SHOWDOWN
ON THE
BURGESS SHALE

Almost a decade ago, Harvard paleontologist and Natural History columnist Stephen Jay Could published Wonderful Life: The Burgess Shale and the Nature of History (W. W. Norton and Company, 1989). In addition to chronicling ongoing work on the Burgess creatures, Gould used these fascinating fossils to exemplify his view of evolution. A few months ago, in The Crucible of Creation: The Burgess Shale and the Rise of Animals (Oxford University Press, 1998), invertebrate paleontologist Simon Conway Morris, of Cambridge University, a key player in Burgess research, challenged Gould's interpretations. We invited Conway Morris to summarize his argument, which we publish here, along with Gould's reply.--Eds.

THE CHALLENGE
By Simon Conway Morris

Few books on paleontology have achieved the wide readership of Stephen Jay Gould's Wonderful Life, which popularized research spearheaded by Harry Whittington at Cambridge on the 520-million-year-old Burgess Shale, found between two peaks in the Canadian Rockies near Banff. But Gould did much more than chronicle discoveries concerning these Cambrian fossils; he also set forth his own deeply held views on the mechanisms and nature of evolution--and even on humankind's place in the universe--as the "lessons" to be drawn from the Burgess Shale. In my new book, The Crucible of Creation, I argue that the major premises and conclusions of Wonderful Life must be seriously challenged. Let me begin with some matters of interpreta-

The recorded history of life on earth extends from 3.5-billion-year-old bacteria to our modem biota of oak trees, great white sharks, people, and many other organisms of stunning diversity. If evolution had followed a path of smoothly rising complexity, then our cultural preferences for progress would be fulfilled and paleontology would validate our deepest hopes and expectations. But life's bumpy and unpredictable course challenges us at every turn. Why did unicellular organisms of bacterial grade hold exclusive sway for nearly 2 billion years--more than half of de's duration on earth? When multicellular animals of modem design finally entered the fossil record, why did nearly all phyla make their initial appearance in an interval so brief (perhaps no more than 5 to 10