Interview with David Raup

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By Steve Brusatte
Source: Dino Land Paleontology Interviews

This January I had a chance to interview renowned paleontologist Dr. David Raup over e-mail. This was a rare opportunity to talk to one of paleontology's most well known scientists. In fact, Stephen Jay Gould once called him "the world's most brilliant paleontologist." Dr. Raup is best known for his theory that mass extinctions occur every 26 million years. This theory was originally proposed in a 1984 with University of Chicago colleague Dr. J. John Sepkoski. Since the paper's release this theory has been the subject of numerous books and popular articles, including a cover story on Time Magazine. Here are the highlights of our interview:

S.B.: What can you tell me about your early experiences in paleontology? Were you interested as a child? Did anyone mentor you?

D.R.: Although my parents were both naturalists, I can remember no childhood interest in paleontology. Living in the Boston area, fossils were almost nonexistent. As a teenager, I was far more interested in skiing and camping. The first of many important mentors was in college: John Clark, a crusty vertebrate paleontologist/sedimentologist then on the Chicago faculty.

S.B.: What colleges did you attend and what degrees did you obtain?

D.R.: I started at Colby College in Maine and transferred to the University of Chicago after two years where I got a BS. Then Harvard for graduate work (because my first choice, Michigan, did not honor the Chicago degree) ending up with MA and PhD degrees. Throughout, I majored in geology, with heavy emphasis on paleontology and biology.

S.B.: I have briefly read about your professional career (at the Field and U of Chicago). Can you briefly trace through what positions you have held and what significant events have occurred at them?

D.R.: I taught at Caltech, Johns Hopkins, University of Rochester, and University of Chicago. Between Rochester and Chicago, I was a curator and Dean of Science at Field Museum of Natural History. In 1994, I retired to a small island in northern Lake Michigan. Also, for short periods, I was a visiting professor in Germany (Tuebingen) and on the faculty of the College of the Virgin Islands. Throughout, I was heavily involved in joint programs with biology and in promoting training of paleontologists in modern marine environments.

S.B.: Most people know you as an "extinction scientist." (Dr. Sepkoski answered many of my questions regarding the periodic extinction theory in our interview, so I will be light on the topic compared to what I would normally ask!). In addition to the monumental and groundbreaking theory of periodic mass extinctions, what other "extinction work" have you done?

D.R.: I have been in and out of extinction research since the late 70s. For a while, I thought mass extinctions were merely instances of chance coincidence of independent species extinctions. That clearly was wrong. I have done several projects on selectivity (or lack thereof) of the major extinctions. Also lots of time devoted to extraterrestrial influences, especially comet and asteroid impact. I have come to the view that large-body impact is responsible for far more extinctions that we appreciate -- perhaps including those pulses of extinction that usually define stratigraphic stages. Maybe even zones? I have tried to prove this in a couple of papers in Paleobiology but the idea is still pretty soft. Most of my research since 1983 has been supported by NASA as part of its interest in the evolution of complex life (here and elsewhere).

S.B.: How did the research into biodiversity that led to the periodic extinction theory begin?

D.R.: Jack Sepkoski's Compendium of the ranges of about 3500 fossil marine families became available in the early 80s and I could not resist looking for patterns involving standing diversity, extinction rates, etc. Later, Jack's genus-level data base -- an order of magnitude larger -- provided even greater potential.

S.B.: How did you initially get involved in Dr. Sepkoski's exhausting cataloging of extinction and species' biodiversity rates?

D.R.: We were faculty colleagues at Rochester and Chicago. I never did any of the actual cataloguing but our friendship gave me access to his data (and his quick mind). Collaboration was inevitable.

S.B.: At the time of publication, what opinions did you have on the Alvarez hypothesis? Did you initially accept it or doubt it? And, how far into your research regarding biodiversity and extinction timings were you when the Alvarez paper was published?

D.R.: I have talked about my reaction to the original Alvarez paper pretty extensively in my trade book The Nemesis Affair (recently re-issued). In general, I was highly skeptical of the Alvarez idea but also very hopeful. I had been working on the idea of impact causing mass extinction for 2-3 years by 1980, so I should have been ready.

S.B.: Were you surprised at how intense and vast the dinosaur extinction debate became? Did you expect all of these physicist and astronomers to become involved?

D.R.: It was really a wonderful period of interdisciplinary collaboration. Getting astronomers and physicists interested in paleontology and what we could tell them about earth history was exciting! I'm glad it worked out that way -- and those guys made some really important contributions quite apart from iridium, etc. Also, paleontologists have had a habit of isolating themselves from the rest of the scientific community. The interaction with people in other disciplines has been good medicine.

S.B.: Several mathematicians and paleontologists have offered mathematical theories that say that your periodic extinction hypothesis is simply an mirage, a false image, of statistics. What do you have to say about this?

