Don’t Call it “Darwinism”

Eugenie C. Scott Glenn Branch 0 ) National Center for Science Education , P.O. Box 9477, Berkeley, CA 94709-0477, USA Evolutionary biology owes much to Charles Darwin, whose discussions of common descent and natural selection provide the foundations of the discipline. But evolutionary biology has expanded well beyond its foundations to encompass many theories and concepts unknown in the 19th century. The term Darwinism is, therefore, ambiguous and misleading. Compounding the problem of Darwinism is the hijacking of the term by creationists to portray evolution as a dangerous ideologyan ismthat has no place in the science classroom. When scientists and teachers use Darwinism as synonymous with evolutionary biology, it reinforces such a misleading portrayal and hinders efforts to present the scientific standing of evolution accurately. Accordingly, the term Darwinism should be abandoned as a synonym for evolutionary biology. - We will see and hear the term Darwinism a lot during 2009, a year during which scientists, teachers, and others who delight in the accomplishments of modern biology will commemorate the 200th anniversary of Darwins birth and the 150th anniversary of the publication of On the Origin of Species. But what does Darwinism mean? And how is it used? At best, the phrase is ambiguous and misleading about science. At worst, its use echoes a creationist strategy to demonize evolution. Even a cursory search of the Internet for Darwinism reveals that the term is not used consistently. Historians and philosophers of science customarily use Darwinism to refer to the ideas advanced by Charles Darwin, especially the idea of evolution by natural selection, sometimes including related ideas such as sexual selection. This also is how Darwins contemporary, Alfred Russel Wallace, who independently formulated the idea of evolution by natural selection, used the term in his book Darwinism (1889). Yet Darwins account of evolution by natural selection involves two separable concepts, and it was not accepted as a whole. In On the Origin of Species, Darwin persuasively presented his view that living things descended with modification from common ancestors, and within a decade or so, the majority of the scientific community in Great Britain accepted the basic idea of evolution (with North American scientists not far behind). Darwins second proposal, that the main engine driving evolutionary change was natural selection, was not nearly as successful in convincing his contemporaries. In the 19th century, a major obstacle to the acceptance of natural selection as a general mechanism of evolution was the assumption that inheritance was a blending process. Blending would result in a reduction of variation each generation, and natural selection depends on variation constantly being available. It was not until the twentieth century, after the rediscovery of Mendels conception of particulate inheritance, that natural selection was recognized as a powerful mechanism of adaptation and change. The point of this historical digression is to illustrate the conceptual and historical decoupling of Darwins two big ideasevolution (common ancestry) and the mechanism of natural selection. The former was accepted decades in advance of the latter. Today, with the insight provided by Mendelian and molecular genetics, natural selection is recognized as a primary component of evolutionary change, especially adaptation. This further complicates the meaning of the term Darwinism. Does it refer to evolution? Natural selection? Evolution by natural selection? Modern evolutionary biologists tend not to use Darwinism very often, exceptagainin a historical sense to refer to Darwins ideas. British biologists, perhaps motivated by patriotic pride, are more likely to refer to evolutionary biology as Darwinism than their American colleagues, but even in Darwins homeland, the term now tends to be used as a pejorative (Liberman 2007). When they are speaking of the theoretical core of modern evolutionary biology, scientists tend to use the phrase the synthetic theory of evolution to refer to the augmentation of Darwins natural selection theory with Mendelian genetics in the 1930s and 1940s, followed by the development in the 1940s and 1950s of mathematical systems allowing the modeling of evolution in populations. Not in his wildest dreams could Darwin have dreamed of the scope and power of developments following the modern synthesis. Petto and Godfrey (2007) list many components of modern evolutionary biology that are decidedly nonDarwinian in the sense that Darwin knew nothing about them. This, of course, does not mean that they are incompatible with Darwins ideas, still less that they are refutations of Darwin! But components of modern evolutionary biology such as endosymbiosis, epigenetics, transposons, horizontal gene transfer, somatic hypermutation, neutralism, evo-devo, and the like illustrate that evolutionary biology has not been idle since Darwin shuffled off this mortal coil in 1882. Using Darwinism as synonymous with evolutionary biology is thus a touch unfair to the men and women who have contributed to the scientific edifice to which Darwin provided the cornerstone, including (to name a few) Wallace, Huxley, Weisman, De Vries, Romanes, Morgan, Weidenreich, Teilhard, von Frisch, Vavilov, Wright, Fisher, Muller, Haldane, Dobzhansky, Rensch, Ford, McClintock, Simpson, Hutchinson, Lorenz, Mayr, Delbrck, Jukes, Stebbins, Tinbergen, Luria, Maynard Smith, Price, Kimura, Ostrom, Wilson, Hamilton, and Gould, to say nothing of even more who are still contributing to evolutionary biology. As Olivia Judson (2008) recently commented, terms like Darwinism suggest a false narrowness to the field of modern evolutionary biology, as though it was the brainchild of a single person 150 years ago, rather than a vast, complex and evolving subject to which many other great figures have contributed. So at best, Darwinism is an ambiguous term, having no settled meaning more definite than something to do with Darwins ideas. This alone would be an adequate reason for teachers and scientists to avoid using it. However, there is another reason to avoid using the term: it plays into the hands of a creationist campaign to suggest that evolution is a disreputable ideology. This is not a new campaign, but intelligent design creationismthe latest incarnation of antievolutionismprosecutes it with unprecedented vigor. The first step in the intelligent design creationist version of this campaign has been to encourage the publics preexisting association of Darwinism with a generic conception of evolution, as opposed to the historical Darwins insights. This is illustrated very clearly by examining a change in Of Pandas and People, the intelligent design creationist textbook that figured centrally in Kitzmiller v. Dover (Lebo 2008). Figure 1 illustrates the same page from each of the two editions (Davis and Kenyon 1989; Davis a (...truncated)