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2017-08-30 15:11:20   •   ID: 1647

Obsidian tools of Pastoral Neolithic groups from the Lake Naivasha basin (Kenya)

Figure 1
Saharan herders and hunters spread southward to the Sahel, reaching eastern Africa by 4.5 k.a. cal BP. The earliest pastoralists entered southern Kenya through the Great Rift Valley by 3,2 k.a. cal BP, having migrated southward from the Lake Turkana region where they had arrived ca 4 k.a. cal BP. 

In southern Africa they arrived with sheep and cattle around 2 k.a. cal BP. Exploratory lithic analysis in southern Kenya has identified numerous stylistic attributes that differentiate two distinct Pastoral Neolithic groups from one another, and from the hunter-gatherers who occupied the region during a time period of roughly 2000 years, approximately between 3,2 and 1,2 k.a. cal BP. 

These early migrants relied on herds that include African cattle, goats, sheep introduced through the Nile corridor, and donkeys. There is no evidence of plant cultivation or agriculture being practiced in southern Kenya during the Pastoral Neolithic.

These entities co-occupied a large territory for almost 2 k.a and yet maintained rigid differences in material culture, ceramic styles and burial practices.

Geo-chemical  sourcing analyses have substantiated these differences, showing that the “Elmenteitan” and “Savanna Pastoral Neolithic” (SPN) groups obtained obsidian for tool production from two discrete sources in the Great Rift Valley.

Figure 2
For both SPN and Elmenteitan producing groups, Obsidian was the dominant source of lithic raw material for tool production, although there was occasional use of other raw materials.

SPN groups were linked together through their reliance on a small cluster of grey obsidian sources in the Lake Naivasha (Picture 2; Wikimedia commons) basin while Elmenteitan sites are sourced to a discrete outcrop of green obsidian on the northeast slope of Mt. Eburru, only 10 km north of the SPN source.

These sources do not appear to have been exploited by foraging groups before and the patterns of SPN and Elmenteitan source preference are maintained within a 250 km radius from the Rift Valley sources.

In addition qualitative differences in lithic typology and technology exist, and help distinguishing between Elmenteitan and SPN assemblages. Elmenteitan blades are longer and less curved than those of the SPN, and are more likely to be notched /strangled and retain evidence of intensive use. In addition, there is a preference for single-ended concave endscrapers on blades in the Elmenteitan, in contrast to the more common appearance of double-ended scrapers from SPN sites in southwestern Kenya.

Goldstein showed by analyzing reduction pattern and intensity of obsidian scrapers that there are clearly indications "that communities across a large landscape had regular and consistent access to obsidians from distant sources". Cooperation and long distance networks seem to be one pattern of technological organization between different groups in this region.