I just had a student ask me some questions about evolution.  Since I spent a little time on this, I thought I would post it here, in case someone else might find it useful.  I left the student as anonymous.
STUDENT:Hi professor Oakley, I had your Macroevolution course last year, and  am now in Ken Kosik's Neurobiology course this quarter.  We've been  talking a good deal about the evolution of the nervous system, and I  had a few questions I figured you would be most qualified to answer.
Professor Kosik brought up your research on the genes conserved from  sponge to human that, in humans, are important in the formation of  eyes.  I remember you mentioned this during Macro, too, and that,  despite being used by Creationists as evidence for Creation, it is, in  fact, further evidence for evolution.
OAKLEYWell, the bottom line is that creationism is not science, it is a  faith.  My own philosophy is that faith and science are completely  separate, "non-overlapping magisteria".  One can have faith in a creator  and also accept the scientific facts of evolution; I know several people  who fit this precise description. (I personally am agnostic, I don't  care if there is some sort of creator or not, I don't see any reason why it should matter to my life).
Creationism is simply not a science, it does not present testable  hypotheses, because one can always say "that is how the designer made  it".  I prefer to use the term "anti-evolutionists" to describe people  who twist logic to call into question the scientific facts of evolution.  My goal is to distinguish the magisteria - divine creation is not impossible, but it is unscientific.
See this article for what I mean by non-overlapping magisteria, in SJ  Gould's words:
http://www.stephenjaygould.org/library/gould_noma.htmlIn contrast to creationism, science presents hypotheses.  One hypothesis  of evolution is global common ancestry, the hypothesis that all life is  derived from a single common ancestor.  This hypothesis is supported  when we find highly non-random similarities among organisms - like a  nearly universal genetic code, for example.  We could find scientific  facts that contradict universal common ancestry, such as a non-DNA form  of life - therefore it is a testable hypothesis.
There are many other testable hypotheses in evolutionary biology, such  as "natural selection is a primary mechanism driving evolutionary  change". We talked in macroevolution about how people test for the  requirements of natural selection (variation, super-fecundity, heritability, and differential  survival due to or correlated with the heritable trait).  We also talked about inferring selection on genes using  neutral theory as a null model.
STUDENT  Why is this?  Also, where can I find your paper on this topic online?
OAKLEYHere is a good blog about our eye research:
http://www.tuibguy.com/?p=209Here is the paper:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0001054and a news story that was in many newspapers:
http://www.mcclatchydc.com/staff/robert_boyd/story/21106.htmlRegarding the synapse research, that Ken probably talked about in your  class, here is a news article:
http://blog.newsweek.com/blogs/labnotes/archive/2007/06/06/irreducible-complexity-is-reducible-afterall.aspxHere is the original paper for that:
http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0000506STUDENT:
We covered the topic of "exaptation" in Neuro and this, too, makes me  wonder about evolution.  If we don't know the original purpose of a  gene that eventually helped us make an eye, who's to say that it ever  had a purpose?
OAKLEY:
We can make inferences about the functions of genes using phylogeny and  comparative biology.  If two genes share the same function, then likely  their ancestral gene had the same function.  There are statistical  models for working out more complicated cases, too.
So, in the case of our eye research, we do have a good idea of the  previous function.  Eyes use phototransduction, which is a GPCR-based  transduction pathway.  We can see by inferring the history of genes used  in eyes, that they are closely related to other GPCR pathways.  GPCR  pathways very generally transmit signalls from outside cells to inside  cells, and "tell" that cell to do something.  In the case of vision, a  gene (called opsin) evolved light sensitivity.  But opsin is related to  other GPCR genes that transmit signals, but not light signals.  In this  way, we can see that light perception evolved from other signaling genes.
STUDENT:
It seems like assuming that the gene DID once have a purpose implies  evolution - isn't this a circular argument?
OAKLEY:
In the case of opsin visual pigment genes, we can infer that the  ancestral gene did have a function.
STUDENT:
I'm not sure I've worded this incredibly clearly, but I'm sure you get  a lot of questions like this, so you probably have a good feeling for  the problems people  tend to have with evolution.  Evolution, since  taking your course, has pretty much become the entire basis on which I  understand biology, but in these cases I'm not so sure it makes sense.
OAKLEY:
Your thoughts on the centrality of evolution are shared by some great scientists (I didn't know he was Russian Orthodox Christian, supporting my point above):   
Theo. Dobzhanski