Creationism debate confuses evolution theory and evidence
THERE seems to be considerable confusion over the scientific issues involved in the evolution/creationism debate. It is not a confrontation between Darwinian evolution and a literal interpretation of Genesis, as many commentators implied in reporting the recent Supreme Court nullification of the Louisiana law mandating balanced treatment of ``evolution science'' and ``creation science.'' Such a simplistic view obscures the crucial distinction between evolution as a historical fact and theories as to how it occurs. Scientists are convinced that earthly life has developed from simple beginnings to a rich diversity of complex forms over several billion years. But scientists vigorously debate evolution theory, which has gone well beyond what Darwin proposed.
Many - although not all - creationists also recognize life's long development. For example, the American Scientific Affiliation - a creationist organization - has produced a booklet for science teachers that rejects the biblical literalism which holds that the universe was created in six calendar days within the past 10,000 years. Instead, the Affiliation would look for a creator's hand in guiding the development of life throughout the history of the scientists' ancient earth.
Darwin didn't invent the concept of evolution. As Harvard paleontologist Stephen Jay Gould has pointed out, this was a common ``heresy'' in his day.
What Darwin did do was to convince scientists that evolution had actually occurred and to put its study on a sound scientific basis. Gould considers Darwin's greatest contribution to be the establishment of a scientific methodology for studying the evolutionary past.
Darwin also proposed a mechanism by which evolution proceeds. He envisioned small variations in form and function constantly arising in organisms. Where a variation helped an organism to survive and produce offspring in a given environment, it would persist. He called the process natural selection - a slow evolution of organisms in response to environmental conditions.
Darwin's methodology and the concept of natural selection still guide paleontologists. But there is much more to evolution science today.
Researchers no longer see organic life's development as necessarily being a slow, continuous process. Mass extinctions, perhaps caused by climate change or an asteroid impact, are followed by an outburst of evolutionary change. Some scientists see species evolving in stair-step fashion, in which periods of rapid change (a few thousands or tens of thousands of years) punctuate long periods (millions of years) of stability. There's lively debate among proponents of these and other views of how evolution occurs.
Darwin knew nothing of molecular biology. Today, scientists trace a species's lineage in the molecular structure of its genes. They see evolution taking place within the chemistry of living cells as well as at the level of the whole organism.
Darwin saw the rise of life as an improbable occurrence of random chemical arrangements that natural selection preserved. There were no extensive experiments in his day to discover what might actually have happened. Modern experiments have shown that, far from being chance products, amino acids, proteins, and other building blocks of organic life arise automatically from precursor materials as these materials interact according to basic physical laws, under favorable conditions. Furthermore, these chemicals evolve automatically to produce structures that mimic some of the forms and functions of primitive cells.
As Mae-Wan Ho of Britain's Open University, Peter Saunders of King's College in London, and Sidney Fox of the University of Miami observed last year in New Scientist, it may be that ``life and the [genetic] code are thus not accidents frozen by natural selection but largely consequences of the stereochemical properties of the molecules.'' While this view is controversial, it can be studied in the laboratory. Thus, laboratory research has been added to Darwin's historical methodology in the scientific study of the development of life on earth.
It is this many-faceted on-going science story that should be told in public school biology courses. Creationists want those courses to include the possibility of - and the ``scientific'' evidence for - a creator as well. There is no such ``scientific'' evidence. The concept of a supernatural creator is inherently religious. It has no place in a science class. Nevertheless, creationists who are not biblical literalists should be able to join biologists in recognizing the underlying kinship of all earthly life that evolution research has established.
A Tuesday column. Robert C. Cowen is the Monitor's natural science editor.
