Beyond Uniformitarianism: What Biology Can Teach Geology

There are scientific assumptions so deeply embedded in our thinking that we stop seeing them as assumptions. Uniformitarianism is one of them.

The familiar formulation — the present is the key to the past — sounds almost self-evident. The physical laws operating today are assumed to have operated in the past, and processes we can observe now are treated as the basis for reconstructing processes that occurred millions or billions of years ago. It is difficult to imagine modern science without this principle.

But two centuries of use have blurred something that deserves to be pulled apart: what exactly is supposed to be uniform? Processes? Rates? Environmental conditions? Physical laws? Biological mechanisms? The answer matters enormously, and it is not as obvious as the slogan suggests.