One thing that is clear in the “Us” is that where high concentrations of easily accessible protein was available along coastlines in the form of fish and crab etc., humans grew larger brains.

This was well before cultivation of sugars around river beds in Mesopotamia, and domesticating of animals for readily stored food led to high art. And things like money, and hierarchy, servitude, and in the record of shovel discovery, tooth decay and communal disease.