I had the great privilege of contributing to a new article published in PLOS ONE yesterday that was coordinated by my colleague, Dr. Kristin Krueger, of Loyola University Chicago. The piece has been summarized nicely by Katherine J. Wu at PBS NOVA. I provide a short summary and a few additional thoughts here. Neandertal and early modern human anterior tooth-use Reconstructions of Neandertal behavior frequently call attention to their anterior tooth (incisor and canine) wear. Some incredible examples of extreme anterior dental wear are documented among some of the earliest well-published Neandertal fossils (for example: La Ferrassie and Forbe's Quarry) and the iconic photo by Erik Trinkaus of Shanidar 1's anterior dental wear (see below) is widely used to illustrate the phenomenon. This high degree of wear in the front teeth is most frequently interpreted as evidence that Neandertals used their "teeth-as-tools" or as a "third hand" regularly. In fact, it's often rare not to see a behavioral reconstruction of Neandertal that doesn't depict them using their "teeth as tools" in a museum display, artistic reconstruction, and television popular science documentaries. Above left: Shanidar 1 Neandertal with heavy anterior tooth wear (Photo: Erik Trinkaus). Above right: Artistic reconstruction of a Neandertal using its anterior teeth (as a "third hand") to clamp down on a piece of meat while they cut it into smaller pieces using a stone tool with their free hand. This behavior is also routinely called "stuff and cut" - a phrase that can be attributed to C. Loring Brace. Above: Artistic reconstruction of a Neandertal group from El Sidron Cave featuring a Neandertal woman using her teeth to assist in hide scraping activities. Another behavior that leaves traces on teeth is the use of toothpicks which I discuss elsewhere. Artwork by Emmanuel Roudier. The robust build of Neandertal skulls and their large anterior teeth are a stark contrast to the smaller teeth and more gracile skulls of modern humans. These morphological differences were coupled with the observations of heavy anterior dental wear, and many researchers saw aspects of Neandertal cranial and dental morphology as adaptations that helped dissipate the high bite forces and/or repetitive loading of the anterior teeth and face when engaging in the use of teeth-as-tools. This "Anterior Dental Loading Hypothesis" has held a prominent position in Neandertal research. But why use your teeth as tools? The technological capacities of the Neandertals were (and often still are) considered impoverished or inferior to those of Upper Paleolithic early modern humans. Thus, early modern humans were thought to possess a degree of technological ingenuity that reduced morphological selection for the robust cranial and dental features found in Neandertals and their predecessors. The anterior dental loading hypothesis and ideas of "Neandertal inferiority/modern human superiority" have been challenged on a number of grounds. However, dental wear can provide direct evidence for how the anterior dentition was used among Neandertals and early modern humans. However, few studies directly compare Neandertals and early modern human dental wear, and none have used dental microwear texture analysis to test these ideas. Above: The Shanidar 1 Neandertal (left) compared to an early modern human from Předmostí (right). Many cranial features, and the front teeth in particular, are quite large and "robustly built" in Neandertals but reduced in size and "gracile" in early modern humans. This is where our new paper jumps into the discussion. The research, coordinated by Dr. Krueger, uses dental microwear texture analysis of the surfaces of anterior teeth to explore similarities and differences in Neandertal and early modern human tooth-using behaviors. The results were surprising given the amount of previous research emphasizing behavioral and morphological differences between the two groups. We compared Neandertal and early modern human anterior dental microwear textures to each other as well as to a large comparative databases for human groups with considerable variation in temporal, ecological, geographic, and cultural backgrounds (see map below). While I have written elsewhere about how molar microwear texture can be used to reconstruct diets in Homo sapiens and Neandertals, the microwear textures on the anterior teeth are somewhat different. Incisors and canines are not only involved in the breakdown of food but are frequently used in a variety of non-dietary tasks. Therefore, dental wear on front teeth is a palimpsest of behavioral signatures related to dietary and non-dietary (using the “teeth-as-tools”) behaviors as well as various environmental factors (often related to the presence or absence of grit and dust). The excellent contextual information available for the human groups used for comparative purposes includes information on the