Stages In the four divisions of prehistoric stone-working, Soft hammer percussion may have emerged around the same time in Africa. Unlike the earlier Mode 1 industries, it was the core that was prized over the flakes that came from it. Another advance was that the Mode 2 tools were worked symmetrically and on both sides indicating greater care in the production of the final tool. Mode 3 technology emerged towards the end of Acheulean dominance and involved the
Levallois technique, most famously exploited by the
Mousterian industry. Transitional tool forms between the two are called Mousterian of Acheulean Tradition, or MTA types. The long
blades of the
Upper Palaeolithic Mode 4 industries appeared long after the Acheulean was abandoned. As the period of Acheulean tool use is so vast, efforts have been made to classify various stages of it such as
John Wymer's division into Early Acheulean, Middle Acheulean, Late Middle Acheulean and Late Acheulean
Manufacture The primary innovation associated with Acheulean
hand-axes is that the stone was worked symmetrically and on both sides. For the latter reason, handaxes are, along with
cleavers,
bifacially worked tools that could be manufactured from the large flakes themselves or from prepared cores. Tool types found in Acheulean
assemblages include pointed, cordate, ovate,
ficron, and
bout-coupé hand-axes (referring to the shapes of the final tool), cleavers, retouched flakes,
scrapers, and segmental chopping tools. Materials used were determined by available local stone types;
flint is most often associated with the tools but its use is concentrated in Western Europe; in Africa
sedimentary and
igneous rock such as
mudstone and
basalt were most widely used, for example. Other source materials include
chalcedony,
quartzite,
andesite,
sandstone,
chert, and
shale. Even relatively soft rock such as
limestone could be exploited. Stone
knapping with limited digital
dexterity makes the
center of mass the required direction of flake removal. Physics then dictates a circular or oval end pattern, similar to the handaxe, for a leftover core after flake production. This would explain the abundance, wide distribution, proximity to source, consistent shape, and lack of actual use, of these artifacts. Mimi Lam, a researcher from the
University of British Columbia, has suggested that Acheulean hand-axes became "the first commodity: A marketable good or service that has value and is used as an item for exchange."
Distribution {{Location map+|Afro-Eurasia|float=center|caption=Map of
Afro-Eurasia showing important sites of the Acheulean industry (clickable map).|places= from
Saint Acheul The geographic distribution of Acheulean tools – and thus the peoples who made them – is often interpreted as being the result of
palaeo-climatic and
ecological factors, such as
glaciation and the
desertification of the
Sahara Desert. Until the 1980s, it was thought that the humans who arrived in East Asia abandoned the hand-axe technology of their ancestors and adopted
chopper tools instead. An apparent division between Acheulean and non-Acheulean tool industries was identified by
Hallam L. Movius, who drew the
Movius Line across northern India to show where the traditions seemed to diverge. Later finds of Acheulean tools at Chongokni in
South Korea and also in
Mongolia and
China, however, cast doubt on the reliability of Movius's distinction. Since then, a different division known as the Roe Line has been suggested. This runs across
North Africa to
Israel and thence to India, separating two different techniques used by Acheulean toolmakers. North and east of the Roe Line, Acheulean hand-axes were made directly from large stone nodules and cores; while, to the south and west, they were made from flakes struck from these nodules. ==Acheulean tool users==