How did life on earth originate? Did replication or metabolism come first in the history of life? In this book, Freeman Dyson examines these questions and discusses the two main theories that try to explain how naturally occurring chemicals could organize themselves into living creatures. The majority view is that life began with replicating molecules, the precursors of modern genes. The minority belief is that random populations of molecules evolved metabolic activities before exact replication existed. Dyson analyzes both of these theories with reference to recent important discoveries by geologists and chemists. His main aim is to stimulate experiments that could help to decide which theory is correct. This second edition covers the enormous advances that have been made in biology and geology in the past and the impact they have had on our ideas about how life began. It is a clearly-written, fascinating book that will appeal to anyone interested in the origins of life.