In the old days -- the really old days -- tribes had puffy head minders. That's how baptism was invented, according to the possum member of Pundita's foreign policy team.
The minder would be sitting around shooting the breeze, then suddenly grab a stick and run off to whack somebody with it. People never knew why, of course, but eventually they decided that they must have been thinking about getting ready to show off.
Showing off, in the old days, was really dangerous. Tribes with too many know-it-alls tended to get raided by saber-toothed tigers and all manner of poisonous snakes.
But still, people didn't want to get whacked. So they'd run and jump in a lake or river when they saw the minder running up. They'd stay underwater as long as they could then come up shouting, "Thank you minder, for saving me from a puffy head!"
Worked every time. The minder would go back to sitting at the campfire and shooting the breeze.