Wonderful Life: The Burgess Shale and the Nature of History Read online

  On September 3, Walcott was even more successful: “Found a fine lot of Phyllopod crustaceans and brought in several slabs of rock to break up at camp.” In any event, he continued to collect, and put in a full day for his last hurrah on September 7: “With Stuart and Mr. Rutter went up on fossil beds. Out from 7 A.M. to 6:30 P.M. Our last day in camp for 1909.”

  If I am right about his discovery of the main bed in 1909, then the second part of the canonical tale—the week-long patient tracing of errant block to source in 1910—must be equally false. Walcott’s diary for 1910 supports my interpretation. On July 10, champing at the bit, he hiked up to the Burgess Pass campground, but found the area too deep in snow for any excavations. Finally, on July 29, Walcott reported that his party set up “at Burgess Pass campground of 1909.” On July 30, they climbed neighboring Mount Field and collected fossils. Walcott indicates that they made their first attempt to map the Burgess beds on August 1: “All out collecting the Burgess formation until 4 P.M. when a cold wind and rain drove us into camp. Measured section of the Burgess formation—420 feet thick. Sidney with me. Stuart with his mother and Helen puttering about camp.” “Measuring a section” is geological jargon for tracing the vertical sequence of strata and noting the rock types and fossils. If you wished to find the source of an errant block that had broken off and tumbled down, you would measure the section above, trying to match your block to its most likely layer.

  I think that Charles and Sidney Walcott located the phyllopod bed on this very first day, because Walcott wrote for his next entry, of August 2: “Out collecting with Helena, Stuart and Sidney. We found a fine lot of ‘lace crabs’and various odds and ends of things.” “Lace crab” was Walcott’s field term for Marrella, chief denizen of the phyllopod bed. If we wish to give the canonical tale all benefit of doubt, and argue that these “lace crabs” of August 2 came from dislodged blocks, we still cannot grant a week of strenuous effort for locating the mother lode, for Walcott wrote just two days later, on August 4: “Helena worked out a lot of Phyllopod crustaceans from ‘Lace Crab’layer.”

  The canonical tale is more romantic and inspiring, but the plain factuality of the diary makes more sense. The trail lies just a few hundred feet below the main Burgess beds. The slope is simple and steep, with strata well exposed. Tracing an errant block to its source should not have been a major problem, for Walcott was more than a good geologist—he was a great geologist. He should have located the main beds right away, in 1909, in the week after he first discovered the soft-bodied fossils. He did not have an opportunity to quarry in 1909—the only constraint imposed by limits of time—but he found many fine fossils, and probably the main beds themselves. In 1910, he knew just where to go, and he set up shop in the right place as soon as the snow melted.

  Walcott established his quarry in the phyllopod bed of the Burgess Shale and worked with hammers, chisels, long iron bars, and small explosive charges for a month or more in each year from 1910 through 1913. In 1917, at age sixty-seven, he returned for a final fifty days of collecting. In all, he brought some eighty thousand specimens back to Washington, D.C., where they still reside, the jewel of our nation’s largest collection of fossils, in the National Museum of Natural History at the Smithsonian Institution.

  Walcott collected with zeal and thoroughness. He loved the West and viewed his annual trips as a necessary escape for sanity from the pressures of administrative life in Washington. But back at the helm of his sprawling administrative empire, he never found even the entering wedge of ample time to examine, ponder, ruminate, observe again, obsess, reconsider, and eventually publish—the essential (and incompressible) ingredients of a proper study of these complex and precious fossils. (The significance of this failure will emerge as an important theme in chapter IV.)

