I've heard it said that the more educated you are, the more liberal you are likely to be.
I would think that this is a pretty obvious conclusion, actually. The more educated someone is, the more they know. The more they know, the more prideful (or at least confident) they become in that knowledge (perhaps this is a controversial statement, but if you think about it, it is true - evolutionists seem pretty happy and confident that they know where life came from). The more confident they are in their knowledge, the more they think they can figure out an answer for everything. The more they think they can figure out all the answers, the less room there is for God, the supernatural, and conservative thought.
Another reason that Academia is more evolutionist is that the majority tends to rule (whether it's right or not). Evo is believed by the majority of academics, so it rules regardless of its validity.