Case Study: Catholic Perspective on Evolution #5 cont

The evolutionary sciences are especially susceptible to difficulty in establishing certitude. Unlike physics or chemistry, which are verifiable through controlled laboratory experimentation, the evolutionary disciplines are essentially historical. All the forms of paleontology (including paleoanthropology, the study of ancient man) seek to determine what happened to living things over the course of time. When researchers advance hypotheses to explain fossil phenomena, they are giving *reasonable interpretations* which are verifiable only through subsequent research. Later findings may confirm these explanations, or perhaps render them less plausible, or even prove them *wrong*--that is, very highly unlikely. Thus what is generally accepted by specialists today may be outmoded only a few years from now. The field is highly dynamic.

Evolutionary research over the past century, and especially in recent years, has taken many such twists and turns, often leading in unexpected directions. This unsettled condition stands to reason. The relative scarcity of fossil evidence, the high reliance on imaginative interpretation, the inherent problem of verification--all combine to make this "detective" work subject to ongoing uncertainty. Unfortunately, textbooks seldom convey the cautious and provisional nature of evolutionary thinking at any given time. Science knows less for certain about evolutionary phenomena than is generally supposed.

The history of science offers many examples of this self-corrective process. It is worth our while to examine a few of these, even briefly, to see the dynamic at work. (And, parenthetically, it is interesting to see how many outmoded scientific beliefs still survive in popular thinking.)*