In the movie It's A Wonderful Life, George Bailey tells Uncle Billy that the three most exciting sounds are of anchor chains, plane motors, and train whistles. To me, one is that of a page being turned. Books transport you into periods and worlds that you can never hope to visit, most existing in either the past or the heads of their authors.

Wonderful Life by Stephen Jay Gould focuses on two periods. One spans ...more

In the movie It's A Wonderful Life, George Bailey tells Uncle Billy that the three most exciting sounds are of anchor chains, plane motors, and train whistles. To me, one is that of a page being turned. Books transport you into periods and worlds that you can never hope to visit, most existing in either the past or the heads of their authors.

Wonderful Life by Stephen Jay Gould focuses on two periods. One spans roughly 70 years since 1909 when C D Walcott discovered the Burgess Shale fossils in the Canadian Rockies. Walcott, in Gould's memorable words, shoe-horned every last Burgess animal into a modern group, viewing the fauna collection as a set of primitive or ancestral versions of later, improved forms. The view remained largely unchallenged until the 1970s and '80s, during which time H B Whittington, D Briggs, and S C Morris published painstakingly researched papers that significantly revised the fossil groupings. Some fossils have still not found a place in known existing or extinct groups.

The other period is the Middle Cambrian epoch on the geological timescale. The Cambrian period is well known for the Cambrian Explosion, the relatively accelerated evolution of more complex forms of life over a timeline of just 10-80 million years. The Burgess Shale fossils date from around 505 million years ago, placing them squarely in the Middle Cambrian epoch and just after the Explosion. The value of the Walcott discovery is the astonishing range of fossils found in the shale, and their near complete preservation. In an ecological study of the find described by Gould, Morris cites the following statistics

- 73300 specimens collected
- Nearly 88% animals
- 86% soft bodied, 14% with shells
- 119 genera in 140 species

Gould uses the two events to illustrate some of his controversial ideas. He argues that an important lesson from Burgess Shale is that chance plays a major role in evolution. In his own words, current patterns were not slowly evolved by continuous proliferation and advance, but set by a pronounced decimation (after a rapid initial diversification of anatomical designs), probably accomplished with a strong, perhaps controlling, component of lottery. Richard Dawkins, in a review of the book, praises the form (and some content - he says Gould makes worm anatomy descriptions unputdownable) but tears into the themes that Gould weaves - that much larger diversity prevailed in "Burgess Shale times" than exists today, that this contradicts current thinking and that evolutionists should be shocked by Gould's conclusion.

The book, as Dawkins found, is captivating. The story of the fossil discovery, its misinterpretation and the subsequent research that corrected it all read as close as one can get to a paleontological thriller. Gould is often eloquent, and always interesting, even as he goes into the anatomical details of the curious creatures -

A five eyed, long proboscis-bearing, 3-4 inch creature called Opabinia regalis that evoked general hilarity when Whittington first showed it to the Paleontological Association of Oxford;

Anomalocaris canadensis named before Walcott discovered parts of it in Burgess Shale (the name didn't prevent Walcott mistaking the different parts as either entire animals in themselves or parts of other animals);

Hallucigenia sparsa, a bizarre creature with seven pairs of stilts on one side of the trunk and seven tentacles on the other (portrayed in the book according to prevailing convention as walking on the stilts, while newer finds in China indicate that there might be a second set of tentacles with claws which are the legs. The stilts are on top acting as defence mechanisms!).

The Smithsonian has a gallery of specimens from the Burgess Shale.

It has been a long while since I got into this much biological detail, and Gould doesn't shy away from technical descriptions. I am glad I stuck with it though, and recommend the book to anyone who wants to know what kind of shenanigans life was up to 500 million years ago. Needless to say, the Darwin Wars are just one illustration of what shenanigans life is up to now. Long may we shenanigate.

Gould named the book after the movie, to emphasize how chance and contingency influence evolution....less