Climate During the Late Holocene in the Sahara and the Sahel: Evolution and Consequences on Human Settlement

Conclusion

The onset of desert conditions in the Sahara began earlier in the north than in the south, where more favorable levels of precipitation led to the maintenance for a long time of northern Sahelian conditions. In order to understand the evolution of Neolithic and post-Neolithic cultures, however, we need to gain a more precise knowledge of the geography and chronology of events.

In a context where water becomes a scarce resource, human groups have long attempted to postpone the inevitable, inventing new stock breeding techniques, developing new ways of using water (wells, hydro-agricultural innovations), metallurgy, or agriculture in the southern Sahara’s mountain valleys and around Sahelian rivers where rice, for instance, was cultivated in the valley of the Niger prior to 2000 bp (McIntosh, 1993).

People have adapted, as long as it was possible and desirable. Yet, population movements toward the south are evident from 4000 bp on, intensifying a millennium later as levels of aridity become more acute. Many human groups, having readied the limits of their capacities to adapt, or wishing no longer to adapt to the new conditions, began, in some cases quite early, to migrate toward the south.

Relations between these different episodes are not well established. Many different groups may have joined in the process. What is certain, however, is that each arid phase has drawn herders and farmers of that time to seek refuge in the northern Sahel—between 20° and 18°N.