The Middle Stone Age of the northern Kenyan Rift: age and context of new archaeological sites from the Kapedo Tuffs.

Rift Valley sites in southern Ethiopia and northern Kenya preserve the oldest fossil remains attributed to Homo sapiens and the earliest archaeological sites attributed to the Middle Stone Age (MSA). New localities from the Kapedo Tuffs augment the sparse sample of MSA sites from the northern Kenya Rift. Tephrostratigraphic correlation with dated pyroclastic deposits from the adjacent volcano Silali suggests an age range of 135-123ka for archaeological sites of the Kapedo Tuffs. Comparisons of the Kapedo Tuffs archaeological assemblages with those from the adjacent Turkana and Baringo basins show broad lithic technological similarity but reveal that stone raw material availability is a key factor in explaining typologically defined archaeological variability within this region. Spatially and temporally resolved comparisons such as this provide the best means to link the biological and behavioral variation manifest in the record of early Homo sapiens.