Neanderthal behaviour, diet, and disease inferred from ancient DNA in dental calculus.

Recent genomic data have revealed multiple interactions between Neanderthals and modern humans, but there is currently little genetic evidence regarding Neanderthal behaviour, diet, or disease. Here we describe the shotgun-sequencing of ancient DNA from five specimens of Neanderthal calcified dental plaque (calculus) and the characterization of regional differences in Neanderthal ecology. At Spy cave, Belgium, Neanderthal diet was heavily meat based and included woolly rhinoceros and wild sheep (mouflon), characteristic of a steppe environment. In contrast, no meat was detected in the diet of Neanderthals from El Sidrón cave, Spain, and dietary components of mushrooms, pine nuts, and moss reflected forest gathering. Differences in diet were also linked to an overall shift in the oral bacterial community (microbiota) and suggested that meat consumption contributed to substantial variation within Neanderthal microbiota. Evidence for self-medication was detected in an El Sidrón Neanderthal with a dental abscess and a chronic gastrointestinal pathogen (Enterocytozoon bieneusi). Metagenomic data from this individual also contained a nearly complete genome of the archaeal commensal Methanobrevibacter oralis (10.2× depth of coverage)-the oldest draft microbial genome generated to date, at around 48,000 years old. DNA preserved within dental calculus represents a notable source of information about the behaviour and health of ancient hominin specimens, as well as a unique system that is useful for the study of long-term microbial evolution.

Stable isotopic evidence for land use patterns in the Middle Euphrates Valley, Syria.

OBJECTIVES: Stable carbon and nitrogen isotope ratios (δ13 C and δ15 N) were used to reconstruct the history of subsistence strategies in the middle Euphrates valley, NE Syria, in six temporal subsets dating from the Early Bronze Age (c. 2300 BCE) to the Modern period (19th/20th century CE). The study aims to demonstrate that changes in political and social organization over time, for which the archaeological record suggests different goals of land use and modes of production, register through dietary patterns that are reflected in isotopic data. MATERIALS AND METHODS: 173 dentin samples were taken from human individuals buried at three sites (Tell Ashara, Tell Masaikh and Gebel Mashtale) together with 15 animal bone samples. Distribution of the δ13 C and δ15 N values in collagen was interpreted in diachronic perspective, and with regard to lifetime shifts between childhood and adolescence. RESULTS: Diachronically, isotope signatures indicate a clear decrease in δ15 N values accompanied by a small shift in δ13 C values between the Old Babylonian (c. 1800-1600 BCE) and the Neo-Assyrian (c. 850-600 BCE) subsets. A major shift in δ13 C values occurred between the Early Islamic (c. 600-1200 CE) and Modern (c. 1800-1950) periods. Ontogenetic changes only occur in a few individuals, but these suggest change of residence between childhood and adolescence. DISCUSSION: The depletion in 15 N from the Neo-Assyrian period onwards is best explained in terms of a shift from intensive to extensive farming, triggered by the fall of regional city-states after the Old Babylonian period and the formation of large supra-regional polities in the Neo-Assyrian period and later. The enrichment in 13 C during the Modern period was most likely the effect of more widely utilizing the dry steppes, abundant in C4 plants, as pasture.

Temporal pattern of dental caries at the western flank of the Central Plateau of Iran, c. 2700 BCE - 1600 CE.

OBJECTIVE: To analyze the overall frequency and inter-tooth patterns of caries in three populations from ancient cemeteries located along the western border of the Central Iranian Plateau as a means to explore whether the populations of Iran had greater access to fermentable sugars after the establishment of the great empires. MATERIALS: Dental collections from Kafarved-Varzaneh (Early Bronze Age, MNI=66), Estark-Joshaqan (Iron Age, MNI=57), Tappeh Poustchi (Timurid and Safavid Period, MNI=34), together with comparative data from NE Syria. METHODS: Frequencies of dental caries per tooth categories, location and size of carious lesions are analyzed using Smith's Mean Measure of Divergence, Correspondence Analysis, χ2 and Kruskal-Wallis tests. RESULTS: There are minimal differences in overall frequencies of carious lesions at Iranian sites, regardless of the chronology, but notable differences at Syrian sites. The inter-tooth pattern at the Iron Age cemetery in Estark appears distinctly different than the other Iranian sites and the comparative samples from Syria. CONCLUSIONS: Divergent subsistence strategies may be linked with different inter-tooth patterns since people buried at Estark were mobile herders, while the other cemeteries were used by settled farmers. SIGNIFICANCE: This comprehensive research on dental caries in three chronologically diverse populations in Iran sheds light on the association between dental caries and subsistence strategies, and introduces the Smith's Mean Measure of Divergence to explore inter-tooth carious patterns, which may prove useful to other researchers seeking to understand the relationships between subsistence, diet, and the presence of carious lesions. LIMITATIONS: The studied sample size is relatively small and therefore its temporal/regional distribution produces low-resolution results. SUGGESTIONS FOR FURTHER RESEARCH: More systematic research on the patterns of dental caries is necessary to produce more fine-grained reconstructions of diet and subsistence in Iran and around the globe.

