A case of Developed Oldowan in the Acheulean?

At Olduvai Gorge, contemporary tool assemblages from Middle and Upper Bed II have been assigned to two categories, Developed Oldowan B and Acheulean. Stiles has argued that both of these are variants of the Acheulean, whereas Mary Leakey sees them as two separate traditions. The Acheulean site complex at Kilombe in Kenya combines elements resembling both the Acheulean and Developed Oldowan B, suggesting strongly that at this site the two belong to the same cultural tradition, but also confirming the reality of the two sets of material. Since at Kilombe the two elements are not distinguished by raw materials, their presence must relate to size/shape choices made by the human mind, probably under the influence of different functional needs.