On the Nature of Controversies in Evolutionary Biology

ON THE NATURE OF CONTROVERSIES IN EVOLUTIONARY BIOLOGY MAZINB. QUMSIYEH* While en route to a scientific meeting recently, I chanced on an article entitled "Life after Darwin" [1] in one of the airline magazines. The conclusion ventured that "even acknowledging that no scientific theory can fully measure up to Popperian standards, it would still seem that some theories are better than others. Darwinism is probably one of the others" [1, p. 50]. The author refers to the proposition made by Sir Karl Popper in 1919 that a major criterion for a scientific hypothesis is its "falsifiability." Although recently challenged [2], this "Popperian standard " has permeated all aspects of biology. The importance of falsifiability and problems with its definition aside, this doctrine has been used as a banner against classic views of selection and adaptation. In "Life after Darwin," the hypothesis of "punctuated equilibrium" was portrayed as being more falsifiable than that of Darwinian selection and as being its antithesis. Punctuated equilibrium proposes that species undergo little or no evolutionary change over long periods oftime punctuated by brief periods of speciation and rapid evolutionary change [3]. Most biologists agree that the rates of evolutionary change vary over time and also between taxa and at different levels of biologic organization , although they would not question Darwin's principal theory of evolution through natural selection operating at the level of the individThis essay received honorable mention in the 1988 Dwight J. Ingle Memorial Writing Award competition for young authors. The author acknowledges numerous discussions with colleagues and mentors who helped shape the ideas in philosophy and biology expressed in this paper—even though these colleagues may not agree with some of the conclusions. Special thanks are extended to K. John Morrow, Ray C. Jackson, Robert J. Baker, Fred B. Stangl, Jr., Craig S. Hood, Linda Daniels, Christy Wright, and Mike Kennedy . *Department of Pharmacology, St. Jude Children's Research Hospital, 332 North Lauderdale, Memphis, Tennessee 38101. Present address: Division of Genetics, Suite 523, University of Tennessee—Memphis, 711 Jefferson Avenue, Memphis, Tennessee 38163.© 1990 by The University of Chicago. All rights reserved. 003 1-5982/90/3303-0681$1 .00 Perspectives in Biology and Medicine, 33, 3 ¦ Spring 1990 | 421 ual. Thus, punctuated equilibrium should certainly not be viewed as incompatible with the modern synthesis of views on evolution [4, 5]. Such characterizations have become common in popular literature. This is but one of the many recent controversies in evolutionary biology in which attacks and counterattacks rage and subside in mysterious ways. Some evolutionary controversies have drifted from intellectual exchanges to political diatribes. The scientific debates regarding the mechanisms of evolution are portrayed by religious fundamentalists as indicating a bankruptcy of the whole idea ofevolution. Battles over "creation science" in the public school curricula exemplify the results of this perception . Clearly, understanding controversies about evolution that result in heated exchanges is vital not only to basic science but also to the health ofevolutionary science as an enterprise and its perception by the general public. The scientific approach invariably involves choices between opposing methodologies and hypotheses. At any one time, scientists have—as they should—divergent views on issues for which there is a dearth of data and ample room for speculation. Issues such as the degree of divergence in DNA sequences of two populations, the relationships of a group of species, or Mendelian versus blending inheritance are intrinsically more amenable to new evidence and resolution than are concepts regarding the tempo and mode of evolution. The question thus remains, Are controversies over mechanism and level in evolution ever resolved and, if so, how? Do opposing parties reach a level of compromise and synthesis of ideas? Does an evolutionary theory advance when a new generation arrives that is more receptive to it? Or does the new generation devise its own ideas and arguments, ignoring the old controversies? It is not my intention to critically evaluate any of the currently debated evolutionary hypotheses. Rather, my aim is to present a view of evolutionary controversies using three examples in the areas of systematic philosophy, subspecies designation, and sociobiology. Systematic Philosophies Since the time of Linnaeus, the founder of modern classification, the procedures and methods of classification...