Stable isotope analysis has become an essential tool in investigations of ancient migration and paleodietary reconstruction. Because the biogeochemistry of bone collagen and apatite is well known,... Show moreStable isotope analysis has become an essential tool in investigations of ancient migration and paleodietary reconstruction. Because the biogeochemistry of bone collagen and apatite is well known, current methods rely almost exclusively on analyses of bones and teeth; however, dental calculus represents a potentially additional biological source of isotopic data from ancient skeletons. Dental calculus is a mineralized bacterial biofilm that forms on the surfaces of teeth. Sampling dental calculus does not damage the dentition and thus can be used in cases where it is not possible to perform destructive analyses of conventional mineralized tissues. Like bone and dentine, dental calculus contains both inorganic and organic components, allowing measurement of C, N, O, H, and Sr isotopes. Additionally, dental calculus forms as serial, non-remodeling laminar accretions on the tooth surface, opening up the possibility of analyzing discrete time points during the lifetime of an individual. However, as a microbial biofilm and not a human tissue, the biochemistry of dental calculus is complex, containing multiple calcium phosphate mineral phases, organic and inorganic food remains, hundreds of human and bacterial proteins, and diverse biomolecules from thousands of endogenous bacterial taxa. Isotopic investigation of dental calculus is still in its infancy, and many questions remain regarding its formation and processes of diagenesis. This chapter (1) reviews the unique advantages presented by dental calculus as a novel source of biological isotopic data, (2) critically evaluates published isotopic studies of dental calculus, and (3) explores the current challenges of dental calculus stable isotope analysis through a case study of an Ancient Puebloan Basketmaker II population from the American Southwest. Show less
Industrialization—including urbanization, participation in the global food chain and consumption of heavily processed foods—is thought to drive substantial shifts in the human microbiome. While... Show moreIndustrialization—including urbanization, participation in the global food chain and consumption of heavily processed foods—is thought to drive substantial shifts in the human microbiome. While diet strongly influences stool microbiome composition, the influence of diet on the oral microbiome is largely speculative. Multiple ecologically distinct surfaces in the mouth, each harbouring a unique microbial community, pose a challenge to assessing changes in the oral microbiome in the context of industrialization, as the results depend on the oral site under study. Here, we investigated whether microbial communities of dental plaque, the dense biofilm on non-shedding tooth surfaces, are distinctly different across populations with dissimilar subsistence strategies and degree of industrialized market integration. Using a metagenomic approach, we compared the dental plaque microbiomes of Baka foragers and Nzime subsistence agriculturalists in Cameroon (n = 46) with the dental plaque and calculus microbiomes of highly industrialized populations in North America and Europe (n = 38). We found that differences in microbial taxonomic composition between populations were minimal, with high conservation of abundant microbial taxa and no significant differences in microbial diversity related to dietary practices. Instead, we find that the major source of variation in dental plaque microbial species composition is related to tooth location and oxygen availability, which may be influenced by toothbrushing or other dental hygiene measures. Our results support that dental plaque, in contrast to the stool microbiome, maintains an inherent stability against ecological perturbations in the oral environment. Show less
Background: Leucine-rich repeat kinase 2 (LRRK2) inhibition is a promising therapeutic approach for the treatment of Parkinson's disease (PD).Objective: The aim of this study was to evaluate the... Show moreBackground: Leucine-rich repeat kinase 2 (LRRK2) inhibition is a promising therapeutic approach for the treatment of Parkinson's disease (PD).Objective: The aim of this study was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of the potent, selective, CNS-penetrant LRRK2 inhibitor BIIB122 (DNL151) in healthy participants and patients with PD.Methods: Two randomized, double-blind, placebo-controlled studies were completed. The phase 1 study (DNLI-C-0001) evaluated single and multiple doses of BIIB122 for up to 28 days in healthy participants. The phase 1b study (DNLI-C-0003) evaluated BIIB122 for 28 days in patients with mild to moderate PD. The primary objectives were to investigate the safety, tolerability, and plasma pharmacokinetics of BIIB122. Pharmacodynamic outcomes included peripheral and central target inhibition and lysosomal pathway engagement biomarkers.Results: A total of 186/184 healthy participants (146/145 BIIB122, 40/39 placebo) and 36/36 patients (26/26 BIIB122, 10/10 