Fig 1.
Early Bantu sites in Eastern and Southeastern Africa.
The three great lakes are, from North to South, Victoria, Tanganika and Nyasa (the latter is also called Malawi). Symbols are colored according to their calibrated dates. Diamonds indicate the five sites used as possible origins of the spread. The five diamonds are, from Northeast to West and then South, Katuruka in Tanzania, Mucucu II in Rwanda, Kabacusi in Rwanda, Mubuga V in Burundi, and Kalambo Falls at the southern edge of lake Tanganika. The green color (upper left) denotes rainforest areas.
Table 1.
Absolute correlation coefficients obtained for five possible origins of the spread and different datasets.
Values close to 0.8 or higher are shown in bold. The parentheses around the Eastern data results from Kalambo falls indicate that this site would not in principle correspond to the Eastern spread, due to its location to the South of the area West of lake Victoria (Fig 1).
Fig 2.
Linear regression of the earliest Bantu data in eastern and southeastern Africa assuming an origin of the spread at Mubuga V.
(a) Sites corresponding to a southwards spread from west of Lake Victoria. (b) Sites corresponding to an eastwards spread from west of Lake Victoria.
Fig 3.
Estimation of the percentage of cultural effect in the southern spread of eastern Bantu.
(a) Comparison of the range of the observed speed (hatched rectangle) and that predicted from a demic-cultural model, Eq (1) (area between the dotted and dashed curves). From the consistency region (black area), it follows that C≥0.65. (b) Cultural effect predicted by Eq (2) for the maximum and minimum theoretical speeds in panel (a) (dotted and dashed lines). From the range of C obtained in (a), i.e. C≥0.65, using Fig (b) we reach the conclusion that the cultural effect was in the range 19–47%.
Fig 4.
Estimation of the percentage of cultural effect in the eastwards spread of eastern Bantu.
(a) Comparison of the range of observed speeds (hatched rectangle) and that predicted from a demic-cultural model, Eq (1) (area between the dotted and dashed curves). From the consistency region (black area), it follows that C≤1.1. (b) Cultural effect predicted by Eq (2) for the maximum and minimum theoretical speeds in panel (a) (dotted and dashed lines). From the range of C obtained in (a), i.e. C≤1.1, using panel we reach the conclusion that the cultural effect was in the range 0–28%.