Generalization and Discovery by Assuming Conserved Mechanisms: Cross-Species Research on Circadian Oscillators

In many domains of biology, explanation takes the form of characterizing the mechanism responsible for a particular phenomenon in a specific biological system. How are such explanations generalized? One important strategy assumes conservation of mechanisms through evolutionary descent. But conservation is seldom complete. In the case discussed, the central mechanism for circadian rhythms in animals was first identified in Drosophila and then extended to mammals. Scientists' working assumption that the clock mechanisms would be conserved both yielded important generalizations and served as a heuristic for discovery, especially when significant differences between the insect and mammalian mechanism were identified.