Well, diagnosing a civilization is a little like diagnosing an illness. If you have four or more of the following symptoms, you might be a civilization. Surplus production. Once one person can make enough food to feed several people, it becomes possible to build a city, another symptom of civilization. It also leads to the specialization of labor, which in turn leads to trade. Like, if everybody picks berries for a living, there is no reason to trade, because I have berries and you have berries. But if I pick berries for a living and you make hammers, suddenly we have cause to trade.