From one of the great iconoclasts of modern biology, a groundbreaking work that sets out, for lay and scientific readers alike, a new theory of the origins of species How do new species evolve? Although Darwin identified inherited variation as the creative force in evolution - the raw source for the origin of new species - he never figured out where it comes from. His successors, known as neo-Darwinists, thought they had discovered the answer when they merged evolutionary theory with modern genetics: new species arise from the gradual accumulation of random mutations of DNA. But despite its acceptance in every major textbook, there is no documented instance of a new species actually arising by this means. And since random mutation was the only accepted mechanism, this meant that, for a full century and a half after Darwin published his theory of the origin of species, there was not a single generally accepted instance of an origin of any species. The distinguished biologist Lynn Margulis and the writer Dorion Sagan take a radically new approach to this question. They have combed a huge range of obscure reports to show that speciation events are not, in fact, rare or hard to observe. Origins of Species demonstrates, with well-documented examples drawn from every part of the living world, that most species originate when different types of organisms merge their genomes. Genomes are acquired by infection, feeding, and other ecological associations, and then inherited. This is the first work to integrate and analyze the overwhelming mass of evidence, now scattered in obscure journals, for the role of bacterial and other symbioses in the creation of plant and animal diversity. Sure to be seen as a groundbreaking and controversial book, it provides the most powerful explanation of speciation yet given.