Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2005

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Claim CA210:

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Response:

1. The difference in predictive power between evolution and other sciences is one of degree, not kind. All theories are simplifications; they purposely neglect as many outside variables as they can. But these extraneous variables do affect predictions. For example, you can predict the future position of an orbiting planet, but your prediction will be off very slightly because you can not consider the effects of all the small bodies in the solar system. Evolution is more sensitive to initial conditions and extraneous factors, so specific predictions about what mutations will occur and what traits will survive are impractical. It is still possible to use evolution to make general predictions about the future, though. For example, we can predict that diseases will become resistant to any new widely used antibiotics.
   
   
2. The predictive power of science comes from being able to say things we would not have been able to say otherwise. These predictions do not have to be about things happening in the future. They can be "retrodictions" about things from the past that we have not found yet. Evolution allows innumerable predictions of this sort.
   
   
3. Evolution has been the basis of many predictions. For example:
   
   
   • Darwin predicted, based on homologies with African apes, that human ancestors arose in Africa. That prediction has been supported by fossil and genetic evidence (Ingman et al. 2000).
   • Theory predicted that organisms in heterogeneous and rapidly changing environments should have higher mutation rates. This has been found in the case of bacteria infecting the lungs of chronic cystic fibrosis patients (Oliver et al. 2000).
   • Predator-prey dynamics are altered in predictable ways by evolution of the prey (Yoshida et al. 2003).
   • Ernst Mayr predicted in 1954 that speciation should be accompanied with faster genetic evolution. A phylogenetic analysis has supported this prediction (Webster et al. 2003).
   • Several authors predicted characteristics of the ancestor of craniates. On the basis of a detailed study, they found the fossil Haikouella "fit these predictions closely" (Mallatt and Chen 2003).
   • Evolution predicts that different sets of character data should still give the same phylogenetic trees. This has been confirmed informally myriad times and quantitatively, with different protein sequences, by Penny et al. (1982).
   • Insect wings evolved from gills, with an intermediate stage of skimming on the water surface. Since the primitive surface-skimming condition is widespread among stoneflies, J. H. Marden predicted that stoneflies would likely retain other primitive traits, too. This prediction led to the discovery in stoneflies of functional hemocyanin, used for oxygen transport in other arthropods but never before found in insects (Hagner-Holler et al. 2004; Marden 2005).
   
   With predictions such as these and others, evolution can be, and has been, put to practical use in areas such as drug discovery and avoidance of resistant pests.
   
   
4. If evolution's low power to make future predictions keeps it from being a science, then some other fields of study cease to be sciences, too, especially archeology and astronomy.

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