placebo) were randomized/treated in the phase 1 and phase 1b studies, respectively. In both studies, BIIB122 was generally well tolerated; no serious adverse events were reported, and the majority of treatment-emergent adverse events were mild. BIIB122 cerebrospinal fluid/unbound plasma concentration ratio was similar to 1 (range, 0.7-1.8). Dose-dependent median reductions from baseline were observed in whole-blood phosphorylated serine 935 LRRK2 (<= 98%), peripheral blood mononuclear cell phosphorylated threonine 73 pRab10 (<= 93%), cerebrospinal fluid total LRRK2 (<= 50%), and urine bis (monoacylglycerol) phosphate (<= 74%).Conclusions: At generally safe and well-tolerated doses, BIIB122 achieved substantial peripheral LRRK2 kinase inhibition and modulation of lysosomal pathways downstream of LRRK2, with evidence of CNS distribution and target inhibition. These studies support continued investigation of LRRK2 inhibition with BIIB122 for the treatment of PD. (c) 2023 Denali Therapeutics Inc and The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. Show less
Mammalian mastication represents a vital initial step in digestion with any change in its relative energetic cost detracting from the net energy gain from foods. Although the energetic efficiency... Show moreMammalian mastication represents a vital initial step in digestion with any change in its relative energetic cost detracting from the net energy gain from foods. Although the energetic efficiency of masticatory effort is one of the fundamental concepts through which the functional morphology and evolution of the human masticatory system is explored, nothing is known currently about the associated metabolic costs and how this is influenced by the item being chewed. Here, using respirometry and electromyography of M. masseter, we demonstrate that chewing by human subjects represents a measurable energy sink. Chewing a tasteless odorless gum elevates metabolic rate by 10-15% above basal levels. The energy expenditure increases with gum stiffness and is paid for by greater muscle recruitment. For modern humans it is likely that mastication represents a small part of the daily energy budget. However, for our ancestors, before the onset of cooking and sophisticated food processing methods, the costs must have been relatively high, adding a novel energetic dimension to the interpretation of hominin dentofacial fossils. Show less
Dental calculus has proven to contain a wealth of information on the dietary habits of past populations. These insights have, to a large extent, been obtained by the extraction and identification... Show moreDental calculus has proven to contain a wealth of information on the dietary habits of past populations. These insights have, to a large extent, been obtained by the extraction and identification of starch granules contained within the mineralised dental plaque from a wide range of regions and time periods. The scope of previous studies have been limited to microfossil extraction and identification to reconstruct dietary preferences from the archaeological record, and few studies have attempted to address the biases of starch retention in dental calculus. Those that have considered this problem have been limited to in vivo studies on modern humans and non-human primates. Here, we present a multispecies oral biofilm model, which allows experimental research on starch incorporation and retention to be conducted on in vitro dental calculus in a controlled laboratory setting. The biofilms were exposed to treatment solutions with known quantities of dietary starches (wheat and potato) during the 25 days growth period. After this, the starch granules were extracted from the mature biofilm (by dissolution in EDTA), and counted. We show that the granule counts extracted from the model dental calculus represented a low proportion (ranging from 0.06% to 0.16%) of the total number of granules exposed to the biofilms throughout the experiment. Additionally, we found that the ratios of granule sizes from the extracted starch granules differed from the original treatment solutions, with large granules (>20 μm) consistently being under-represented. We also found a positive correlation between the absolute granule counts and dry-weight of the biofilm (r = 0.659, 90%CI[0.463, 0.794]), meaning the absolute quantity of starch granules will increase as the size of the calculus deposit increases. A similar, but weaker correlation was found between the concentration (count per mg) of granules and dry-weight (r = 0.3, 90%CI[0.0618, 0.506]). Our results complement and reinforce previous in vivo studies suggesting that dental calculus presents a very small, and partly biased picture of the original dietary intake of starches, with an over-representation of plants producing granules smaller than 20 μm in size. The experimental model presented here is well-suited to address the need for further validation of methods and biases associated with dietary research on dental calculus. Show less
