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*To*: dinosaur@usc.edu*Subject*: Here's the NYT Mass Extinction article*From*: dunn1@IDT.NET*Date*: Tue, 2 Sep 1997 21:54:27 +0000*In-reply-to*: <340C4C3E.B73003A7@interport.net>*Reply-to*: dunn1@IDT.NET*Sender*: owner-dinosaur@usc.edu

> From: "D.I.G." <dinosaur@interport.net> > Todays NY TImes, 2 September 1997, Page C3 (The Science Section) > Article entitled: > Many small events may add up to one mass extinction. (I left off the > capital letters). > > A fractal model of extinctions indicates that the meteors may not be the > overriding factor in "boundary" mass extinctions. > > Interesting. Here it is. I ask that everyone please respect the copyright and not reprint it in any naughty copyright-infringing ways. I transmit this article for fair-use educational purposes only. I am neither directly affiliated with the managers or editors of this electronic mailing list or with the University of Southern California, nor am I operating under any express or implied ageny relating in any way to any of the abovementioned entities. Larry Dunn Copyright 1997 The New York Times Company The New York Times September 2, 1997, Tuesday, Late Edition - Final SECTION: Section C; Page 3; Column 1; Science Desk LENGTH: 1123 words HEADLINE: Many Small Events May Add Up to One Mass Extinction BYLINE: By MALCOLM W. BROWNE BODY: DID the mass extinctions that have punctuated the history of life on this planet have a common cause, or were they just statistical fluctuations nudged to extremes by many unrelated causes? Since 1980, heated scientific debates have arisen from this and related questions. Many disagreements have centered on the wave of extinctions at the end of the Cretaceous period some 65 million years ago that saw the demise of the dinosaurs, the marine shellfish called ammonites, and many other large groups of animals. Partisans of various opposing theories have argued that major mass extinctions throughout the 3.5-billion-year history of life on earth have been caused by the impact of large meteors, by volcanic eruptions that covered an area the size of a continent, by protracted ice ages, by changes in sea level, epidemics and many other factors. But a collaboration of European scientists has raised another possibility: mass extinctions may be caused by complex, interacting conditions that cannot be encompassed by any simple explanation. The scientists reported in the Aug. 21 edition of the journal Nature that their analysis of data culled from the fossil record reveals statistical patterns over time that mathematicians describe as "fractal." In this kind of pattern, the frequency of an event taking place is inversely proportional to its intensity; for example, the statistical expectation is that there will be a certain number of small earthquakes for every large one. The report suggests that extinctions of all magnitudes, from the smallest to the most devastating, probably had many different causes and that future mass extinctions may be intrinsically unpredictable. Moreover, the impact of an asteroid or a continental blast of volcanic lava may not be needed to kill off a large proportion of the earth's animals and plants, the authors said; relatively small changes in global conditions may sometimes combine in complex ways to precipitate catastrophic consequences. There is growing evidence that the mass extinction at the end of the Cretaceous period occurred about the same time that a monster meteor struck the Yucatan Peninsula. And yet, efforts to link other major extinctions with similar impacts have largely failed. One of the authors of the Nature paper, Dr. Michael J. Benton, a paleontologist at the University of Bristol, England, said in an interview that he believes the Cretaceous extinction was the only one of the "big five" mass extinctions for which there is fairly good evidence that a large meteor impact occurred about the same time. (The other four occurred at the end of the Cambrian period 500 million years ago, at the end of the Devonian period 350 million years ago, at the end of the Permian period 230 years ago -- the most devastating of all -- and at the end of the Triassic period 195 million years ago.) Moreover, there are several meteor craters of about the same size as the Yucatan crater (110 miles in diameter) that do not correspond in time to any known mass extinction, Dr. Benton said. The European study was headed by Ricard V. Sole, a physicist at the Polytechnic University of Catalonia, Barcelona, with his student, Susanna C. Manrubia, with Dr. Benton and Dr. Per Bak, a physicist at the Niels Bohr Institute in Copenhagen, Denmark. The European scientists who conducted the new study culled statistics from the fossil record and concluded that extinctions large and small fit a fractal pattern known as "scale-invariant self-similarity." This means, roughly, that a common statistical pattern pervades