Late Pleistocene and Holocene Lithic Variability in Southeastern Ethiopia: Implications for the Understanding of the Middle and Late Stone Age of the Horn of Africa
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Late Pleistocene and Holocene lithic variability in Southeastern Ethiopia: implications for the understanding of the Middle and Late Stone Age of the Horn of Africa Alice Leplongeon1,2*, David Pleurdeau2 and Erella Hovers3 * Corresponding author: [email protected] 1 McDonald Institute for Archaeological Research, Downing Street, CB2 3ER Cambridge, UK 2 Département de Préhistoire, UMR 7194 CNRS, Muséum national d'Histoire naturelle, Sorbonne Universités, 1 rue René Panhard, 75013 Paris, France 3 Institute of Archaeology, The Hebrew University of Jerusalem, Mt Scopus, Jerusalem 91905, Israel 1 Abstracts The Late Pleistocene is a key period to understand the shift from the Middle (MSA) to the Late Stone Age (LSA) in Africa. More generally, it is also a crucial time for elucidation of changes in the technological behaviours of human populations in Africa after the main Out of Africa event of modern humans ca. 60-50 thousand years ago. However, the archaeological record for this period is relatively poor, particularly for the Horn of Africa. Here we present a detailed analysis of the lithic assemblages from Goda Buticha (GB), a cave in southeastern Ethiopia, which has yielded a long stratigraphic sequence including Late Pleistocene and Holocene levels. This study (1) contributes to a better knowledge of the late MSA in the Horn of Africa; (2) documents a late Holocene LSA level (GB – Complex I); (3) highlights the presence of MSA characteristics associated with LSA features in the Holocene (GB – Layer IIc). This adds to the emerging record of great lithic technological variability during the Late Pleistocene and Holocene in this region. Le Pléistocène récent est une période clé pour comprendre le changement du Middle (MSA) vers le Late Stone Age (LSA) en Afrique. Plus généralement, c’est une période-clé pour comprendre les changements dans les comportements techniques des populations humaines en Afrique, après l'épisode principal Out of Africa des Hommes modernes, ca 60-50 ka. Cependant, les données archéologiques pour cette période sont relativement rares, particulièrement pour la Corne de l'Afrique. Nous présentons ici une analyse détaillée des assemblages lithiques de la grotte de Goda Buticha (GB), située près de Dire-Dawa, en Ethiopie, et qui a livré une longue séquence stratigraphique incluant des niveaux datés du Pléistocène récent et de l'Holocène. Cette étude (1) contribue à une meilleure connaissance du MSA récent de la Corne de l'Afrique ; (2) décrit un niveau LSA de l'Holocène récent (GB – complexe I) ; (3) souligne la présence de caractéristiques MSA associées à des traits LSA très tard dans l'Holocène (GB – couche IIc). Ces nouvelles données attestent de la grande variabilité technique au Pléistocène récent et à l'Holocène dans cette région. 2 1. Introduction Understanding the mechanisms behind the “transition(s)” between major techno-cultural complexes has been the focus of recent archaeological research. There are two facets to such efforts. One is theoretical, and focuses on clarifying what is meant by the term “transition” (e.g. Hovers & Kuhn 2006; Camps & Chauhan 2009). The other is practical, attempting to apply the criteria derived from theoretical considerations to the archaeological record (e.g. “transitional industries” of the Late Pleistocene in Europe and Africa, Early Upper Palaeolithic or early Late Stone Age (LSA) industries/cultures (see Tostevin 2000, 2003; Hovers & Kuhn 2006; Kuhn 2013; Tostevin 2013). In this context, the shift from the Middle Stone Age (MSA) to the Late Stone Age (LSA) in Africa has been the topic of major discussion because of its numerous specificities, including the fact that the same hominin species, Homo sapiens, is regarded as the maker of most of the MSA and of the LSA material cultures (e.g. Basell 2008). Moreover, this shift seems to have taken place asynchronously across geographic regions. Some of the sites document very early LSA (>50 ka BP) (e.g. Border Cave in South Africa (Villa et al. 2012), Mumba rockshelter in Tanzania (Prendergast et al. 2007; Diez-Martin et al. 2009; Gliganic et al. 2012), Enkapune Ya Muto in Kenya (Ambrose 1998), while other localities present relatively late MSA (e.g. Rose Cottage Cave in South Africa (~28 ka uncal BP (Clark 1997; Wadley 1997)); sites within the Wasiriya Beds on Rusinga Island (>30-45 ka, eastern Lake Victoria Basin, (Tryon et al. 2010)); B1s3 in the Ziway-Shala Basin in Ethiopia (~33-34 ka cal BP; (Ménard et al. 2014)) (see fig. 1). Such instances demonstrate the great variability of the material cultures and lithic industries dated to the Late Pleistocene and indicate a complex pattern for the shift from the MSA to the LSA. This state of affairs has led some researchers to avoid the terms Middle and Late Stone Age in their descriptions of the assemblages (e.g. at Mochena Borago (Brandt