Among archaeological micro-remains, starches can be used as a tool for reconstructing past environments, diets, and trade patterns through the identification of the plants collected and consumed by... Show moreAmong archaeological micro-remains, starches can be used as a tool for reconstructing past environments, diets, and trade patterns through the identification of the plants collected and consumed by ancient populations. Starch grains preserved in dental calculus and on stone tools have been recovered from archaeological material from sites around the world. However, the ability to identify archaeological starch grains relies on having a broad (i.e., many taxa) and deep (i.e., many individuals from the same taxon) reference collection from modern plants. Only a small handful of such reference collections have been published, and thus far none have been created for taxa from the Eastern Mediterranean. This region is rich in plants that have been used for their starch-rich seeds and roots since prehistory, and many of the wild taxa are the progenitors of domesticated species that were cultivated in the Neolithic and remain economically important today. To help document the history of human interactions with these plant taxa, we present here a reference collection based on the analysis of 220 individual plant parts (e.g., seeds, tubers) from 188 modern Levantine plant species (both wild and domestic), and three non-native plants that are frequently found as modern contamination. Of the examined plant samples, 110 from 106 taxa (species and subspecies) contained starches. We also provide a key based on this collection to aid in the identification of archaeological starch remains. Show less
The evolutionary history of the modern human dietary repertoire is a major research challenge. However, for various reasons, existing information about ancient diets is heavily biased towards the... Show moreThe evolutionary history of the modern human dietary repertoire is a major research challenge. However, for various reasons, existing information about ancient diets is heavily biased towards the consumption of animal foods. Plants are known to be important components of modern hunter-gather diets, and the inclusion of plant foods and the development of processing technologies have been implicated in grade shifts within the hominin lineage. Using a behavioral ecology framework, the ERC-funded HARVEST project has asked: What types of plants did hominins eat, and why did they choose the ones they did? Analyses of microremains and residues preserved in dental calculus has provided a snapshot of the kinds of foods consumed. We have furthermore developed a model dental calculus system that allows us to develop new analytical methods and address hidden biases associated with the extraction and analysis of microremains. Our studies of food preferences and energetic costs of various subsistence-related behaviors among the Baka have highlighted the interactions between cultural mores, individual preferences, and energetic constraints. Our analysis of variation in plant properties among microhabitats in African environments similar to those used by hominins has allowed us better model what nutritional qualities drive their food choices. Finally, we have assessed how the energetic costs of fire might influence food processing choices. Results from these studies have indicated that plants were an essential part of the hominin dietary repertoire throughout our evolutionary history, and that the consumption of plants is determined by environmental, caloric, cultural, and personal influences. Show less
Dental calculus is increasingly used by researchers looking at diet in past populations. These studies employ a range of methods including microscopy, and DNA and protein extraction. Despite the... Show moreDental calculus is increasingly used by researchers looking at diet in past populations. These studies employ a range of methods including microscopy, and DNA and protein extraction. Despite the promise of these methods little attention has been given to the potential biases associated with the accumulation of dietary compounds into dental calculus during the lifetime of an individual. Our recently-developed oral biofilm model has the potential to elucidate these biases by growing in vitro dental calculus in a controlled environment. Here we report on one validation test of the system, which explored whether our model calculus mineralizes in a manner similar to actual calculus. FTIR was conducted on multiple samples across 25 days of model calculus growth. Results show an overall increase in the inorganic component relative to organic over the course of the experiment. This is especially evident in the hydroxyapatite peak at 1040 and doublet at 605 and 565 wave-numbers (cm -1), and a reduction in intensities of the peaks at 1546 and 1654 wavenumbers (cm-1). IR splitting factors (IRSF) ranged from 2.38–3.30, indicating a similar level of crystallinity to modern human-derived calculus samples (IRSF 3.46–3.76). The final model calculus consisted mainly of carbonated hydroxyapatite, the principal component of real calculus, although with a higher organic component than the comparative modern samples. This and prior validation of the model dental calculus suggests that it is a viable method to supplement the analysis of fossil dental calculus. Show less
