The recent flurry of letters about the creationism-evolution debate seems to have produced more smoke than illumination.

Much of the rhetoric here and in the popular press indicates an erroneous impression of the roe of theory in science as epitomized by the common creationist mantra that "Evolution is not a fact but only a theory."

What is a theory? It is a tentative explanation or generalization about a collection of observations concerning some facet of nature. The role of theory is to provide synthesis that can be tested and which are always subject to revision or even rejection in the face of new, controverting evidence.

Even if a theory ultimately proves incomplete or wrong, it would still have been a good theory if it served to organize a body of knowledge and to stimulate and guide further investigation.

Difficult as it is for most people to accept, there is no such thing as absolute proof in science, in religion or indeed in any realm of human existence. We strive to discover truth, but we can never be certain we have found absolute truth, which makes the term "fact" a semantical nightmare.

Darwin's theory, The Origin of Species by Natural Selection, was most assuredly a good theory in that it has served as a unifying concept in biology for 146 years. It was incomplete in its initial form because it could not explain how a new character, thus a new species, might arise, but it did a superb job of explaining how changing environments selected or filtered and preserved individuals that were better adapted to the changing circumstances.

Drawing upon the abundant evidence of successful breeding of animals and plants, Darwin inferred that over time, somehow certain characteristics became dominant in a portin of population and eventually became prominent enough to constitute a new species.

Not until the early 20th century did the new fied of genetics offer a substantial explanation of how speciation might occur. First was the recognition of mutations, to be followed by countless investigations of the details of inheritance, including the milestone recognition of the structure of DNA by Crick and Watson.

These advances have modified and improved the theory, suggesting, for example, that natural selection is not the only mechanism of enhancing adaptation. Such advances havenot falsified the fundamental Darwinian concept, however.

The fossil record was actually an embarrassment for Darwin because it did not in 1859 reveal obvious transitional forms, so-called "missing links," which were implied by his theory. It is often claimed that no missing links exist, therefore the theory must be entirely wrong.

This would be an illogical conclusion to reach even if there were no missing links, but in fact the first such link was discovered only four years after Origins was published: The Jurassic Archaeopteryx with a reptilian skeleton and clear impressions of feathers was found in a quarry in Germany.

Some years later off the coast of Africa a fish was caught, a Coelacanth, which is vitually identical to the late Palezoic lob finned fish, which paleontologists had already postulated was the ancestor of all land vertebrates.

Still, more recently a successon of transitional forms of ancient whales has been discovered in Egypt and Pakistan. Seaching more and more widely over the world has yielded more and more missing links.

Examplary of the continuing modification of scientific theories was the concept of punctuated equilibrium developed by paleontologist Stephen J. Gould and Niles Eldridge in the 1970s.

They suggested that we should not expect a greate number of mising link transitions because new species apparently have arisen on the fringe of the geographic range of a species where their preservation potential is very low.

If by mutation the new form gains an adaptive advantage, then it would thrive and spread rapidly. Punctuated equilibrium postulates long periods of stability of species and short bursts of speciation. So, concluded Gould and Eldridge, the seemingly patchy fossil record with its many apparent gaps may be more complete than had long been thought.

Most of the creationist arguments are more than 100 years old and tend to ignore or misrepresent the greate strides in the biological sciences during the 20th century, especially those from genetics.

Faith alone, either pro or con, is irrelevant to the scientific validity of evolution theory. The real issue is whether creationism/intelligent design is appropriate in a science curriculum alongside evolution.

R. H. Dotts Jr.
Madison, Wis.
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