The Emergence of the Acheulean in East Africa and Beyond

We review below the Acheulean of East Africa from two perspectives: the history of research and the current state of the art. The definition of Acheulean industries has changed considerably over 150 years and since the earliest research in Africa. A brief presentation of the main discoveries, of the many theories, and of the various methods used in Acheulean archaeological research will help in understanding the current debate and the topics addressed in this volume.

In 2009, Hovers and Braun published in Springer’s Vertebrate Paleobiology and Paleoanthropology Series the volume “Interdisciplinary Approaches to the Oldowan,” stemming from the symposium of the 2006 SAA meeting in Puerto Rico. Many contributors focused on the description of the Oldowan as a lithic production system, showing the high technical variability of the techno-complexes. As pointed out by Braun and Hovers (2009: 4), even if most or all scholars agree that the study of Oldowan behaviors is fundamental to understand early hominin evolution, “not all would agree on a definition of the Oldowan.” Forty years after it was first defined (Leakey 1971, 1975), many sites scattered over approximately one million years are labelled as “Oldowan” in large-scale syntheses. While the available data are highly fragmented both in time and space, and the study of lithic assemblages follows different theoretical and methodological approaches, major overviews simply take for granted that a correlation among the East African assemblages is inescapable. However, the term Oldowan is still a vague concept, lacking a comprehensive definition of what an Oldowan technology is. Additionally, who were the authors of the Oldowan stone tools remains an open question.

Nine years after the publication of Hovers and Braun’s volume, this is a short overview and update of the current state of our knowledge of the Oldowan technical behaviors recorded in East Africa, to put in the proper perspective specific sites with “emerging” Acheulean.

On the western side of the Turkana basin, the sedimentological members of the Nachukui Formation expose a unique succession of archaeological site complexes ranging from 0.7 to 3.3 Ma. Following the analysis of the oldest and most remarkable lithic assemblages, we propose a model clarifying the chronology and possible operative modes of the first stone knappers; the technological components which around 1.76 Ma led to a new method in stone working: shaping. It appears that they gradually substituted newly mastered technical advances for the initial selection of blocks or cobbles naturally displaying a suitable shape. The alternating of conceptual advances, first concretized in the appropriate selection of natural block shapes, then in major technical innovations, seems to have been the rhythm of a very slow and hesitant tempo, leading to the formalization of the oldest Acheulean lithic assemblages then to a new technological world from 1.0 Ma.

The emergence of the Acheulean is a major topic, currently debated by archaeologists researching all over East Africa. Despite the ongoing discussion and the increasing amount of available data, the mode(s) of the technological changes leading to this emergence remain(s) largely unexplained. Overall, there is a dearth of continuous stratigraphic sequences recording both the late Oldowan and the early Acheulean at the same site. Accordingly, the technological changes cannot be evaluated taking into account the variability of each microregional context. Besides, the early Acheulean must be defined not only with respect to the Oldowan, but also in comparison with the following middle Acheulean.

At Melka Kunture, on the Ethiopian highlands, the rather continuous record allows a diachronic analysis from ~1.7 to ~0.85 Ma in a single microregion. In this paper we address the emergence and later developments of the Acheulean in the perspective of technical responses to the qualities/limits of raw materials (lithology, dimensions, geometry). A comparative techno-economic perspective makes it possible to investigate the nature of technological change(s) taking into account the role played by lithic resource availability and constraints in the same paleolandscape.

Our results demonstrate that in this area the main novelties leading to the early Acheulean were new concepts in small and large débitage, in addition to the manufacture of large tools. These innovations emerged at Melka Kunture over two hundred thousand years, during a continuous cultural process leading from the late Oldowan to the early Acheulean. On the opposite side, at the end of the Early Pleistocene, the innovations are not a small qualitative step, but rather a gaint leap. We underline the strong techno-economic discontinuity between the early Acheulean and the middle Acheulean.

There is also evidence that Homo ergaster/erectus produced both the Oldowan and the early Acheulean at Melka Kunture. Accordingly, the technological changes leading to the emergence of the Acheulean on the Ethiopian highlands are not explained by a newly developing hominin species. Conversely, the middle Acheulean develops while Homo heidelbergensis, a new and more encephalized type of hominin, appears on the scene.

