturing one eubacterium invading another leading to the origin of mitochondria. It now appears that mitochondria stem from the Rickettsia which only invade eucaryotes. The absence of cell walls in various Archaea make them prime candidates as the host organism in symbiosis, and this should have been featured in the book with Archaea as the origin of the cytoplasm. But you can't classify Archaea with a light microscope and that's what old-fashioned microbiologists want to do. The differences lie in the realm of biochemistry and molecular biology and often aren't visible to the eye.

This is one of the best histories of life on earth that I have ever read. I highly recommend it. It covers much of the often ignored very early history of life (3.8 billion years ago to the appearance of animals) in better deatil than I have found in any other book written at the popular level. In particular, the importance of the eukaryotic/prokaryotic symbiosis is emphasized as well as the development of photosynthesis that released free oxygen into the earth's atmosphere 2-2.5 billion years ago. The information on the Eidiacara organisms is a little thin, and some of that later chapters are very speculative, but still I recommend the book. It's one of the very few books that I could say that I had a hard time putting it down.

A theory of everything book begins with the big bang and concludes either with modern humanity or our someday-to-be colonization of the stars. This offering by the mother/son team of Margulis and Sagan is now 16 years old and a bit ragged around the edges, but still an informative read. Margulis' claim to fame is the symbiosis theory now standard fare in college biology texts. It states that mitochondria and chloroplasts were once free living bacteria that became trapped in other bacteria, giving rise to eukaryotic cells. Margulis also hypothesizes that flagella were once free living spirochetes. Her emphasis on nonhuman life (mostly prokaryotic) as the dominant biological mover is refreshing and she takes us on a virtual tour of the inception of life on this planet, accompanied by a nifty geological time chart, through to some pretty farout scenarios of how life might escape our one day to be dead sun. She goes as far as to posit Homo photosyntheticus, or plant people, who have chloroplasts in their skin and eat light.

Most of us think of evolution as darwinian survival of the fittest, with cheetahs and gazelles in a competitive arms race for survival. This book more accurately portrays selective mechanisms as predominately cooperative and microbially based. Certainly we would not be here to contemplate at all were it not for our ancestor bacteria, and this mocrobial history is written into our very genome. Approximately 5 % of our genome is putatively defunct viruses for example.

Chapter 2 is a pretty good synopsis of prebiotic chemistry. Chapter 4 gives a good definition on the disparateness between sex and reproduction. Chapter 5 shows how bacteria are essentially one ubiquitous species that casually transfer genes horizontally. Chapter 10 gives a great account of meiosis and mitosis and their permutations in the two biological domains, as well as fairly debunking the notion that the value of sex is its superior ability to offer genetic variability over fissioning prokaryotes. In Chaper 11 she gives a good account of how plants and animals (veritable colonies of bacteria) came to colonize the land on earth. Humans enter the scene in chapter 12 via neotony. The last chapter, chapter 13, goes out on a variety of speculative limbs in conclusion.

While this book contains its share of factual errors, probably due to its age, its a well crafted popsci book that makes geotemporal biology accessible to the lay reader.

This is an outstanding and very readable book on the world of microbes. Beautifully written and filled with insights, it should be required reading for biology students. I couldn't put it down and I hated biology in high school! I takes you from the beginnings of our planet to the present time, showing the reader the crucial role of microbes in the creation and maintenance of all life. This book will also be of interest to any serious student of the Gaia hypothesis. Read it and you will never think of cells, bacteria and viruses the same way again. You will come away with a humbling and enlightened view on man's place in a world created, dominated, and maintained by microbes.

For those of you who don't know, Lyn Margulis is the ex wife of the late Carl Sagan (prior to Ayn Druian) and Ms. Margulis is Dorian Sagan's mother.Together, they make an excellent writing team.

This book is an excellent scientific account of how life originated on earth. It tells how the earth's environment came to host organic molecules, leading up to bacterial communities and on to higher organisms.

Chapter by chapter, this book outlines the progression of life from it's origin 3.9 billion years ago up to present day. Very well written, and easy to understand, I found it to be very enjoyable.

Microcosmos is a fine reference book for nonfiction, index and all, and I think it should be in everyone's private library.

I am he first to state that I am no biologist--- it's just that simple. But even I can understand the more complicated aspects of this book. Beginning with the pre-Cambrian era, Margulis and Sagan bring the reader to an easy understanding of a world we inhabit--one that we require just to exist--but one that we rarely glimpse. If Cosmos speaks of the very large, than Microcosmos speaks of the very, very small--and does it very well. There is no need for even a basic understanding of biology for the reader, as the authors walk us through step by step. Even the reasonable complicated natures of RNA and DNA are explained--not simply described. Perhaps most interesting, at least to myself, is the authors understanding of the chemical beginnings of life. It would seem to indicate that perhaps life is the inevitable result of chemical processes--the implications are plain. I will state that there are inadequate adjectives with which I can recommend this book. It is without a doubt, one of the most interesting, though provoking, and easy to understand books on science I have had the pleasure to read. I cannot recommend this book strongly enough.

Worth reading for some intersting facts, but I prefer the similar "Vital Dust" by Christian de Duve, which seems to convey far more information in the same number of pages, although it is also less easy to read. Microcosmos also contains one surprising error that creationists will like, by stating wrongly that no species has ever been seen to evolve into a new species.