David Raup
Palaeontologist who rejected field work for computer analysis of Darwinism and extinction theories
DAVID RAUP, who has died aged 82, was an American “statistical palaeontologist” whose claim that 60 per cent of all extinctions had been caused by random “outside” events, rather than Darwinian evolutionary forces, provoked the fury of fellows of the Royal Society.
Classical Darwinism implies that species become extinct because they cannot compete with more successful species, or because conditions change and they are then less fitted for survival. In the 1980s, however, the theory was challenged by scientists including Stephen Jay Gould of Harvard and Raup, the Sewell Avery Distinguished Service Professor at the University of Chicago.
As palaeontologists go, Raup was something of an oddity. He was one of the few in his field who never discovered an extinct plant or animal. He seldom got his hands dirty digging for fossils, preferring to sit in front of a computer screen, number-crunching. Yet Stephen Jay Gould once described him as “the world’s most brilliant palaeontologist”. In books such as Extinction: Bad
Genes or Bad Luck (1991) Raup argued that the history of life on Earth has been marked by arbitrary catastrophic events, in which whole species have been wiped out on an unimaginable scale. He calculated that over 3.5 billion years of organic life, Earth had been home to perhaps five to 50 billion species of which, at the most, only 5 to 50 million are living now – a 99.9 per cent failure rate.
This “truly lousy survival record”, he argued, has little to do with evolutionary “fitness”. The rate of extinction is so overwhelming that the causes must be almost random – survival of the luckiest, not necessarily the fittest.
In 1983, while doing a computer analysis of 27,000 marine species that died off during the past 250 million years, Raup and a colleague identified a cycle of catastrophic mass extinctions occurring every 26 million years. At a lower level they found that pulses of extinction had occurred on average every million years. Extinction periodicity, as it became known, led to an upsurge of interest in the study of catastrophic events such as huge volcanic eruptions, comet strikes and of changes in the Earth’s magnetic field that may have coincided with periods of mass extinction.
Such theories provoked the wrath of Darwinists. But Raup did not see himself as an anti-Darwinist, observing that “Darwin is like Scripture, you can find anything you want in it”, and he was unfazed by the prospect that one day his theories might be proved wrong. His 26million-year extinction cycle fitted in with the controversial theory that the dinosaurs died after a “death star” known as Nemesis knocked comets out of their paths 65 million years ago and sent them crashing to Earth.
In his book The Nemesis Affair: A Story of the Death of Dinosaurs and the Ways of Science (1986), Raup admitted that the Nemesis theory, was “a matter of fairly abstruse statistical inference with rather messy data” which could turn out to be “a major step forward in our understanding of the natural world or an embarrassing period of near-insanity in scholarship”. The book showed how, time after time, scientists’ belief systems impair their ability to evaluate and test new ideas dispassionately, and he did not regard himself as an exception to the rule.
David Malcolm Raup was born in Boston on April 24 1933, inheriting his habit of contrary thinking from his father, Hugh, a Harvard botanist who challenged received wisdom when he argued that forest fires play an important role in maintaining ecological balance and are not necessarily bad. His mother, Lucy, was also a botanist with an interest in lichens. From the age of two Raup tagged along on his parents’ plant collecting expeditions to the Arctic.
At Colby College, Maine, Raup majored in geology and also studied mathematics and accounting. He went on to take a degree at the University of Chicago, followed by a PhD in Palaeontology at Harvard.
While researching his thesis, he collected 10,000 samples of living and fossilised sand dollars (a species of flattened, burrowing sea urchins) along the Pacific coast from Mexico to Alaska. It took a computer to handle all the detailed data, and the experience led to the conviction that computers could revolutionise the field of fossil science.
In particular, he founded an entirely new field when he created a model that uses computer graphics to illustrate what seashells might look like if evolution had taken different turns, an exercise which has helped to focus scientific research on the question of why biological organisms take the form they do rather than other, perfectly plausible, alternatives.
Raup taught at numerous institutions, most notably the universities of Rochester and Chicago. His other publications include
(1971, with Stephen Stanley), which has become a standard textbook.
Raup is survived by his wife Judith, by a stepson and by a son from an earlier marriage. David Raup, born April 24 1933, died July 9 2015