Stephen Jay Gould: An obituary 4/5/04. By Vidyanand Nanjundiah Vidyanand Nanjundiah examines the impact of Stephen Jay Gould, evolutionist and prolific writer, who died in May 2002.

Stephen Jay Gould was both prolific and very successful as a writer. Few scientists can have attained the level of public popularity that he did. Because of his chatty style, readers were able to vouch for a degree of familiarity with what they admired. His output was prodigious. He churned out approximately 300 longish essays for the magazine Natural History. The essays were collected and published in a number of best-selling books.

With rare exceptions he wrote about the same thing, namely evolution and its implications. What he had to say was set off against the background of the Darwinian picture of evolution. That picture, known as natural selection, sees evolution as a continual incorporation of favourable variations in the hereditary material. The variations themselves are believed to occur randomly and with no regard for whether they are beneficial or harmful. The outcome of natural selection is adaptation, the appearance that organisms give of being exquisitely designed to suit their environments.

Gould was a confirmed evolutionist, but he was not happy with the air of seeming inevitability of evolutionary explanations based on natural selection. For him evolution was a fact, a wonder, built on a series of historical contingencies and erratic in its course. It was what Darwin had said it was, but it was much more too – a melange resulting from accidents, chance events and constraints.The study of evolution was an essential part of human culture.

As a populariser of evolutionary ideas he was arguably without a peer in our time. Richard Dawkins, the other well-known populariser of evolutionary theory, may have been (and is) a better purveyor of scientific ideas, but Dawkins's best prose comes packaged in a spare style that does not make for the same level of mass appeal.

Besides these popular pieces, Gould's output included more specialised books. 'The Mismeasure of Man' is a passionately written, meticulous dissection of the absurdities and horrors that the concept of the intelligence quotient (IQ) has given rise to. Wonderful Life is an almost lyrical account of the bizarre-looking, 530 million year-old fossil invertebrates discovered in the Burgess Shale deposits in the Canadian Rockies. In 'Ontogeny and Phylogeny', Gould attempted to resurrect the study, championed forcefully by Darwin, of embryonic development as a fundamental clue to evolutionary relationships. And in 'Rocks of Ages: Science and Religion in the Fullness of Life', Gould got on the wrong side of both rationalists and the religious-minded by saying that the domains of science and religion did not overlap; you could have your cake and eat it too. His last book, 'The Structure of Evolutionary Theory', came out just before his death.

Gould the writer was a huge success. His essays are immensely readable and laced liberally with quotations and allusions; baseball lore and the Bible were favourites.

Gould's big ideas

Ironically, enormously successful as he was, 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 way of looking at evolution, a way that was not generally accepted.

There were three big ideas that he was (in part) responsible for and tried to push hard. The best-known of these was embodied in the phrase, one might even say slogan, 'punctuated equilibrium'. This referred to the hypothesis proposed by Eldredge and Gould in which 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.

The second of Gould's noteworthy hypotheses was put forward in a paper written jointly with his Harvard colleague Richard Lewontin. The ornate title contained the message: "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist program". Gould and Lewontin claimed that many features of living forms existed, not because they aided survival or reproduction, but because of the sheer profligacy of nature. Unlike what a strict Darwinian interpretation would demand, the reason for their being was not in any way related to the use to which they were put.

The analogy was to the decorations found in spandrels, empty spaces between the perimeter of a dome and a pair of adjacent arches. The spandrels were by-products of erecting a dome that was supported by arches, not elements of design in their own right. The point, said Gould and Lewontin, is that the spandrels are made use of because they happen to be there; they are not designed with an architectural requirement in mind.

This attack on so-called pan-adaptationism or 'Darwinian fundamentalism' was in line with Gould's constant flailing at what he thought was narrow-minded evolutionary orthodoxy. The spandrel argument was later used in a modified form by Gould and Vrba. The special word this time was 'exaptation', meaning a structure whose evolution served a function quite unrelated to what it was subsequently used for. (To take Dr Pangloss's own outrageous example, the human nose was ideally suited to hold up spectacles, but obviously it could not have evolved for that purpose.)

Gould's third big engagement with conventional Darwinism was to stress 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. For example, the famous asteroid impact that pushed the dinosaurs on their way to extinction opened up the field for us mammals, but the diversification of mammalian lineages was in no way a logical consequence of the age of the dinosaurs. Historical contingency, rather than physical determinism, seemed to him the true hallmark of evolution.

Reaction to Gould

In striking contrast to the more or less unmixed praise of the general public, he elicited a decidedly mixed bag of reactions from his peers. Probably part of the reason for this was the assertion that his favourite ideas were fundamentally new.

As I have said, 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 none of the three cases was an entrenched and dogmatic establishment ranged against him, as he tended to suggest. Rather, he was calling attention to aspects of evolution that were already recognised but 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-stressed.

Two other features of his forays into evolutionary biology deserve to be applauded. Firstly, it is a fact that for many, Darwinism meant adaptation and adaptation alone. Here he performed the immense service of making people go back to the original literature and appreciate the breadth of the picture that Darwin had sketched.

Secondly, as with any aspect of science, the study of evolution often descends into arcane detail. Many scientists either do not see, or do not have time for, the big picture. Gould was a prominent exception. 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.

Stephen Jay Gould, Professor of Zoology at Harvard University, died on 20 May 2002 of lung cancer.

Professor Vidyanand Nanjundiah, Indian Institute of Science, Bangalore, India. E-mail: vidya@ces.iisc.ernet.in .

Adapted from an article in Wellcome History, Issue 22, February 2003.