Early Acheulian & Developed OldowanB / m)peninj12
Biface/Handaxe. Peninj, West Natron, Tanzania (c. 1.3-1.5 MYA). This Early Acheulian biface ('handaxe') and the one that follows next take us to the third level of Early Acheulian biface gestalt complexity. It appears to have a 'three-tiered', 8-faceted set of thematic shapes. It actually is quite remarkable set of iterations. Each tier has its sides marked by a mirror symmetry of concave shapes (the lower tier might be read as two convex shapes, or the right concavity accidentally convex). At the top it has a rectilinear natural break in symmetrical opposition to a pointed natural break at the bottom.
Illustration © T. Wynn. T. Wynn. (1989). The Evolution of Spatial Competence. Urbana, IL: University of Illinois Press: fig. 12. (yellow highlight added)