EVOLUTIONISM. Darwin's theory of evolution by natural selection has been profoundly influential among scientists and others on both sides of the Atlantic from the time of its introduction; throughout its history, Americans have contributed to the theory's development and to its uses beyond science. An American botanist, Asa Gray, was among the select group of naturalists with whom Darwin corresponded about his work even prior to his decision to publish his theory. Copies of On the Origin of Species were circulating in American cities before the end of 1859, the year of its publication in Britain, and American naturalists were quick to engage in debates over the theory's meaning and implications. For the most part, working naturalists in America were enthusiastic about the general idea of organic evolution; while many wanted to maintain a place for divine influence in the case of human development, they welcomed a scientific account of the origin of species that was grounded in Darwin's careful observations and naturalistic mechanisms. Americans contributed some very significant evidence in support of Darwin's work. In addition to Gray's botanical studies, the paleontologist O. C. Marsh presented fossil discoveries of dinosaurs and of a developmental series of horse skeletons that provided Darwin's defenders with some of their favorite and most compelling arguments.
The Development of a Scientific Consensus for Natural Selection
Despite this generally enthusiastic reception of Darwin's work by American naturalists, very few if any actually embraced his theory in all its details. Darwin's proposed mechanism of evolution—natural selection—seemed even to many of his supporters to be inadequate to describe fully the development of life on earth. Some, like Asa Gray, suggested that divine intervention had guided the production of variations in individuals. Others argued that external environmental factors were the source of most variations, an idea that Darwin himself increasingly embraced, although he continued to argue that its influence was slight compared to that of natural selection. The ortho-genticists remained largely unchallenged among the community of evolutionists until the 1880s, when a more rigorous debate about the mechanisms of evolution broke out. While the ortho-geneticists sought to retain some role for the inheritance of acquired characteristics, aggressive neo-Darwinians cited laboratory experiments and other evidence to support their position that natural selection alone drove the evolution of species because the inheritance of acquired characters was impossible.
Understanding the mechanisms of evolution continued to be a difficult problem after 1900. Darwin had provided no convincing account of how characteristics passed from one generation to another, and without one, arguments against Larmackism and other variant accounts of evolution remained less than invincible. But the rediscovery of Gregor Mendel's identification of units of heredity (genes) pointed scientists in a productive direction for finally giving the theory of evolution an appropriate mechanism to support natural selection. Bringing together these two theories—evolution and genetics—was a formidable scientific challenge. American scientists were very important to the development over several decades of what came to be known as the "modern synthesis" of genetics and evolutionary theory. Among the most significant contributors to the modern synthesis were the population biologist Sewall Wright, who during a long career at the University of Chicago helped to develop a theoretical framework to integrate genetics with natural selection. Another American, the Russian-born Theodosius Dobzhansky, wrote the first widely influential book on the synthesis, Genetics and the Origin of Species (1937). Dobzhansky's work grew in part out of his collaboration with the pioneering genetics experiments with fruit flies undertaken at Columbia University under the leadership of Thomas Hunt Morgan. Wright and Dobzhansky were two among many important American scientists who developed and continued to refine Darwinian evolutionary theory through the twentieth century.
Social and Philosophical Applications of Evolutionary Theory
Darwin's theory of evolution by natural selection proved compelling to those studying social and philosophical developments as well. This affinity between the general Darwinian idea of evolution of life and social thought followed nearly immediately on the heels of Darwin's publication. In England, the work of Herbert Spencer on so called Social Darwinism linked the notion of survival of the fittest to a particular model of industrialized society. In the United States, perhaps the strongest influence of evolutionism upon a field outside science can be seen in the development of pragmatism, an American philosophical movement that made great use of the insights of evolutionary theory. Pragmatism emphasized the importance of change and experience to understanding reality, in contrast with idealist accounts that emphasized eternal or essential qualities. By accepting that reality itself is plastic and malleable, the pragmatists saw knowledge as an instrument to help humans adapt to and use the world around them. Change, experience, particularity: all of these concepts came out of Darwinian evolutionary theory, as did the idea that life is a struggle of an individual within his environment. Evolutionism inspired the pragmatist philosophers to develop a philosophical system that was consonant with the leading science of the day and that promised a "modern" alternative to the static idealism of the past.
Academic philosophy was not the only area where Darwinism influenced American thought. Ideas and concepts connected, sometimes loosely, with evolutionism were incorporated into social and political agendas during the first decades of the twentieth century. One area where evolutionary concepts were abused in a policy setting was the immigration debate that took place in Congress following World War I. Opponents of immigration adopted the language of evolution to describe immigrants from eastern Europe and other unpopular regions as "unfit" and therefore a threat to the future survival of the American population should they arrive and dilute the superior resident stock. They backed up their claims with evidence from mental and physical exams that had in most cases themselves been designed with these same biases in place. Similar arguments were mounted in defense of various eugenic policies adopted in the United States during the 1920s and 1930s. For example, a number of states adopted policies legalizing the sterilization of female criminals and mental patients on the grounds that their children could only be a detriment to the population. Similarly, anti-miscegenation laws were said to protect against a weakening of the races through maladaptive mixing. The idea of evolutionism and in particular the bowdlerized notion of "survival of the fittest" that so often dominated popular explanations of Darwinism were thus very influential in American social thought and policy, although the actual connections between evolutionary theory and these uses was usually quite tenuous.
Opposition to Evolutionism
While some American thinkers found the ideas of evolution irresistible and widely applicable, others found them to be frightening and dangerous. For conservative Christians, the concept of organic evolution was an unacceptable one as it contradicted the account of the origin of life given in the Bible. While many Christians found ways to read the biblical account of life's origins that could accommodate the concepts of evolution (for example, to consider that the days referred to in Genesis may have represented very long periods of actual time), fundamentalists insisted that the Bible be read literally. With no room for compromise, the conflict between fundamentalist Christians and evolutionists grew intense and has from time to time erupted into widely publicized struggles for control over the teaching of the history of life in America's schools. An early episode in the battle between "creationists" and evolutionists was the notorious Scopes trial in 1925, when a Tennessee teacher was found guilty of violating that state's new law against the teaching of evolution. For several decades creationists had little influence or respect; then, beginning in the 1970s and continuing into the next century, they discovered that by presenting creationism as being based on scientific principles (although the science was dubious), they could make some strategic progress. Concepts such as "scientific creationism," which tried to challenge the facts of evolution such as the fossil record and radiological dating practices, and "intelligent design," which resurrected the nineteenth-century argument that complex structures such as eyes could not have arisen from chance variation, were used to challenge the principle that evolutionary theory alone deserved to be presented in textbooks and classrooms. Creationists argued for balanced treatment of their theories alongside evolution, and paradoxically suggested that to do otherwise was to ignore the basic scientific practice of considering competing theories on a subject.
American scientists have been important to the development of evolutionary theory since Darwin's day, and American philosophers and social scientists have made use of the theory directly and as a model for many important developments in their own fields. On the other hand, the theory receives strangely circumspect treatment from the general public. The tenacious debates between creationists and scientists have left their mark on textbooks and classrooms, where the treatment of evolution is far less rigorous than it would be in the absence of controversy. Despite its universal endorsement by scientists, the public treats evolution skeptically, with polls showing that only about half the population accepts the theory without reservation. These numbers reveal that a reluctance to embrace evolutionism by Americans extends well beyond the community of fundamentalist Christians. More than any other scientific theory, evolutionism has invited Americans to form their own opinions about its validity—a unique and intriguing response of culture to science.
Glick, Thomas F. The Comparative Reception of Darwinism. Austin: University of Texas Press, 1974.
Gould, Stephen Jay. Ever since Darwin: Reflections in Natural History. New York: Norton, 1977.
Moore, James R. The Post-Darwinian Controversies: A Study of the Protestant Struggle to Come to Terms with Darwin in Great Britain and America, 1870–1900. Cambridge, U.K.: Cambridge University Press, 1979.
Numbers, Ronald L. Darwinism Comes to America. Cambridge, Mass.: Harvard University Press, 1998.
gives a good history and overview.
Although evolutionary theory in sociology is attributed to Herbert Spencer, it is clear that it was taken for granted by writers as diverse as Karl Marx, Friedrich Engels, Émile Durkheim, and V. Gordon Childe. The fact that it can be traced in the work of both radical and conservative theorists is indicative of the profound cultural importance of evolutionism for Western thought. See also CHANGE, SOCIAL; DARWINISM; EVOLUTIONARY UNIVERSALS; FRAZER, SIR JAMES GEORGE; MATRIARCHY; MORGAN, LEWIS HENRY; PARSONS, TALCOTT; PROGRESS; SOCIAL ANTHROPOLOGY.