<http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/04/14/RV119833.DTL>
A Darwinian leap Stephen Jay Gould proposes that catastrophes triggered mass changes in species viewed by David Perlman, Chronicle Science Editor Sunday, April 14, 2002 �2002 San Francisco Chronicle URL: http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/04/14/RV119833.DTL The Structure of Evolutionary Theory By Stephen Jay Gould BELKNAP/HARVARD; 1,433 PAGES; $39.95 Charles Darwin published the first edition of "The Origin of Species" in 1859, and in my own copy of his sixth and final edition, the great scientist refined his revolutionary theory of natural selection and added details to his compilation of the evidence for it -- all in a modest book of 338 pages. With Darwinian diffidence he called it an "abstract." Now comes Stephen Jay Gould, the Harvard paleontologist, to boldly redefine Darwin in light of what the world has learned from more than 150 years of progress in genetics, molecular biology and the fossil record. It has taken Gould 20 years to do it, and he clearly intends his magnum opus to be both a tribute to Darwin and a definitive (for now, at least) declaration of a new and much more complex version of how species actually have emerged again and again since life began on Earth. Fascinating, discursive, dogmatic, intensely personal and often quite technical, "The Structure of Evolutionary Theory" is also in most of its sections readily accessible to lay readers -- and well worth the effort. With more than 1,400 pages and a bibliography of 1,000-plus entries, this summation of Gould's idiosyncratic life work will undoubtedly arouse tremendous enthusiasm in loyal Gouldites and scathing denunciation from those who, in the internecine warfare that has characterized debates over the mechanisms of evolution, condemn his science as shallow, slipshod and derivative, and himself as churlish, arrogant and boastful. Essential to Gould's thinking on evolution for the past 30 years is the concept he has called "punctuated equilibrium," the idea that evolution does not proceed along an infinitely slow course where, as Darwin saw it, individual organisms change and new species emerge in response to environmental pressures that weed out the unfit through a kind of Malthusian "survival of the fittest" and preserve the organisms best adapted to new environments. But Darwin, ever the uniformitarian, conceded that huge gaps in the fossil record of his time posed the most crucial threat to his gradualist picture of natural selection. In 1972, Gould and his colleague Niles Eldredge, now at New York's American Museum of Natural History, published an influential paper that in effect saw those gaps in the fossil record as what Gould calls "valuable information rather than frustrating failure." Fossils in long-buried sediments of the Devonian period in Michigan, for example, established that primitive, clamlike brachiopods remained unchanged for countless thousands of years, and that in fact no intermediate fossil forms at all lay between those species and the new and very different brachiopod species that succeeded them after a major "mass extinction" killed off 90 percent of all living species some 367 million years ago. Thus, Eldredge and Gould concluded that "stasis is data," and that instead of Darwin's minute adaptational changes in individual organisms, evolution must proceed by huge leaps and bounds, with species remaining unchanged for long periods of time until some major event, most probably environmental and quite possibly global, creates an opening for entirely new species to emerge in very brief bursts. (Caveat lector: In the world of paleontology, "short" and "long" don't mean what we think they mean. A short burst to geologists can mean many thousands of years; a long period can be many millions.) Thus, the phenomenon of mass extinction is a key driver for evolution, as Gould maintains, and there have been at least five such events since life emerged on Earth nearly 4 billion years ago, all acting on entire arrays of species and genera. In an exceptionally clear narrative, for example, Gould discusses the extinction of the world's dinosaurs about 65 million years ago, as the late Luis Alvarez, the Berkeley Nobel laureate in physics, and his son, geologist Walter Alvarez, revealed more than 20 years ago. That extinction began when a gigantic comet or asteroid hit Earth during the boundary between the Cretaceous and Tertiary geologic periods, and all the dinosaurs (except the birds, of course) vanished rapidly along with a major part of the world's marine species. Earth's newly emptied ecological niches then speedily filled with new emerging species, and -- it should be a joy to us humans -- there was plenty of room for mammals and ultimately our own hominid ancestors to fill the space. Africa's once geologically violent rift valley, for example, created by ancient tectonic forces of volcanism and earthquakes, may well be the reason that hominids began there when our early lineage separated from the apes 5 to 8 million years ago. So to Gould mass extinctions are at least one key to the "punctuated equilibrium" concept, which has led Gould's naysayers -- particularly the so-called creation scientists and proponents of "intelligent design" -- to insist in spurious triumph that Gould denies Darwin, when in fact Gould does anything but. "My love of Darwin and the power of his genius" is a recurrent theme in this massive book, but -- and it's typical of Gould -- he adds that "I honor Darwin's struggles as much as his successes, and I focus on his few weaknesses as entry points for needed revision," and declares with a flash of effulgence: "Clearly I do not honor Darwin by hagiography, if only because such obsequious efforts would make any honest character cringe (and would surely cause Darwin to spin in his grave, thus upsetting both the tourists in Westminster Abbey and the adjacent bones of Isaac Newton)." If Gould is noted (or infamous) for curmudgeonly self-importance and a refusal to concede the possibility of error, one of many footnotes and incidents attests to his often-overlooked ability to be modest: "I engaged in long and vociferous arguments with my graduate students . . . about the criteria of species selection," he recalls. "I now believe that they were right, and I was wrong." Gould's detailed arguments and scholarly exegesis of the historical literature on evolution's forebears and conflicts fully justify the length of this book. But the nuggets of Gould, the literate and rambunctious scientist, give it delicious flavor on page after page. One zoologist's work, for example, Gould brands "insufferably self- indulgent" but he immediately backtracks to call the same work "adequately justified." He pays tribute again and again to "Darwin's continued, pervasive relevance"; and while attacking those who attack Eldredge and him for "our trickery, our bombast, our dishonesty, (and) our quest for personal fame," he declares in the typical Gould prose that is a constant delight in this truly scientific tome: "As arrogant as I may be in general, I am not sufficiently doltish or vainglorious to imagine that I can meaningfully address the deep philosophical questions embedded within this general inquiry of our intellectual ages." This is a brilliant, controversial, thorough and immensely readable updating of Darwin. Yet the reader may well ask, "But what does Gould really believe?" One cannot know, and Gould eschews belief in favor of evidence. Deep down, one hopes, Gould's secret night thoughts might just parallel those of Ursula Goodenough, the distinguished cell biologist who supports him and links her own belief in both religion and science to declare in "The Sacred Depths of Nature": "The continuation of life reaches around, grabs its own tail, and forms a sacred circle that requires no further justification, no Creator, no superordinate meaning of meaning, no purpose other than that the continuation continue until the sun collapses or the final meteor collides. I confess a credo of continuation." �2002 San Francisco Chronicle
