The theory was that only the fear of war could motivate people to give up the simple life and form complex societies.
only people who have never lived "the simple life" could propound that theory.
The only basic is cooperation, whether for protection; agriculture; pooling of resources; fostering specialization, or any other reason in any specific case, can really be stated. Ascribing a universal reason is way to simplistic when dealing with those carnsarned human critters.
As to Caral...
Stacked rocks; smoked organic dope; and made love, not war: a Hippie's dream city.
Well, the Egyptians 'did' cocaine, cigarettes and hashish: The Cocaine Mummies