[.ca] Microcosmos: Four Billion Years of Microbial Evolution (ISBN 0520210646)

An action packed theory of everything book:
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.

On microbes: the real rulers of the planet.:
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.

vague and lacking substance:
disclaimer: I am not a native speaker (but quite used to read englich). I found the book quite vague and lacking in details, some images would have helped further. I did not expect an undergraduate book with many chemical formulas, but many ideas seemed only sketched. I can not say that anything is really wrong but I was left with the impression that the claims were not really substantiated. I am now reading "the origins of life" (Smith and Szathmáry) which -- while even shorter and somewhat dense -- I like much more. It is more precise and the authors clearly tell, what is substantiated "knowledge" and what is speculation. They even avoid using under-defined jargon like "complexity" with a refreshing acknowledgment of their own limitation in giving a clear definition.

Don't miss the beginning . . .:
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 \oand some inhabiting us!\c 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.

A wonderful look at how life began....:
This book was quite eye opening. It takes billions of years of evolution and tracks it at the microscopic level (hence the title). After reading it, you have to take another look at all the different forms of life here on our planet. I am very glad I bought this book and look forward to reading more from both of these authors.