ABSTRACT
Environments in which populations live are subject to change as a result of many general forces: climate change (seasonal or even more random), draughts and flooding, fire, and activities of other populations. Small bands of hunter-gatherers are less likely in their cyclical movement through a territory to change the ecology; indeed, the movements of bands is intended to give resources a chance to recover after a short period of gathering and hunting at a particular campsite. Moreover, markets institutionalize gift giving, which, as Marcel Mauss recognized, makes an interaction moral because the gift symbolizes a relationship among individuals. The institutionalization of exchange in markets, however, took a comparatively long time to evolve. There were clearly exchanges of personal objects throughout human history, and as horticultural societies began to evolve (along with their herding and fishing variants), barter in exchanges of resources increased.
