Between the ninth and third millennia B.C. wetter conditions prevailed over most of Africa. Lakes and rivers were fuller and some of the internal basins were temporarily linked, especially in the ‘Middle African’ belt. This comprises the southern Sahara and Sahel, stretching from the Upper Niger to the Middle Nile, with a south-easterly extension into the Upper Nile basin and the East African rift valleys. This situation was exploited by people who developed a decidedly aquatic economy and culture. From their waterside camps and settlements archaeologists have recovered bones of fish and aquatic animals which these people ate, as well as the distinctive harpoon-heads carved from bone with which they obtained them, and also pottery, bearing peculiar decoration executed with fish-bones and water-shells, made in imitation of (fishing-) baskets. Boating and other cultural developments are deducible. The harpoons date back to 7,000 b.c. at least; the pottery dates back to more than 6,000 b.c. and was clearly an African invention. It reflects important developments in gastronomy and home life.
In the Kenya rift valley the main stage of Leakey's ‘Kenya Capsian’ culture is essentially the local manifestation of this far-flung ‘aquatic civilization’.
Its greatest extent was achieved during the wettest times of the seventh millennium b.c., and probably involved the expansion of Negroid peoples across this continent-wide savanna belt. Also explained perhaps is the extensive, though now fragmented, distribution of languages which Greenberg combines in his ‘Nilo-Saharan’ super-family. It is suspected that aspects of this ancient aquatic way of life may be maintained or reflected by latter-day isolated or ‘unclean’ lake or swamp communities. This subject has been largely neglected by African culture-historians.
Drier conditions in the late sixth and fifth millennia b.c. signalled a decline of this aquatic civilization and, in particular, broke its geographical continuity. Nevertheless, there was a qualified revival in many parts in the fourth and third millennia. In the Kenya rift this later phase seems to equate with the first stage of the ‘stone bowl cultures’. Around Lake Victoria a devolved relic survived until the eve of Bantu expansion about two thousand years ago. Other late or modified examples are known on the Nile and in the western Sudan. Generally, however, the viability and prestige of an aquatic way of life were undermined by the second millennium b.c. In the Sahara and Sahel as well as in the northerly parts of eastern Africa this decline was paralleled by the spread of pastoralism as a new basis of subsistence and prestige. Those who introduced cattle to Kenya from Ethiopia were Cushitic-speakers maintaining, significantly, a fish-taboo.
This subject should prove of considerable historiographical interest. The aquatic way of life flourished through Middle Africa at the very time when grain-agriculture and stock-raising were being pioneered in the Near East; and the slow spread of agriculture in Africa, sometimes considered an indication of ‘backwardness’, may be partly explicable by the very success of the aquatic life and of its distinct cultural tradition which was ascendant for a while across the widest part of the continent.