[btbuildem]

Are you referring to the Paleolithic? These "societies" (nomadic bands, really) generally operated on principles of reciprocity and gift economies.

Debt in that context was more of a social obligation - but served a similar purpose as what we understand debt to be today: to compel someone to do something. It engendered bonds of trust and interdependence, helping ensure the survival of the group. Food sharing was often obligatory: today's hunter who shares his catch with you becomes tomorrow's recipient when you make the kill.

You're right to note that the agricultural revolution was special -- in that the accumulation of surplus allowed people to store it, and lend it out. This lead to wealth being quantified and introduced the concept of interest.

"Capitalism" - as characterized by the drive to continuously reinvest in order to generate more wealth - doesn't come into play for another ten thousand years. The different prerequisites (wage labour, financial systems, property relations) arrive at different times - but we could say, ballpark, around the 16th century, with the advent of the chartered companies (eg, East India)?