I did say it'd be funny, not good.
RE max: just as human brains start life half formed and silly, they end life that way too. It is well established that we suffer cognitive decline after a lifetime of various insults to the brain and general aging. Nobody is ever as sharp as they were in the mid twenties. We try and make up for this with wisdom but we all go to the grave early or a shell of ourselves.
The cognitive arguments around a minimum extend to a maximum. Realistically you can't, but you can't have a well defined minimum either. I think it would be cool to let anyone interested vote, provided they can pass some general knowledge stuff first if they're say under 16 or 14 or something to demonstrate they're cognizent of what they're doing.