Monday, 21 October 2013

Why Wrested Scriptures is wrong on evolution - Part 2

In  part 2,  I examine where Ron Abel's attack on evolution immediately goes astray, and that is in failing to properly define evolution. If you fail to properly define the subject you are attacking, then everything you say loses credibility since you are attacking a parody of the subject.

Abel’s attack on evolution began with a reasonable request to insist on a correct definition of evolution. Unless evolution is properly defined, any discussion will be flawed as what will be attacked is not evolution, but a parody of it. Unfortunately, Abel did just that by failing to define evolution correctly. 

He wrote:

1. Insist on a definition of the term evolution. Biology texts use the term in the following three ways:

a) The gradual change in the characteristics of species over the course of time. The Christadelphian need not concern himself with this definition of evolution, since minor changes do occur within species without a change in their essential nature. (E.g. humans today are on the average taller and heavier than humans of a hundred years ago.)
b)  'Horizontal differentiation' - the diversification of a single type into a number of types of creatures with similar characteristics. Again, the Christadelphian need not concern himself with this definition since different types of dogs may have come from one dog type, but they are still dogs.
c)  'Vertical evolution' - the development of existing forms1 from a few primitive forms with increasing complexity and development through the ages. It is this definition which conflicts with the special creative acts of God outlined in Genesis.

Evidence for a) and b) is often mistakenly advanced in support of c).

This is an extremely poor definition of evolution, as it fails to differentiate between evolution as fact (namely the abundant evidence of common descent and large scale evolutionary change) and evolution as theory (the theoretical mechanism proposed to explain how evolution occurred). There was no excuse for Abel’s flawed definition as Darwin himself on at least two occasions was at pains to differentiate between fact and theory. In 1863, four years after the first edition of the Origin was published, Darwin wrote:

Whether the naturalist believes in the views given by Lamarck, or Geoffroy St.-Hilaire, by the author of the Vestiges, by Mr. Wallace and myself, or in any other such view, signifies extremely little in comparison with the admission that species have descended from other species and have not been created immutable; for he who admits this as a great truth has a wide field opened to him for further inquiry.[1]

while in 1871 he wrote in The Descent of Man that:

Some of those who admit the principle of evolution, but reject natural selection, seem to forget, when criticising my book, that I had the above two objects in view; hence if I have erred in giving to natural selection great power, which I am very far from admitting, or in having exaggerated its power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations.[2]

Darwin could not have been any clearer in pointing out that when he wrote his book, he had two goals. The first was to show that an evolutionary process had occurred, and to show this he assembled a considerable amount of evidence from biogeography, comparative anatomy and embryology. The second goal was to propose a theoretical explanation for how evolution had occurred, and this was his theory of natural selection.

He was only partly successful in achieving these goals. Within a short time after the publication of his book, the scientific community rapidly accepted that an evolutionary process had occurred. The evidence even then was considered overwhelming. However, he was less successful in convincing the scientific world that natural selection could explain evolution, due in no small part to the lack of a decent theory of heredity. In fact, by the late 19th century, natural selection fell out of favour[3] with alternative theories of evolution such as orthogenesis, mutationism, theistic evolution and Lamarckianism enjoying support until the first half of the 20th century with the creation of the modern evolutionary synthesis, which incorporated natural selection along with insights from genetics, ecology and palaeontology.

However, it needs to be stressed that the fact of evolution was not seriously questioned, as the evidence for it was regarded as overwhelming, even if there was significant debate about the mechanism of evolutionary change. Too many special creationists confuse debate about the theoretical mechanism of evolutionary change with common descent and large-scale evolutionary change, and then erroneously conclude that doubts about the former mean the latter never occurred. This is nonsense, and makes as much sense as concluding that since we do not have a complete theoretical explanation of gravity due to the fact that general relativity does not explain gravity at the quantum level, gravitational lensing, planetary motion and gravitational attraction do not occur. The level of disbelief that a physicist would experience if told this by a layperson is exactly the same experienced by biologists who are confidently told by fundamentalist Christians with no understanding of biology that common descent is false because of problems – real or imagined – with the currently accepted theory of evolution.

The evidence for common descent is considerable, and includes:

  • Palaeontology
  • Comparative anatomy
  • Developmental biology
  • Biogeographic distribution of species
  • Comparative genomics
 It is interesting to note that in the mid-19th century, despite the relative sparseness of the fossil record and the fact that comparative genomics as a discipline was over a century in the future, the evidence for common descent was regarded as compelling. The fossil record and comparative genomics have made a powerful case for common descent irrefutable.

Just the genomic evidence alone is compelling. If common descent was true, then we would expect genetic ‘errors’ such as broken genes, insertion of mobile genetic elements or insertion of retroviral genetic material following viral infection to be inherited by species descending from a common ancestor in which these ‘genetic errors’ first occurred. Conversely, there is no reason if special creation was true for God to deliberately insert the same non-functional genetic element into closely related species in exactly the same place in their respective genomes. What the genomics revolution has shown is that we see many of these ‘genetic errors’ in exactly the same place as predicted by common descent. John Coffin, a leading expert in virology comments on how the pattern of ancient retroviral infection in genomes confirms common descent:

Because the site of integration in the genome, which comprises some three billion base pairs in humans, is essentially random, the presence of an ancient provirus at exactly the same position in different, but related, species cannot occur by chance, but must be a consequence of integration into the DNA of a common ancestor of all the species that contain it. It evolution of retroviruses follows, therefore, that we can infer what viruses were present millions of years ago by examining the distribution of endogenous proviruses in modern species.[4]

As the following video presentation shows, common descent is the only credible explanation for the pattern of endogenous retroviral elements in human and ape genomes. At this point, I need to stress that this is only one of the lines of evidence that confirm common descent.

 Having failed to properly define evolution, Abel’s suggested strategy to rebut evolution falls apart. He was attacking a straw man version of evolution, and anyone unfortunate enough to take his strategy to heart and try to take on an informed friend would result in significant embarrassment. There is some value in taking apart the rest of Abel’s flawed attack on evolution if only to show how mistaken contemporary Christadelphians are in offering it as a definitive rebuttal of evolution.

[1] Darwin CR. Origin of species [Letter]. Athenaeum 9 May: 617; 1863.
[2] Darwin C. The descent of man, and selection in relation to sex. London: John Murray; 1871.
[3] This is often referred to as the ‘eclipse of Darwinism’, to use the phrase employed by Julian Huxley.
[4] Coffin JM “Evolution of Retroviruses: Fossils in our DNA” Proceedings of the American Philosophical Society (2004) 148:3, 264-280