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.

Violence trends in the ancient Middle East between 12,000 and 400 BCE.

How did interpersonal violence develop in early human societies? Given that homicide records are only available for the more recent period, much of human history remains outside our purview. In this paper, we study violence trends in the very long run by exploiting a new dataset on cranial trauma and weapon-related wounds from skeletons excavated across the Middle East, spanning the pre-Classical period (around 12,000-400 BCE). The dataset includes more than 3,500 individuals. We find evidence that interpersonal violence peaked during the Chalcolithic period (around 4,500-3,300 BCE). It then steadily declined during the Early and Middle Bronze Ages (around 3,300-1,500 BCE) and increased again between the Late Bronze and the Iron Age (1,500-400 BCE). By documenting variations in violence patterns across a vast temporal and geographical scale in an incredibly rich historical setting, we broaden perspectives on the early history of human conflict.

Reconstructing breastfeeding and weaning practices in the Bronze Age Near East using stable nitrogen isotopes.

OBJECTIVES: Breastfeeding and childhood diet have significant impact on morbidity and mortality within a population, and in the ancient Near East, it is possible to compare bioarchaeological reconstruction of breastfeeding and weaning practices with the scant textual evidence. MATERIALS AND METHODS: Nitrogen stable isotopes (δ15 N) are analyzed here for dietary reconstruction in skeletal collections from five Bronze Age (ca. 2,800-1,200 BCE) sites in modern Lebanon and Syria. We employed Bayesian computational modeling on cross-sectional stable isotope data of collagen samples (n = 176) mainly from previous studies to test whether the bioarchaeological evidence aligns with the textual evidence of breastfeeding and weaning practices in the region, as well as compare the estimated weaning times to the global findings using the WARN (weaning age reconstruction with nitrogen isotope analysis) Bayesian model. RESULTS: Though the Near East sites in this study had different ecological settings and economic strategies, we found that weaning was introduced to the five sites at 0.5 ± 0.2 years of age and complete weaning occurred around 2.6 ± 0.3 years of age on using the WARN computational model. These weaning processes are within the time suggested by historical texts, though average estimated weaning age on the Mediterranean coast is later than inland sites. DISCUSSION: Compared globally, these Near Eastern populations initiated the weaning process earlier but completed weaning within the global average. Early initial weaning may have created short spacing between pregnancies and a high impact on demographic growth within these agricultural populations, with some variation in subsistence practices accounting for the inland/coastal discrepancies.

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.

Estimation of collagen presence in dry bone using combined X-ray and neutron radiography.

Thermal neutron radiography and X-ray radiography are characterised by different penetration depths in various materials, for example in collagen and hydroxyapatite, two major components of bone. Neutron radiography penetrates hydroxyapatite easier than collagen and, conversely, in X-ray radiography attenuation is higher in hydroxyapatite than in collagen. This effect allows estimation of collagen presence in dry bone. In our study we show that differences between the two imaging methods are sufficient to produce significant results when bone areas with higher and lower content of collagen are being compared.

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.

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.

A possible "grinder" from Tell Arbid, Syria.

ABSTRACT: Cereal grinding has been practiced in Mesopotamia since the Upper Palaeolithic. While evidence of cereal grinding is clear from the archaeological and textual records, what remains unclear is whether the activity leaves signs on the skeleton in the form of markers of occupational stress (MOS). A particular constellation of MOS (e.g., osteoarthritis, traumatic injuries, and accessory articular facets) has previously been used to infer the habitual grinding of grain. These same MOS were recently observed in the skeleton of a female discovered in the Middle Bronze Age cemetery at Tell Arbid, NE Syria. Through differential diagnosis our results suggest that it remains problematic to identify grain-processing activities from the skeleton, even when a bioarchaeological approach is carried out.

Isotope evidence for agricultural extensification reveals how the world's first cities were fed.

This study sheds light on the agricultural economy that underpinned the emergence of the first urban centres in northern Mesopotamia. Using δ13C and δ15N values of crop remains from the sites of Tell Sabi Abyad, Tell Zeidan, Hamoukar, Tell Brak and Tell Leilan (6500-2000 cal bc), we reveal that labour-intensive practices such as manuring/middening and water management formed an integral part of the agricultural strategy from the seventh millennium bc. Increased agricultural production to support growing urban populations was achieved by cultivation of larger areas of land, entailing lower manure/midden inputs per unit area-extensification. Our findings paint a nuanced picture of the role of agricultural production in new forms of political centralization. The shift towards lower-input farming most plausibly developed gradually at a household level, but the increased importance of land-based wealth constituted a key potential source of political power, providing the possibility for greater bureaucratic control and contributing to the wider societal changes that accompanied urbanization.

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.

Early urbanization and mobility at Tell Brak, NE Syria: the evidence from femoral and tibial external shaft shape.

Urbanization at Tell Brak began in the late 5th millennium BCE and the site reached its maximum size in the Late Chalcolithic (LC) 3, ca. 3900-3600 BCE. During that time, a large midden was formed at the edge of the early city, now known as Tell Majnuna. Rescue excavations at Tell Majnuna revealed several clusters of commingled human remains and a cemetery on the top. Several human skeletons dated to the LC 3 and Early Bronze Age (EBA) were found also at Tell Brak itself and it was possible to investigate differences in cross-sectional femoral and tibial shaft shapes between LC 3 and EBA to test the hypothesis that rapid and extensive urbanization in the LC 3 induced increase in mobility. External midshaft and subtrochanteric measurements of at least 152 femora and measurements of 55 tibiae at the nutrient foramen were taken to investigate the differences in the level of terrestrial mobility between four LC 3 and one EBA chronological subsets. Also the correlation was examined between shaft cross-sectional shapes and frequency of linear enamel hypoplasia (LEH) in canines, as a proxy indicator of population stress. Due to post-mortem damage, sex assessment was based only on the size of measured bones. In spite of the limited quality of the gathered data, significant differences in femoral midshaft shape in males were observed between the LC 3 and EBA subsets and the average shape index scores appeared to be correlated with the LEH frequencies. No such result was obtained for females, suggesting that only males were more mobile in the LC 3 and their mobility level was associated with general population stress. In contrast, in females the average shape of subtrochanteric femoral cross-section was more variable between temporal subsets. The patterns of temporal differences in tibial cross-section at the nutrient foramen were not conclusive due to the small sample size. Obtained results suggest that males in the LC 3, the period of rapid urbanization, were more mobile than in the EBA, when the population size was considerably smaller. This mobility may have been related to need of searching for alternative resources for the overpopulated early city.

Technical note: false catastrophic age-at-death profiles in commingled bone deposits.

Age-at-death profiles obtained using the minimum number of individuals (MNI) for mass deposits of commingled human remains may be biased by over-representation of subadult individuals. A computer simulation designed in the R environment has shown that this effect may lead to misinterpretation of such samples even in cases where the completeness rate is relatively high. The simulation demonstrates that the use of the Most Likely Number of Individuals (MLNI) substantially reduces this bias.

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.