Evolutions That Never Evolved : WONDERFUL LIFE: The Burgess Shale and the Nature of History by Stephen Jay Gould (W. W. Norton: $15.95; 347 pp., illustrated)

Stephen Jay Gould's new book, "Wonderful Life," recounts two fascinating and previously little-known stories, one about evolution and the other about evolutionary science. The first concerns the relationships between present life on our planet and a set of strange and ancient animals. The second, told as a five-act drama, recounts how three British scientists came to understand these relationships. Gould ranks the work of his paleontological colleagues among the greatest creative achievement of our species, comparable, in his view, to the cave paintings of Lascaux or the cathedral windows of Chartres. Gould goes on to reflect on the importance of contingency in evolutionary history and of concept in evolutionary science.

About 530 million years ago, in an area of ocean about the size of a city block, a mudslide asphyxiated tens of thousands of small marine animals. Most of the trapped organisms lived on the bottom of a shallow sea bed, though others swam or floated above. Their rapid burial insulated them from immediate decay, and their remains became preserved (and chemically transformed) in a rock formation called the Burgess Shale, which now lies high in the Canadian Rockies. The Burgess Shale presents an unequaled snapshot of life in the middle of the Cambrian Period, the earliest span of geological time from which we have abundant fossil evidence of recognizably modern animals.

The discoverer of the Burgess Shale, Charles Doolittle Walcott, was a distinguished leader of the early 20th-Century American scientific establishment. Though his role as secretary of the Smithsonian Institution left him little research time, he interpreted the Burgess animals as primitive members of still-living groups (such as crustaceans, jellyfish and polychaete worms) or of the best-studied group of fossil invertebrates, the trilobites. Walcott thus completely missed the revolutionary significance of his magnificent find.

According to Gould's engaging account, the real meaning of the Burgess animals only began to emerge in the 1970s, when three British paleontologists--Harry Whittington, Derek Briggs, and Simon Conway Morris--undertook to reexamine Burgess fossils, including those originally collected by Walcott. Whittington, Briggs and Conway Morris realized that many Burgess fossils were not merely flat impressions but were three-dimensional relics that they could dissect and inspect, carefully chipping away layers with dental drills. They thus converted the snapshot into a set of stereoscopic images. Their subsequent work, and Gould's book, are attempts to fit these new photographs into a videotape of early animal evolution.

The diversity of anatomical designs among the Burgess animals far exceeds that of all the creatures in all of today's oceans. More baldly stated, the Burgess Shale is full of oddballs: Opabinia, with five eyes, a front-facing nozzle, and a U-shaped gut; Nectocaris, which looks something like a large insect in the front and a fish in the rear; Odontogriphus, a flat animal with both teeth and tentacles; Dinomischus, a sessile animal that resembles a goblet on a long stem; Amiskwia, another swimming animal with tentacles on its head and fins on its sides and tail, and the most peculiar Hallucigenia (see above) , with seven pairs of spines pointing down and seven tentacles pointing up. Altogether, the Burgess animals represent 25 basic body plans, of which only four survive in present-day organisms. The explosion of animal life in the early Cambrian (or Precambrian), then, gave rise to much more than the precursors of modern life. The question, then, is why some forms continued and others perished.

Gould's reflections center around this question. Did the losers disappear because of their inferiority in competition or merely because they had the wrong tickets in a lottery? Could an ancient biologist have predicted which forms would survive and evolve and which would not? Was the evolution of present life, including our own species, in any way be predictable?

Gould's view is embodied in the book's title, borrowed from the Frank Capra film, "It's a Wonderful Life," in which a guardian angel shows a suicidal Jimmy Stewart what his town would have been without his having been there. Gould argues that we cannot ever know what our planet's life would have been like if we replayed history with even minor changes. The present is contingent on what has come before, a statement equally true, according to Gould, of evolutionary history and of history in general.

This conclusion probably will not shock most readers. The value of Gould's book does not lie in its view of history, however, but in its presentation of science. The four scientists whose work Gould discusses are human beings, dressed in street clothes rather than priestly vestments. They differ in personalities, politics, and intellectual perspectives. And, as is the case for all scientists, their ways of collecting and interpreting data depend on their conceptual framework. Thus, Walcott, caught in the view that evolution was inevitably progressive, had to "shoehorn" the Burgess animals into categories that might be precursors of present-day creatures. Whittington, Conway Morris and Briggs, on the other hand, were not so constrained, perhaps because, by the 1970s, evolutionary biologists (influenced by Gould himself, among others) better understood the role of chance, particularly in the face of recurring geological changes, such as continental and occasional meteoric collisions. Mass extinctions of once-flourishing forms pose little problem for modern biologists, though they certainly did for Walcott.

Gould would like the public to perceive the Burgess story as even more important and fascinating than the story of the rise and fall of the dinosaurs. He laments that the dinosaurs get more press because they are bigger and more frightening than the Burgess animals, the largest of which are a few inches long. Another problem in capturing the public's attention, however, is that people are generally unfamiliar with marine life: Most of us would be hard pressed to distinguish between the weird wonders of today's seas and those of the Cambrian Period. Here, Gould is an excellent guide, patiently explaining the characteristics of modern phyla and classes.

Gould intends "Wonderful Life" to be a book for lay people as well as for scientists. And so it should be. Understanding how evolutionary biologists actually work, as Gould so lovingly details, ought to stop the persistent claims that the great creation myths have anything to do with science.

Unfortunately, however, Gould has written "Wonderful Life" in a way that interferes with its accessibility. To stress the humanness of the scientific enterprise (and his own involvement in it), for example, he refers to contemporary scientists alternately by their first and last names. Whittington thus intermittently appears as Harry, Briggs as Derek, and Conway Morris as Simon. But there is also a lot of Steve in both text and footnotes--how he came to write the book and what he thinks of scientific administrators, the New York Yankees, Stephen King and the English setting of Haydn's "Creation." He leaves the reader with the impression that the great enterprises of science and culture are just agenda items in the continuing meetings of a worldwide club, of which Gould is an important member.

Gould's asides convince the reader that the author is an exceptional man, a master of pop and high culture as well as of biological research and historical scholarship. Gould thus demonstrates by his own example that science is not an isolated activity but is intimately connected with other creative endeavors. But by continually introducing himself into his narrative, Gould unwittingly fosters an old (and, in my opinion, incorrect) notion that science is the province of an academically inbred elite whose members are (like Gould) the former apprentices of great teachers and the confidants of similarly eminent scientists, novelists and sportswriters. Surely Gould does not mean to suggest that scientific insight depends on clubbiness or class. Such a message would seriously clash with his noble and successful efforts to give broad public access to biology's aesthetic and intellectual wonders.

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