Strontium Isotopes from the Earth to the Archaeological Skeleton: A Review

Strontium isotope analysis of archaeological skeletons has provided useful and exciting results in archaeology in the last 20 years, particularly by characterizing past human migration and mobility. This review covers the biogeochemical background, including the origin of strontium isotope compositions in rocks, weathering and hydrologic cycles that transport strontium, and biopurification of strontium from to soils, to plants, to animals and finally into the human skeleton, which is subject to diagenesis after burial. Spatial heterogeneity and mixing relations must often be accounted for, rather than simply ``matching' a measured strontium isotope value to a presumed single-valued geologic source. The successes, limitations and future potential of the strontium isotope technique are illustrated through case studies from geochemistry, biogeochemistry, ecology and archaeology.

Stable Carbon and Oxygen Isotope Spacing Between Bone and Tooth Collagen and Hydroxyapatite in Human Archaeological Remains

Spacing between stable isotope values in bones and teeth is a valuable tool for examining dietary influences and diagenesis. This study examines carbon and oxygen isotope values from collagen and hydroxyapatite (structural carbonate and phosphate) in archaeological human bones and teeth to derive species‐specific correlation equations and isotope spacing values. The δ¹³C_collagen and δ¹³C_{structural carbonate} in bone and dentin collagen show a strong correlation (R = 0.87, 0.90, respectively) with an average Δ¹³C_carb‐coll spacing of 5.4‰. The consistency of this isotope spacing with other large mammals and in humans with both low and high protein intake (as indicated by enriched δ¹⁵N values) suggests a similar allocation of protein‐derived carbon and whole diet‐derived carbon to collagen and structural carbonates, respectively, as other terrestrial mammals regardless of absolute meat intake. The δ¹⁸O_{structural carbonate} and δ¹⁸O_phosphate show the strongest correlation in enamel (R = 0.65), weaker correlations in dentin (R = 0.59) and bone (R = 0.35), with an average Δ¹⁸O_carb‐phos of 7.8‰. This isotope spacing is slightly lower than previously reported for large mammals and limited available data for humans. The results potentially indicate species‐specific fractionations and differing access to body water and blood‐dissolved inorganic carbonates in the presence of collagen formation. The use of correlation between δ¹⁸O_{structural carbonate} and δ¹⁸O_phosphate to determine diagenetic state is not recommended. The strength of this correlation observed in bones and teeth is variable and alternate indicators of diagenetic state (i.e. C:N ratios of collagen) provide more robust and independent evidence of isotope preservation despite presence/absence of a strong isotope correlation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Molar crown height: not always a reliable method for the evaluation of age-at-death

In this study, we tested the validity of molar crown height, which changes according to the degree of tooth wear, for the evaluation of age-at-death. The sample consisted of 372 first and second molars (lower and upper) from 157 individuals of known sex and age-at-death. For each molar, we measured the height of the two cusps most subjected to wear (protocone and hypocone for the upper M1 and M2; protoconid and hypoconid for the lower M1 and M2). The correlation between crown height and age-at-death was assessed by linear regression analysis. The resulting models were not very robust since a significant correlation was only found for a small part of the sample, at best (maxillary M1) around 35%. The result slightly improved when bucco-lingual diameter (BL diameter), ante-mortem tooth loss and dental caries were considered, mainly for the maxillary M2 for which the model using age-at-death and BL diameter as independent variables explained 47% of the sample (p < 0.001).     

Age attribution in domestic sheep by skeletal and dental maturation: A pilot study of available sources

The aim of the study was to assess the quality of the available evidence pertaining to the effects of sex and castration on the timing of skeletal and dental maturation in sheep. The initial premise was that our present knowldge of the effects of these factors is inadequate, and that currently available published sources and reference specimens are insufficient to allow confident interpretation of archaeological data. A literature survey was carried out, and adequately documented sheep skeletons in a number of major collections were recorded. The results show that the published evidence is contradictory and ambiguous, particularly with regard to the effects of castration, and that currently available reference material is mostly too diverse in origin and in quality of documentation to allow comparison of well-controlled samples. Some evidence was found to suggest that castration may delay epiphysial fusion during the second year, without delaying fusion of earlier- and later-fusing elements. Overall, it is concluded that much of the received wisdom on skeletal maturation in sheep is poorly founded and unreliable, and that tightly controlled test populations are needed if better data are to be obtained.     

