Early Hominid Dispersals: a Technological Hypothesis for ``Out Of
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Quaternary International 223-224 (2010) 36e44 Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint Early hominid dispersals: A technological hypothesis for “out of Africa” Eudald Carbonell a, Robert Sala Ramos a,*, Xosé Pedro Rodríguez a, Marina Mosquera a, Andreu Ollé a, Josep María Vergès a, Bienvenido Martínez-Navarro a,b, José María Bermúdez de Castro c a Institut Català de Paleoecologia Humana i Evolució Social (IPHES). Àrea de Prehistòria, Universitat Rovira i Virgili. Avgda. Catalunya, 35. 43002 Tarragona, Spain b ICREA. Institució Catalana de Recerca i Estudis Avançats, Spain c Centro Nacional de Investigación sobre Evolución Humana (CENIEH), Burgos, Spain article info abstract Article history: Homo is the only genus that responds to environmental pressures by adopting such strategies as non- Available online 25 February 2010 standardized behaviour, a general diet, and technology. Considering that basic idea, this paper intro- duces the general hypothesis that the Pliocene and Early Pleistocene Homo dispersals within and out of Africa were consequences of that human characteristic behaviour. In particular, they were driven by a process starting with the emergence of technology, followed in a second phase by its socialization. From this point, social reorganization within communities (changing behaviours and social, cultural and economic strategies) occurred, driving demographic growth, and frequently geographic expansion. Ó 2010 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction et al., 2002), and H. antecessor may have an Eurasian origin (Carbonell et al., 2005). Therefore, the extent to which technology The end of the twentieth century witnessed increasing interest influenced hominin dispersals is the purpose of this paper. in and debate about the circumstances that led Plio-Pleistocene and Some issues can be taken into consideration as starting points: 1. Early Pleistocene hominids to disperse out of Africa (Dean and There was not a single out-of-Africa hominin dispersal event; 2. Delson, 1995; Carbonell et al., 1996, 1999a, 2008a; Arribas Based on current knowledge, the only hominin genus that left Africa and Palmqvist, 1999; Turner, 1999; Aguirre and Carbonell, 2001; during the Plio-Pleistocene was Homo; 3. Other hominin genera Bar-Yosef and Belfer-Cohen, 2001; Mithen and Reed, 2002). The coexisting with Homo evolved and went extinct in Africa, particu- debate has focused on resolving when, how and where the earliest larly Australopithecus and Paranthropus. The latter may have started waves of hominid dispersal occurred, with special emphasis on the to adopt a generalist feeding strategy, combining scavenging, particular mechanisms that conditioned and determined these hunting and gathering (Sillen, 1992; Lee-Thorp et al., 1994, 2000). dispersals and the ways in which early Homo arrived and settled Even though they may have also invented technology, Homo was the Eurasia (Rolland, 1992; Carbonell et al., 1996, 2008a; Dennell and only hominin genus that was successful in dispersing out of Africa Roebroeks, 1996; Martínez-Navarro et al., 1997; Oms et al., 2000; due to its systematic application of a set of adaptive strategies Roebroeks, 2001). (Carbonell et al., 2008a): systematic adoption of technology as As the debate continues, it shows how little is known about a mean for resources supply, a generalist diet (as has been proposed certain key aspects of human evolution. In particular, some of the by Anton et al., 2002, and Anton and Swisher, 2004) and a non- hypotheses proposed during the last decade have to be amended standardized behaviour. Technology meant that humans were able due to the change in the knowledge about the chronology of the to diversify their behaviour, and so they disposed of a wide range of dispersals. Elsewhere, it was proposed that the technological shift responses to better adapt to new and heterogeneous situations. In to Mode 2 in Africa could have pushed some Mode 1 population sum, technology appears as the more powerful adaptation for within Africa to move into Eurasia (Carbonell et al., 1999a). This humans. hypothesis was based both in a younger chronology for the Dmanisi Despite this role, hypotheses based on technological develop- record and in the consideration that Homo antecessor was certainly ment to explain human dispersals and evolution have not been an African species. Today, the date for Dmanisi exceeds that of the thoroughly developed. The significance of the different stages first evidence for Mode 2 in Africa (Asfaw et al., 1992; de Lumley within each Mode on dispersals should be considered, not only the shift to Mode 2. It is also appropriate to review the chronology of * Corresponding author. Tel.: þ34 9779730; fax: þ34 977558386. different dispersal events and to show the possible relation to E-mail address: [email protected] (R. Sala Ramos). technological phases. This approach, termed the “The Out of Africa 1040-6182/$ e see front matter Ó 2010 