Essay using Gould's _Wonderful Life_

[david ford]

I. Introduction

Paleontologist Steven Jay Gould's book _Wonderful Life: The Burgess Shale
and the Nature of History_ (1989) describes the story of the discovery and
richness of the Burgess Shale. The Burgess Shale is important to
paleontologists because it contains soft parts of animals from the
Cambrian explosion. Soft parts are needed to understand diversity and
anatomical structure since most organisms lack hard parts and since the
hard parts that do exist often reveal little about underlying
organization. Because soft part fossils are rare and contain much
valuable information, paleontologists treasure them.

Besides soft parts, the Burgess Shale has provided paleontologists with a
new model of evolution's history. Instead of slowly progressing upward as
commonly believed, evolution is seen to occur in spurts, with the prime
example being the Cambrian explosion, organisms from which are fossilized
in the Shale. During the Cambrian explosion, all the modern phyla the
earth has ever seen quickly appeared. Subsequent evolution progressed
only through variations upon the original structures. A conceptual
framework of initial wide disparity, or differences in anatomical
structure, followed by massive decimation, during which most body forms
become extinct, has been developed to explain the data and replace the
incorrect interpretation of evolutionary history as being a slow, gradual
process.

II. Why Walcott Imposed the Shoehorn

Charles Doolittle Walcott force-fitted, or as Gould put it, "shoehorned,"
the Shale's data into his preconceived religious and historical opinions.
His work and philosophy led to this failure in interpretation. Walcott's
duties as an administrator robbed him of sufficient opportunity to
carefully examine the Burgess fossils he had collected during field
studies, and he died intending to eventually make the specimens the
principal subject of his attention.

Walcott's guiding philosophy, according to which study of nature would
support his political, religious, and social sentiments, also harmed his
interpretation of the Burgess Shale. Walcott held that science and
religion complemented each other. Since God had revealed Himself in
nature and nature's laws, science could, through studying nature, discover
basic moral principles for use in religion. The progressive character of
natural evolution meant that these moral standards were continually being
improved. Walcott therefore interpreted the Burgess Shale in terms of
natural and moral improvement to accommodate his socio-religious beliefs.

This doctrine of continuous incremental evolutionary progression in nature
and humanity constitutes another area in Walcott's philosophy influencing
his interpretation of the Shale organisms. Because Walcott, like Charles
Darwin, believed that the story of life was one of constant improvement,
by necessity he interpreted the Burgess fauna as primitive predecessors
for far more complex and varied descendants. Unable to find any
Precambrian fossil remains of Cambrian forerunners, Walcott proposed the
existence of a Lipalian interval during which no fossil deposition
occurred.

III. Whittington Helps End the Shoehorn

The validity of Walcott's shoehorn in placing all Burgess organisms within
known categories was severely questioned by Harry Whittington's meticulous
study of the Burgess fossils. Whittington examined the purported
trilobite _Marrella splendens_ to reveal differences between _Marrella_
and all other trilobites. Doubts were similarly raised about the validity
of Walcott's categorization of _Yohoia tenuis_ as a brachiopod, while
study of _Opabinia regalis_ conclusively showed that it could not be
classified within known phyla. These and other misidentifications
prompted Whittington and colleagues to formulate an innovative view of
Burgess fauna. No longer were they described as evolutionary precursors
of later and improved animals, but instead, included organisms unlike any
existing today.

Just as Walcott's working life and philosophy influenced his Burgess Shale
interpretation, so also did Harry Whittington's background and methods
enable him to challenge the orthodox interpretation of Burgess Shale
fossils. Whittington had previously examined specimens preserved in
silica. After forming an opinion about what a three-dimensional structure
might look like, he would check his opinion by dissolving the silica,
gaining much invaluable experience for working with the Burgess organisms.
Also indispensable was Whittington's spatial ability and drawing skills.
A genius when it came to matters visual, Whittington could transfer from
three to two dimensions and back again with ease.

