Journal of Human Evolution 64 (2013) 645e657 Contents lists available at SciVerse ScienceDirect Journal of Human Evolution journal homepage: www.elsevier.com/locate/jhevol Modeling trophic resource availability for the first human settlers of Europe: The case of Atapuerca TD6 Guillermo Rodríguez-Gómez a, Jesús Rodríguez a,*, Jesús Ángel Martín-González b,1, Idoia Goikoetxea a, Ana Mateos a a Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca s/n, 09002 Burgos, Spain b Departamento de Matemáticas y Computación, Universidad de Burgos, Burgos, Spain article info abstract Article history: Food resource availability strongly influences the survival opportunities of all organisms. The effect of Received 15 June 2012 animal food resource availability on the survival and dispersal of hominin populations is hotly debated. Accepted 24 February 2013 In this article, we present a mathematical model that provides estimations of the maximum and mini- Available online 28 March 2013 mum available resources for secondary consumers in a palaeocommunity. This model provides insights into the intensity of competition and the available niche space for hominins in Europe during the early Keywords: Galerian (1.2e0.8 Ma). Published data from the Atapuerca TD6 assemblage were used in combination Palaeolithic with the model to investigate trophic dynamics and resource availability for a Homo antecessor popu- Hunteregatherers Mathematical models lation 800,000 years ago. The effect on our results of the possible presence at Atapuerca of some large Homo antecessor carnivores not recorded in the fossil assemblage is also evaluated. Results indicate the existence of a rich ecosystem at Atapuerca at the end of the Early Pleistocene. Secondary production was abundant enough to maintain a hunteregatherer population and a rich carnivore guild more diverse than that recorded in the TD6 assemblage. Based on these results, the practice of cannibalism by H. antecessor cannot be explained by a long-term scarcity of resources. High food availability at TD6 implies a low to moderate level of competition for resources between carnivores and humans. According to this interpretation, an empty niche for a highly carnivorous omnivore existed in Europe during the early Galerian, and it was successfully exploited by Homo. Ó 2013 Elsevier Ltd. All rights reserved. Introduction Spielmann (1983), Speth (1989) and Milton (2000) agreed that hominins could have been forced to live on animal matter including The tempo, mode and conditioning of the earliest human set- fat, and most researchers assume that large mammals were a tlement in Europe during the Pleistocene are hotly debated (e.g., common source of meat for hominins during the Early Pleistocene Moncel, 2010; Palombo, in press). Trophic resource availability is (e.g., Binford, 1981, 1985; Marean, 1989; Gaudzinski and Roebroeks, one of the main constraints for the dispersal of any species, and 2000; Roebroeks, 2001; Speth, 2010). Large mammal hunting has there are several reasons to consider meat as a key resource for been documented in Africa at 1.8 Ma (millions of years ago) (Bunn Early Pleistocene hominins. Most recent hunteregatherer societies and Pickering, 2010), and in Europe primary access to carcasses is have a high reliance on animal food (Cordain et al., 2000), and it is evident at Atapuerca, 0.8 Ma (Díez et al., 1999; Saladié et al., 2011). generally accepted that animal resources were also essential to In summary, meat and fat were key resources for Pleistocene Pleistocene hominins in Europe (Roebroeks, 2001; Hublin and hunteregatherer populations even if meat represented only 30% of Richards, 2009). Studies of recent hunteregatherer populations their diet, as observed in some recent hunteregatherers. show that animal resource consumption represents between 30% The ability of hominins to obtain animal resources from their and 60% of their nutritional intake (Jenike, 2001; Leonard et al., environment is conditioned by the abundance of prey, their 2007). Although no consensus has been reached, Speth and ecological characteristics, and the intensity of the competition with carnivores for these resources. Thus, several authors have linked the survival opportunities of the first European hominins to their ability to compete with carnivores. Palombo (2010) proposed that * Corresponding author. E-mail address: [email protected] (J. Rodríguez). competition for prey or carrion with large carnivores, including 1 Temporarily assigned to CENIEH. Pachycrocuta brevirostris (short-face hyaena), Megantereon whitei 0047-2484/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jhevol.2013.02.007 646 G. Rodríguez-Gómez et al. / Journal of Human Evolution 64 (2013) 645e657 