Changing gradients of climate change in Southern Africa during the past millennium: Implications for population movements

Climates of equatorial East Africa and subtropical Southern Africa have var ied inversely over long periods of time. The high-resolution delta O-18 sta lagmite record from Cold Air Cave in the Makapansgat valley in South Africa and a similar resolution lake-level record for Lake Naivasha in Kenya have been in anti-phase for much of the last thousand years. A similar relation ship is evident in the twentieth century meteorological record. The changes in rainfall in the two regions on multi-decadal to centennial scales have influenced both settlement patterns and livelihoods of Iron Age agricultura lists. The resulting latitudinal gradient of change may have been a signifi cant factor in promoting southward migration of Sotho-Tswana speaking peopl e from equatorial East Africa during the first few centuries of the last mi llennium and earlier. This would have occurred at times when environments i n the north were deteriorating and those to the south were ameliorating.