My patients often ask me why we have wisdom teeth since they usually need to be removed. The answer is, they are vestigial organs — things that we still have from our ancestors that we no longer need or use.  As we evolved, our jaws have shortened and therefore most of us no longer have the room for these teeth.  Some of us — the lucky ones — don’t even develop wisdom teeth any more.

This article is an interesting one about wisdom teeth and other vestigial organs:

Useless Human Traits That Once Had a Purpose