Research group at boston university has just published a study which looked at players who had started playing tackle football before the age of 12. The average american male life expectancy is 75 years. If we start that study now, we'll have definitive proof somewhere around the turn of the next century. You call people up at the height of their grief and ask them for brain tissue before the body of their loved one is buried or cremated. It's what chris nuinsky of the concussion foundation does.