In AFL, it's concussion. Twice in two weeks, players have been suspended for tackles that led to the knock-out of opponents. No one has cogently suggested how either might have tackled differently for a guaranteed less drastic outcome. Nor has anyone shown how these tackles differed from dozens of others every weekend except for the chance of their unfortunate outcome.

As such, the suspensions are as much as anything a marketing exercise, meant to persuade us that we will eliminate concussions if only we stamp hard and often enough. We won't. The only remedy is to eliminate tackling.

That is not to deny that it is a live issue. As stronger players tackle more forcefully on harder grounds, it is not going to go away, except on a stretcher.

In the US, a study has found that all but one of 111 former NFL players showed signs of CTE, a nasty degenerative brain disease caused by repeated hits to the head. The physician who first blew the whistle on this plague nearly a decade ago is Bennet Omalu. Initially, the NFL laughed him out of his laboratory, but eventually was dragged round to the extent that it has paid out around $1.5 billion in compensation.

In an interview with England's Daily Telegraph this week, Omalu widened his alarm to include heading in soccer, saying it was leading to a comparable instance of CTE. Omalu says anyone who does not see cause-and-effect has rocks in their head. He cites a 2005 Purdue university study that found the impact of heading a goalkeeper's long clearance was similar to an American football collision or a boxer's punch.

This has long been a low-pitched ringing in soccer's ears. A 1998 study of professional soccer players in the Netherlands found greater than average brain impairment. Studies by two English universities this year back that up. In 2002, former England striker Jeff Astle died at 59 from what was found to be the legacy of years of headers.

Soccer authorities now are where the NFL was, hoping a Panadol will make the problem go away. The FA is "doing studies", FIFA says there is "no true evidence".

Footballs now are not the sodden, soggy things they were once. Then, they really were rocks on their heads. Still, Omalu advocates, among other measures, a ban on heading under the age of 18. He also names six sports that should not be played by under 18s: boxing, wrestling, ice hockey, mixed martial arts, American football and rugby. AFL either does not scare or register.

So, how far do we go to protect? No heading? No or milder tackling? These are very nearly existential questions. Players say they know the risks, but do they? In Friday's Age, Wayne Carey made clear in he did not, and is paying the price.

A poll of athletes once found alarmingly many who said they would take a performance-enhancing drug now, knowing it would kill them in 10 years, if it guaranteed Olympic gold. But would they? In a recent Good Weekend, author Frank Robson wrote that he thought he would happily smoke his way to an early grave - until he got almost to its lip.

There is no easy answer. The AFL can't guarantee against head injury, but it can recognise that it sits on a continuum. Somewhere to the left is the mean and niggly spirit in which many games are now played. No player can brush by another without some sort of push, shove or punch. Upon kicking a goal, it is practically de rigueur to bowl over your opponent.

Extraordinarily, this sandpit machismo is celebrated. In fact, we've reached a point where you can nakedly assault your man 80 metres from the ball and win plaudits, but if you don't return the ball in centimetre-perfect fashion, it's 50 metres, 50 more if you protest. A crackdown, a la jumper punches, is in order. Two early free kicks would do it. Soft? Only if you think off-the-ball attack by the unprovoked on the unaware is hard. It's not, and never was. And if you think it is intrinsic to the game's theatre, then you are admitting that alone it is not much of a game.

A nobler polity won't solve concussion. But it is not a bad place to begin if sports like AFL are to maintain their pre-eminence in a society less inclined than ever to countenance heads on platters as good sport.