. "Tempo and Mode in the Macroevolutionary Reconstruction of Darwinism." Tempo and Mode in Evolution: Genetics and Paleontology 50 Years After Simpson. Washington, DC: The National Academies Press, 1995.
The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Darwin's Uniformitarianism and the Downgrading of Macroevolution
Charles Lyell was Darwin's guru and intellectual father figure. Darwin commented, in a statement that (for once in his writing) does not reek of false modesty in proper Victorian taste, "I always feel as if my books came half out of Lyell's brain" (in F. Darwin, 1903, p. 117). Much of Lyell's thinking did not contribute to Darwin's evolutionism and may have acted as an impediment to transmutation—in particular, Lyell's steady-state vision of change without direction. But we can scarcely doubt that Lyell's major working postulate and philosophical premise—his uniformitarian vision—became just as firmly embedded in Darwin's thought and scientific action.
Lyell's uniformitarianism held that the full panoply of past events, even those of greatest extent and apparent effect, must be explained as extrapolations from causes now operating at their current observable rates and intensities. In other words, and invariably, the small and immediate may be extended and smoothly accumulated—drop by drop and grain by grain—through time's immensity to produce all scales of historical events. Time is the great enabler. No uniquenesses should be attributed to events of large scale and long times; no principles need be established for the great and the lengthy; all causality resides in the smallness of the observable present, and all magnitudes may be explained by extrapolation.
Darwin accepted and promulgated Lyell's uniformitarian vision in all its uncompromising intensity. Extrapolationism (the methodological side of uniformity) underlies and unites the otherwise disparate pieces and opinions in the Origin of Species. What other principle could coordinate, for example, Darwin's hostility to mass extinction (1859, pp. 317–329), his brilliant section on graded structural transition in the evolution of complex and "perfect" organs like the eye (pp. 186–189), his initial case of pigeon breeding as a model for change at all scales (pp. 20–28), and even his choice of the phrase "natural selection" as an analogy to small-scale changes produced by breeders and called "artificial selection.''
Consider just two statements from the Origin of Species on the power of geological time to build small and present changes into any observed or desired effect. First, on nature's greater power based on time and fuller scrutiny:
As man can produce and certainly has produced a great result by his methodical and unconscious means of selection, what may not nature effect? Man can act only on external and visible characters: nature cares nothing for appearances … She can act on every internal organ, on every shade of constitutional difference,