Quaternary International 322-323 (2014) 1e6 Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint Introduction The evolution of hominin behavior during the OldowaneAcheulean transition: Recent evidence from Olduvai Gorge and Peninj (Tanzania) 1. Introduction vague concept, which includes definitions spanning the presence/ absence of the “fossil directeur” (i.e., handaxes) (Leakey, 1936, The emergence of human behavior, understood as a distinct 1951; de la Torre and Mora, 2013), its representation in specified adaptive pattern among primates, which created a material record frequencies (Kleindienst, 1962; Leakey, 1971), or its definition in in the form of archaeological sites, has been widely studied during technological terms (e.g., Boëda, 1991; see review in; Diez-Martín the Oldowan phase of human evolution. Behavior, as a crucial part and Eren, 2012). of adaptation, is tightly linked to ecology. The Olduvai Paleoecology The evolutionary interpretation of the “fossil directeur” has a and Paleoanthropology Project (TOPPP) stressed the importance of biological component understood in traditional Darwinian terms: studying archaeological sites and the behavior represented therein each stone tool industry was made by a specific hominin taxon. within their broader paleoecological settings. A multidisciplinary The earliest Acheulean slightly postdates the earliest set of effort integrating the geology, paleobotany, paleochemistry and clearly-defined H. erectus (Beyene et al., 2013), by a substantial archaeology of Olduvai Bed I was published as a monographic issue amount of time if including earlier Homo remains not fitting the of Quaternary Research in 2010. In this collective work, compelling Homo habilis hypodigm (Wolpoff, 1999). In addition, the binomial evidence was provided of the heuristic value of conceiving archae- H. erectus-Acheulean fails to explain why H. erectus georgicus did ology within the broader framework of paleoecology. not have an Acheulean technology or why the presence of H. erectus In the past five years, TOPPP has collected a wealth of informa- outside Africa precedes by several hundreds of thousands of years tion from a diversity of sites both at Olduvai Bed I and Bed II, the earliest occurrence of non-African Acheulean. It also does not including most of the few anthropogenic sites that are categorized explain why if H. erectus emerged at least by 1.7 Ma, the over- as Developed Oldowan and Acheulean. This information is archae- whelming majority of the archaeological record until 1.5 Ma is Old- ological (technological, behavioral, taphonomic) as well as owan. Only two sites (Kokiselei 4 and Konso Gardula) have been geomorphological, geological, geochemical, paleobotanical and documented as Acheulean prior to 1.5 Ma (Beyene et al., 2013). de paleontological. Using this information jointly, we can address la Torre and Mora (2013) argue that Oldowan sites could be attrib- the evolution of human behavior from the Oldowan through uted to H. habilis and Acheulean sites could be attributed to H. erec- Developed Oldowan and Acheulean in conjunction with the evo- tus. Their argument is that sites under tuff IIB are Oldowan and lution of landscapes in two of the most important localities for those above this marker are all Acheulean. However, no in situ fossil this type of study in Africa: Olduvai Gorge and Peninj (Lake of H. erectus is known under Bed III. Only a surface find is reported Natron) (Tanzania). The relevance of this information for Quater- for Bed II: OH 9. This fossil was discovered in a gully in which only nary and human evolutionary studies is evident. There is a vac- Beds III and IV and a small portion of upper Bed II are exposed uum of behavioral information for Developed Oldowan and (Leakey, 1971). The portion of Bed II exposed corresponds to the Acheulean hominins in comparison with older Oldowan homi- section of this bed overlying tuff IID; so, if OH9 belongs in these nins. Site functionality is basically unknown in these more recent strata, it certainly overlies several Bed II Acheulean and most Devel- sites. The comparison of the three types of archaeological record oped Oldowan sites. Therefore, the bulk of Developed Oldowan/ and their landscapes will contribute to understand this crucial Acheulean sites comprised between tuff IIB and tuff IIC (six out of part of human evolution. Understanding to what extent Homo the eleven sites documented by Leakey for all Bed II) are either erectus hominins were behaviorally similar or different from early devoid of hominin fossils or only physically associated to remains Homo will contribute to more accurate reconstructions of the evo- of H. habilis and Paranthropus. Linking stone tool assemblages to lution