Hominid butchers and biting crocodiles in the African Plio-Pleistocene.

Zooarchaeologists have long relied on linear traces and pits found on the surfaces of ancient bones to infer ancient hominid behaviors such as slicing, chopping, and percussive actions during butchery of mammal carcasses. However, such claims about Plio-Pleistocene hominids rely mostly on very small assemblages of bony remains. Furthermore, recent experiments on trampling animals and biting crocodiles have shown each to be capable of producing mimics of such marks. This equifinality-the creation of similar products by different processes-makes deciphering early archaeological bone assemblages difficult. Bone modifications among Ethiopian Plio-Pleistocene hominid and faunal remains at Asa Issie, Maka, Hadar, and Bouri were reassessed in light of these findings. The results show that crocodiles were important modifiers of these bone assemblages. The relative roles of hominids, mammalian carnivores, and crocodiles in the formation of Oldowan zooarchaeological assemblages will only be accurately revealed by better bounding equifinality. Critical analysis within a consilience-based approach is identified as the pathway forward. More experimental studies and increased archaeological fieldwork aimed at generating adequate samples are now required

3D enamel profilometry reveals faster growth but similar stress severity in Neanderthal versus Homo sapiens teeth

Early life stress disrupts growth and creates horizontal grooves on the tooth surface in humans and other mammals, yet there is no consensus for their quantitative analysis. Linear defects are considered to be nonspecific stress indicators, but evidence suggests that intermittent, severe stressors create deeper defects than chronic, low-level stressors. However, species-specific growth patterns also influence defect morphology, with faster-growing teeth having shallower defects at the population level. Here we describe a method to measure the depth of linear enamel defects and normal growth increments (i.e., perikymata) from high-resolution 3D topographies using confocal profilometry and apply it to a diverse sample of Homo neanderthalensis and H. sapiens anterior teeth. Debate surrounds whether Neanderthals exhibited modern human-like growth patterns in their teeth and other systems, with some researchers suggesting that they experienced more severe childhood stress. Our results suggest that Neanderthals have shallower features than H. sapiens from the Upper Paleolithic, Neolithic, and medieval eras, mirroring the faster growth rates in Neanderthal anterior teeth. However, when defect depth is scaled by perikymata depth to assess their severity, Neolithic humans have less severe defects, while Neanderthals and the other H. sapiens groups show evidence of more severe early life growth disruptions

Ecogeographic variation in Neandertal dietary habits: Evidence from microwear texture analysis

For over 100,000 years, Neandertals inhabited a variety of ecological zones across western Eurasia, between glacial and interglacial conditions. To elucidate the still poorly understood effects of climatic change and variability, and possible competition on the Neandertal subsistence patterns, this study employed dental microwear texture analysis to reconstruct the dietary habits of 54 Neandertal, Pre-Neandertal, and early Upper Paleolithic (EUP) modern human specimens from 28 sites in western Eurasia. Microwear signatures of seven modern hunter-gatherer groups (n = 155) of known and diverse diets were analyzed for comparative purposes. Microwear signatures of Neandertals and Pre-Neandertals are correlated with variation in vegetation-cover, such that individuals from cold-steppe/tundra vegetation had less complex microwear surfaces than those from forested environments. The microwear pattern of the EUP fossils did not differ significantly from those of the Pre-Neandertal groups and northern and central European Neandertals, which suggests that the former had a more varied diet. However, significant differences in microwear signatures were found between the southern European Neandertals and the EUP fossils. In accord with the stable isotope results, microwear analysis classifies Neandertals as top-level carnivores. However, dental microwear analysis detected some subtle dietary differences. Thus, the microwear signatures of Neandertals and Pre-Neandertals from steppe/tundra vegetation are similar to meat-eating Fuegians from comparable habitats, whereas those of Neandertals and pre-Neandertals from forested environments resemble the Chumash, who inhabited a Mediterranean-like environment. Neandertals from the deciduous forests of southern Europe have a microwear signature that falls within the ranges of Australian and African aborigines with mixed diets. EUP fossils have microwear signatures that resemble those of both the modern Chumash and Fuegians

Dietary reconstruction of the El Sidrón Neandertal familial group (Spain) in the context of other Neandertal and modern hunter-gatherer groups. A molar microwear texture analysis

Here, we present the analysis of occlusal molar microwear textures of eight individuals from the El Sidrón Neandertal group (Spain). The aims of the study were: 1) to document potential age-, sex-, and maternal lineage-related differences in diet within a Neandertal familial group, and 2) to place the diet of El Sidrón individuals in the context of those of other Neandertal groups. This study also offers an interpretation of the diet of the El Sidrón Neandertals by comparing their microwear signatures to those of recent hunter-gatherer populations with diverse but known diets. The intra-group examination of the microwear signatures are consistent with the females of the El Sidrón group having had more abrasive diets or having used their teeth in more para-masticatory activities than did the males. Aside from the potential sex-related differences in diet, no additional intra-group dietary separation, such as by age group or maternal lineage, was observed. In comparison to other Neandertals, El Sidrón individuals, as a group, have microwear signatures most similar to those of other Neandertals from wooded habitats and different from those that lived in more open habitats. This result is expected based on the available paleoenvironmental reconstructions from El Sidrón Cave. The diet of the El Sidrón Neandertals, just like their Neandertal counterparts from similar wooded habitats, is interpreted as having been mixed, consisting of both meat and vegetable foods