Once there was a dog and a man.
The dog chased and the human ran.
The dog got leaner, the man fitter.
But sometimes got bit, and being bit got bitter.

Chased, one day, a bone in hand.
The man devised a clever plan.
Raising the club, he flung it aside.
The dog caught its meal in mid-stride.

From that day on man carried meat.
To offer dog a tasty treat.
Dog, it seems, had trained its master.
No more racing to get faster.

Thirty thousand years then past.
Pavlov trained at dog at last.
Humans are slow, but can learn.
As the world, in due time, turns.