diet, non-dietary behaviors, environment, and other factors that we use to interpret the results obtained for the Neandertals and early modern humans. Above: Map showing the location of human groups used to compare and contextuale the dental microwear texture results for Neandertals and early modern humans. Map is from Krueger 2015. Interestingly, we found that the Neandertals and early modern humans exhibited very similar anterior dental microwear texture results. The values for both of these Pleistocene human groups were closest to those of the Point Hope Tigara hunter-gatherers from Alaska in our comparative sample. The Tigara are known to have used their anterior teeth in a variety of non-dietary, clamping and grasping behaviors such as as processing/softening animal hides and working sinew into thread. Thus, one way of interpreting the data for Neandertals and early modern humans were engaging in a similar range of clamping and grasping behaviors with the front teeth. Clothing and hide processing are reasonable behaviors documented in bioarchaeological and ethnohistoric contexts. Above: Scatter plot of Neandertal and early modern human dental microwear texture values (Tfv = textural fill volume & epLsar = anisotropy) with 95% confidence interval ellipses. Note the extensive overlap in variation. Above: Means and 95% confidence intervals for textural fill volume (Tfv) and anisotropy (epLsar) for the Neandertal, early modern human, and Holocene/ethnohistoric comparative groups. Note the closeness of the means Tigara group to the Pleistocene humans. The colloquial meaning of "neandertal" reflects the long-held notion of a major behavioral gap that separates the Neandertals from "us". However, the scientific and public perception of the Neandertals is undergoing a sort of renaissance at present. Many behaviors once associated with modern humans - like the controlled use of fire or creation of cave art and personal ornaments - are now documented in Neandertal contexts. The dental evidence presented here is also significant given the long-held view that Neandertals relied so heavily on their bodies, teeth, and brawn over technological and cultural solutions to complete their daily activities whereas early modern humans were thought to use brains, culture, and technology over brawn. However, the dental evidence tells a different story - there's little noticeable difference between the Neandertals and early modern humans in terms of tooth-using behaviors. I am of the opinion that the presumption of a major behavioral gap has persisted for so long because early modern humans were so infrequently compared directly to Neandertals in so many analyses. Instead, Holocene and/or ethnohistoric peoples were generally used (and sometimes still are) as proxies for early modern humans from the Pleistocene. While it should be obvious that historical and contemporary hunter-gatherers from disparate locations (common examples come from East and South Africa, the Arctic, and Australia) are not equivalent to Ice Age hunter-gatherers from Europe, uncritical comparisons were (and occasionally still are) the norm in paleoanthropological research. The work presented here shows how direct comparisons between Neandertals and early modern humans blur the divisions once thought to exist for anterior tooth-using behaviors. Whereas the data from recent human groups can be used to refine interpretations of Pleistocene behavior rather than be used as proxies for the early modern human behavior. Lastly, this publication is available freely (open access) and all data is freely downloadable in the online supplemental information. This was a really fun piece to contribute to and I am really proud of how it turned out. Many thanks to the first author for the chance to collaborate! Really looking forward to seeing what research Dr. Krueger sinks her teeth into next.... References FREE FREE FREE DOWNLOAD!
Krueger KL, Willman JC, Matthews GJ, Hublin J-J, and Pérez-Pérez A. 2019. Anterior tooth-use behaviors among early modern humans and Neandertals. PLOS ONE 14(11):e0224573, doi.org/10.1371/journal.pone.0224573. Krueger KL. 2015. Reconstructing diet and behavior in bioarchaeological groups using incisor microwear texture analysis. Journal of Archaeological Science: Reports 1:29-37, http://dx.doi.org/10.1016/j.jasrep.2014.10.002. Krueger KL, and Ungar PS. 2009. Incisor microwear textures of five bioarcheological groups. International Journal of Osteoarchaeology 20(5):549-560, dx.doi.org/10.1002/oa.1093. Krueger KL, Ungar PS, Guatelli-Steinberg D, Hublin J-J, Pérez-Pérez A, Trinkaus E, and Willman JC. 2017. Anterior dental microwear textures show habitat-driven variability in Neandertal behavior. Journal of Human Evolution 105:13-23, http://dx.doi.org/10.1016/j.jhevol.2017.01.004.
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John C. Willman
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