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
