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Here's the NYT Mass Extinction article



> 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"