It was the dominant technology for the vast majority of human history and more than one million years ago it was Acheulean tool users who left Africa to first successfully colonize Eurasia. Their distinctive oval and pear-shaped handaxes have been found over a wide area and some examples attained a very high level of sophistication suggesting that the roots of human art, economy and social organisation arose as a result of their development. Although it developed in Africa, the industry is named after the type site of Saint Acheul, now a suburb of Amiens in northern France, where some of the first examples were identified in the nineteenth century.
Later, Jacques Boucher de Crèvecœur de Perthes, working between 1836 and 1846, collected further examples of hand-axes and fossilised animal bone from the gravel river terraces of the Somme near Abbeville in northern France. Again, his theories attributing great antiquity to the finds were spurned by his colleagues until one of de Perthe's main opponents, Dr Jean Paul Rigollot, began finding more tools near Saint Acheul. Following visits to both Abbeville and Saint Acheul by the geologist Joseph Prestwich, the age of the tools was finally accepted.
Louis Laurent Gabriel de Mortillet described the characteristic hand-axe tools as belonging to L'Epoque de St Acheul in 1872. The industry was renamed as the Acheulean in 1925.
Providing calendrical dates and ordered chronological sequences in the study of early stone tool manufacture is difficult and contentious. Radiometric dating, often potassium-argon dating, of deposits containing Acheulean material is able to broadly place the use of Acheulean techniques within the time from around 1.65 million years ago to about 100,000 years ago. The earliest accepted examples of the type, at 1.65 m years old, come from the West Turkana region of Kenya although some have argued for its emergence from as early as 1.8 million years ago.
In individual regions, this dating can be considerably refined; in Europe for example, Acheulean methods did not reach the continent until around one million years ago and in smaller study areas, the date ranges can be much shorter. Numerical dates can be misleading however, and it is common to associate examples of this early human tool industry with one or more glacial or interglacial periods or with a particular early species of human. The earliest user of Acheulean tools was Homo ergaster who first appeared almost 2 million years ago. Not all researchers use this formal name however and instead prefer to call these users early Homo erectus. Later forms of early humans also used Acheulean techniques and are described below.
Relative dating techniques (based on a presumption that technology progresses over time) suggest that Acheulean tools followed on from earlier, cruder tool-making methods, however there is considerable chronological overlap in early prehistoric stone-working industries and there is evidence in some regions that Acheulean tool-using groups were contemporary with other, less sophisticated industries such as the Clactonian and then later, with the more sophisticated Mousterian too. It is therefore important not to see the Acheulean as a neatly defined period or one that happened as part of a clear sequence but as one tool-making technique that flourished especially well in early prehistory. The enormous geographic spread of Acheulean techniques also makes the name unwieldy as it represents numerous regional variations on a similar theme. The term Acheulean does not represent a common culture in the modern sense, rather it is a basic method for making stone tools that was shared across much of the Old World.
The very earliest Acheulean assemblages often contain numerous Oldowan-style flakes and core forms and it is almost certain that the Acheulean developed from this older industry. There have been no excavated examples of transitional tool forms however.
The Mode 1 industries created rough flake tools by hitting a suitable stone with a hammerstone. The resulting flake that broke off would have a natural sharp edge for cutting and could afterwards be sharpened further by striking another smaller flake from the edge if necessary (known as retouch). These early toolmakers may also have worked the stone they took the flake from (known as a core) to create chopper cores although there is some debate over whether these items were tools or just discarded cores.
The Mode 2 Acheulean toolmakers also used the Mode 1 flake tool method but supplemented it by using bone, antler, or wood to shape stone tools. This type of hammer, compared to stone, yields more control over the shape of the finished tool. 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 for material from Britain. These schemes are normally regional and their dating and interpretations vary.
In Africa, there is a distinct difference in the tools made before and after 600,000 years ago with the older group being thicker and less symmetric and the younger being more extensively trimmed. This may be connected with the appearance of Homo heidelbergensis in the archaeological record at this time who may have contributed this more sophisticated approach.
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. In all cases the toolmakers worked their handaxes close to the source of their raw materials suggesting that the Acheulean was a set of skills passed between individual groups.
Some smaller tools were made from large flakes that had been struck from stone cores. These flake tools and the distinctive waste flakes produced in Acheulean tool manufacture suggest a more considered technique, one that required the toolmaker to think one or two steps ahead during work that necessitated a clear sequence of steps to create perhaps several tools in one sitting.
A hard hammerstone would first be used to rough out the shape of the tool from the stone by removing large flakes. These large flakes might be re-used to create tools. The tool maker would work around the circumference of the remaining stone core, removing smaller flakes alternately from each face. The scar created by the removal of the preceding flake would provide a striking platform for the removal of the next. Misjudged blows or flaws in the material used could cause problems, but a skilled toolmaker could overcome them.