  Walcott did publish several papers with descriptions of Burgess fossils that he labeled “preliminary”—in large part to exercise his traditional right to bestow formal taxonomic names upon his discoveries. Four such papers appeared in 1911 and 1912 (see Bibliography)—the first on arthropods that he considered (incorrectly) as related to horseshoe crabs, the second on echinoderms and jellyfish (probably all attributed to the wrong phyla), the third on worms, and the fourth and longest on arthropods. He never again published a major work on Burgess metazoans. (A 1918 article on trilobite appendages relies largely on Burgess materials. His 1919 work on Burgess algae, and his 1920 monograph on Burgess sponges, treat different taxonomic groups and do not address the central issue of disparity in the anatomical design of coelomate animals. Sponges are not related to other animals and presumably arose independently, from unicellular ancestors. The 1931 compendium of additional descriptions, published under Walcott’s name, was compiled after his death by his associate Charles E. Resser from notes that Walcott had never found time to polish and publish.)

  In 1930, Percy Raymond, professor of paleontology at Harvard, took three students to the Burgess site and reopened Walcott’s old quarry. He also developed a much smaller quarry at a new site just sixty-five feet above Walcott’s original. He found only a few new species, but made a fine, if modest, collection.

  These specimens—primarily Walcott’s, with a small infusion from Raymond—formed the sole basis for all study of the Burgess Shale before Whittington and colleagues began their revision in the late 1960s. Given the supreme importance of these fossils, the amount of work done must be judged as relatively modest, and none of the papers even hint at an interpretation basically different from Walcott’s view that the Burgess organisms could all be accommodated within the taxonomic boundaries of successful modern phyla.

  I well remember my first encounter with the Burgess Shale, when I was a graduate student at Columbia in the mid-1960s. I realized how superficially Walcott had described these precious fossils, and I knew that most had never been restudied. I dreamed, before I understood my utter lack of administrative talent or desire, about convening an international committee of leading taxonomic experts on all phyla represented in the Burgess. I would then farm out Amiskwia to the world’s expert on chaetognaths, Aysheaia to the dean of onychophoran specialists, Eldonia to Mr. Sea Cucumber. None of these taxonomic attributions has stood the test of subsequent revision, but my dream certainly reflected the traditional view propagated by Walcott and never challenged—that all Burgess oddities could be accommodated in modern groups.

  Since one cannot set out deliberately to find the unexpected, the work that prompted our radical revision had modest roots. The Geological Survey of Canada, in the course of a major mapping program, was working in the southern Rocky Mountains of Alberta and British Columbia in the mid-1960s. This general effort almost inevitably suggested a reexamination of the Burgess Shale, the most famous site in the region. But no one anticipated any major novelty. Harry Whittington got the nod as paleontologist-in-chief because he was one of the world’s leading experts on fossil arthropods—and everyone thought that most of the Burgess oddities were members of this great phylum.

  My friend Digby McLaren, then head of the Geological Survey and chief instigator of the Burgess restudy, told me in February 1988 that he had pushed the project primarily for (quite proper) chauvinistic reasons, not from any clear insight about potential intellectual reward. Walcott, an American, had found the most famous Canadian fossils and carted the entire booty back to Washington. Many Canadian museums didn’t own a single specimen of their geological birthright. McLaren, declaring this situation a “national shame,” set forth (in his only partially facetious words) “to repatriate the Burgess Shale.”

  For six weeks in the summers of 1966 and 1967, a party of ten to fifteen scientists, led by Harry Whittington and the geologist J. D. Aitken, worked in Walcott’s and Raymond’s quarries. They extended Walcott’s quarry some fifteen meters northward and split about seven hundred cubic meters of rock in Walcott’s and seventeen in Raymond’s quarry. Besides substituting helicopters for horses and using smaller explosive charges (to avoid jumbling strat
igraphic information by throwing fossiliferous blocks too far from their source for proper identification), these modern expeditions worked pretty much as Walcott had. The greatest invention since Walcott, as Whittington notes (1985b, p. 20), is the felt-tipped pen—a godsend for labeling each rock immediately upon collection.

