Evolution by Catastrophe: Does it indicate Intelligent Design? (cont.)
By Bibhu Dev Misra (IIT, IIM)
Raup’s
observations that the extinction or survival of a species is a
‘chance’ event, is supported by the studies done by
Macquarie University paleobiologist John Alroy. He says, ‘Mass
extinction fundamentally changes the dynamics. It changes the
composition of the biosphere forever. You can’t simply predict
the winners and losers from what groups have done before’[iii].
The mass extinction event itself is short lived, very often below the
resolving power of geologic record (<10,000 years), and possibly
instantaneous.
Therefore, ‘Evolution
by Catastrophe’ (a term used by Rampino in the ‘Encyclopedia
of Planetary Sciences’) is in marked disagreement with standard
Darwinian concepts of evolution. A new school of evolutionary
thought, known as ‘Punctuated Equilibrium’ was
developed independently by Harvard paleontologists Steven Jay Gould
and Niles Eldredge (1972). They proposed that speciation occurs
rapidly at times of environmental stress, and the long intervals
(millions of years) between speciation are marked by general stasis,
with little evolutionary change. Most species appear in the fossil
record looking much the same as when they disappear. And in times
of environmental stress, speciation happens abruptly within a space
of a few thousand years. New species appear all at once and 'fully
formed.'
Gould
and Eldredge believe that speciation occurs so rapidly at times of
stress that there is very little time for transitional forms to be
fossilized. This is why we do not find any ‘missing links’
in the fossil data. In the 1970s, a number of examples of gradualism
in the fossils were proposed by others in order to refute the concept
of ‘punctuated equilibrium’. Gould and Eldredge dismissed
these claims arguing ‘that virtually none of the examples
brought forward to refute our model can stand as support for phyletic
gradualism.’[iv]
Endnotes
|