of subsequent Homo taxa. The present volume introduces hominin types based on the presence or absence of hominin fossils important advances made on the reconstruction of Bed I hominin is an epistemically futile exercise. For example, Paranthropus is still paleoecology during the Oldowan and its transition into the a widely represented hominin in Bed I and II sites: FLK Zinj, FLK NN Acheulean during the formation of Bed II. (probably OH8) (Gebo and Schwartz, 2006), HWK, BK, SC. If using Bunge (1998) argued that to scientifically address any topic, it the same chrono-stratigraphic associative arguments, it could was necessary to properly define the object of study prior to the equally be supported that Oldowan or Acheulean tools were formulation of hypotheses (Domínguez-Rodrigo, 2012). Unfortu- made by this taxon. nately, this has not been frequently done in archaeological research Although the Developed OldowaneAcheulean debate has dealing with the Acheulean. The definition of Acheulean is still a prompted varied interpretations, such as the impact of raw material 1040-6182/$ e see front matter Ó 2014 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2014.01.017 2 Introduction / Quaternary International 322-323 (2014) 1e6 (Stiles, 1977,1979, 1980, 1991), representation of different reduction This prompted the conversion of Hay’s paleogeographic interpreta- sequences (Jones, 1994) or functional differences (Gowlett, 1986; tion into the “Ecological hypothesis of early African Acheulean”,in Domínguez-Rodrigo et al., 2009a), most of these approaches which it was claimed that the bipolar distribution of Oldowan sites emphasize the overall similarity of Developed Oldowan and Acheu- (near the lake) and Acheulean sites (distant from the lake, lean sites in Olduvai Bed II. Variability is most generally conceived commonly in alluvial settings with fluvial input) had a functional- as triggered by functional and ecological factors (Leakey, 1975; Hay, behavioral cause determined by ecology (Domínguez-Rodrigo 1976; Domínguez-Rodrigo et al., 2009a). The only seeming et al., 2005). Neither Hay (1976) nor Domínguez-Rodrigo et al. consensus of all these diverse interpretations is that “the Acheulean (2005) framed the duality according to sedimentary facies (lacus- is recognized by the presence of bifaces rather than by any other trine versus fluvial). Fluvial facies are an integral part of the lacus- criterion” (Lycett and Gowlett, 2008:22e23) and, to a lesser extent, trine systems (even in their proximal sections). Hay (1976) the ability to produce large flakes (Isaac, 1969). If we take this defi- discussed extensively lacustrine sands and sandstones. Therefore, nition as a starting criterion to identify Acheulean sites, then we one could find a site in a fluvial context just a few meters away must admit that it is an utterly useless one when we attempt to un- from the lake shoreline. Both Oldowan and Acheulean sites are derstand the large array of assemblages that have traditionally been found associated with fluvial facies in Bed II. However, both types classified as either Developed Oldowan or traditional Acheulean of sites are ecologically and paleogeographically located in different within an ecological framework. Alternatively, archaeologists settings. Oldowan sites, as Hay (1976) remarked, occur in higher should ponder whether they want a technological definition of frequencies near the lake and Acheulean sites distally to it. these sites (i.e., some of the technical steps undertaken to craft In order to see this dual distribution properly, one has to select some tools in Acheulean and Developed Oldowan sites were sites within defined chronological markers, which allow compari- similar) or a functional/adaptive definition, which has the potential sons of location according to specific geomorphological reconstruc- for scientifically-based behavioral reconstructions. A technical tions. For Olduvai, the best stratigraphic interval for this purpose is approach to this question will not by itself provide an explanation the one comprised between tuff IIB and tuff IIC, where most of the for site functionality, especially because this is contingent on Developed Oldowan and the Acheulean sites co-exist (Fig. 1A). The what criteria are determined to be illustrative of technological Olduvai Acheulean sites show a high proportion of handaxes (HX) importance when comparing Acheulean to Developed Oldowan when compared to complete small flakes (SF). Using Leakey’s sites and also on methodological shortcomings stemming from in- (1971) data, the HX:SF ratio for EF-HR is 0.33. MNK Main site ferences derived from small and statistically unreliable small sam- (ratio ¼ 0.03), FC West occupation floor (ratio