Life on a Young Planet: The First Three Billion Years of Evolution on Earth

This book is beautifully written and tells a fascinating story, not only about the evidence of life in the Precambian period on to the Cambrian Explosion but also about the history of such studies and the pros and cons of different theories. It is not a page-turner; the reader must be ready to think. But a thinking reader, even one with no science background, will learn a lot.

Who knew? To be a paleontologist these days you need to know more than a little about biology, molecular biology, physics, chemistry, geology, plate tectonics, climatology, fossils of course - and be something of an adventurer. Knoll is also a fine writer - clear, interesting, capable of good descriptive prose. Truthfully, I am not all that interested in fossils, and I didn't get much from the color pictures, although others may. The quality of the writing got me through many of these sections. My reward was the many state of the art discussions, such as: the role of combined organisms in evolution: the genesis of the explosion of life forms which has occurred several times in earth's history; the origin of earth's current atmosphere (yes, that is important to reading the fossil clues). Knoll is great at identifying issues, explaining why some theories are no longer tenable, giving the arguments for the rest, and explaining his hunches. We all know that current levels of oxygen are due to photosynthesis, but it is not so simple, because if that were all there were to it, the earth would have had a high oxygen atmosphere hundreds of millions of years before it did. If you are interested in global warming, get this book, and just read the relevant chapters. Knoll cannot give background in all the subject areas, so he does not try for any. I would have been happier if I knew more about some of the bacteria he discusses, and an introductory chapter on what constitutes a fossil would have saved me some time (the material is there). However, if you know something about RNA/DNA, and have read at least one good article on plate tectonics, I think you will be OK.

This book is a rolling voyage over the waves of eras and eons, fossils and nucleotides, chemistry and physics. The story sways with a rhythm that is both soothing and stimulating. On the voyage we are taught how life may have begun, how it evolved, how it changed it's environment -- indeed how it changed the entire planet. We see how slowly life moved at first, and how it suddenly accellerated to its current frenzy. The author, our ready guide throughout this voyage, culminates the trip with perhaps the most profound and moving epilog I have ever read in a book of this kind. Well done. Accessible. Fun. Instructive. Powerful.

Knoll provides what may be the finest description of the sciences of early life available. Bringing together such fields as geology, biochemistry, genetics and, of course, his own science of paleontology, he presents a vivid image of how life formed long ago. The subtitle is deceptively simple. "First three billion years" rolls off the tongue easily. Knoll demonstrates the quest to understand how life originated has been elusive and arduous. The search, he reminds us constantly, is far from over. We may not even gain meaningful grasp of the subject if we restrict the inquiry to this planet.Knoll asserts the benchmark for comprehending how life may have started was the Urey-Miller experiments of the 1950s. By assuming a particular composition of Earth's early atmosphere and bombarding that recipe with electricity to duplicate lightning, Urey and Miller produced amino acids. Knoll credits these experiments not with showing how life began, but by their stimulation of much further research. Since then, geologists have revealed increasingly older rocks. Instead of buried deep beneath the surface as might be expected, they are often found well exposed. Knoll's expeditions to chilly Siberian sites are offset by the roaring desert of outback Australia. Both locations have provided researchers with new information on composition, chemical and environmental processes, and, most significantly, Precambrian fossils.The many research fields now involved in developing a picture of life's beginnings indicate how complex a task unveiling "simple" can be. Early life, of course, was microscopic. Sometimes it isn't fossils that are found, but spoor remains - tracks once left in mud, images of forms, and, most intriguing for many, chemical signatures. The chemical, is usually carbon, that fundamental element of life. But other elements, iron, sulfur and oxygen also carry messages about living processes. Knoll manages a delicate arabesque as he presents us with the evidence obtained and the interpretations derived from it. He carefully delineates the fossil information given by the rocks, mixing it with geological and geochemical processes. Various researchers are given voice through his narrative. Where issues are contentious, and most ideas of early life fit that description, he explains the reasons behind the stance, then offers his own choice. While the conflict is rarely solved, none of his solutions are arbitrary or based on personality. You are still left to satisfy your own mind through his references. Knoll's prose presents this information and discussion with clarity and balance. At the end, with these lucid explanations as background, he considers that answers to many of our questions may be found on our nearest planetary neighbour - Mars.Beyond the informative text provided, Knoll enhances the book with site photographs to convey the scale of the locations excavated. Ancient landscapes are today stark, and the photos do little to c