The man who chipped away at every presumption that defined evolutionary science
No one who reads a newspaper, however cursorily, could miss the news that Stephen Jay Gould, Professor of Zoology at Harvard University, died of lung cancer on May 20, 2002. He had fought his way out of another cancer, a rare form of abdominal cancer, 20 years ago. His reaction to that affliction was to go to the library as soon as he could after surgery, where he learnt that the prognosis for his type of cancer (mesothelioma) was gloomy, the median life expectancy after discovery being eight months. But Gould read more carefully. What resulted was an essay; typically, it was witty, somewhat wordy and hyperbolic at the same time. The essay discussed how to interpret statistical information; and in particular, the fact that the median was not the same as what was most likely.
Gould was a prolific and very successful writer. Much of his writing was on evolution and its implications. As a populariser of evolutionary ideas, he was arguably without a peer in our time. Gould the writer was a huge success. A large number of people would never have thought about science and evolution had it not been for him. His essays are immensely readable, and laced liberally with quotations and allusions. But Gould's stature as a popular writer was limited by the fact that much of what he wrote was in order to advocate his own special way of looking at evolution.
He tried hard to push some ideas. The best-known of these was embodied in the phrase 'punctuated equilibrium'. This referred to a hypothesis proposed by Niles Eldredge and him. In it they said, roughly speaking, that nothing happened in evolution for most of the time: species did not generally change except for geologically brief episodes during which ancestral forms were 'suddenly' replaced by their quite distinct descendants. Gould constantly kept attacking what he thought was narrow-minded evolutionary orthodoxy. He stressed again and again that the large-scale features of evolution had more to do with accidents and constraints than with a steady and unbroken chain of cause-and-effect links.
The general public's response to Gould verged on the adulatory. Some went so far as to call him a second Darwin; others say that "just like Darwin", he was an organiser and synthesiser more than an original worker. Both statements go overboard in their enthusiasm. Even in his popular work, Gould lacked the range, insight, originality and forcefulness that are the hallmarks of a truly great thinker (for example, J B S Haldane at his best). In striking contrast to the more or less unmixed praise of the general public, he elicited a mixed bag of reactions from his peers.
Gould mounted three major campaigns. The first was in support of long epochs of evolutionary stasis punctuated by brief periods of change; the second against adaptation as a universal explanation for the diversity of life; and the third in favour of contingencies and constraints as significant factors in evolution. In all three cases he was calling attention to aspects of evolution that were not accorded the prominence that he gave them (for good reasons, the others would rejoin).
His sustained attacks provoked people to sit up and re-examine their own picture of evolution, which was all to the good. He constantly hammered away at the idea that the course of embryonic development is difficult to tinker with, that developmental constraints act as important checks on the potentially open-ended character of natural selection. The importance of keeping this in mind cannot be over-emphasised. Further, Gould performed the immense service of making people go back to the original literature and appreciate the breadth of the picture that Darwin had sketched. The questions he asked touched on nothing less than the grand sweep of evolution. Most of all, though, Gould wrote in a manner that made people see that science could be fun. He will be long remembered for this.
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