 It has become common scientific practice in research in toxicology, drug development, pathology and therapeutics to explore human biomedical phenomena by performing experiments on nonhuman animals and then extrapolating the results to humans (animals play many roles in biomedical research, but one important role is as predictors of human biomedical phenomena).Shanks claims that a prediction problem exists due to the fact that humans and their nonhuman models have taken divergent evolutionary trajectories, and are thus not qualitatively identical systems (once compensation has been made for purely quantitative differences in body weight, for example).Put bluntly, the prediction problem boils down to this