  In 1975, Des Collins of the Royal Ontario Museum mounted an expedition to collect fossils from the debris slopes in and around both quarries. He was not permitted to blast or excavate in the quarries themselves, but his party found much valuable material. (The Burgess Shale is so rich that some remarkable novelties could still be found in Walcott’s spoil heaps.) In 1981 and 1982, Collins explored the surrounding areas, and found more than a dozen new sites with fossils of soft-bodied organisms in rocks of roughly equivalent age. None approach the Burgess in richness, but Collins has made some remarkable discoveries, including Sanctacaris, the first chelicerate arthropod. If Walcott’s phyllopod bed arose when a turbidity current triggered a mudslide, then many other similar slides must have occurred at about the same time, and other Lagerstätten should abound. As I write this book in the summer of 1988, Des Collins is out searching for more sites in the Canadian Rockies.

  Paleontology is a small and somewhat incestuous profession. The Burgess Shale has always stood over my world like a colossus. Bill Schevill, the last survivor of Raymond’s 1930 expedition and later a great expert on whales, stops by my office for a chat now and then. G. Evelyn Hutchinson, who described the strange Aysheaia and the equally enigmatic Opabinia in 1931 (getting one basically right and the other equally wrong), and who later became the world’s greatest ecologist and my own intellectual guru, has regaled me with stories about his foray, as a young zoologist, into the peculiar world of fossils. Percy Raymond’s collection sits in two large cabinets right outside my office. I was first appointed to Harvard as a very junior replacement for Harry Whittington, who had just taken the chair in geology at Cambridge (where he studied the Burgess for the next twenty years on a transoceanic shuttle). I am no expert on older rocks or the anatomy of arthropods, but I cannot escape the Burgess Shale. It is an icon and symbol of my profession, and I write this book to pay my respects, and to discharge an intellectual debt for the thrill that such creatures can inspire in a profession that might reinterpret Quasimodo’s lament as an optimistic plea for fellowship: Oh why was I not made of stone like these!

  CHAPTER III

  Reconstruction of the Burgess Shale: Toward a New View of Life

  A QUIET REVOLUTION

  Some transformations are overt and heroic; others are quiet and uneventful in their unfolding, but no less significant in their outcome. Karl Marx, in a famous statement, compared his social revolution to an old mole burrowing busily beneath the ground, invisible for long periods, but undermining traditional order so thoroughly that a later emergence into light precipitates a sudden overturn. But intellectual transformations often remain under the surface. They ooze and diffuse into scientific consciousness, and people may slowly move from one pole to another, having never heard the call to arms. The new interpretation of the Burgess Shale ranks among the most invisible of transformations for two basic reasons, but its power to alter our view of life cannot be matched by any other paleontological discovery.

  First, the Burgess revision is an intensely intellectual drama—not a swashbuckling tale of discovery in the field, or of personal struggle to the rhetorical death waged by warring professionals battling for the Nobel gold. The new view trickled forth, tentatively at first but with more confidence later on, in a series of long and highly technical taxonomic and anatomical monographs, published mostly in the Philosophical Transactions of the Royal Society, London, the oldest scientific journal in English (dating back to the 1660s), but scarcely an item on the shelf of your corner drugstore, or even your local library, and not the sort of publication scrutinized by the journalists responsible for selecting the tiny part of scientific activity destined for public notice.

  Second, all the standard images of scientific discovery were violated by the revision of the Burgess Shale. All the romantic legends about field work, all the technocratic myths about machine-based novelty in procedure, were fractured or simply bypassed.

  The myth of field work, for example, proclaims that great alterations in ideas arise from new, pristine discoveries. At the end of the trail, after weeks of blood, sweat, toil, and tears, the intrepid scientist splits a rock from the most inaccessible place on the map, and cries Eureka! as he spies the fossil that will shake the world. Since the Burgess revision was preceded by two full seasons of field work, in 1966 and 1967, most people would assume that discoveries of this expedition prompted the reinterpretation. Well, Whittington and company did find some wonderful specimens, and a few new species, but old Walcott, a maniacal collector, had been there first, and had worked for five full seasons. He therefore got most of the goodies. The expeditions of 1966 and 1967 did spur Whittington into action, but the greatest discoveries were made in museum drawers in Washington—by restudying Walcott’s well-trimmed specimens. The greatest bit of “field work,” as we shall see, occurred in Washington during the spring of 1973, when Whittington’s brilliant and eclectic student Simon Conway Morris made a systematic search through all the drawers of Walcott’s specimens, consciously looking for oddities because he had grasped the germ of the key insight about Burgess disparity.

