Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation

et al. (2011) Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation. PLoS ONE 6(3): e14769. doi:10.1371/journal.pone.0014769 Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation Luca Fiorenza 0 Stefano Benazzi 0 Jeremy Tausch 0 Ottmar Kullmer 0 Timothy G. Bromage 0 Friedemann Schrenk 0 Karen Rosenberg, University of Delaware, United States of America 0 1 Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute , Frankfurt am Main, Germany , 2 Palaeoanthropology Department, Faculty of Arts and Science, University of New England , Armidale , Australia , 3 Department of Anthropology, University of Vienna , Vienna , Austria , 4 Department of Science, Borough of Manhattan Community College , New York , New York, United States of America, 5 Institute of Ecology, Evolution & Diversity, Johann Wolfgang Goethe University , Frankfurt am Main, Germany , 6 Departments of Biomaterials and Biomimetics and Basic Science and Craniofacial Biology, New York University College of Dentistry , New York, New York , United States of America Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. - Neanderthal diet The study of dietary habits together with paleoecological analyses, allow researchers to obtain information regarding subsistence strategies in ancient human populations. In particular, many scientists have attempted to reconstruct the Neanderthal diet using associated faunal remains and lithic industry [13], stable isotope signatures [410] and dental microwear analysis [11]. These techniques suggest that Neanderthals from northern and middle latitudes were primarily active hunters subsisting on large and medium sized herbivores, while the southern Neanderthals from Mediterranean coastlines had a more diversified diet enriched by the exploitation of small animals and marine shellfish [3,1215]. Although a few studies indicate that early Homo sapiens were also active hunters focusing mainly on the consumption of terrestrial herbivores [9,16], the analysis of faunal assemblages, stone tool technologies and stable isotopic studies indicate that early Homo sapiens exploited a broader dietary spectrum than Neanderthals [3,12,1721]. Based on these data, Hockett and Haws [3] suggested that such a restricted diet in Neanderthals was lacking in essential nutrients, which could have increased maternal and fetal-to-infant mortality rates while also decreasing overall life expectancy. However, along Mediterranean coastlines where climatic fluctuations were less severe, isolated glacial refuges possibly existed. These likely would have contained a wide variety of dietary resources that may have enriched the Neanderthal diet and prolonged their survival [14]. Alternatively, a more diversified early Homo sapiens diet could have led to a demographic expansion resulting in increased competition with Neanderthal populations [2,3]. New archaeological and paleontological evidence suggests that Neanderthals probably did, to some extent, exploit broader, more diverse food types. The Middle Paleolithic Mousterian cave deposits of Amud and Kebara (Israel) contain numerous plant fossils such as legumes, pistachios and acorns [2224]. Also, microscopic examination of stone tools found at the Mousterian site of La Quina (France) show evidence of plant processing [25]. Finally, the existence of microfossil plant remains trapped in the dental calculus of Shanidar 3 of northern Iraq also may indicate the dietary intake of plant foods [26]. High Neanderthal dietary variation has also been suggested from dental microwear studies [27,28]. The analysis of buccal microwear has shown that widely distributed Neanderthals from Europe and the near East of the Middle Paleolithic were characterized by heterogeneous microwear patterns. This heterogeny is inferred to have been caused by the exploitation of varied food resources reflecting climatic fluctuations rather than geographic dispersion [27]. Alternatively, a recent study of occlusal microwear indicates strong eco-geographic dietary variation in Neanderthals while also demonstrating the exploitation of a large dietary spectrum [28]. Tooth wear Normal (non-malocclusal) tooth wear is a dynamic, necessary and natural process caused by two main factors: attrition and abrasion [2932]. Attrition is defined as the mechanical wear produced by the contacting surfaces of opposing teeth. Attritional wear produces well-defined highly pitched, flat surfaces called wear facets [3133]. Wear facets are generally created by contact during normal mastication [3436]. However, wear facets can also be produced by other non-masticatory activities such as bruxism (a pathological grinding of the teeth) [33]. Abrasion is produced by the friction of exogenous materials forced over the tooth surfaces [2931]. Some foods themselves are abrasive (seed husks etc.). However, other foreign objects can also cause abrasion such as dust present in the environment or elements accidentally introduced with food preparation [29,31]. Abrasion can also be due to tools used in oral hygiene [30,37]. The action of food on a tooth surface is not anatomically specific; it does not create distinct and localized wear rather occurring over the whole occlusal surface [31]. The masticatory cycle begins with vertical mandibular movements (puncture-crushing), during which time the food is pulped and tooth-to-tooth contact is rare [3841]. This is followed by a rhythmic chewing phase, or power stroke, wherein the attritional contacts between opposing teeth produces wear facets [3841]. The power stroke is divided into two phases: phase I occurs when opposing molar crests shear past one another until the food is crushed (...truncated)