The problem with looking at things as evidence for evolution is that you inevitably start from the assumption that evolution did occur. Thus "x is caused by y because y is the only reasonable evolutionary explanation of x," and "evolution is true because y causes x." If you read closely, you can see this happening in a recent New York Times article.[1] The age of genes controlling skin color is at once proof that humans have evolved "recently," and that they have evolved "recently" proof that there were changes in diet or lifestyle.
The problem here is that such nearly circular logic can only be held as a viable theory if you accept the sole break in the circle as true. In this case, if you accept that a solely material cause must be responsible, then you are good to go. If however, you allow for any non-evolutionary causes, then you are faced with the question "why should I accept that this is in fact caused by evolution?" The answer that it must have been caused by evolution because we see it no longer satisfies.
- Mr. Nicholas Wade. "Still Evolving, Human Genes Tell New Story" The New York Times 2006-03-07. http://www.nytimes.com/2006/03/07/science/07evolve.html?pagewanted=1&ei=5088&en=03aecd6036986b0e&ex=1299387600&partner=rssnyt&emc=rss