"'Dates back to Ancient Egypt'. Evidence, please?"
The Ancient Egyptian tale of two tomb robbers eating stolen figs in a tomb they were raiding and deciding which of them should stand and keep watch by who spoke first is indexed and motifed in the Stith Thomson index and is referred to in a number of collections

Humour relies on surprise.
Not necessarily - 'funny' usually is
Humour, in my opinion, is based on observing absurdity - Billy Connolly is humourous in his observation of human frailty, based on observation
Jim Carroll