Life on a Young Planet: The First Three Billion Years of Evolution on Earth (Princeton Science Library)

Australopithecines, dinosaurs, trilobites--such fossils conjure up images of lost worlds filled with vanished organisms. But in the full history of life, ancient animals, even the trilobites, form only the half-billion-year tip of a nearly four-billion-year iceberg. Andrew Knoll explores the deep history of life from its origins on a young planet to the incredible Cambrian explosion, presenting a compelling new explanation for the emergence of biological novelty.

The very latest discoveries in paleontology--many of them made by the author and his students--are integrated with emerging insights from molecular biology and earth system science to forge a broad understanding of how the biological diversity that surrounds us came to be. Moving from Siberia to Namibia to the Bahamas, Knoll shows how life and environment have evolved together through Earth's history. Innovations in biology have helped shape our air and oceans, and, just as surely, environmental change has influenced the course of evolution, repeatedly closing off opportunities for some species while opening avenues for others.

Readers go into the field to confront fossils, enter the lab to discern the inner workings of cells, and alight on Mars to ask how our terrestrial experience can guide exploration for life beyond our planet. Along the way, Knoll brings us up-to-date on some of science's hottest questions, from the oldest fossils and claims of life beyond the Earth to the hypothesis of global glaciation and Knoll's own unifying concept of ''permissive ecology.''

In laying bare Earth's deepest biological roots, Life on a Young Planet helps us understand our own place in the universe--and our responsibility as stewards of a world four billion years in the making.

The book is balanced and avoids taking the route of sensationalism. A reader who is interested in biology and evolution can learn a lot from it. The book, however, does have two problems. First, it assumes that the reader is familiar with biology and genetics at the introductory University level. Readers with no previous knowledge will probably find themselves getting lost in the dense text. The second problem is that the book's ending is somewhat unsatisfactory. The author stops his discussion of the evolution of life at the Cambrian Explosion and ends the book with a chapter about what lessons that the early history of Earthly life teach about the prospects of life elsewhere in the Universe. This jump is jarring and leaves the reader feeling that the book is lacking a conclusion.

All in all I highly recommend this book to anyone who already knows the difference between eukaryotic and prokaryotic life. If, however, you need to do a Google search to understand that last sentence then this book may be a bit too advanced for you.


Wide ranging.   September 2, 2004
algo41 (cinnaminson, nj United States)
27 out of 27 found this review helpful

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.




A fine balance   January 3, 2004
Stephen A. Haines (Ottawa, Ontario Canada)
19 out of 20 found this review helpful

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 convey the nippy Kotuikan cliffs or the roasting Precambrian site of North Pole, Western Australia. A collection of plates offers stunning colour images of ancient fossils and some modern equivalents. He further diagrams phylogenetic trees showing the relationship of organisms and why they are considered related. Not all life, he reminds us, has followed the path to complexity. With a good, but not exhaustive, reading list to examine, the reader may continue the pursuit. The younger reader may even wish to further the knowledge we have. Knoll exhorts the next generation of early life researchers to examine the questions and go afield to provide more answers. There are few worthier causes. [stephen a. haines - Ottawa, Canada]


A rolling voyage through time.   May 9, 2004
Robert C. Martin (Green Oaks, IL United States)
12 out of 13 found this review helpful

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.


The Three Billion Year Old Cold   February 20, 2006
Marc Ruby™ (Warren, MI USA)
7 out of 7 found this review helpful

Let me confess early on that I am by no means a student of paleontology. Other than my encounters with dinosaurs-in-print during my youth and some required college courses, my knowledge is limited to the occasional book or pointed lecture by a friend. Life On A Young Planet is this year's occasional book, and it has proved to be a very interesting and informative one as well.

Andrew Knoll is a professor of Natural History at Harvard and has all the necessary awards, fieldwork, and publications to make him an easily recognized fixture on the protobiological horizon. That he also manages to write very well with the kind of humility that seems rare among the sciences these days is an accomplishment. That he can make tiny, ancient bacteria into an interesting and even compelling narrative is special.

This is a history of the beginnings and adventures of life, as it first appears, weakens, and then reappears over a tremendous span of time. Knoll combines hard science, personal narrative and an occasional bit of speculation into a cogent synthesis. We get to tour some of the oldest stone beds on the planet and discover surprises, confirmations, and more than a few puzzles. Expect to befriend countless bacteria on their way to future greatness. Knoll does his best to be even handed, and makes an effort to present the many sides of the issues of his field.

The author builds steadily to his core points. We gradually come to see how life and the environment go hand in hand as species flourish and then disappear. This is quite a pageant, and Knoll wants us to understand that, at any time, life is fragile, and we as humans have become an environmental force to be reckoned with. If we do not learn to behave, more than the existence of our own species is at stake. "I don't know whether God decreed the carrier pigeon," Knoll states in conclusion, "but if he did, it was not for us to exterminate."