Biology Before Darwin

The 18th and early 19th centuries marked widespread application of the scientific method in the life sciences. Exploration of the world was flooding western intellectual centers with a seemingly endless array of new plants and animals and steady advances were being made in understanding the basics of the structure and function of animals and plants.

At the start of this period, one issue that did not arise was the question of any significant history for the world of life. The Christian Bible, including both the Old and New Testaments, was considered authoritative with respect to the origin of the world and its subsequent history. The Old Testament included two accounts of the creation of the world by God (in the Book of Genesis) and this was considered beyond question. When the Creation occurred was less clear, but most theological authorities accepted a date of around 4004 BC, computed by a Bishop Ussher, based on his tabulation of the lives of biblical patriarchs, prophets, and other major figures. Since the world was thus only about 6000 years old, the history of the world and of all life was basically congruent with human history. All living things were the descendants of those animals and plants brought into being by the Creation. Although some might have been lost in biblical catastrophes such as the Flood, the task of the new science of biology (not yet recognized as distinct from the broader field of Natural History) was to catalog and understand the living products of Divine Creation. While no major intellectual figures of this period questioned the biblical version of history, advances in various branches of Natural History raised puzzling and persistent questions with respect to how one could reconcile this new information with the accepted view of Divine Creation.

Comparative anatomy deals with the study of the structure of animal bodies. As more information on the subject emerged, there were numerous interesting questions that arose:

Starr and Taggart, 1989, Biology - the Unity and Diversity of Life

Vestigial structures are features of the body that may be fully functional in some animals, but which are present, typically in rudimentary form, with no known functions in others. It is estimated that the human body contains over 100 such structures. In the illustration above, the coccyx or "tail-bone" is shown. This is a fused length of vertebrae that is essentially a much-shortened version of the tail present in most mammals. This rudimentary tail is also equipped with vestigial muscles and nerves, yet it is short, rigid, contained completely within the body in most people, and completely non-functional! Other examples of such structures in humans include the vermiform appendix, wisdom teeth, and the rudimentary muscles to move or articulate the ears. In the case of the appendix and wisdom teeth, the structures are not only non-functional, but they have the potential for serious infection or even death.

Such structures can also be found in most other animals. Also shown above is a skeletal view of what would be the pelvic region of a boa - a large snake. Snakes obviously do not have legs, yet these boas have the vestigial remnants of both pelvic girdles and limbs, complete with a rudimentary claw. If animals are the products of a unique creative event, complete with the implication of divine perfection, why do these structures, which have fully functional analogs in other animals, occur? One might argue for divine whim or some unknowable function or reason, but such explanations had already been rejected in the development of the physical sciences.

Campbell, 1996, Biology

Homologous structures present another puzzle. These are structures that, although they may have quite different functions and external form in different animals, are never the less constructed of essentially the same anatomical elements. The forelimbs of vertebrates, of which several samples are shown above, are a classic example of this phenomenon. The human arm and hand, the fore-limb of a cat, the flipper of a whale, and the wing of a bat are highly divergent in terms of function, yet are built from modified versions of the same basic bones, along with essentially similar muscle and nerve groups, even when all of these are not functional (see vestigial structures, above). If each creature is uniquely designed for its role in life, why this commonality of structural elements? Much or the argument for Creation rests on the perfection of design in organisms, yet, in truth, many features of animals seem "jury-rigged" as if there was some obsessive compulsion to modify existing structures, when far more elegant solutions are available.

These and many other anatomical puzzles didn't shake the foundations of religious orthodoxy, but they were real questions for which there were no answers.

Linnaeus (Karl von Linne') created the binomial system of nomenclature in 1758, along with an artificial system for classifying organisms based on the degree of shared traits or characteristics. An interesting question, which tended to be ignored at the time, was why was it even possible to classify organisms in such a fashion? If each was a unique product of creation, classification should be an elusive goal. This is not to say that classification is easy, but, at a simple level, a child can do it!

The stratigraphic rock record exposed in the Grand Canyon of the Colorado River, Arizona. Levin, 1996, The Earth Through Time.

Georges Cuvier, whose career spanned the late 18th and early 19th century, was an anatomist who became fascinated with the fossil deposits of the Paris Basin. What astonished him, as his studies proceeded, was the fact that as one excavated fossils from older and older (deeper and deeper) rock layers, the fossils seemed to record distinct intervals in history that were dominated by groups of animals quite different from today. Using the biblical flood as a model, he advanced the theory of Catastrophism to reconcile biblical and fossil history. According to this view, God engaged in multiple creations, each populated by more diverse, complex, and "modern" creatures than the one before. When each of these ancient worlds had run its course, according to divine plan, the Creator visited a catastrophe on the world which "cleared the decks" for the next creative episode. Genesis, in Cuvier's view, simply recorded the last of these episodes - important because it was in the last Creation that humans were created.

The giant tortoises (land turtles), endemic to the Galapagos Islands off the west coast of South America. Starr and Taggart, 1989, Biology - the Unity and Diversity of Life

Buffon was another French contemporary of Cuvier but his specialty was biogeography - the study of the distribution of plants and animals. What puzzled Buffon was that many isolated islands and continents had endemic species of plants and animals - organisms found there and nowhere else. The puzzle, particularly with respect to animals, was how they managed to reach these isolated areas. The question was legitimate, since the biblical account in Genesis records two times when all the animals in the world were located at one geographic point. The first was the Garden of Eden, when all the animals paraded by Adam to receive their names, while the second was the account of the Flood, where the surviving pairs of animals left the Ark at the point where it came to rest. Birds presented no difficulty, but how could animals, like the giant tortoises shown above, who could neither fly nor swim, make the journey to their isolated homes, and why should they do so in preference to the many other places that might be suitable for them?

In order to counter these very practical difficulties, Buffon conceived of the theory of Centers of Creation. In this hypothesis, the Genesis account simply records God's activities in the general area of the Middle East. God, Buffon reasoned, must also have been active in creating unique creatures at other isolated points on the globe, whose history is not recorded in the Bible. In essence, Buffon was forced to spread Creation in space, beyond the limits of the Genesis account, just as Cuvier had been forced to spread Creation into multiple events in time.

Many of the natural historians of the time were aware that there was a solution in the form of an evolutionary view of life. If life had appeared or been created in a very simple state, and then had gradually diversified and become more complex through its history, many of the questions being posed could be resolved. Evolution was not a new idea but there were two practical difficulties in the path to wide acceptance of such a view. The first was time. The 6000 years permitted for earth history was simply too short to permit significant change in life forms. Animal and plant species seemed quite stable today and the Bible essentially described the early world as populated by essentially those same kinds of organisms. The second problem was that no one had yet proposed a creditable mechanism by which life forms could change with time. Until such difficulties could be resolved, the biblical account, with all of its problems, would continue to be accepted as the only alternative by most naturalists.

Ralph E. Taggart (taggart@msu.edu)