Once the roughout shape was created, a further phase of flaking was undertaken to make the tool thinner. The thinning flakes were removed using a softer hammer, such as bone or antler. The softer hammer required more careful preparation of the striking platform and this would be abraded using a coarse stone to ensure the hammer did not slide off when struck.
Final shaping was then applied to the usable cutting edge of the tool, again using fine removal of flakes. Some Acheulean tools were sharpened instead by the removal of a tranchet flake. This was struck from the lateral edge of the hand-axe close to the intended cutting area, resulting in the removal of a flake running across the blade of the axe to create a neat and very sharp working edge. This distinctive tranchet flake can been identified amongst flint-knapping debris at Acheulean sites.
Use-wear analysis on Acheulean tools suggests there was generally no specialization in the different types created and that they were multi-use implements. Functions included hacking wood from a tree, cutting animal carcasses as well as scraping and cutting hides when necessary. Some tools may have been better suited to digging roots or butchering animals than others however.
Alternative theories include a use for ovate hand-axes as a kind of hunting discus to be hurled at prey. Puzzlingly, there are also examples of sites where hundreds of hand-axes, many impractically large and also apparently unused, have been found in close association together. Sites such as Melka Kunturé in Ethiopia, Olorgesailie in Kenya, Isimila in Tanzania and Kalambo Falls in Zambia have produced evidence that suggests Acheulean hand-axes may not always have had a functional purpose.
Recently, it has been suggested that the Acheulean tool users adopted the handaxe as a social artefact, meaning that it embodied something beyond its function of a butchery or wood cutting tool. Knowing how to create and use these tools would have been a valuable skill and the more elaborate ones suggest that they played a role in their owners' identity and their interactions with others. This would help explain the apparent over-sophistication of some examples which may represent a "historically accrued social significance".
One theory goes further and suggests that some special hand-axes were made and displayed by males in search of mate, using a large, well-made hand-axe to demonstrate that they possessed sufficient strength and skill to pass on to their offspring. Once they had attracted a female at a group gathering, it is suggested that they would discard their axes, perhaps explaining why so many are found together.
Until the 1980s it was thought that the humans that arrived in East Asia abandoned the hand-axe technology of their ancestors and adopted chopper tools instead. An apparent division between the 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' distinction. Since then, a different division known as the Roe Line has been suggested. This runs across North Africa to Israel and then to India and separates 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 whilst to the south and west they were made from flakes stuck from these nodules.
The symmetry of the hand-axes has been used to suggest that Acheulean tool users possessed the ability to use language; the parts of the brain connected with fine control and movement are located in the same region that controls speech. The wider variety of tool types compared to earlier industries and their aesthetically and well as functionally pleasing form could indicate a higher intellectual level in Acheulean tool users than in earlier hominines. Others argue that there is no correlation between spatial abilities in tool making and linguistic behaviour and that language is not learnt or conceived in the same manner as artefact manufacture.
Lower Palaeolithic finds made in association with Acheulean hand-axes such as the Venus of Berekhat Ram have been used to argue for artistic expression amongst the tool users. The incised elephant tibia from Bilzingsleben in Germany and ochre finds from Kapthurin in Kenya and Duinefontein in South Africa are sometimes cited as being some of the earliest examples of an aesthetic sensibility in human history. There are numerous other explanations put forward for the creation of these artefacts however and there is no unequivocal evidence of human art until around 50,000 years ago, following the emergence of modern Homo sapiens.
The kill site at Boxgrove in England is another famous Acheulean site. Up until the 1970s these kill sites, often at waterholes where animals would gather to drink, were interpreted as being where Acheulean tool users killed game, butchered their carcasses and then discarded the tools they had used. Since the advent of zooarchaeology, which has placed greater emphasis on studying animal bones from archaeological sites, this view has now changed. Many of the animals at these kill sites have since been found to have been killed by other predators and it is likely that people of the period supplemented hunting with scavenging from already dead animals.
Only limited artefactual evidence survives of the users of Acheulean tools save the stone tools themselves. Cave sites were exploited for habitation but the hunter-gatherers of the Palaeolithic also possibly built shelters such as those identified in connection with Acheulean tools at Grotte du Lazaret and Terra Amata near Nice in France. The presence of the shelters is inferred from large rocks at the sites which may have been used to weigh down the bottoms of tent-like structures or serve as foundations for huts or windbreaks. These stones may have been naturally deposited, but in any case, a flimsy wood or animal skin structure would leave few archaeological traces after so long. Fire was seemingly being exploited by homo ergaster and it would have been a necessity in colonising colder Eurasia from Africa. Conclusive evidence of mastery over it this early is difficult to find however.