Abstract
By the mid-first millenniuma.d., Middle Niger cities took the form of many separate mounds clustered together. Many of these mounds may have been settlements of specialists. This distinctive city form may have had its origin in segmented, but articulated, Late Stone Age communities in the southern Sahara. The Pulse Model is an attempt to reconstruct the circumstances of environmental change and interactions among these communities that encouraged occupational specialization. The model predicts the best locations to search for evidence of early specialization, namely the several north–south trending palaeochannels of the southern Sahara. There, groups increasingly concerned with intensification of production within separate microenvironments would nevertheless have been in close contact. Climate shifts over the past several millennia create a ‘pulse’ of population movements, or shifts of ecological adaptations, along these long corridors. However, adaptation to climate change and stress incompletely explains the emergence of specialization. Tradition, myths, legends and material reinforcements of divisions between present-day ethnic and artisan groups in the Middle Niger suggest the ways in which corporate identity may have been constructed and maintained in the very distant past. If corporate identity can emerge in a form that discourages conflict between groups, the result might be increasingly specialized responses to climate change and to the economic and social opportunities of early urbanism. There should be no sharp discontinuity between the emerging specialization of the last millenniab.c.and the earlier clustered urbanism of cities such as Jenne-jeno. Middle Niger urbanism is an intensification of prehistoric social dynamics, not a revolutionary process.