Getting Older, Not Better Stephen Jay Gould Questions Optimism of Evolutionary Biology

Article excerpt


The Spread of Excellence From Plato to Darwin

By Stephen Jay Gould 245 pages, Harmony Books, $25 HAMLET LABELED HUMANS "the quintessence of dust." Philosopher Thomas Hobbes called our lives "nasty, brutish and short." But leave it to the irrepressible popularizer of paleontology, Stephen Jay Gould, to call us an accident: one that should never have happened, one that could never be repeated. To convey his dismal assessment, Gould presents the usual cases of evolutionary progress - plankton, horses, crustaceans, and (his particular objects of affection) bacteria - but employs them to question the optimism of traditional evolutionary biology. His exhaustive (and often labored) statistical analysis suggests that, while individual species may well move toward their optimal achievable "best" through the process of natural adaptation and selection, history reveals no discoverable movement toward ever-better species. What he is arguing for is a new way of looking at our world and its living past, a view that leads him even to chastise such exemplars of rational humanity as Plato. Gould disparages him for the habit he instilled in successive generations of thinkers - "a tendency to abstract a single ideal or average as the `essence' of a system and to devalue or ignore variation among the individuals that constitute the full population." As support, Gould wanders far afield, to the disappearance of the .400 batting average in baseball, which, he insists, is a consequence not of diminished ability, but rather of the evolution in the game through time - improved performance by all players. In his statistical terminology, "as the mean" (the average of abilities) "moves toward the wall" (the right edge of the graph of human physical potential) "variation must decrease" (the best specimens clump more toward the middle). Well, a book that plays host to both starfish and Stargell is self-evidently eccentric. It's a congeries of reflections, but one that has something for everyone - students of evolution, students of biology, baseball lovers, theologians. The glue that (barely) unites Gould's disparate excursions is the concept of "modality." In every species and phylum he investigates, Gould advises that we disregard the one or two most astonishing phenomena. We should ignore the mean (the average), and the median (the arithmetical center), and immerse ourselves rather in the mode: the most usual form an organism adopts. In a distressingly high percentage of cases, these group closely to what statisticians term the "left wall," - elementary simplicity; only in rare, eccentric and numerically irrelevant cases do t hey evolve toward any sort of impressive complexity. …