Williams, F.L.; Schmidt, C.W.; Henry, A.G.; Droke, J.L.; Becam, G.; De Lumley, M.A. 2022
Neandertals are characterized as highly carnivorous from nitrogen isotopes and fauna remains. However, it has become increasingly clear that plants also were included in their diets, even during... Show moreNeandertals are characterized as highly carnivorous from nitrogen isotopes and fauna remains. However, it has become increasingly clear that plants also were included in their diets, even during challenging environmental conditions. Southwest France during late Marine Isotope Stage (MIS) 4 and early MIS 3 was a particularly cold and arid time interval associated with open steppe habitat dominated by reindeer, which were hunted by the Neandertals of La Quina cave. One of these individuals, La Quina 5, is examined using dental microwear texture analysis (DMTA) and plant microremain analysis to reconstruct the diet. Reference samples for the DMTA include Hortus (n " 5), Krapina (n " 19), Malarnaud, Spy I, Vindija (n " 4), as well as Holocene Homo sapiens having various subsistence strategies (n " 150). For the plant microremain analysis, we compared La Quina 5 to Spy I and II, Shanidar III, La Ferrassie and a modern reference sample. La Quina 5 may have relied signi ܪcantly on hunted resources in the cold glacial interval of Heinrich Stadial 6 or 5, indicated by a low complexity value that suggests limited hard food consumption. Plant microremains, such as starch grains from grass seeds and plant underground storage organs, are evidenced in the dental calculus. These coarse and poorly processed plant foods were masticated using varied movements of the jaws compared to most other Neandertals, reflected in the low anisotropy of La Quina 5. These findings emphasize the consumption of plant foods in Neandertal diets even during Ice Age climate extremes. Show less
Power, R.C.; Henry, A.G.; Moosmann, J.; Beckmann, F.; Temming, H.; Roberts, A.; Le Cabec, A. 2022
Purpose: Dental calculus forms on teeth during the life of an individual and its investigation can yield information about diet, health status, and environmental pollution. Currently, the... Show morePurpose: Dental calculus forms on teeth during the life of an individual and its investigation can yield information about diet, health status, and environmental pollution. Currently, the analytical techniques used to visualize the internal structure of human dental calculus and entrapped inclusions are limited and require destructive sampling, which cannot always be justified.Approach: We used propagation phase-contrast synchrotron radiation micro-computed tomography (PPC-SR-μCT) to non-destructively examine the internal organization of dental calculus, including its microstructure and entrapped inclusions, on both modern and archeological samples.Results: The virtual histological exploration of the samples shows that PPC-SR-μCT is a powerful approach to visualize the internal organization of dental calculus. We identified several important features, including previously undetected negative imprints of enamel and dentine growth markers (perikymata and periradicular bands, respectively), the non-contiguous structure of calculus layers with multiple voids, and entrapped plant remains.Conclusions: PPC-SR-μCT is an effective technique to explore dental calculus structural organization, and is especially powerful for enabling the identification of inclusions. The non-destructive nature of synchrotron tomography helps protect samples for future research. However, the irregular layers and frequent voids reveal a high heterogeneity and variability within calculus, with implications for research focusing on inclusions. Show less
What present-day foragers do for their living and what they eat have long been privileged areas for exploring human behavior, global health, and human evolution. While many studies have focused on... Show moreWhat present-day foragers do for their living and what they eat have long been privileged areas for exploring human behavior, global health, and human evolution. While many studies have focused on hunting and meat acquisition, less attention has been given to gathering and plant foods. Despite evidence of variation in both nutritional quality and energetic costs of gathering different plants, the overall effort spent on gathering in relation to other subsistence tasks is still under explored. In the current context of economic, climate, and social changes, many forager societies also rely on other subsistence strategies, including agriculture and wage labor. In this study, we aim to explore the place of gathering in the livelihood of a mixed economy society, the Baka forager-horticulturalists of southeastern Cameroon, by comparing the involvement and the costs of activities related to food acquisition. From a pool of 153 adult participants (97 women and 56 men), we collected 246 daily records using a GPS (Global Positioning System) tracker combined with heart rate monitor and time allocation recalls. We compared the duration, distance traveled, and the intensity of work, measured by calculating the metabolic equivalent of task (MET), of subsistence activities related to food acquisition. Results from this work show that gathering activities, performed by both women and men, are energetically costly, with higher MET values than hunting and fishing activities. Furthermore, the MET values vary depending on the targeted plant foods. We discuss these insights in the overall framework of subsistence patterns, merging them with the socio-cultural and environmental factors that might explain Baka livelihood and subsistence strategy. Show less
The founding processes of the first state of ancient China with a known written record, the Shang dynasty (3600-3046 cal BP), have been poorly understood. Recent discoveries of a host of... Show moreThe founding processes of the first state of ancient China with a known written record, the Shang dynasty (3600-3046 cal BP), have been poorly understood. Recent discoveries of a host of archaeological sites dating to the proto-Shang culture (4000-3600 cal BP) have helped elucidate the transition to the Shang culture. Nevertheless, there are few investigations about the mode of subsistence and economy of the proto-Shang culture, and how this might have shaped the transition to statehood. In this present study, we analyzed the starch grains preserved in dental calculus and teeth surfaces from 16 samples from the site of Nancheng in order to gain a better understanding of the subsistence strategy and plant consumption of proto-Shang people. We also performed experiments to test how different cooking methods may lead to size changes in the starches of four Poaceae plants, in order to identify the processing methods used by the proto-Shang people. The results indicate that Triticum aestivum, Coix lacryma-jobi, Setaria italica and some yet-unidentified roots and tubers were consumed by these individuals. These data indicate a broader spectrum of plant consumption than that seen by previous archaeobotanical and stable isotope analyses. Such a broad spectrum of plant consumption provided a substantial economic base for proto-Shang people and might be one of the factors supporting the subsequent development of the Shang state culture. Show less
The founding processes of the first state of ancient China with a known written record, the Shang dynasty (3600-3046 cal BP), have been poorly understood. Recent discoveries of a host of... Show moreThe founding processes of the first state of ancient China with a known written record, the Shang dynasty (3600-3046 cal BP), have been poorly understood. Recent discoveries of a host of archaeological sites dating to the proto-Shang culture (4000-3600 cal BP) have helped elucidate the transition to the Shang culture. Nevertheless, there are few investigations about the mode of subsistence and economy of the proto-Shang culture, and how this might have shaped the transition to statehood. In this present study, we analyzed the starch grains preserved in dental calculus and teeth surfaces from 16 samples from the site of Nancheng in order to gain a better understanding of the subsistence strategy and plant consumption of proto-Shang people. We also performed experiments to test how different cooking methods may lead to size changes in the starches of four Poaceae plants, in order to identify the processing methods used by the proto-Shang people. The results indicate that Triticum aestivum, Coix lacryma-jobi, Setaria italica and some yet-unidentified roots and tubers were consumed by these individuals. These data indicate a broader spectrum of plant consumption than that seen by previous archaeobotanical and stable isotope analyses. Such a broad spectrum of plant consumption provided a substantial economic base for proto-Shang people and might be one of the factors supporting the subsequent development of the Shang state culture. Show less
Neanderthals are known primarily from their habitation of Western Eurasia, but they also populated large expanses of Northern Asia for thousands of years. Owing to a sparse archaeological record,... Show moreNeanderthals are known primarily from their habitation of Western Eurasia, but they also populated large expanses of Northern Asia for thousands of years. Owing to a sparse archaeological record, relatively little is known about these eastern Neanderthal populations. Unlike in their western range, there are limited zooarchaeological and paleobotanical studies that inform us about the nature of their subsistence. Here, we perform a combined analysis of carbon and nitrogen stable isotopes on bone collagen and microbotanical remains in dental calculus to reconstruct the diet of eastern Neanderthals at Chagyrskaya Cave in the Altai Mountains of Southern Siberia, Russia. Stable isotopes identify one individual as possessing a high trophic level due to the hunting of large- and medium-sized ungulates, while the analysis of dental calculus also indicates the presence of plants in the diet of this individual and others from the site. These findings indicate eastern Neanderthals may have had broadly similar subsistence patterns to those elsewhere in their range. Show less
