River Out of Eden

River Out of Eden: A Darwinian View of Life is a 1995 popular science book by Richard Dawkins. The book is about Darwinian evolution and summarizes the topics covered in his earlier books, The Selfish Gene, The Extended Phenotype and The Blind Watchmaker. It is part of the Science Masters series and is Dawkins's shortest book. It is illustrated by Lalla Ward, Dawkins's wife. The book's name is derived from Genesis 2:10 relating to the Garden of Eden. The King James Version reads "And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads." River Out of Eden has five chapters. The first chapter lays down the framework on which the rest of the book is built, that life is like a river of genes flowing through geological time where organisms are mere temporary bodies. The second chapter shows how human ancestry can be traced via many gene pathways to different most recent common ancestors, with special emphasis on the African Eve. The third chapter describes how gradual enhancement via natural selection is the only mechanism which can create the observed complexity of nature. The fourth chapter describes the indifference of genes towards organisms they build and discard, as they maximise their own utility functions. The last chapter summarises milestones during the evolution of life on Earth and speculates on how similar processes may work in alien planetary systems. Dawkins begins the book by stating that all our ancestors reached adulthood and begot at least one child before they died. In a world where most organisms die before they can procreate, descendants are common but ancestors are rare. But we can all claim an unbroken chain of successful ancestors, right back to the first single-celled organism. If the success of an organism is measured by its ability to survive and reproduce, then all living organisms can be said to have inherited "good genes" from successful ancestors. Each generation of organisms is a sieve against which replicated and mutated genes are tested.