In this paper, we present and discuss pollen data from the Early Pleistocene (1.8 to 1.6 Ma) – we use the revised timescale approved by IUGS, in which the base of the Pleistocene is defined by the GSSP of the Gelasian Stage at 2.588 (2.6) Ma (Gibbard et al. 2010) – and from the Mid-Pleistocene Transition (0.9 to 0.6 Ma) at Melka Kunture (Upper Awash, Ethiopia). At 2000 m asl in the Ethiopian highlands, these deposits yield many rich and successive archaeological sites, notably documenting the late Oldowan, the emergence of the Acheulean and the middle Acheulean. The stratigraphic position of the fifteen pollen samples is checked by ⁴⁰Ar/³⁹Ar dating and by geological investigation. Furthermore, they are now correlated to archaeological layers whose excavated lithic industries have been reinterpreted. Our study shows that mountain forest trees belonging to the present-day Afromontane complex were already established in Ethiopia at ~1.8 Ma and that the knappers of the Oldowan and early Acheulean could cope with mountain climatic conditions that had a large diurnal temperature range. Moreover, the new interpretation of pollen results emphasizes changes that occurred in the vegetation cover at 200- or 300-thousand-year snapshot intervals, one during the Early Pleistocene and another one later on, during the Mid-Pleistocene Transition. These changes concerned plant species and their respective abundance and appear to have been related to rainfall and temperature variability. The proportion of forest trees increased during wet episodes, whereas the influence of Afroalpine grassland indicators increased during cool and dry episodes. Variations in Early Pleistocene pollen data from Melka Kunture at ~1.8–1.6 Ma are consistent with isotopic evidence of precession variability as recorded at Olduvai and Turkana archaeological sites at ~2–1.8 Ma. For the Mid-Pleistocene Transition, variations in pollen data seem to match the climatic variability of isotopic and long pollen records from the Mediterranean region, notably upon the onset of dominant 100 ka-long glacial/interglacial cycles.

Konso in Ethiopia and Kokiselei in Kenya, both dated to ~1.7 million years ago (Ma), and FLK West, a recently reported site from Olduvai dated to 1.7 Ma, are the earliest Acheulean sites known in East Africa. Ongoing archaeological investigations at Gona, in the Afar Depression of Ethiopia, have also produced early Acheulean stone assemblages at several sites, estimated to ~1.6–1.2 Ma. A number of sites, including BSN-12 and OGS-12, have yielded archaeological materials comparable to the earliest Konso artifacts. The stone assemblages from the Gona sites consist of crudely made handaxes, cleavers, and picks, as well as Mode I (Oldowan) cores, and débitage. A variety of raw materials were exploited at Gona, with trachyte, rhyolite, and basalt being the most common.

Our understanding of the behavioral and ecological background for the emergence of the Acheulean is still limited. Preliminary comparisons of BSN-12 and OGS-12 with other early Acheulean sites demonstrate variability in paleoecological settings as well as raw material use. Current archaeological evidence indicates that early Homo erectus/ergaster use of this new technology was already in place in East Africa ~1.75 Ma. At Gona and elsewhere in Africa, continued survey and excavations are needed to document sites with potential for yielding archaeological traces that will help our understanding of the Oldowan–Acheulean transition, the identity of the toolmakers, and the function of the early Acheulean Large Cutting Tools (LCTs).

The Pleistocene record of Peninj, dated to 1.5–1.4 Ma and located on the Western shore of Lake Natron (Tanzania), is one of the classic archaeo-paleontological sources for the study of the early Acheulean in Africa. Beginning with the seminal project led by Glynn Isaac in the decades of 1960s and 1980s, other research programs have been carried out in Peninj since then, particularly the landscape archaeology approach undertaken by M. Domínguez-Rodrigo between 1995 and 2005. In 2007, fieldwork was resumed in the area and a new project is currently in progress. As a result of this long-lasting scientific effort, the variety of geological, contextual, technological, and spatial information gathered so far can shed light on a number of aspects related to the early Acheulean record identified in the three different archaeological areas of Peninj (the Type Section, the North and the South Escarpments). This paper presents a synthesis of the history of research in Lake Natron and the geology of the Peninj Group. It also reviews some of the main discussions related to the Type Section technology, the bifacial hierarchical centripetal method hypothesis, and the Oldowan–Acheulean dichotomy for the attribution of the lithic samples in the framework of the archaeological record of Peninj. The paper includes a synthesis of the new data gathered in the Acheulean sites of the Escarpments in the course of the present research project and, finally, a regional interpretation of the early Acheulean of the Lake Natron.