  The myth of the laboratory invokes the same misconception, transferred indoors—that new ideas must arise from pristine discoveries. According to this “frontier mentality,” one can advance only by “seeing the unseen”—by developing some new method to discern what, in principle, could not be perceived before. Progress therefore requires that the boundaries of complex and expensive machinery be extended. Novelty becomes linked inextricably with miles of glassware, banks of computers, cascading numbers, spinning centrifuges, and big, expensive research teams. We may have come a long way from those wonderful Art Deco sets of the old horror films, where Baron Frankenstein harnessed the power of lightning to quicken his monsters, but the flashing lights, tiers of buttons, and whirling dials of that enterprise neatly captured a myth that has only grown since then.

  The Burgess revision did require a definite set of highly specialized methods, but the tools of this particular technology do not extend beyond ordinary light microscopes, cameras, and dental drills. Walcott missed some crucial observations because he didn’t use these methods—but he could have employed all Whittington’s techniques, had he ever found time to ponder, and to recognize their importance. Everything that Whittington did to see farther and better could have been done in Walcott’s day.

  The actual story of the Burgess may reflect science as practiced, but this basic truthfulness doesn’t make my job any easier. Mythology does have its use as a powerful aid to narrative. Yet, after considering many possible modes of composition, I finally decided that I could present this information in only one way. The revision of the Burgess Shale is a drama, however devoid of external pomp and show—and dramas are stories best told in chronological order. This chapter, the centerpiece of my book, shall therefore proceed as a narrative in proper temporal sequence (preceded by an introduction on methods of study and followed by discussion of the wider implications).

  But how to establish chronology? The obvious method of simply asking the major players for their memories cannot suffice. Oh, I did my duty in this regard. I visited them all, pad and pencil in hand. The exercise made me feel rather foolish, for I know these men well, and we have been discussing the Burgess Shale over beer and coffee for nearly two decades.

  Besides, the worst possible source for what Harry Whittington thought in 1971, when he published his first monograph on Marrella, is Harry Whittington in 1988. How can one possibly peel away an entire edifice of later thought to recover an embryonic state of mind unaffected by the daily intellectual struggles of nearly twenty subsequent years? The timing of events becomes jumbled in retrospect, for we arrang
e our thoughts in a logical or psychological order that makes sense to us, not in chronological sequence.*

  I call this the “my, how you’ve grown” phenomenon. No comment from relatives is more universally detested by children. But the relatives are correct; they haven’t visited for a long time and do accurately remember the last meeting long ago, while a child sees his past dimly through all the intervening events. Freud once remarked that the human mind is like a psychic Rome in violation of the physical law that two objects can’t occupy the same space at the same time. No buildings are demolished, and structures from the time of Romulus and Remus join the restored Sistine Chapel in a confusing jumble that also heaps the local trattoria upon the Roman bath. The recovery of chronological order requires contemporary documents.

  I have therefore worked primarily from the published record. My procedure was simplicity itself. I read technical monographs in strictly chronological order, focusing almost entirely on the primary works of anatomical description, not the fewer articles of secondary interpretation. I may be a lousy reporter, but at least I can proceed as no journalist or “science writer” ever would, or could. The men who revised the Burgess Shale are my colleagues, not my subjects. Their writings are my literature, not the distant documents of another world. I read more than a thousand pages of anatomical description, loving every word—well, most of them at least—and knowing by personal practice exactly how the work had been done. I started with Whittington’s first monograph on Marrella (1971), and only stopped when I ran out at Anomalocaris (Whittington and Briggs, 1985), Wiwaxia (Conway Morris, 1985), and Sanctacaris (Briggs and Collins, 1988). I don’t know that I have ever had more fun, or experienced more appreciation for exquisite work beautifully done, than during the two months that I devoted to this exercise.