spock has less appendixes that one, and no problems with digestion.
It's obviously not essential for digestion, but I have heard that it does actually produce some form of bacteria or w/e that is used in digestion. It's probably not only produced there though.
Someone want to like, confirm this by posting a source, or are we just spouting random bullstuff?
Again, I can't back it up, but I have heard that it was used previously for our ancestors for use in balancing while walking on two legs.
Probably something that we gained while becoming bipedal.