In the Amazon Basin the greatest violence sometimes begins as a flicker of light beyond the horizon. There in the perfect bowl of the night sky, untouched by light from any human source, a thunderstorm sends its premonitory signal and begins a slow journey to the observer, who thinks: the world is about to change." Watching from the edge of the Brazilian rain forest, witness to the sort of violence nature visits upon its creatures, Edward O. Wilson reflects on the crucible of evolution, and so begins his remarkable account of how the living world became diverse and how humans are destroying that diversity. Wilson, internationally regarded as the dean of biodiversity studies, conducts us on a tour through time, traces the processes that create new species in bursts of adaptive radiation, and points out the cataclysmic events that have disrupted evolution and diminished global diversity over the past 600 million years. The five enormous natural blows to the planet (such as meteorite strikes and climatic changes) required 10 to 100 million years of evolutionary repair. The sixth great spasm of extinction on earth caused this time entirely by humans may be the one that breaks the crucible of life. Wilson identifies this crisis in countless ecosystems around the globe: coral reefs, grasslands, rain forests, and other natural habitats. Drawing on a variety of examples such as the decline of bird populations in the United States, the extinction of many species of freshwater fish in