title: Life on a Young Planet: The First Three Billion Years of Evolution on Earth - Updated Edition (Princeton Science Library)
author:  Andrew H. Knoll 
description: <b>"Winner of the 2003 Book Award in Science, Phi Beta Kappa"</b><br /><br />"A fascinating book. . . . The catastrophic surface narrative of this impressive and intriguing book would surely have pleased Stephen Jay Gould; but I think its deterministic subtext would have pleased Charles Darwin still more."<b>---Matt Cartmill, <i>Times Literary Supplement</i></b><br /><br />"In a book so well written that nonspecialists and specialists alike will find much to savor, [Knoll] captures both the excitement of scientific discovery and the intricacies of scientific interpretation. . . . Readers interested in substance will certainly not be disappointed." (<i>Publishers Weekly</i>)<br /><br />"Andrew Knoll is an ideal guide through this early phase of life's history on the Earth. . . . [O]ne of the strengths of Knoll's book is that it presents science as the open-ended endeavor that it is.... <i>Life on a Young Planet</i> . .. expresses better than most the bumptious vitality and sheer fun of open-minded research."<b>---Stefan Bengtson, <i>Nature</i></b><br /><br />"<i>Life on a Young Planet</i> stands apart from it predecessors in two fundamental respects. First, Knoll is perhaps the most qualified person to write such an epic: a renaissance man whose text is filled with insightful quotes from authors ranging from Darwin to Dickins to Dyson. . . . Second . . . this book describes the coevolution of life on Earth as an integrated biochemical system that has profoundly and irrevocably changed over time."<b>---Guy M. Narbonne, <i>Science</i></b><br /><br />"A balanced, excellent account of current theories and discussions of the origin and early evolution of life. . . . Knoll is able to convey difficult scientific issues with a minimum of jargon, using a brisk and witty prose. . . He is a gifted storyteller with a knack for choosing the right anecdote. . . . A browse through Knoll's book will enlighten both the cognoscenti and those unfamiliar with the complexities of reading a fossil record. . . . Knoll manages to present a multidisciplinary field in an interdisciplinary volume."<b>---Antonio Lazcano, <i>American Scientist</i></b><br /><br />"Knoll is well placed to tell this amazing story, and he does so with verve."<b>---Douglas Palmer, <i>New Scientist</i></b><br /><br />"
zlib_text: 39
  ORIGIN AND EVOLUTION OF LIFE
  Chapter 3
  ORIGIN AND EVOLUTION OF LIFE
  Life had a beginning.  Since when life appeared
  on Earth?  What is the mechanism involved in
  the origin of life ? Such questions are very
  difficult to answer because we cannot go back
  in time and observe life's beginning. Since its
  appearance, life on Earth has changed through
  time. Hence, the history of life actually
  comprises two events  first, the origin of life
  and, second, the mechanism involved in the
  changes of living organisms through time or
  evolution of life.
  3.1 ORIGIN OF LIFE
  The oldest surviving terrestrial rocks, about 4.3
  billion years old, contain no definite trace of life,
  at least not recognisable as yet. Some rocks,
  about 3.9 billion years old, contain carbonates.
  Geologists interpret that these carbonates have
  resulted from life processes. Therefore, life was
  present on Earth about 3.9 billion years ago.
  However, the oldest microfossils discovered so
  far are that of photosynthetic cyanobacteria
  