and Homotherium latidens, could have delayed human expansion in where hominin remains have been found together with abundant Europe during the Early Pleistocene because the first Homo pop- faunal remains and a rich collection of lithic artifacts. Thus, the TD6 ulations in Europe lacked weapons to successfully confront such assemblage provides both biological information about the first formidable opponents. Accordingly, several authors proposed that European settlers and evidence of their nutritional and cultural the Early Pleistocene European human populations would have activities. We developed a model using Leslie (1945, 1948) matrices, relied on the scavenging of ungulate carcasses in such adverse a tool currently used in population dynamic studies, to refine conditions (Turner, 1992; Martínez-Navarro and Palmqvist, 1996; previous approaches (see above). A main contribution of our model Arribas and Palmqvist, 1999). However, it has also been proposed is that it provides a representation of the age structure of primary that competition for carcasses was very strong in the Early Pleis- consumer populations and a distribution of the available biomass in tocene because of the presence of the large and aggressive giant body size categories. This allowed us to evaluate the effect of hyaena P. brevirostris in the European Faunal Complex (Palombo, several predation pressure intensities on available biomass and to 2010). However, some authors highlight the abundance of scav- better estimate biomass availability for each secondary consumer. engeable food in the European Early Pleistocene ecosystems, Thus, our model provides insights into competition for resources assuming that sabertooths left a large amount of food at a kill among secondary consumers, and the survival opportunities in because machairodontines hunted large ungulates and were ill- southern Europe at the end of the Early Pleistocene for a hominin adapted to break bones (Turner, 1992; Arribas and Palmqvist, with a significant meat component in its diet. In this way, the 1999). In addition, the dental characteristics of M. whitei have hypothesis that human expansion through Europe was limited at been taken as evidence of the inability of this sabertoothed cat to this time by resource availability may be tested. effectively clean the meat from the bones of their prey (Marean, 1989; Martínez-Navarro and Palmqvist, 1995; Palmqvist et al., Materials and methods 1996, 2005, 2007; Arribas and Palmqvist, 1999). With the turnover at the beginning of the Middle Pleistocene, The TD6 ‘Aurora stratum’ assemblage Pachycrocuta and other large carnivores became extinct (Turner, 1992). It has been suggested that the appearance of new carni- The Sierra de Atapuerca includes several archaeological and vores in Europe like Crocuta crocuta and the progressive increase in palaeontological sites, dating from the Early Pleistocene to the herbivore richness enabled human populations to compete more Holocene, which have been excavated since 1981 (Carbonell et al., effectively for carcasses and promoted the expansion of Homo 1999a). For a detailed description of the geology of Sierra de throughout Europe (Palombo, 2010; Rodríguez et al., 2012). An Atapuerca see Parés and Pérez-González (1999) and Pérez- alternative explanation is the replacement of Homo antecessor González et al. (2001). The Gran Dolina (TD) site is a cave infill populations by a new immigrant hominin species (Homo hei- 18-m thick with a stratigraphic sequence of 11 stratigraphic units, delbergensis) with a more advanced technology: the Acheulean named TD1eTD11 from bottom to top (Gil, 1997; Parés and Pérez- (Jiménez-Arenas et al., 2011). González, 1999; Pérez-González et al., 2001). Parés and Pérez- Thus, two factors should be taken into account to evaluate food González (1999) interpreted the palaeomagnetic reversal at the resource availability for early Palaeolithic hunteregatherers: 1) the limit between the TD7 and TD8 layers as the MatuyamaeBrunhes amount of biomass that can be extracted from the populations of boundary. The TD6 unit has a reversed polarity that has been large herbivores, and 2) the intensity of competition within the interpreted as post-Jaramillo (0.990e0.780 Ma) (Parés and Pérez- carnivore guild for those resources. Quantification of the trophic González, 1999; Pérez-González et al., 2001). Radiometric dating relationships within mammalian palaeocommunities may help to of ungulate teeth by ESR/UeTh indicated an average age between evaluate competition strength in past ecosystems and provide es- 780 and 875 ka (thousand years) for TD6 and an age of timations of resource availability for ancient human populations. 731 Æ 63 ka for the ‘Aurora Stratum’ (TD6-2)