You're right. I was posting from a position of considerable ignorance about what low IQs might mean in practice.
What would you expect to see from a civilization with an average IQ of 70?
Farming, simple irrigation systems, pottery and other crafts (with objects of great beauty made for the upper class), walled cities, some siege engines, long distance trade, domestication of animals, iron working, sailing, class divisions, chariots and writing.
This they could all eventually develop with no input from the outside in favourable climactic conditions.
Exposed to outside influence I think they can pick up things like clockwork, ocean worthy ships, machine tools, the internal combustion engine, radio and television (and improve it on their ow...
Please remember to have no heroes or villains, but this just looks plain bad to be honest. I'm lowering my estimation of the quality of Stephen J. Gould's work in this area.
USA today:
Haha. Humans.
The paper itself: