Introduction to Paleoanthropology/Acheulean Technology

Homo ergaster/erectus, the author of the Acheulean industry, enjoyed impressive longevity as a species and great geographic spread. We will review several cultural innovations and behavioral changes that might have contributed to the success of H. ergaster/erectus:
 * stone-knapping advances that resulted in Acheulean bifacial tools;
 * the beginnings of shelter construction;
 * the control and use of fire;
 * increased dependence on hunting.

The Acheulean industrial complex
(1.7 million - 200,000 years ago)

Stone tools
By the time Homo ergaster/erectus appeared, Oldowan choppers and flake tools had been in use for 800,000 years. For another 100,000 to 400,000 years, Oldowan tools continued to be the top-of-the-line implements for early Homo ergaster/erectus. Between 1.7 and 1.4 million years ago, Africa witnessed a significant advance in stone tool technology: the development of the Acheulean industry. The Acheulean tool kit included:
 * picks;
 * cleavers;
 * an assortment of Oldowan-type choppers and flakes, suggesting that the more primitive implements continued to serve important functions;
 * mainly characterized by bifacially flaked tools, called bifaces.

A biface reveals a cutting edge that has been flaked carefully on both sides to make it straighter and sharper than the primitive Oldowan chopper. The purpose of the two-sided, or bifacial, method was to change the shape of the core from essentially round to flattish, for only with a flat stone can one get a decent cutting edge.

One technological improvement that permitted the more controlled working required to shape an Acheulean handax was the gradual implementation, during the Acheulean period, of different kinds of hammers. In earlier times, the toolmaker knocked flakes from the core with another piece of stone. The hard shock of rock on rock tended to leave deep, irregular scars and wavy cutting edges.

But a wood or bone hammer, being softer, gave its user much greater control over flaking. Such implements left shallower, cleaner scars and produced sharper and straighter cutting edges.
 * With the Acheulean Industry, the use of stone (hard hammer) was pretty much restricted to the preliminary rough shaping of a handax, and all the fine work around the edges was done with wood and bone.

Acheulean handaxes and cleavers are generally interpreted as being implements for processing animal carcasses. Even though cleavers could have been used to chop and shape wood, their wear patterns are more suggestive of use on soft material, such as hides and meat. Acheulean tools represent an adaptation for habitual and systematic butchery, and especially the dismembering of large animal carcasses, as Homo ergaster/erectus experienced a strong dietary shift toward more meat consumption.

Acheulean tools originated in Africa between 1.7 and 1.4 million years ago. They were then produced continuously throughout Homo ergaster/erectus'  long African residency and beyond, finally disappearing about 200,000 years ago.

Generally, Acheulean tools from sites clearly older than 400,000 to 500,000 years ago are attributed to Homo ergaster/erectus, even in the absence of confirming fossils. At several important Late Acheulean sites, however, the toolmakers' species identity remains ambiguous because the sites lack hominid fossils and they date to a period when Homo erectus and archaic Homo sapiens (e.g., Homo heidelbergensis) overlapped in time.

Other raw materials
Stone artifacts dominate the Paleolithic record because of their durability, but early people surely used other raw materials, including bone and more perishable substances like wood, reeds, and skin.

A few sites, mainly European, have produced wooden artifacts, which date usually between roughly 600,000 and 300,000 years ago:
 * Ex. At the site of Schöningen, Germany, several wooden throwing spears, over 2 m long. They arguably present the oldest, most compelling case for early human hunting.

Diffusion of Technology
Wide variability in stone tools present with H. erectus. In Eastern Asia, H. erectus specimens are associated not with Acheulean tools, but instead with Oldowan tools, which were retained until 200,000 to 300,000 years ago.

This pattern was first pointed out by Hallam Movius in 1948. The line dividing the Old World into Acheulean and non-Acheulean regions became known as the Movius line. Handax cultures flourished to the west and south of the line, but in the east, only choppers and flake tools were found.

Why were there no Acheulean handax cultures in the Eastern provinces of Asia?
 * history of research;
 * other explanations:
 * quality of raw materials (fine-grained rocks rare)
 * different functional requirements (related to environment and food procurement)
 * "bamboo culture": bamboo tools used in place of stone implements to perform tasks;
 * Early dates in Java and Dmanisi explain situation
 * Acheulean developed in Africa from the preceding Oldowan Tradition only after 1.8 Myrs ago, but if people moved into eastern Asia at 1.8 million years ago or before, they would have arrived without Acheulean tools.

In sum, while the Acheulean tradition, with its handaxes and cleavers, was an important lithic advance by Homo ergaster over older technologies, it constituted only one of several adaptive patterns used by the species. Clever and behaviorally flexible, H. ergaster was capable of adjusting its material culture to local resources and functional requirements.