D.R.: Evaluating statistical testing of messy data often produces this kind of criticism. The ongoing debate over the significance of global warming data is just one example: good (and honest) statisticians have made good arguments on both sides of the issue. For periodic extinction, I know of 13 complete re-analyses of the Sepkoski data that have been published by independent investigators. Of these, five found our periodicity to be significant whereas eight found no significant periodicity. Had these studies used the new genus-level data, I suspect periodicity would have fared better. In any event, the periodicity of extinction must, I think, remain an open question until we have either more data or data of a completely different kind. The data we have now could be argued either way.

S.B.: Can you tell me your first thought after all of the biodiversity data was calculated through the computer and the nice little chart of 26 million year intervals came out?

D.R.: My first thought was: "It can't be right!"

S.B.: Deep down do you "believe" that mass extinctions are really periodic?

D.R.: I believe they really are periodic but I cannot prove it. One problem is that in time-series analysis, one can establish a departure from randomness rather easily but proving a particular periodicity within that is nearly impossible.

S.B.: Several explanations have been offered to explain extinction periodicity. Which one do you find most valid?

D.R.: There is no good independent evidence for any of them. Several are plausible (e.g., Nemesis) but completely unconfrimed (by sightings or other evidence).

S.B.: I recall that a few years ago a team of scientists (possibly led by Whitmire) announced that they may have discovered a tenth planet in our solar system (I think this was about five years ago...when I was in the 5th grade or so). Do you think this possible discovery could be the "missing explanation" into the mystery of periodic mass extinctions?

D.R.: As with the other proposals, the Planet X idea is plausible but unproven.

S.B.: Over the past decade, after the discovery of the Chixculub crater and the naming of all of these feathered dinos, the idea of periodic mass extinctions have "fallen" from the "front pages of paleontology." Why do you believe that this theory sort of "fell off the face of the earth," except to devoted paleontologists and paleo fans, that is?

D.R.: Probably because there is, as yet, no way to extend the research -- and thus there is no news. The extinction record has been analyzed about as thoroughly as possible and searches for Nemesis have failed to find the companion star. If we polled the broad scientific community, I think we would find that most people do not think there is a periodicity in extinction. Although periodicity is not discussed much these days, it has surely not been forgotten - either by astronomers or paleontologists. With the newly automated sky surveys now under way, a companion star or tenth planet may be found -- if such there be. Or, perhaps, we will figure out some way to date large numbers of lunar craters -- which would settle the question immediately (one way or another!). So, I think periodicity is on the back burner but not forgotten -- any more than continental drift was forgotten.

S.B.: I have never read your book (unfortunately!), but can you briefly tell me about the process of writing it and the major ideas that it conveys?

D.R..: I have written a couple of trade books: THE NEMESIS AFFAIR and EXTINCTION: BAD GENES OR BAD LUCK? has lots of reviews of both which will give you an idea of their style and content.

S.B.: Now off of the extinction path, what other major research projects have you been involved in?

D.R.: Over the years, I have worked with a bunch of different topics including biocrystallogaphy of echinoderm skeletons, mathematical models of morphology, microevolution in the ammonite Kosmoceras, and a variety of simulation models of macroevolution. Unlike most paleontologists, I have not concentrated on a single taxon and stratigraphic interval.

S.B.: Currently, what are you up to? Are you involved in any paleo projects?

D.R.: I am fairly active with the Santa Fe Institute and a new project there to develop methods and approaches to dealing with the evolutionary exploration of morphospace. In this, there is heavy emphasis on computer simulation of growth and form in organisms.

S.B.: What do you feel about the Field Museum's acquisition of Sue?

D.R.: I have mixed feelings.

S.B.: How do you see the field of paleontology in the next century? What do you see instore for the struggle between evolutionists and creationists (had to ask this one)?

D.R.: Paleontology has, over the past 20 years, come out of its shell (closet?) so that it now interacts with other branches of science far more effectively than before. When I was in school, all you needed to become a paleontologist was interest and energy. You didn't have to know much. It was assumed that you spent enough time with your chosen taxonomic group to know all you needed to know. In other words, paleontology operated as a closed system, largely isolated from other branches of science. This has changed and I expect it will continue to change. It is often said that this trend has "killed" conventional systematic paleontology. But this is not true. Thanks to the increase in the total number of paleontologists, there are now far more systematic paleontologists than when I started. They are a smaller percentage of the total but there are lots more of them. In other words, I think old-style paleontology is healthy and thriving and that much new and exciting has been added. Also, taxonomic procedures have improved vastly thanks to the influence of cladistic approaches.

On the creation-evolution debate, I foresee continued conflict. Both sides will continue to lie, cheat, and steal to make their points.

S.B.: One last question, over your entire career, if you could pick one greatest moment, what would it be?

D.R.: Too many great moments to pick one. I have been extremely fortunate.


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