Randomness in Evolution

John Tyler Bonner, one of our most distinguished and insightful biologists, challenges here one of the central principles of evolutionary biology. In this concise and elegantly written book, he makes the bold and provocative claim that part of biological diversity can be explained by something beyond natural selection.

With his usual style of wit and accessibility, Bonner argues for the underestimated role that randomness or chance plays in evolution. Due to the tremendous and lasting influence of Darwin's natural selection, the importance of randomness has been, to some extent, overshadowed. Bonner shows how the effects of randomness differ for organisms of different sizes and how, the smaller the organism, the more likely it is that morphological differences are random and selection may not be involved at all. He traces the increase in size and complexity of organisms over geological time and examines the varying importance of randomness at different size levels, from microorganisms to large mammals. Bonner also discusses how sexual cycles vary depending on size and complexity, and how the tendency to move away from randomness in higher forms has even been reversed in some social organisms.