Unexpected level of stupidity

[Bunburryist]

Mesopotamia is very, VERY flat.  And a flood of only moderate proportions can cover a great deal of land.  I have this image of a guy, his wife, and a kid or two, along with goat, a few chickens, and maybe a dog or two floating around on the remains of a house in a flood.  Stories tend to grow in time.  So after a while he had a brother-in-law and a couple of cousins, 3 goats, 16 chickens, and maybe a cat or two with the dogs.  When one considers that in a generally illiterate society where the average life-span was about 30 years, stories can evolve, very, VERY fast.  We don't appreciate the extent to which writing tends to freeze historical accounts.  Without writing, stories - like language itself (which can change rather quickly in small, illiterate societies) - can morph from guy on a raft with a few animals to an ark in not too many generations.  Throw in a god and people looking for a reason for something they don't understand (why floods happen) and you're off and running.