Fernando Diez-Martín

Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II.

New archaeological excavations and research at BK, Upper Bed II (Olduvai Gorge, Tanzania) have yielded a rich and unbiased collection of fossil bones. These new excavations show that BK is a stratified deposit formed in a riverine setting close to an alluvial plain. The present taphonomic study reveals the second-largest collection of hominin-modified bones from Olduvai, with abundant cut marks found on most of the anatomical areas preserved. Meat and marrow exploitation is reconstructed using the taphonomic signatures left on the bones by hominins. Highly cut-marked long limb shafts, especially those of upper limb bones, suggest that hominins at BK were actively engaged in acquiring small and middle-sized animals using strategies other than passive scavenging. The exploitation of large-sized game (Pelorovis) by Lower Pleistocene hominins, as suggested by previous researchers, is supported by the present study.

First Partial Skeleton of a 1.34-Million-Year-Old Paranthropus boisei from Bed II, Olduvai Gorge, Tanzania

Recent excavations in Level 4 at BK (Bed II, Olduvai Gorge, Tanzania) have yielded nine hominin teeth, a distal humerus fragment, a proximal radius with much of its shaft, a femur shaft, and a tibia shaft fragment (cataloged collectively as OH 80). Those elements identified more specifically than to simply Hominidae gen. et sp. indet are attributed to Paranthropus boisei. Before this study, incontrovertible P. boisei partial skeletons, for which postcranial remains occurred in association with taxonomically diagnostic craniodental remains, were unknown. Thus, OH 80 stands as the first unambiguous, dentally associated Paranthropus partial skeleton from East Africa. The morphology and size of its constituent parts suggest that the fossils derived from an extremely robust individual who, at 1.338±0.024 Ma (1 sigma), represents one of the most recent occurrences of Paranthropus before its extinction in East Africa.

AN EXPERIMENTAL STUDY OF BIPOLAR AND FREEHAND KNAPPING OF NAIBOR SOIT QUARTZ FROM OLDUVAI GORGE (TANZANIA)

Recent excavations carried out in several Bed I and Bed II sites have shown that hominins at Olduvai Gorge used both bipolar and freehand knapping methods for quartz reduction. Due to the petrographic nature of quartz and to its heterogeneous response to fracture, the identification of bipolar knapping at any given site can be ambiguous and controversial. This work aims to overcome this problem by developing an experimental referential framework for the recognition of characteristic features of flakes produced through both bipolar and freehand reduction of Naibor Soit quartz cores. The final goal of this work is to use a set of variables related to the response of local Olduvai quartz to freehand and bipolar fracture, obtained through two independent controlled experiments, in order to statistically differentiate the diagnostic technological traits that best indicate bipolar reduction on this raw material type.

The Origin of The Acheulean: The 1.7 Million-Year-Old Site of FLK West, Olduvai Gorge (Tanzania).

The appearance of the Acheulean is one of the hallmarks of human evolution. It represents the emergence of a complex behavior, expressed in the recurrent manufacture of large-sized tools, with standardized forms, implying more advance forethought and planning by hominins than those required by the precedent Oldowan technology. The earliest known evidence of this technology dates back to c. 1.7 Ma. and is limited to two sites (Kokiselei [Kenya] and Konso [Ethiopia]), both of which lack functionally-associated fauna. The functionality of these earliest Acheulean assemblages remains unknown. Here we present the discovery of another early Acheulean site also dating to c. 1.7 Ma from Olduvai Gorge. This site provides evidence of the earliest steps in developing the Acheulean technology and is the oldest Acheulean site in which stone tools occur spatially and functionally associated with the exploitation of fauna. Simple and elaborate large-cutting tools (LCT) and bifacial handaxes co-exist at FLK West, showing that complex cognition was present from the earliest stages of the Acheulean. Here we provide a detailed technological study and evidence of the use of these tools on the butchery and consumption of fauna, probably by early Homo erectus sensu lato.

The Middle to Later Stone Age Technological Transition in East Africa. New Data from Mumba Rockshelter Bed V (Tanzania) and their Implications for the Origin of Modern Human Behavior

Recent re-excavation of Mumba Rockshelter unearthed an unbiased lithic sample from Bed V. Technological analysis has permitted a reinterpretation of the so-called Mumba Industry, a transitional industry between Middle and Later Stone Ages originally defined by Mehlman (1989). Our data confirm Mehlman’s observation that the “evolutionary” markers in Mumba Bed V are basically typological. However, our study differs from his in that we classify all of Bed V as LSA based on the combined analyses of typology and technology in our excavated assemblage. From a technological perspective, no changes have been observed throughout the sequence, and continuity is the main technological characteristic of the series. The only transitional marker from Lower through Upper Bed V is the appearance of the geometric crescent in the latter, taking into account that microliths exist throughout the sequence. This evidence casts some doubts on previous interpretations and underscores the need to recover a larger sample using modern excavation techniques. It also stresses the need to define the MSA/LSA transition in better terms, combining techno-typological criteria.

New Excavations at Mumba Rockshelter, Tanzania

Mumba Rockshelter in northern Tanzania presents one of the richest and most complete archaeological sequences in East Africa for the Middle Stone Age through the Iron Age. Past excavations of the shelter revealed an extremely rich lithic and faunal assemblage, but were problematic, either because of poor excavation and recording methods (in the 1930s), or because the materials were never fully studied (in the 1979/1981 excavations). In both cases, excavators had concluded that the shelter contained a deposit without visible separation between archaeological levels. Re-excavation of Mumba, using modern techniques for recording spatial data, show that the previous geological and archaeological sub-divisions of the shelter deposits need much revision. The results of the excavation have implications for the interpretation of the “transitional” Mumba Industry in the Pleistocene levels and for the co-occurrence of ceramic traditions in the Holocene levels.

The origin of the Acheulean. Techno-functional study of the FLK W lithic record (Olduvai, Tanzania)

The Acheulean materials documented in FLK West dated c. 1.7 Ma. are the focus of the present work. An original techno-functional approach is applied here to analyze the origin of Acheulean tools. According to the results, these tools were employed in different functional contexts in which tasks of different durations that transformed resources with different resistances were carried out. The exploitation of large and resistant resources suggests that the economic mechanism governing the manufacture of these tools was an increase in the demand of the work load. The decision processes underlying the production of these tools have thus an evident functional motivation. However, the presence of a refined handaxe in the studied sample indicates that the design form and production principles of handaxe manufacture were the result of an abrupt emergence rather than a long gradual development. The integration of mechanical and ergonomic investigation in our research has been crucial to explain how a core-and-flake industry gave way to a technology based on the production of large and heavy shaped tools.

The East African Early Acheulean of Peninj (Lake Natron, Tanzania)

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. Dominguez-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.