The archaeology of the Middle Pleistocene deposits of Lake Eyasi, Tanzania

Ongoing archaeological research at North Lake Eyasi has produced a wealth of information, including a new hominid fossil and several archaeological sites dating to the end of the Middle Pleistocene. One of the sites (WB9) has been excavated and has produced evidence of multiple processes in its formation, including evidence of functional associations of stone tools and faunal remains which are scarce for this time period. The stone tool industry is based on a core and flake industry, which is not very diagnostic and attributed to MSA. Earlier heavy-duty tools classified as Sangoan may derive from the underlying Eyasi Beds. The stratigraphic provenience of previous fossil hominids is unknown. Surface collections from the Eyasi lake, thus, comprise two different sets of stone tools and fossils, which can only be clearly differentiated in the field. This advises against the use of previously curated collections as a homogeneous sample. Earlier definitions of the Njarasa industry should be revised. This work presents results on the paleoecology of the area and of its paleontological and archaeological information, with special reference to the excavation of WB9, the most complete site discovered in the area so far. This contributes to the limited information available about site functionality and hominid subsistential behaviour in East Africa during the end of the Middle Pleistocene. A technological study from WB9 also shows the variability of stone tool traditions at this time.