Wednesday, March 11, 2015
Was Darwin "Debunked" about extinctions?
A recent comment I saw was that "Darwin's theory on extinction has been debunked, see this takedown" and a link to Darwin, Then and Now.
The link is to a website maintained to promote an anti-science book written by Richard William Nelson.
Darwin is always a favorite target as if he had been the last authority on evolutionary biology rather than the first. "Darwin's theory on extinction has been debunked" is built on the false claim was that Darwin thought that all species extinction must be very slow. This was based on a partial citing of a sentence fragment ripped from context, AKA a Quote Mine. The actual section from the definitive 6th edition of Darwin's "The Origin of Species" was "On Extinction" in Chapter XI regarding the fossil record. It reads;
"Both single species and whole groups of species last for very unequal periods; some groups, as we have seen, have endured from the earliest known dawn of life to the present day; some have disappeared before the close of the palæozoic period. No fixed law seems to determine the length of time during which any single species or any single genus endures. There is reason to believe that the extinction of a whole group of species is generally a slower process than their production: if their appearance and disappearance be represented, as before, by a vertical line of varying thickness the line is found to taper more gradually at its upper end, which marks the progress of extermination, than at its lower end, which marks the first appearance and the early increase in number of the species. In some cases, however, the extermination of whole groups, as of ammonites, towards the close of the secondary period, has been wonderfully sudden."
The bold italic sentence fragment was the whole of "Darwin's theory" according to Mr. Nelson.
So all Darwin has said is that the disappearance of entire Genera, or Families is commonly slower than their appearance and diversification in the fossil record. He referred to a well known instance of rapid extinction. We do know today that there have been unusual events on time scales unimagined by Darwin, or his contemporaries. Time scales of millions and tens of millions of years have marked the ends of great eras, and the extinctions of millions of species, even entire phyla. These mass extinctions are commonly followed by equally rare periods of rapid diversification of species among the survivors.
Mr. Nelson's falsehood that Darwin's "theory of extinctions" was disproven by the rapid man-made extinction of the Great Auk is a fraud of his own invention. The Great Auk (Pinguinus impennis) extinction was sudden. But the extinction of the Family it was has been much slower than their origin. Further, Darwin was focused on the fossil record and was not addressing the human interventions into species diversity.
It is in perfect accord with evolutionary biology.
The discovery of mass extinctions following extraordinary events like the "Snowball Earth," Meteor impacts, or massive flood volcanoes was touted by Steven Jay Gould 45 years ago as "overturning Darwinism." He got his tenure at Harvard and then calmed down. We are in the midst of another extraordinary event. This is one we have done on our own starting with the invention of agriculture 10,000 years ago.