By Steve Brusatte
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
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
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
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
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
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
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?
Amazon.com 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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