I was reading around AiG (as you do), and I came across this article called (
Your appendix...it's there for a reason).
Now, everyone agrees there is a reason for the human veriform appendix, the question revolves around what that reason is.
It is known that there is a larger collection of lymphoid tissue in the appendix than many other areas of the gastro-intestinal tract. The creationists argue that this is because the Creator gave us the appendix because of that function.
However, I argue (and I'm sure others have, but I can't find anything on it at the moment) that it is the other way around: the function evolved because of the structure.
The human veriform appendix is very susceptible to infection. Appendicitis has a very high mortality rate when untreated. Therefore, there would be a great selection pressure acting to keep people from dying from appendicitis.
So, what do you need to combat an infection? Lymphocytes. Where do they come from? Lymphoid tissue. So, it makes sense that the appendix will have lymphoid tissue, given its susceptability to infection.
The lymphoid tissue, present within the entire of the GIT, especially Peyer's patches of the ileum, could probably have evolved to increase in number in certain locations with relative ease (compared to other evolutionary developments). With such a concentration of lymphoid tissue, it is then easy for it to take on a role in the immune system.
Therefore, I conclude that it is precisely
because the appendix is vestigial (thus small and easily infected), that it needs to have this immune function to protect itself.
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