Icons (False Idols) Of Evolution 7 - Darwin's Finches - posted by bornagain 7777777 (bornagain7777777) - tangle.com

My Question: DARWIN'S FINCHES. Why do textbooks claim that beak changes in Galapagos finches during a severe drought can explain the origin of species by natural selection--even though the changes were reversed after the drought ended, and no net evolution occurred?

NCSE's Answer: Textbooks present the finch data to illustrate natural selection: that populations change their physical features in response to changes in the environment. The finch studies carefully--exquisitely--documented how the physical features of an organism can affect its success in reproduction and survival, and that such changes can take place more quickly than was realized. That new species did not arise within the duration of the study hardly challenges evolution!

My Response in Outline:

(a) The NCSE is evading the question, which is not whether the finch data demonstrate natural selection (they do), but whether those data explain the origin of new species (they don't).

(b) To the extent that scientific theories are supposed to rely on evidence, the finch study DOES challenge Darwin's theory of the origin of species by natural selection. No one doubts that natural selection occurs, but every time it has been observed (as in the finches) it has occurred only within existing species.

My Response in Detail:

(a) The question is not whether the finch data demonstrate natural selection, but whether those data explain the origin of new species. In the 1970s, biologists Peter and Rosemary Grant watched as a severe drought killed 85% of a particular finch species on one island in the Galapagos archipelago. The survivors had (on average) slightly larger beaks, enabling them to eat the hard seeds that had weathered the drought; but average beak size returned to normal after the rains returned. There was no net change, and no new species emerged. In fact, several species of Galapagos finches now appear to be merging through hybridization--the exact opposite of producing new species. Yet some textbooks--and a publication of the U. S. National Academy of Sciences (NAS)--make it sound as though the finch studies showed how new species can originate. Miller and Levine's Biology: The Living Science (1998) tells students: 'It might take only between 12 and 20 droughts to change one species of finch into another!' According to Science and Creationism: A View from the National Academy of Sciences (1999), the Grants' observations showed that 'if droughts occur about once every ten years on the islands, a new species of finch might arise in only about 200 years,' making the Galapagos finches 'a particularly compelling example of speciation [a technical term for the origin of new species].' Both the Miller-Levine textbook and the NAS booklet neglect to mention that the data actually point to oscillating selection with no net change, and now to the merging of species through hybridization. The question is not whether the Grants observed natural selection--they did--but why the evidence is exaggerated to make it appear to show much more. The NCSE fails to answer this question.16

(b) The fact that no new species arose in the course of the Grants' study does not refute the theory of evolution. It certainly 'challenges' it, however, because scientific theories need to be supported by evidence. Darwin's theory, as expressed in the title of his 1859 book, was The Origin of Species by Means of Natural Selection, and the Galapagos finches are held up by our nation's premier science organization as a 'particularly compelling example' of this. Yet the finch data do not show cumulative changes in beak size, much less the origin of species through natural selection. No one doubts that natural selection occurs, but every time it has been observed (as in the finches) it has occurred within existing species. For example, natural selection has often been observed in bacteria. Because of their rapid generation times, bacteria ought to be the easiest organisms in which to observe the origin of species through natural selection. Yet as British bacteriologist Alan H. Linton wrote in 2001: 'Throughout 150 years of the science of bacteriology, there is no evidence that one species of bacteria has changed into another.' Faced with this lack of evidence for a key element of Darwin's theory, some defenders of the theory--even in the prestigious NAS--have taken to exaggerating the finch data. Although this does not refute the theory, it hardly inspires confidence in it. As Berkeley law professor and Darwin critic Phillip E. Johnson wrote in 1999: 'When our leading scientists have to resort to the sort of distortion that would land a stock promoter in jail, you know they are in trouble.

http://www.evolutionnews.org/2008/08/inherit_the_spin_the_ncse_answ.html#more
« Close