Four thousand years of plant exploitation in the Lake Chad Basin (Nigeria), part III: plant impressions in potsherds from the Final Stone Age Gajiganna Culture

摘要

Late Holocene climatic changes caused a large scale regression of the Lake Chad shoreline followed by an expansion of settlements into previously unexplored territories. Numerous Final Stone Age sites of the Gajiganna Culture (1,800 to 800 b.c.) in the Lake Chad Basin (northeast Nigeria) yielded plant impressions in potsherds. The ceramics of Phase I (1,800-1,400 b.c.) were mineral tempered, and plant impressions, mainly of Paniceae, were caused only by incidental inclusion. In contrast, a considerable number of the sherds from Phase II (1,500-800 b.c.) were intentionally tempered with chaff derived from domesticated pearl millet (Pennisetum glaucum), wild Paniceae and wild rice species (Oryza cf. barthii and O. cf. longistaminata). This plant spectrum suggests the exploitation of the wet wild areas, and also the cultivation of pearl millet on sandy soils. The evidence suggests that agricultural practices were established late and were introduced from elsewhere. During the time of seasonally occupied sites in Phase I, the subsistence strategy was based on herding, fishing, and gathering, while in Phase II there are signs of permanent settlements and agriculture. The evidence from the plant impressions indicates that in the Final Stone Age Gajiganna Culture around 1,000-800 b.c., pearl millet became well established while the gathering of wild millets and rice was still practised.