The wisdom tooth example cannot possibly be taken seriously as a beneficial mutation, or even a neutral mutation since it has a definite effect in eliminating wisdom teeth. It gets all philosophically confused to try to figure out how the absence of such teeth MIGHT conceivably confer a benefit. It seems to me that if it involves the destruction of a gene, that ought to be the defining factor, and I can't see such destruction as a positive in any sense whatever.
I don't have any scientific explanation for this, but, in my case, the elimination of wisdom teeth would have been a VERY good thing. I had some problems with jaw alignment as an adolescent, even though I had "perfect" teeth. When my wisdom teeth began coming in at 18 I had a serious problem. Before they came in I had issues with my jaw locking and when they started coming in my orthodontist called for immediate extraction through oral surgery (meaning they went in and cut them out from my gums before they could surface). They did this because I had TMJ and the entrance of my wisdom teeth would negate the braces I had had before this (to correct the TMJ) and cause my jaws to lock up. In an evolutionary context (and without modern medicine), I might have had a couple of kids before this happened and consequently starved to death due to the fact that I could not eat (allegedly before 30), but my "fitness" would be less that of the woman who didn't have wisdom teeth or whose jaw was big enough to fit all the teeth without any complications. Without modern medicine, I would be dead in my 20's and my defective" gene may be passed on, but not as sucessfully as someone who has a gene that gets rid of wisdom teeth and has children until menopause sets in. (BTW my jaws still click and I cannot take large bites of food).
There is no "destruction" of a gene involved. Rather, a modified or changed gene which confers a benefit or a detriment or no affect at all depending on the circumstance or environment of the individual. There could have been a time when large, powerful back molars conferred an advantage to humans and their jaws compensated for it. Eliminating wisdom teeth does not mean that there is a net loss of "information" or whatever you describe it as. The "information" changes and if it is beneficial or neutral to the species or individual it stays. If is deleterious, it goes (not immediately). Period. If you are "philosophically confused" maybe you should learn a bit more before you decide what "MIGHT conceiably confer a benefit" as opposed to what you think cannot.
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