Subsistence patterns and diet
Early discoveries of Homo ergaster/erectus fossils in association with stone tools and animal bones lent themselves to the interpretation of hunting and gathering way of life. Nevertheless this interpretation is not accepted by all scholars and various models have been offered to make sense of the evidence.

First Scenario: Scavenging
Recently, several of the original studies describing Homo ergaster/erectus as a hunter-gatherer have come under intense criticism. Re-examination of the material at some of the sites convinced some scholars (L. Binford) that faunal assemblages were primarily the result of animal activity rather than hunting and gathering.

Animal bones showed cut marks from stone tools that overlay gnaw marks by carnivores, suggesting that Homo ergaster/erectus was not above scavenging parts of a carnivore kill.

According to these scholars, at most sites, the evidence for scavenging by hominids is much more convincing than is that for actual hunting.

Which scenario to choose?
The key point here is not that Homo ergaster/erectus were the first hominid hunters, but that they depended on meat for a much larger portion of their diet than had any previous hominid species.

Occasional hunting is seen among nonhuman primates and cannot be denied to australopithecines (see A. garhi). But apparently for Homo ergaster/erectus hunting took an unprecedented importance, and in doing so it must have played a major role in shaping both material culture and society.

Shelter and fire
For years, scientists have searched for evidence that Homo ergaster/erectus had gained additional control over its environment through the construction of shelters, and the control and use of fire. The evidence is sparse and difficult to interpret.

Shelter
Seemingly patterned arrangements or concentrations of large rocks at sites in Europe and Africa may mark the foundations of huts or windbreaks, but in each case the responsible agent could equally well be stream flow, or any other natural process.

Therefore there appears to be no convincing evidence that Homo ergaster/erectus regularly constructed huts, windbreaks, or any other sort of shelter during the bulk of its long period of existence. Shelter construction apparently developed late in the species' life span, if at all, and therefore cannot be used as an explanation of H. ergaster's capacity for geographic expansion.

Fire
Proving the evidence of fire by Homo ergaster/erectus is almost equally problematic. Some researchers have suggested that the oldest evidence for fire use comes from some Kenyan sites dated about 1.4 to 1.6 million years ago. Other scholars are not sure. The problem is that the baked earth found at these sites could have been produced as easily by natural fires as by fires started - or at least controlled - by H. ergaster/erectus.

Better evidence of fire use comes from sites that date near the end of Homo erectus'  existence as a species. Unfortunately, the identity of the responsible hominids (either Homo erectus or archaic Homo sapiens) is unclear.

The evidence at present suggests that fire was not a key to either the geographic spread or the longevity of these early humans.

Out-of-Africa 1: Behavioral aspects
Researchers proposed originally that it was not until the advent of handaxes and other symmetrically shaped, standardized stone tools that H. erectus could penetrate the northern latitudes. Exactly what, if anything, these implements could accomplish that the simple Oldowan flakes, choppers and scrapers that preceded them could not is unknown, although perhaps they conferred a better means of butchering.

But the Dmanisi finds of primitive hominids and Oldowan-like industries raise once again the question of what prompted our ancestors to leave their natal land.

Yet, there is one major problem with scenarios involving departure dates earlier than about 1.7-1.4 million years ago, and that is simply that they involve geographic spread before the cultural developments (Acheulean industry, meat eating, fire, shelter) that are supposed to have made it possible.

A shift toward meat eating might explain how humans managed to survive outside of Africa, but what prompted them to push into new territories remains unknown at this time.

Perhaps they were following herds of animal north. Or maybe it was as simple and familiar as a need to know what lay beyond that hill or river or tall savanna grass. Also an early migration could explain technological differences between western and eastern Homo erectus populations.

The link between butchering tools and moves into northern latitudes is the skinning and preparation of hides and furs, for reworking 1. into portable shelters, and 2. into clothing. more skilful skinning meant that skins would be better preserved, while fire would lead to meat preservation (smoking) by the simple need to hang cuts of butchered meat high up out of reach of any scavenging animals within smoke filled caves or other dwellings. Having smoked meat then allowed deeper incursions into otherwise hostile terrain, or a long-term food supply available in harsh winters. With readily available and storable energy resources, and protective clothing, they could push out into harsh northern latitudes with comparative ease.

Summary
Overall, the evidence suggests that Homo ergaster was the first hominid species to resemble historic hunter-gatherers not only in a fully terrestrial lifestyle, but also in a social organization that featured economic cooperation between males and females and perhaps between semi-permanent male-female units.