et al. 2012)). The difficulty to relate lithic assemblages dated to Marine Isotopic Stages (MIS) 4-3 to the general schema of the 3 MSA and LSA highlights the need for detailed studies on local and regional scales in order to best understand cultural change. This is especially important for the end of the Pleistocene where a growing body of genetic studies document complex patterns of dispersals within, out of, and back into Africa (e.g. Campbell & Tishkoff 2010; Hodgson et al. 2014). In the Horn of Africa particularly few sites document the period of MIS 4 and MIS 3, and even fewer are securely dated. This paper focuses on a cave site located in southeastern Ethiopia, Goda Buticha, which yielded a long stratigraphic sequence dated from 62ka to 1ka by means of radiocarbon and optically-stimulated luminescence (OSL) methods (Tribolo et al. 2017; Pleurdeau et al. 2014). This sequence documents a depositional hiatus and chronological gap from ca. 24ka to 8ka. The evidence from Goda Buticha is consistent with stratigraphic records from many other sites in the Horn of Africa, in which archaeological deposits dated to MIS2 are missing. This gap may correspond to either a cessation of human occupation in the region or results from research bias (e.g. Bon et al. 2013; Ménard et al. 2014; Pleurdeau et al. 2014; Ménard & Bon 2015). With such a long chronological gap in the sequence of Goda Buticha, one might expect an abrupt change in material culture characteristics at the site before and after the hiatus in deposition. Yet, preliminary results of the analysis conducted on part of the assemblage indicated that this was not the case at Goda Buticha (Pleurdeau et al. 2014). This paper confirms and analyses in detail the unexpected typo-technological similarities between the assemblages from Goda Buticha, placing this sequence in the context of local scale variability of Late Pleistocene and Holocene lithic variability in the Horn of Africa. 4 2. Late Pleistocene and Holocene record of the Horn of Africa Lithic assemblages from the Late MSA in the Horn of Africa (see fig. 2) are few and characterized by high variability. In addition to the “classical” characteristics of the MSA (Goodwin & Van Riet Lowe 1929; Goodwin 1946), which include flake production by means of Levallois flaking systems and high percentages of retouched points amongst the tool types, many late MSA assemblages from the Horn of Africa show high percentages of elongated blank production or of pointed blank production (K’one, locality 5 extension, (Kurashina 1978); Aduma, locality A5 and later, (Yellen et al. 2005); Porc-Epic, (Pleurdeau 2005a, 2005b); Deka Wede 1, (Bon et al. 2013; Ménard et al. 2014). Lithic assemblages attributed to the LSA in the Horn of Africa are characterized by “general” LSA technological features (e.g. Goodwin 1946; Phillipson 1982), such as prismatic blade or bladelet production, microliths as the dominant tool type, and absence of characteristic MSA Levallois production or retouched points. The earliest LSA of the region is late compared to its adjacent area in East Africa: at FeJx4 around Lake Besaka, three radiocarbon dates obtained from Layer 2 on fragments of ostrich eggshells gave dates between 19-22ka (Brandt 1982 pp. 60–61), while the LSA sequence at Ziway-Shalla only starts during the terminal Pleistocene (Bon et al. 2013; Ménard et al. 2014). The LSA encompasses a great variability in both technology and typology and is sometimes considered as a “catch-all” category (Bon & Fauvelle-Aymar 2014). Within the Late Pleistocene and Holocene archaeological record of the Horn of Africa a number of sites contain assemblages with features of both the MSA and the LSA, and therefore have not been attributed to either one of these cultural taxonomies (see fig. 2). Such instances include the Late Pleistocene levels at Mochena Borago with rare Levallois cores, flake and blade(let) production and retouched tools dominated by scrapers, retouched points and backed pieces (Brandt et al. 2012); at Midhishi 2 in Somalia, Unit CSUb, dated around 18ka, has yielded an assemblage with both 5 Levallois and blade production, backed pieces and retouched points (Gresham 1984); the lower units of Shelter 7 of Laas Geel (Somaliland), considered to be of a Terminal Pleistocene age despite conflicting dates, have yielded material with both Levallois and prismatic blade production, retouched points and microliths. These assemblages have been attributed to a revisited “Hargeisan” (Gutherz et al. 2014). Similarly, the first study of the Goda Buticha material highlighted the presence of both MSA and LSA features throughout the sequence (Pleurdeau et al. 2014). Overall, the tempo and pattern of technological changes during the Late Pleistocene in the Horn of Africa remain unclear, leaving open questions about the persistence, reintroduction, or convergent, independent appearance of MSA features in lithic assemblages throughout the end of the Pleistocene and the Holocene despite the widely-recognized gap corresponding to MIS2 in many of the sites.