Neutron radiography as a diagnostic tool in human osteology.

X-ray radiography (XR) is a standard imaging tool in human osteology. Here we compare a series of human bone and tooth images taken using both X-ray and thermal neutron radiography (TNR) to identify the possible applications of the latter method. The TNR imaging is superior in case of bones contaminated with soil, and combined TNR and XR images may be used to find the areas with high proportion of organic fraction (i.e., collagen) in bone and dentin.

Dental erosion in archaeological human remains: A critical review of literature and proposal of a differential diagnosis protocol.

OBJECTIVE: Although studies of dental wear on archaeological human remains have largely focused on mechanical wear (attrition and abrasion) in the past, chemical wear (erosion) is being increasingly identified as a separate form of wear. This paper aims to review the current state of research and to develop a protocol that may be universally used by biorchaeologists to specifically identify dental erosion. DESIGN AND RESULTS: A critical review of literature has been done in order to highlight the issues related to diagnosis of dental erosion in archaeological human remains. The bodies of work based on the analysis of both modern and archaeological dentitions raise their separate problems. In addition to a need to re-evaluate symptoms of dental erosion, notably dentin 'cupping', it is apparent that no specific protocol is adapted from medical to archaeological sciences. Authors rather rely on tooth wear indices and photographs of modern clinical cases for diagnosis. Furthermore, the diagenetic chemical alternation has rarely been considered as a bias. CONCLUSIONS: Here we suggest a three-step protocol: the primary method is the microscopic identification of dental erosion by SEM, followed by the exclusion of taphonomic aetiology on surrounding bone and soil pH analysis. Archaeologists should also explore possible causative agents of wear using archaeological and historic knowledge about the population being analyzed.

Population history of the middle Euphrates valley: dental non-metric traits at Tell Ashara, Tell Masaikh and Jebel Mashtale, Syria.

Fifty-nine dental non-metric traits were scored using Arizona State University Dental Anthropology System on a sample of teeth from 350 human skeletons excavated at three sites in the lower middle Euphrates valley. The dataset was divided into six chronological subsets: Early Bronze Age, Middle Bronze Age, Early Iron Age with Neo-Assyrian period, Classical/Late Antiquity, Early Islamic (Umayyad and Abbasid) period and Modern period. The matrix of Mean Measure of Divergence values exhibited temporal homogeneity of the sample with only dental non-metric trait scores in the Modern subset differing significantly from most other subsets. Such a result suggests that no major gene flow occurred in the middle Euphrates valley between the 3rd millennium BCE and the early 2nd millennium CE. Only after the Mongolian invasion and large depopulation of northern Mesopotamia in the 13th century CE a major population change occurred when the area was taken over in the 17th century by Bedouin tribes from the Arabian Peninsula.

Sequencing ancient calcified dental plaque shows changes in oral microbiota with dietary shifts of the Neolithic and Industrial revolutions.

The importance of commensal microbes for human health is increasingly recognized, yet the impacts of evolutionary changes in human diet and culture on commensal microbiota remain almost unknown. Two of the greatest dietary shifts in human evolution involved the adoption of carbohydrate-rich Neolithic (farming) diets (beginning ∼10,000 years before the present) and the more recent advent of industrially processed flour and sugar (in ∼1850). Here, we show that calcified dental plaque (dental calculus) on ancient teeth preserves a detailed genetic record throughout this period. Data from 34 early European skeletons indicate that the transition from hunter-gatherer to farming shifted the oral microbial community to a disease-associated configuration. The composition of oral microbiota remained unexpectedly constant between Neolithic and medieval times, after which (the now ubiquitous) cariogenic bacteria became dominant, apparently during the Industrial Revolution. Modern oral microbiotic ecosystems are markedly less diverse than historic populations, which might be contributing to chronic oral (and other) disease in postindustrial lifestyles.

Comment: low dental caries rate in Neandertals: the result of diet or the oral flora composition?

Dental caries is an infectious disease caused by oral acidophilic bacteria feeding on fermentable sugars, e.g. Streptococcus mutans. The frequency of dental caries in Neandertals was very low. This was usually explained as the result of a low-sugar diet. Recent research, however, revealed some regional differences between European and Near Eastern Neandertals, with the latter consuming considerable amounts of plants including highly cariogenic dates. This discovery, compared with the results of research on genetic diversity of S. mutans, may suggest that this species, and perhaps other most virulent species, were absent in the oral flora of Neandertals.