Reductionism: The process of reducing objects or organisms to their smallest parts rather than looking at them as a whole… From Pasteur’s bacteria to the physicist’s atoms, we have grown used to the idea that the smallest things can have the most overwhelming effects. In biology, reductionism fosters the belief that the behavior of an organism or a tissue can best be explained by studying its cells, molecules and atoms and decribing their constitution and function as acurately as possible. However, reductionists often lose sight of the forest in their zeal to examine the ridges on the twigs of the trees.

In the biological sciences, the status once enjoyed by naturalists, who observe how animals live and what they do, has shifted to molecular biologists, who study DNA molecules and segments of these molecules called genes. Molecular biology has become the most prestigious of the biological disciplines. —Ruth Hubbard and Elijah Wald