a certain class of things, regardless of how the size scale varies. According to ideas pioneered by a French mathematician, Dr. Benoit Mandelbrot, fractal patterns manifest themselves throughout nature. Thus, the jagged pattern of a shoreline seems much the same at all scales, whether viewed in fine detail from an inch above or in gross outline a mile above. In the European study, the supposed fractal scale is based on increments of time during which extinctions took place. The scientists plotted patterns of extinctions over different time scales, and found that the patterns over large intervals of time seemed similar (although different in scale) to patterns within smaller time scales. They conclude that the erratic responses of the earth's "biosphere" to perturbations -- including small ones, like the normal fluctuations in the ratios between competing species "provide the main mechanism for the distribution of extinction events." This neither supports nor weakens any particular theory on how the dinosaurs or any other group became extinct. Mathematically speaking, Dr. Benton said, it is equally possible for an extinction to have been the result of the internal dynamics of an ecosystem, or an asteroid impact, or any other influence. But as scientists try to discern a coherent pattern underlying the mass extinctions, doesn't the new report amount to a frustrating return to the starting line? "Yes, I think that's right," Dr. Benton said. "I think the mathematics are perfectly concordant with the idea of all kinds of crises contributing to extinctions, with no explanation particularly favored." Among the critics of this view is Dr. David M. Raup, a statistical paleontologist who retired several years ago from the University of Chicago. Dr. Raup has argued for more than a decade that most extinctions -- minor waves as well as globally catastrophic ones -- result from meteor impacts. The quest for subtle biological interactions and for complex mathematical models to explain how they can add up to mass extinctions is futile, he said, because the evidence is that some 60 percent of all extinctions are caused by extraterrestrial matter: comets, asteroids and other small objects. Regarding Dr. Bak's notion that extinctions occur in fractal patterns independently of specific causes, Dr. Raup said in an interview: "It's intuitively wonderful. A very cuddly idea. But I don't buy it." Statistical explanations of this kind remind him, he said, of the ideas of Dr. Rene Thom, a French mathematician whose "Catastrophe Theory" was popularized in the 1970's as a mathematical model for explaining the abrupt onset of wars, traffic jams, stock crashes, chemical reactions and much more. Catastrophe theory was based on analyses of the topology, or surface structure, of abstract mathematical shapes endowed with "cusps." These cusps, like the tips of upward pointing needles, were places where an object could be sent flying with equal probability in several possible directions, with the slightest push. "Physicists' theories that attempt to explain everything can end up explaining nothing," he said. GRAPHIC: Drawing (David Suter) LANGUAGE: ENGLISH LOAD-DATE: September 2, 1997 Dr. Raup has argued for more than a decade that most extinctions -- minor waves as well as globally catastrophic ones -- result from meteor impacts. The quest for subtle biological interactions and for complex mathematical models to explain how they can add up to mass extinctions is futile, he said, because the evidence is that some 60 percent of all extinctions are caused by extraterrestrial matter: comets, asteroids and other small objects. Regarding Dr. Bak's notion that extinctions occur in fractal patterns independently of specific causes, Dr. Raup said in an interview: "It's intuitively wonderful. A very cuddly idea. But I don't buy it." Statistical explanations of this kind remind him, he said, of the ideas of Dr. Rene Thom, a French mathematician whose "Catastrophe Theory" was popularized in the 1970's as a mathematical model for explaining the abrupt onset of wars, traffic jams, stock crashes, chemical reactions and much more. Catastrophe theory was based on analyses of the topology, or surface structure, of abstract mathematical shapes endowed with "cusps." These cusps, like the tips of upward pointing needles, were places where an object could be sent flying with equal probability in several possible directions, with the slightest push. "Physicists' theories that attempt to explain everything can end up explaining nothing," he said. GRAPHIC: Drawing (David Suter) LANGUAGE: ENGLISH LOAD-DATE: September 2, 1997 Larry "Atheism: a non-prophet organization"

**Follow-Ups**:**Re: Here's the NYT Mass Extinction article***From:*Jeffrey Martz <martz@holly.ColoState.EDU>

**References**:**Mass Extinction in the NY Times***From:*"D.I.G." <dinosaur@interport.net>

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