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2010.02.015 E. Carbonell et al. / Quaternary International 223-224 (2010) 36e44 37 Technological Hypothesis”, emphasises the role played by tech- et al., 2008b). Its age has been established in 1.2 Ma by means of nology in human expansions (Carbonell et al., 1999a, 2008a). paleomagnetism, biostratigraphy and cosmogenic nuclides. To date, the Atapuerca complex is unique in offering a set of sites and levels 2. Current data for the earliest Homo dispersals out of Africa, with different ages in the second half of the Early Pleistocene, with and into Western Eurasia both cultural and biological information on human evolution in Western Eurasia. According to current empirical data, the earliest known tools are Although Mode 2 technology was already developed in Africa at modified stones recovered from archaeological sites in Central East the time of the human occupation of Europe, all the Early Pleisto- Africa, and date at a maximum of 2.6 Ma (Kibunjia, 1994; Semaw cene European sites display Mode 1 lithic assemblages. In general, et al., 1997, 2003; Delagnes and Roche, 2005). These lithic records the European Mode 1 technology is characterized by the wide- are abundant and diversified, suggesting that technology was not spread use of knapping methods to produce simple flakes. These newborn, but already generalized by this time (Panger et al., 2002). methods were sometimes organized and systematic, but the Technology may have emerged previously, and this period may production processes were basic, and lacked different stages of represent the time of its first complete socialization (Carbonell knapping (i.e., preparation of the cores): they lacked process et al., 2009). It is within this hypothetical framework of general- complexity. This Mode 1 technology also produces few small ized tool production and use that early Homo dispersals within retouched flakes and some heavy-duty pebble tools, both mini- Africa and beyond can be understood (Carbonell et al., 2007). mally shaped (Fig. 3). Although these are the general traits for Mode The oldest Homo fossils known out of Africa come from the site 1, the differences between the oldest one in Eurasia, that of Dmanisi of Dmanisi (Georgia) dated to 1.81 Ma (Gabunia and Vekua, 1995; and that of Gran Dolina-TD6 from Atapuerca cannot be neglected. Gabunia et al., 2001; de Lumley et al., 2002). They have been Dmanisi is claimed to have similar archaic technological features to classified as Homo georgicus (Gabunia et al., 2002), and their the African sites between 2.6 and 2.0 Ma (de Lumley et al., 2005). primitive features and variability suggest that these hominins are Gran Dolina-TD6 shows some small shaped tools, as well as, for the extremely close to the Homo speciation threshold. The Dmanisi first time in Europe, an incipient production of bigger flakes to be archaeological record in addition to human fossils is composed by knapped as cores but never shaped into tools (Fig. 4)(Carbonell a large lithic assemblage displaying Mode 1 features close to that et al., 1999b; Rodríguez, 2004). The dominant exploitation strate- shown by the African sites more than 2.0 Ma (de Lumley et al., gies are those common in Mode 1, and include mainly the 2005; Mgeladze, 2008). orthogonal technique but also centripetal and unipolar longitudinal The current known Western Eurasian Early Pleistocene sites are knapping. significantly younger than Dmanisi, and they offer different quali- ties of chronological and archaeological (Fig. 1) and palae- 3. Technological hypothesis for the first out of Africa event ontological data. Pirro Nord (Italy) is claimed to be around 1.4 Ma on biochronological markers (Arzarello et al., 2009). Also in Italy, In the authors' view, the dispersals of Homo were triggered by Monte Poggiolo has an age of 0.9 Ma based on both by paleomag- ethological and cultural mechanisms that differed significantly netism and ESR (Peretto et al., 1998; Falguères, 2003). The last from those of other mammal species, particularly as far as their Italian site to be mentioned is Ceprano, where a human calvarium social behaviour was concerned (Rolland, 1992; Tchernov, 1992; has been previously ascribed by stratigraphical correlation to a time Turner, 1992; deMenocal and Bloemendal, 1995; Roebroeks, span between 0.8 and 0.9 Ma (Ascenzi et al., 1996; Manzi et al., 2001). A crucial factor that determined the earliest dispersals of 2001). However, a Middle Pleistocene age has been proposed for Homo was their capacity to socialize operational intelligence: their this site (Muttoni et al., 2009). capacity to make tools and to diffuse this tool-making behaviour In France there are two main Early Pleistocene sites: Pont- within the Homo species. Technology started to play its crucial role de-Lavaud and Vallonnet. The latter has been dated by means of in the social structures of these early Homo communities. Gener- biostratigraphy, paleomagnetism and ESR to the Jaramillo magnetic alizing tool production and use generated a phenomenon called subchron, between 0.99 and 1.07 Ma (de Lumley, 1988; Yokoyama “social reorganization”.