The Diversity of Life.

How much force does it take to break the crucible of evolution?" If this question piques your curiosity, Pulitzer Prize-winning author and scientist Edward O. Wilson's latest endeavor - an impassioned plea for the preservation of what is left of the Earth's biological heritage - will be the page-turner you just can't put down. What's different about this story is that its ending has yet to be written: it's up to each of us.

Although there have been five mass extinctions over the past 440 million years, Wilson sets out to prove that the sixth, in which we find ourselves right now, is radically different. Writing with a lucidness that borders on poetry, he argues that if the first five extinctions were due largely to natural factors such as asteroids colliding with the earth, blame for the present paroxysm of death and destruction can be laid at the doorstep of one species that has forgotten it evolved with the rest of life on this planet.

Part of the problem Wilson describes is our enormous ignorance - rather ironic, given that much of the justification for human dominance over nature has stemmed from pride in our large brains. To begin with, we have only the vaguest idea of how many species there are in the realm we dominate. The range Wilson ventures is humbling: "close to 10 million or as high as 100 million." Whatever the number, evidence is piling up that the magnitude of the annihilation we have set in motion is massive.

Take the rain forests, believed to be home to more than half the species of plants and animals. Wilson points out that according to the fossil record, the normat pre-human "background" rate of extinction was roughly one species out of one million a year. Now, human activities have "increased the extinction between 1,000 and 10,000 times over this level in the rain forest by reduction in area alone."

Numbers can be numbing, inducing dangerous emotional and psychological detachment from the urgency of a situation. Fortunately, Wilson is able to present his numbers in a way that never lets the reader forget the immensity of this loss of life. His attention to "keystone species" is a case in point. As their name suggests, the removal of these species can cause entire ecosystems to change drastically, with unforeseeable and often dire consequences for other life forms - including, ultimately, humans.

Not one to cry over spilled genes, Wilson turns his attention toward finding practical means of saving what biodiversity...