Whittington realized that though contorted, Burgess animals remained
three-dimensional, and used three methods to resolve this 3-d structure.
Careful excavation, or dissection of the outer part of the fossil,
revealed underlying organization. Since both the fossil and the
impression it made in the surrounding rock contain useful structural
information, part and counterpart were utilized in developing diagrams.
Also used were various odd orientations. After drawing each specimen at
large scale, the pictures were examined collectively to develop an
accurate idea of what an organism looked like. Leaving nothing to
speculation, Whittington's strict fidelity to the rocks forced him to
reject the reigning interpretation of the Burgess organisms.

IV. Natural History is a Science

Gould would like natural history placed on an equal level with
experimental science. Evolutionary theory makes use of documentable
evidence, specifically the fossil record, of which one portion is the
Burgess Shale. Fossils have been made to communicate with the present
through the research of paleontologists as Whittington. The fossil
evidence tells us that, contrary to traditional notions of evolutionary
development in which organisms undergo constant progression, life's
history actually consists of initial wide disparity in body forms followed
by extinction and stability in form in the survivors. Therefore, the fact
that studying the fossil evidence led to this improved view of
evolutionary history is said to support the contention that natural
history is as scientific as are the experimental sciences.

Because historical explanations are based on contingency, those just-so
explanations are needed to understand how organisms became as they are
presently. Provision of such understanding constitutes a second reason
for treating natural history as the science it manifestly is.

Gould's third reason for placing evolutionary history on a par with
experimental science is that the understanding it provides has tremendous
psychological value. To know that humans are the product of countless
numbers of history's proceeding events, of which any one deviation could
easily have resulted in the non-existence of _Homo Sapiens_, is
heartwarming, for it is marvelous that we should have ever been produced.
Because of contingency's role in natural history, the construction of
alternative scenarios can be entertaining. While exploring several
historical possibilities, Gould emphasizes the lack of ability, even if
one were present millions of years ago, to predict what would be
successful and what would suffer miserable extinction.

V. A New View of Evolutionary History

Not one new phylum came into existence following the Cambrian explosion,
of which the Burgess Shale is a snapshot, while only four out of
approximately twenty-five phyla present in the Shale survive to this day.
The Cambrian explosion thus illustrates a recurring theme in natural
history, that of wide initial disparity in anatomical form followed by
extinction. Questions about why one organism died while another lived are
not answerable at this time, though Gould is inclined to believe that
chance plays an important role in survival. A change in rules for
survival can have a marked and unexpected effect on what avoids extinction
during a particular cataclysmic event. Besides chance, Gould thinks that
certain evolved features happen to perform survival functions not
originally intended by evolutionary processes.

The Cambrian Explosion and similar sudden speciation events, which are
followed by extinction and stasis, cast doubt on the popular cone, tree,
and ladder images of evolutionary history. According to ladder
iconography, the various rungs on the evolutionary ladder to man see
constant improvement and increasing complexity. Tree images are
exemplified by the many trees of phylogeny constructed that allegedly
depict the evolutionary ancestors and descendants of organisms using a
tree-like, branching diagram. The cone of increasing diversity is a 3-d
rendering of tree diagrams, and illustrates the gradual rise of diversity
and complexity in life beginning with one or a few simple organisms. The
fact that conscious man appeared at the top of these iconographies
undoubtedly held much appeal.

In place of the ladder, tree, and cone depictions of evolution, Gould
proposes a heavy-bottom bush image to illustrate the idea of punctuated
equilibrium. This theory opposes Darwin's view that the geological record
imperfectly describes gradual evolutionary changes. The history of
evolution is marked by geologically short bursts of creative activity that
punctuate long periods of stasis. During stasis, some species become
extinct, but during mass extinction events, large numbers perish.
Speciation is said to occur within in the chance survivors.

VI. Conclusion

Because of chance's role in survival, because of the past's ramifications
for numerous future possibilities, only one path of which will be
followed, and because there does not necessarily reside an element of
continual improvement within evolutionary development, the existence of
humans is to be considered a wonder. If one were to replay evolution's
tape, humans most probably would not appear. Gould's version of the "for
want of a nail the kingdom was lost" story takes on the highest of stakes.
Such a tale deserves the attention of paleontologist and
non-paleontologist alike.