A Hole in The Ark

By R.Z. Sheppard

TITLE: THE DIVERSITY OF LIFE

AUTHOR: EDWARD O. WILSON

PUBLISHER: HARVARD UNIVERSITY; 424 PAGES; $29.95

THE BOTTOM LINE: A leading biologist's warning about ecological disaster is both top-drawer science and high-level art.

The world is coming to an end. Again. Edward O. Wilson, a pioneer of sociobiology and professor of entomology at Harvard's Museum of Comparative Zoology, lists five earth-shattering events in the past half-billion years. The latest may have been a one-two punch. A meteorite six miles wide struck the Caribbean region 66 million years ago and set off intercontinental volcanic eruptions. The smoke and dust changed the global climate, killing countless plant and animal species.

Earlier mass extinctions, 440 million to 210 million years back, are attributed to the breakup and drift of the single supercontinent known as Pangaea. All these cataclysms, says Wilson, drastically reduced the variety of species. But given world enough and time (at least 20 million years), biological diversity reasserted itself.

The Diversity of Life argues that Homo sapiens does not have the luxury of such a leisurely recovery. Nor does it deserve it, because it is now the leading threat to life-forms, including itself. What Darwin called the tangled bank and Wilson calls the web of life is a highly interdependent system. An event in one part of the web jiggles the whole.

Wilson has mastered his science and the art of teaching it. He moves easily from the macro to the micro, from the eruption of Krakatau to the silent messages of chromosomes. He strives for clarity, but never at the expense of complexity. An explanation of how species evolve may require more attention than Homo televideous is willing to muster. Hang in. Accounts of the author's field experiences convey an excitement of discovery that many readers probably last felt as children examining insects in a patch of grass.

Much of Wilson's expertise derives from his award-winning studies of life on islands where the number of species increases or decreases with the size of habitat. This finding is less obvious than it sounds and has big consequences for large landmasses where biological diversity is rapidly losing out to development and pollution. Wilson estimates that 10,000 species are destroyed each year, a rate that is increasing as the world's population grows toward 10 billion people by the middle of the next century.

So what, critics argue? Evolution is littered with the remains of organisms that didn't make it, and prophecies of ecological doom have replaced nightmares of thermonuclear holocaust. The thinking animal is also the one that worries the most. It should. Wilson's intellectual, aesthetic and moral conception of life on earth suggests that survival may depend on a new age of anxiety.