Riddle of the Feathered Dragons by Alan Feduccia

Author:Alan Feduccia
Language: eng
Format: epub
Publisher: Yale University Press
Published: 2012-03-14T04:00:00+00:00

Small or Large Steps for Evolution

In On the Origin of Species, Charles Darwin made a point of arguing in favor of a view that he articulated with the phrase “natura non facit saltum” (nature does not make jumps, originally from Linnaeus).1 This is essentially the concept of gradualism in biological evolution. In reviewing the book in 1860, aside from coining the term “Darwinism,” Huxley expressed concern with Darwin’s disregard for the possibility of saltation (jumping), or sudden macroevolutionary events in the scheme of biological evolution.2 Darwin seemed to be stuck on the proposition of gradualism, perhaps in part because of his early association with Charles Lyell (1797–1875), England’s most prominent geologist of the day. Lyell’s first and most influential work, the three-volume Principles of Geology (1830–33), introduced the foundational doctrine of the geological sciences, uniformitarianism, summarized by the dictum, “The present is a key to the past.”3 Thus, the natural processes operating in past geologic time were the same as those observed today. Applying his uniformitarian principle, Lyell argued that extant geologic formations had formed through the steady accumulation of small changes over long periods of time, and this principle had an enormous influence on the young Darwin, who was given volume 1 of Principles by John Stevens Henslow just before HMS Beagle began its famous voyage in 1831. The influence is clearly seen when Darwin writes of seeing rock formations on Saint Jago, the first stop of the Beagle, “through Lyell’s eyes.” Ironically, Darwin received volume 2 of Principles while in South America, and in that volume, Lyell clearly rejected organic evolution and substituted instead a concept of “Centres of Creation,” which was not too distant from the later view of Richard Owen.

The term “uniformitarianism” was actually coined by William Whewell in 1832, and he also was responsible for introducing the term “catastrophism,” intending to convey the supernatural process of the earth’s creation by a series of catastrophic events—in other words, by processes that could not be observed today.4 Whewell was a philosopher, scientist, Anglican priest, and one of the Cambridge dons whom Darwin had encountered during his tenure there. Incidentally, Whewell invented the term “scientist.” However, with respect to geology, whatever lingering influence there might have been on Darwin from Whewell was clearly overshadowed by that of Lyell and his famous Principles. Huxley and Darwin had many discussions on the topic of saltation, and in a letter to Lyell dated 25 June 1859, Huxley unveiled his position in stating that “the fixity and definite limitation of species, genera, and larger groups appear to me to be perfectly consistent with the theory of transmutation. In other words, I think transmutation may take place without transition.”5 Then, in a letter to Darwin dated 23 November 1859, Huxley expressed his joy at having read Origin: “a lucky examination having furnished me with a few hours of continuous leisure.” He then brought up what he calls his “only objections,” among which were: “That you have loaded yourself with an unnecessary difficulty in

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