"The Unproven Theory of Evolution"

This post is part of a series of posts that deal with some common Young Earth Creationist (YEC) objections to theistic evolution.  The impetus for these posts came via a comment from a reader on a previous post.  An index of all these posts can be found here.

Here I would like to address this part of Steve’s original comment:

You might argue the the Bible was written and translated by man, and could have errors (I personalty don't believe this to be the case). But I feel compelled to point out to you that evolution itself is only an idea of man and also may have many errors in it. It's all based on observation with the assumption that certain events occurred. Regardless of what information you've received in your studies of evolution, I assure you, to this day, it has not been proven, and I'm totally confidant that it never will be. No one was there to witness it. There is no documented record of it taking place. No one can, or ever will know for sure.

First of all, we would never expect to observe large changes in organisms directly.  In fact, if scientists observed something like a fish turning into a frog, then we would have some good evidence against evolution.  Evolution occurs mainly by the accumulation of small changes over large periods of time.  Of course it hasn’t been directly observed.

Secondly, there is a documented record of evolution taking place.  In fact, there are several documented records.  The fossil record, biological record, and genetic record are our record of it taking place.  Now, I’m sure the question referred to a written record.  Even though this kind of record should not be expected to exist at all, (and of course does not) this does not mean that we cannot be sure that evolution did not occur.

Nothing in the natural world can be proven with total certainty.  In the claim above, the kind of certainty that is being required is only possible through omniscience, which only God possesses.  However, we can achieve a high degree of certainty by examining the evidence.  In the case of evolution, we have vast amounts of evidence from a wide variety of fields.  In each case, the conclusions from each field test the conclusions from each other field. 

The following is just a selection from the three types of “records” above that show that one must be completely ignorant of the data to claim that there is no evidence for evolution taking place. 

Keep in mind that each piece of evidence checks and supports each other piece – this is important – no single piece proves evolution, but as each piece is added, predictions can be made about what further evidence should show… This is how a phenomenon that is directly unobservable is studied.

• Common ancestry predicts a nested hierarchy (groups within groups).   We in fact see an organized, well-defined, consistent hierarchy ("tree of life").
• Different bodies of evidence give the same arrangement of the tree of life.   Morphological/physical, genetic, and biochemical evidence all produce the same phylogenies. 
• Animals from the fossil record fit into the same tree of life.   Despite the claims of evolution deniers, transitional forms have been found.
• The animals found in the fossil record are arranged chronologically in order of increasing complexity and as predicted by the tree of life. (Try doing that with a flood.)
• The geographical distributions of species and groups are consistent with their evolutionary history, e.g. marsupials are found only in Australia.  This piece of evidence is still true when fossil evidence is considered.
• Gradual change predicts a similarity in structure despite a difference in function.   As species change and acquire new functions (swimming, flying), old structures must be adapted to the new function.  This is exactly what is observed; the same bones in the same relative positions are used in human hands, bird wings, whale flippers and horse legs.   Additionally, you never see birds with wings and arms, because wings and arms are adaptations of the same structures. 
• Organisms that evolve the same functions independently should show differing structures to accomplish the function.   Octopus eyes and mammal eyes have opposite ordering of layers, because vision was evolved independently, as confirmed by their place in the tree of life.
•  Since new functions are acquired by adapting old structures, often the resulting structure/system is not optimal.  Examples:  We can choke because our digestive system and respiratory system share parts.   We have a blind spot in our vision because of the suboptimal ordering of the layers.  Octopi do not have the blind spot.
•  Speciation does occur and has been observed, despite claims that it has not.  To me, the most compelling examples of speciation in action are "ring species”.  Also, I have cichlid fish in my aquarium that only come from lakes in Africa that have habitats less than 200 years old.   Most YEC accept this because they have to invoke post-flood speciation to explain the possibility of Noah's Ark.
•  Non-functional (junk) DNA shows a remarkable pattern of inheritance.  For me, this is the most convincing and irrefutable evidence of macroevolution.

Now, although this cannot “prove” with 100% certainty that evolution occurred, it is enough to be very certain that one of two scenarios exists:

Either   1) Evolution occurred.

Or        2) God has gone to extreme lengths to make it look like evolution occurred.

Option 2) is neither the God of the Bible, nor a God I want to worship.  Hence, I am convinced that evolution occurred.