graduate student gave me this manuscript to read, I 

 would see it as a brilliant piece of work (indicating that 

 the student has enormous potential) but I would give it 

 back to be done right!" The editors of Science followed 

 Raup's advice and returned the manuscript to the Nobel 

 laureate and his co-authors with the suggestion that they 

 rework their manuscript, this time "doing it right." 



In 1977 Alfred G. Fischer and Michael A. Arthur 

 published a paper in which they claimed that major 

 extinctions come every 32 million years. Raup's reaction 

 at the time was the same as everyone else's — incredulity. 

 The data was messy, and the authors were very vague 

 about the mechanism that could produce such regular 

 extinctions. However, in 1982, a young colleague of 

 Raup's at the University of Chicago, Jack Sepkoski, 

 published a huge compendium of the origin and 

 extinction of fossil groups. The following year, Raup and 

 Sepkoski began playing with this data to see if they could 

 discern any regularities. Eventually one materialized — 

 periodic mass extinctions every 26 million years. Raup 

 and Sepkoski were very leery. They did not want their 

 names added to the list of gullible scientists and 

 pseudoscientists who had suggested cycles in the fossil 

 record. The implications of their hypothesis were even 

 more fundamental than those of the meteor impact 

 hypothesis. It is one thing to say that a particular mass 

 extinction really was massive and caused by a meteor. 

 The suggestion that many, possibly all mass extinctions 

 were caused by collision with extraterrestrial objects was 

 even more ambitious. But to add to these hypotheses the 

 claim that the collision and subsequent extinctions 

 occur at regular intervals involves a speculative quantum 

 leap. What in heaven's name could cause such regular 

 extinctions? 



When Raup and Sepkoski, after considerable 

 effort, were unable to shoot down their hypothesis, they 

 published. Initially the reaction was mixed. Astro- 

 physicists suggested celestial mechanisms to explain 

 the periodicity of extinction, including a small com- 

 panion star to the .sun which they named "Nemesis," 

 the Death Star. Raup himself suggested periodic 

 reversals of the earth's magnetic poles. In support of 

 Raup and Sepkoski, Walter Alvarez and Rich Muller 

 reported a periodicity of crater formation every 32 

 million years. The extinction and crater cycles even 

 coincided — sort of. But the responses of many of their 

 colleagues were anything but favorable, culminating in 

 an editorial in April of 1985 in the New York Times, 

 concluding that astronomers "should leave to astrologers 

 the task of seeking the cause of earthly events in the 

 stars." 



When Raup started writing up the chronicle of the 



Nemesis affair, he hoped that some resolution would 

 have been reached by the time he was ready to publish. 

 Fortunately for the reader, the controversy continues 

 unabated, even though several editors of journals and 

 science journalists have declared it over. Usually 

 histories of science are written long after the smoke has 

 cleared and we know who is right. As a result, not only is 

 the smoke left out, the power of hindsight is brought to 

 bear on the arguments and evidence. Those scientists 

 who turn out to be right are lauded as "keen observers" 

 and "responsible scientists," while those who opposed 

 them are condemned as being "blinded by preconceived 

 ideas." 



Those scientists who turn out to be wrong are 

 dismissed as "idle speculators" and those who opposed 

 them praised as properly "sober scientists." The real 

 world is not like this at all. When scientists must opt 

 on scientific ideas, the data is always messy and 

 indeterminate. The winds keep blowing. First one side 

 seems to be winning, then the other. One of Raup's goals 

 is to avoid the "sanitized" view of science which 

 characterizes so much of the literature on science. The 

 fact that he does not know who is eventually going to 

 win helps in this respect. We do not know yet who the 

 heroes and villains are. Nor is he in the least tempted to 

 debunk science. There is much more to winning in 

 science than public relations and professional ad- 

 vancement. Data does matter — eventually, to some 

 extent, when all else fails. 



Raup sees as one of the challenges for future 

 paleontologists in studying extinction is to "do a much 

 more thorough job of identifying the winners and losers, 

 so that we have a better chance of learning exactly what 

 environmental stresses were responsible for the 

 disaster." Those of us who study science might well set 

 ourselves a parallel task with respect to scientists and 

 their theories. Who are the winners and the losers, and 

 how were these contests decided? Why was a whole 

 succession of papers by serious, well-placed scientists 

 urging drastic causes for catastrophic effects in the 

 history of life ignored until the paper by Alverez and 

 company? Why was the paper on the periodicity of 

 extinction by Fischer and Arthur dismissed so lightly? 



Raup does not know the answers to these and other 

 questions. As in the case of his 26-million-year cycles of 

 extinction, he has discerned a pattern. Now we need the 

 mechanism. Raup has written an immensely enjoyable 

 book. The only thing more fascinating than dinosaurs 

 munching their Mesozoic vegetation or being terrorized 

 by Tyrannosaurus rex is scientists engaged in battles over 

 their favorite scientific hypotheses. 



