John Tyler Bonner is one of the most distinguished biologists. In this book, he critically examines one of the central tenets of evolutionary biology. In his unique writing style, he challenges the idea that evolution is solely based on natural selection and argues that a series of other factors must be taken into account.

Bonner emphasizes the invaluable role that randomness - or chance - plays in evolution. The author argues that Darwin's radical proposition about natural selection overshadowed the role that random events can have in the evolution of organisms. He even claims that the smaller an organism is, the more likely its morphological differences are a result of chance, while natural selection plays a smaller role.

By examining how various organisms increase in size and complexity over geological periods, Bonner explores the significance of randomness from the earliest microorganisms to the emergence of mammals.

Some of the arguments in the book may fundamentally change the way we understand evolution and the history of the evolution of life.