This paper presents a detailed analysis of the bifacial shaping and the spatial distribution of 85 bifaces recorded in an area of 51.9 m² on the Lower Floor of the TK site, located alongside the Trench I excavated by M. Leakey in 1963.

The repeated use of shaping schemes and patterns demonstrates that the knappers who produced these tools had a good command of the concept of bifacial reduction. These processes were adapted differently to fit the characteristics of the exploited raw material. Formal similarities observed among the handaxes seem to reflect preconceived formal schemes, i.e., mental templates. The presence of handaxe fragments and preforms shows that they were knapped at the site with the aim of being used right there. This tool assemblage was later abandoned without the site having undergone any major alterations after its formation.

This command of the bifacial shaping concept observed at the TK site, dated to ca. 1.353 ± 0.035 Ma, undermines the validity of M. Leakey’s distinction between an early and a middle phase of the Acheulean techno-complex.

The Early Pleistocene Transition from the Oldowan to the Acheulean in eastern Africa was roughly contemporaneous with a number of other events commonly assumed to be connected with hominin evolution. I review here the large mammal evidence, well documented in several major eastern African sites. Definite conclusions are hard to reach because of temporal gaps in the fossil record, and very patchy history of many lineages, but I conclude that, although some groups do show some turnover during this period, most of them did not change more than before or after it. We may conclude that this cultural change did not seriously impact the faunal assemblage. In addition, we may surmise that, since climate change at this period, if any, did not seriously impact the fauna, it is unlikely to have played a major role in human evolution at that time.

Acheulean assemblages—defined by the presence of handaxes and cleavers—are found across much of Asia. The best known are from the Levant and India and date from the Early Pleistocene. Although bifaces have been found in other parts of Asia, they are poorly dated but probably mostly Middle Pleistocene in age. In East Asia, the Movius Line as originally formulated is invalid because Acheulean, bifacial assemblages are present in China as well as the Korean Peninsula. Nevertheless, there are significant differences between some of these assemblages and those from west and south Asia. Problems of dating and differing definitions of “the Acheulean” are current impediments to establishing the spatial and temporal patterning of Acheulean assemblages in Asia. Additional major shortcomings are the lack of information on the climatic context of most Asian Acheulean assemblages, and the almost total absence of information on the identity and subsistence of their makers.

This paper focuses on the early evidence of assemblages with bifacial tools, in particular their technology within the context of chronology and geography, focusing on the sites of La Noira, Arago levels P and Q and Cagny-la-Garenne I–II in France, Brandon Fields, Maidscross Hill, High Lodge and Boxgrove in the UK, and Notarchirico in Italy. Assemblages with bifacial tools, including Large Cutting Tools (LCTs), demonstrate a high diversity of technological and morphological features as early as 700 ka and are contemporary with non-handaxe assemblages. They also show specific features that contrast between northern and southern Europe, such as the use of large flakes for bifacial manufacture, or the presence of cleavers on flakes. Lack of data regarding a local origin and more elaborate bifaces in these sites indicate an early arrival of new traditions in western and southern Europe on a pre-existing hominin presence. The assemblages are compared to those without LCTs such as Happisburgh Site 3 and Pakefield in UK, Isernia La Pineta in Italy, Atapuerca Gran Dolina TD6 and Vallparadis in Spain, Pradayrol and Soleihac in France. Hypotheses on factors behind the variation, such as function, type of site, raw material constraint, and traditions of manufacture, are discussed. The period 800–500 ka is a key episode for examining behavioral changes which occurred in Europe. The discovery of hominin fossils such as the Mauer mandible in Germany led to the definition of Homo heidelbergensis. The emergence of new behaviors such as the ability to produce large flakes and/or large bifacial tools (handaxes, cleavers and others) leads to discussion about new skills, new social organizations, and the arrival or in situ evolution of hominins.