The emergence of large flake-based Acheulian technology: perspective from the highland site-complex of Melka Wakena, Ethiopia

Isaac GL (1969) proposed that Large Cutting Tools (LCTs) made on large flake blanks detached from giant/boulder cores are the key technological variable that distinguishes the Acheulian from the Oldowan. The production of large flake blanks was initially observed in the earliest records of the Acheulian technology in Africa ca. 1.75 Ma, subsequently becoming a technological feature of many sites across eastern Africa. Still, the mode and tempo of evolution of the large flake-based Acheulian technology remains poorly understood. Here we report on the large flake-based Acheulian assemblage at locality MW5 in the Melka Wakena site-complex, chronologically constrained between 1.37 and 1.34 Ma. At the site-complex level we note that aspects related to small flake production remain relatively unchanged since ~ 1.6 Ma. Secondary modification of small flakes by retouch remained marginal and there is only a slight increase in the frequency of structured reduction of cores, compared to the earlier 1.6 Ma assemblage. In contrast, the MW5 lithic assemblages inform of the diachronic shift of lithic techno-economy into a large flake-based LCTs technology. This shift is characterized by: (1) A highly selective use of a specific raw material (glassy ignimbrite) for the production of large flake blanks; (2) transport of prepared large flake blanks from relatively distant sources into the sites as part of a spatially and temporally fragmented reduction sequence; (3) improved know-how of large flake production, (4) the introduction of the Kombewa technology; (5) a unified technological concept for the production of handaxes and cleavers, diverging only in the specific decisions determining their final shape parameters. Taken together, these trends indicate changes in techno-economic strategies related to LCT production, including higher levels of pre-planning in the raw material acquisition stage and higher investment in controlling the morphometric properties of the artifacts.