American Scientist

Lead Review (Full Text)

May - June 1997

The Status of Evolutionism Examined

Monad to Man: The Concept of Progress in Evolutionary Biology. Michael Ruse. 596 pp. Harvard University Press, 1996. $49.95.

Michael Ruse has written an important book on the status of evolutionism that will almost certainly become embroiled in controversy. An early draft was circulated to a number of scholars (this reviewer included) who were invited to comment. Mine were not the only comments that were very negative on certain aspects of the book. The finished version is certainly stronger than the original draft, but this is not because Ruse has backed away from the positions he staked out. Instead, he has strengthened his defenses--although he will not be surprised to find his critics still unsatisfied.

Although the book is a history of evolutionism, Ruse is a philosopher who wants to use history as a means of assessing the theory's status as scientific knowledge. He asks why so many (and not just the creationists) remain skeptical of the theory's scientific credentials. The answer, he argues, is that evolutionism has always been linked to a nonscientific value system based on the idea of progress. Although Darwinian natural selection treats evolution solely as a process of adaptation, few have escaped the belief that (at least in the long run) evolution gives progress toward higher levels of organization, both in biology and, by implication, in social affairs. Despite strenuous efforts to sever the link with progressionism, it persists even today and thus threatens the theory's status as science. For Ruse, scientists' endorsement of evolutionism has almost always had an ideological dimension. This claim is not presented as a threat to the objectivity of science itself; indeed Ruse's thesis hinges on the assumption that there are mature sciences that are not contaminated in this way. The problem is that evolutionism has found it hard to live up to the standards expected of a mature science.

Darwin's sketches of the "coral" of life and the branching of evolution. From Monad to Man.

Ruse traces the history of evolutionism, always attempting to demonstrate the link to progressionist social assumptions. Lamarck and his radical followers of the early 19th century were convinced progressionists. Darwin himself, although he recognized the dangers, continually slipped back into progressionist thinking. Many post-Darwinian evolutionists were quite explicit in their support for progress and thus undermined the credibility of the theory in the scientific community. Those who were serious about their scientific credentials adopted two strategies. At first they simply excluded evolutionism from their biology, reserving it for popular expositions. In the 20th century, efforts were made to create a truly scientific evolutionism by excluding progressionism and concentrating on adaptation. Such efforts were made by the few biologists who genuinely did not care much for progress (W. F. R. Weldon and E. B. Ford) and by those who realized that their progressionism had to be rigidly suppressed (virtually all the rest). Ruse argues that the suppression is seldom complete, however, and brings his story right up to date. For him, modern Darwinists such as E. O. Wilson still allow progressionism to lurk as a hidden assumption beneath the surface of their apparently objective science.

Given the scope of Ruse's survey, he will inevitably be attacked by specialist critics each focusing on a particular part of the story. Having just published an account of late 19th- and early 20th-century evolutionary science, I certainly have my own ax to grind. In the end, however, he will be judged on the strength of his overall argument for a link with progressionism, even if subsidiary positions are undermined. Here it has to be said that Ruse's technique of concentrating on a selection (admittedly large) of individual biologists is open to question. He is right to argue that only fairly detailed biographical studies will tease out the complex relationships between scientific ideas and social values. He is open to the charge, however, that he picks only the examples that best suit his case. He also uses a heavy-handed analytical technique that sometimes distorts the figures with whom he deals. More serious is the fact that his argument is almost unfalsifiable. His primary case rests on those evolutionists who let progressionism leak into their science, but he is quite happy to accept the idea that some have concealed their progressionism in order to play the game of scientific politics. He even concedes that there were a few nonprogressionsts; these show that a pure evolutionism is possible in theory, although rare in practice. The only thing that would disprove Ruse's thesis is a demonstration that there have been large numbers of nonprogressionist evolutionists.

I have to say that I find Ruse's depiction of the earliest evolutionary biologists unconvincing. T. H. Huxley is taken as typical of the first generation of Darwinists, who, Ruse claims, offered progressionist evolutionism for popular consumption only. Huxley is supposed to have kept evolution out of his morphological work: The structure of various species was described without reference to their evolutionary relationships. Ruse concedes that a few of Huxley's followers did use morphology to search for phylogenetic relationships--E. Ray Lankester is offered as the sole example--but argues that this was recognized as trivial almost as soon as it began. That Lankester took progress for granted is undeniable, but his work represents only the tip of a concealed iceberg. Ruse's view of this period is flawed because he does not accept the idea that it was possible to have a science that looked for phylogenetic relationships but that did not concern itself with the evolutionary mechanism. Huxley founded theories about phylogenetic relationships that were debated by morphologists and paleontologists for a generation, yet Ruse makes only a brief reference to his fossil studies. When it came to defining the key steps in the emergence of the vertebrate classes, much of this work did have a progressionist slant. Ruse discusses a handful of American paleontologists, including Henry Fairfield Osborn, to show that this discipline was infected with progressionism, but dismisses it as rapidly marginalized in the more professional atmosphere of the early 20th century. He ignores a great deal of later paleontology and the explosion of interest in biogeography stimulated by the search for the original evolutionary "home" of each major group. This drew on metaphors of invasion and colonization that would have been grist for his mill.

Ruse's handful of examples gives the reader no idea of the amount of effort devoted to phylogenetic research in the decades around 1900. Nor was this early work completely hamstrung by progressionist assumptions. Ruse picks on Lankester as Huxley's most obvious disciple. Yet Huxley's hopes were focused on another morphologist, Francis Balfour, until the latter's untimely death in 1882. Balfour's embryology was founded on the search for phylogenetic relationships, but he made no references to progress and wrote no popularizations. As the brother of Arthur Balfour, later a Conservative prime minister of Great Britain, it is unlikely that he shared Huxley's social opinions. In addition to Balfour's work, there were major debates on invertebrate phylogeny that had no obvious progressionist implications. Ruse is thus wrong on both counts: There was a major effort to apply evolutionism to science in the post-Darwinian era, and this evolutionism was developed both by enthusiasts for progress and by those who were indifferent to it.

Ruse feels more at home with 20th-century efforts to found an evolutionary science based on natural selection. A few of the founding fathers were genuinely indifferent to the idea of progress, but most--in Ruse's view--were progressionists at heart who merely concealed their enthusiasm to present a front of scientific objectivity. Occasionally it leaked right back onto the surface again, as in the case of Julian Huxley. The attempt to professionalize evolutionism has succeeded up to a point, but recent controversies over sociobiology have exposed the concealed foundation. A great deal of Ruse's analysis rings true, but I cannot help wondering if his selection here is just as biased as it was for the earlier period. Clearly evolutionism has been widely caught up in the enthusiasm for a progressionist view of life and society, but to claim that it has seldom been supported except by those who share this enthusiasm is to go farther than many will admit.

Ruse is right to claim that evolutionism has often been associated with progressionism, but there is a more fundamental reason for the indifference shown by many scientists. The biomedical sciences have flourished because they are experimental and have direct practical applications. But their success is based on a profound lack of interest in the question of how the organisms we study were formed. As long as we can fix the machines, we do not care how they were designed--and many rest content with the idea of a supernatural Designer. Evolution requires an interest in origins, and an acceptance of the different techniques needed to study them, which is simply not shared by many biologists.--Peter J. Bowler, History and Philosophy of Science, The Queen's University of Belfast

©American Scientist 1997

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