Sex assessment of medieval Norwegian skeletons based on permanent tooth crown size

The excavation of the Library site in Trondheim uncovered the medieval cemetry of St. Olav's church containing 388 skeletons, of which 248 had skulls with teeth. Sex assessment was based on osteological criteria, and for 145 skeletons sex classification was performed with a high degree of certainty. The remaining 103 were classified as uncertain male, uncertain female and sex undetermined. Mesio-distal and facio-lingual crown widths of permanent teeth in the group of reliably assessed males and females were used in sex-discriminant analyses. A combination of two or more teeth was less effective in discrimination than using one tooth alone. This was due to missing data in the combined variable sets and thereby loss of cases. Missing variables were due to post-mortem tooth loss, attrition or large deposits of calculus. The teeth were ranked according to their power in sex discrimination. The left maxillary first molar (26) represented by its facio-lingual dimension was the best sex discriminator (classified 85 per cent of the cases correctly), followed by the right maxillary first molar (16) also represented by its facio-lingual dimension (classified 77 per cent correctly). With only one variable in the discriminant function, a critical value could be calculated and tabulated for each tooth. This was used in sex assessment of the osteologically undetermined and uncertain groups. Only variables that could sex classify correctly at least 70 per cent of the cases with the Jack-knife procedure were used. Sex assessment could be made for 16 of 24 (66.7 per cent) of the osteologically sex-undetermined adult individuals and for 21 of 44 (47.7 per cent) of the children. Of 35 osteologically uncertainly sex-assessed skulls, only nine (six men and three women) corresponded with dental classification.     

Dama Dentition: A New Tooth Eruption and Wear Method for Assessing the Age of Fallow Deer (Dama dama)

Reliable ageing techniques for wild animals are notoriously challenging to develop because of the scarcity of sizeable collections of known‐age specimens. Without such techniques it is difficult to reconstruct hunting patterns, which is a significant problem for the examination of assemblages from pre‐farming cultures. This paper presents a new method, based on mandibular tooth eruption and wear, for assessing the age of fallow deer. The method was developed from a large collection (n = 156) of known‐age Dama dama specimens, has been blind tested by members of the zooarchaeological community and represents a user‐friendly system with the potential to generate large compatible datasets through which the dynamics of human–Dama relationships can be examined. Copyright © 2016 John Wiley & Sons, Ltd.     

Exceptional rates of dental caries in a scandinavian Early Iron Age population—A study of dental pathology at Alvastra, Östergötland,Sweden

The dental status of Early Iron Age agricultural populations in Sweden has not been extensively documented. The aim of this study was to record caries status in human remains from an Early Iron Age burial ground, Smörkullen, at Alvastra, Östergötland, Sweden. The study included 96 adults and 50 subadults and comprised 1794 permanent teeth in the adults and 468 permanent and 221 deciduous teeth in the subadults. The caries frequency was exceptionally high, afflicting most of the adults (92.6%): 46.2% of the teeth examined showed signs of caries disease. Most of the lesions were shallow. However, around 60% of the adult individuals had moderate and severe lesions, which probably had an immediate impact on health. Lesions were most common in the cervical region and this is probably related to dietary patterns where the starchy, sticky food tended to accumulate around the necks of the teeth. Children showed low caries frequency, whereas most juveniles (91.7%) were affected. Most of the teeth with alveolar bone loss showed no signs of cervical or root caries lesions. However, in cases of moderate and severe loss of alveolar bone, seen mostly in the older age group, the frequency of cervical and root lesions was higher. Few initial caries lesions were observed, indicating an aggressive pattern of disease in this population. The lack of gender‐related differences suggests that the diet was similar for both sexes, across all age groups. Copyright © 2010 John Wiley & Sons, Ltd.     

Dental disease evidence for agricultural intensification in the Nubian C-Group

The results of this study reveal significantly greater frequencies of caries, periapical abscesses and ante-mortem tooth loss in the Lower Nubian C-Group (ca. 2000–1500 BC) compared with the preceding Classic/Terminal A-Group (ca. 3100–2500 BC). More severe tooth wear in the C-Group, which traditionally would be interpreted as consistent with a hunting-gathering subsistence base, can instead be attributed to grit in the diet resulting from the processing of agricultural produce with sandstone and quartzite mortars and grinding stones, and perhaps also to the intentional addition of grit to grain in order to facilitate grinding. The results of this study, when evaluated in the context of complementary archaeological and osteological evidence, indicate that both groups practised a mixed economy but that the C-Group relied more heavily on cereal cultivation.