Life Evolves

Why Evolution Is True 

by Jerry A. Coyne

"Life on earth evolved gradually beginning with one primitive species – perhaps a self-replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection. (3.)

Jerry Coyne summarizes the facts supporting Darwinian evolution. He divides them into six components: the fact of evolution, in the sense of genetic change over time; the idea of gradualism, of changes taking place over many generations (although sometimes they come about relatively quickly, depending on the evolutionary pressures operating); the phenomenon of speciation, whereby new species split off from existing lineages; the common ancestry of different species, since new species, which can be thought of as twigs on the developing branches of life, can be traced back to a common branch, and ultimately to an original ancestor; the mechanism of natural selection, whereby different combinations of genes are reproduced more successfully than others as a result of the different abilities of individual organisms to survive and reproduce in a shared environment; and, finally, the presence of some processes, in addition to natural selection, that contribute to evolutionary change (the most important being what is known as “genetic drift”). The updating of the fossil record, filling in gaps in the story and providing explanations for difficult aspects of the theory all combine to make this book a gem.  For readers interested in exploring some of these ideas on-line there is a beautiful blog at Why Evolution is True .


Why Evolution is True by Jerry A. Coyne. Viking Press, New York. 2009.