You are dealing with a specifically and carefully selected subset of the population here, one whose utility as test subject is highly questionable. Once you factor in all the various things that might be affecting things with pro football players, this population is about useless for teasing any really useful data out of.

Good grief, the prevalence of steroid use alone… The diets? The training regimens? All of the other things that go along with pulling these guys out of the general population and concentrating them in one field? Yeah. Too many wild-ass variables here to really tell you anything.

It’s the same stuff that goes on with domestication–You select for certain traits, and there are obvious physical things that come along with those traits, even across species. Domestic dogs and domesticated foxes, for example? Similar coat patterns, and so forth.

That would seem to be Parkinson’s, Alzheimer’s, and heavy drug use…