OVER THE PAST TWO YEARS, biologist Edward O. Wilson and Outside editor at large David Quammen have been two of the most visible defenders of science in the battle over intelligent design—the idea that the complexity of life on earth could not have arisen without a divine director, i.e., God. United States District Judge John Jones struck down the teaching of intelligent design in public schools in a landmark ruling last December—declaring it religious creationism cloaked in scientific language—but that hasn't stopped Quammen and Wilson from continuing to press their case, each with a refreshingly concise and accessible new book on the fact of evolution by natural selection.

In The Reluctant Mr. Darwin: An Intimate Portrait of Charles Darwin and the Making of His Theory of Evolution (W.W. Norton, $23), Quammen distills the story of the British naturalist and the formation of his world-shaking theory in an engaging story that's part biography, part essay. Quammen's starting point is 1837, the year after Darwin returned from his voyage on the Beagle, when he was just beginning to believe that species—including humans—evolve as they adapt to changes in their environments. The thought was unsettling even to Darwin; science was still tightly bound to religion, with creationism the reigning belief of the day. Yet after combining additional fieldwork with library research and data from other naturalists, he was forced to admit that he was on to something. Instead of publishing, Darwin sat on his radical new theory for 20 years. Finally, panicked by the realization that a rival was about to steal his thunder, he produced his 1859 masterwork, The Origin of Species, in ten months of furious scribbling. "Holding it in his hands," Quammen writes, "he felt an irresistible flush of satisfaction, his private reward between the anguish of creation and the anguish that would come with the book's reception." In Darwin's autobiography, Quammen notes, the aging naturalist wrote with confidence that the idea of divine design had been put to rest. That, of course, was hardly the case.

If Quammen's book can be read as a rebuke to the intelligent-designers (it's as if he's thrusting Darwin in front of them and saying, These are the facts—deal with them!), Wilson's The Creation: An Appeal to Save Life on Earth (W.W. Norton, $22) is a conciliatory effort to find common ground. Structured as an open letter to an imagined Southern Baptist preacher, the book argues against the validity of creationism, while at the same time inviting evangelical Christians to join biologists in an effort to save the earth. "Pastor, we need your help," pleads Wilson, a native Alabaman who was raised a Southern Baptist. "The Creation—living Nature—is in deep trouble." Writing in a warm, open voice, Wilson provides a litany of reasons to slow, stop, and reverse the planet's precipitous decline in biodiversity. These reasons will be familiar to anyone engaged in the environmental debate—everything from the spiritual value of wilderness to the importance of species diversity in the search for new medical drugs—but Wilson wraps them up in an unthreatening package. "If religion and science could be united on the common ground of biological conservation," he writes, "the problem would soon be solved." That might be stretching things a bit, but at least it's a start.

Postcards from Ed: Dispatches and Salvos from an American Iconoclast (purchase)