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Sr-87/Sr-86 ratios in modern and fossil food-webs of the Sterkfontein Valley: Implications for early hominid habitat preference
Abstract
This research addresses the potential contribution of strontium isotopes to the reconstruction of early hominid behavior at the Swartkrans site in the Sterkfontein Valley of Gauteng Provence (formally known as the Transvaal), South Africa. We report that, while there is considerable variability in the 87Sr/86Sr of whole soils within a 15 km radius of this site, available soil and grassland plant 87Sr/86Sr is much less variable and generally above 0.730. This value is higher (more radiogenic) than the 87Sr/86Sr of plants growing within the greenbelt surrounding the Blaaubank stream adjacent to Swartkrans and streamwater itself (0.721).The difference between grassland and riparian strontium isotope composition suggests a method for determining habitat utilization by early hominids. In this study, a geological explanation for a natural difference between Blaaubank stream and grassland Sr is suggested, based on relatively less radiogenic Sr (having lower 87Sr/86Sr values) in the carbonate component of the local dolomite when compared to other nearby geological formations. The explanation was tested initially using a top-down approach in which the 87Sr/86Sr ratios of water, soil, and plants from the entire Blaaubank catchment were measured. Next, a bottom-up approach was used to examine Swartkrans Member I faunal species known to have obtained their Sr from well-defined habitats.The results are that (1) pollution is not the explanation for the relatively low 87Sr/86Sr ratios of the Blaaubank stream, (2) Swartkrans Member I carbonate has a similar 87Sr/86Sr to that of modern Blaaubank water, indicating that relationships seen today existed in the Pleistocene, and (3) Pleistocene riparian fauna have relatively low 87Sr/86Sr ratios when compared to fauna adapted to drier habitats. Together these results make it possible to interpret the strontium isotope composition of Pleistocene early hominids from Swartkrans in terms of habitat utilization.
... The purpose of this study is to infer likely dispersal patterns for South African hominins and to compare these with previous dispersal reconstructions. To do this, we use a novel analytical method, recently validated in a modern primate community (Hamilton et al., 2021), to infer sex-biased dispersal based on previously published strontium isotope ratios from hominin tooth enamel and local plants (Balter et al., 2012;Copeland et al., 2011;Sillen et al., 1998). ...
... Later geological work by Dirks et al. (2016) cast doubt on the rapid erosion rate of the dolomite and suggested instead that the land surface in the Cradle of Humankind has not changed by much in the last few million years. In agreement with this, the majority of fauna reported in Copeland et al. (2011), Balter et al. (2012 and Sillen et al. (1998) have strontium isotope values that fall below the range for the Timeball Hill shale and above that of the Karoo. Given this lack of isotopic matching, even in small rodents, it is unlikely that Timeball Hill and Karoo Supergroup outcrops formed a central part of the Swartkrans/Sterkfontein hominin home range. ...
... The presence of these riprian forests is important in our interpretation of isotopic results. Animals with a preference for food found in riparian areas can differ in their strontium isotope ratios (Hamilton et al., 2019;Sillen et al., 1998) because of geochemical dynamics unique to those riparian zones. The isotopic composition of surface water is primarily due to chemical weathering (Capo et al., 1998); because some minerals dissolve more readily than others, flowing water often does not have an isotope signature that matches the underlying bedrock. ...
... Although bedrock Sr is the ultimate source of Sr to Earth surface systems, its isotopic composition can differ substantially from that of soils, surface water and organisms due to factors such as variation in weathering rates for different minerals or inputs from other sources such as atmospheric aerosols Stewart et al., 1998;Bentley, 2006;Chadwick et al., 2009). For constraining the isotopic variations in source of Sr for provenance studies it is most appropriate to model the "biologically available Sr" as an approximation of the Sr actually assimilated by organisms (Sillen et al., 1998;Price et al., 2002;Hodell et al., 2004;Frei and Frei, 2011). In this regard, a theoretical steady state and time dependent model predicting 87 Sr/ 86 Sr evolution in "biologically available Sr" has been developed . ...
... The maps predict large variations at a range of spatial resolutions, which are promising for provenance studies. Nevertheless, the 87 Sr/ 86 Sr prediction in water could be improved by considering the potential contribution of non-bedrock sources of Sr to water (Sillen et al., 1998;Stewart et al., 1998). In our validation process, we demonstrated the importance of accounting for the contribution of Sr-rich minerals (calcite, dolomite and celestite) because they often buffer the 87 Sr/ 86 Sr of whole rivers. ...
The geographical authentication in the agrifood industry has become a major issue to guarantee the quality of food products. Olive oil (OO) is particularly a complex matrix and establishing a reliable approach for linking OO samples to their origin is an analytical challenge. In this study, the isotopic composition of carbon, strontium and the concentrations of seventeen elements were determined in OOs from Tunisia, Southern France and the South Basque country. The preliminary results overlapped and showed that, taken individually, the isotopic and elemental approaches were not discriminant. A linear discriminant analysis applied to δ13C, 87Sr/86Sr and to the concentrations of 4 selected trace elements (Fe, Mn, V and Cr) allowed to classify, with high resolution, olive oils into 3 groups according to their provenance. The combination of the plant growing environment, the geological background, the mineral composition of the soil and the production process lead to a novel approach to deal with fraudulent practices in OO sector.
... For example, a difference in the isotope values of bones and teeth from the same individual that form at different stages of life indicate whether he or she migrated from isotopically distinct regions in the intervening period between tissue formation (Agarwal 2016;Buikstra et al. 2004;Hrnčíř and Laffoon 2019;Montgomery 2010;Montgomery et al. 2000;Schroeder et al. 2009;Schweissing and Grupe 2003;White et al. 2000). Individuals with isotopic values that fall beyond the range of local baseline values developed from archaeological and modern flora, fauna, water, and geological samples (Grimstead et al. 2017;Hodell et al. 2004;Lachniet and Patterson 2009;Makarewicz and Sealy 2015;Price et al. 2002;Sillen et al. 1998) Price et al. 2007Price et al. , 2008Price et al. , 2010 are also interpreted as having moved to their place of burial. When baseline and comparative human isotopic data from other sites are unavailable, nonlocal individuals may also be identified as those whose isotopic values are statistical outliers from the human data set of interest (Burton and Hahn 2016:119; The postmortem alteration of the chemical composition of bone, or diagenesis, is another concern in isotopic studies of human movement, as interpretations are dependent on the preservation of biogenic (i.e., those formed during life) isotope values. ...
... Nonlocal individuals may also be identified as having bone and/or tooth enamel isotope values that differ from the isotopic baselines established for the burial location (see Grimstead et al. 2017). While isotopic baselines may be developed by analyzing modern geology, soil, plant, and water samples, bioavailable values are more accurately assessed by analyzing modern and archaeological animal tissues (Grimstead et al. 2017;Makarewicz and Sealy 2015;Price et al. 2002;Sillen et al. 1998). A baseline is conventionally developed by calculating the mean and two standard deviations of organic and inorganic environmental samples, and nonlocal individuals are identified as those who fall beyond this range (Price et al. 2002). ...
The Maya who inhabited southeastern Mesoamerica from the Preclassic to Colonial periods (1000 BCE to 1821 CE) have been the focus of intensive archaeological study for
over a century. Recent theoretical and methodological developments have contributed to
nuanced understandings of Maya migration and subsistence practices. Stable sulfur isotope (δ34S) analysis of bone collagen is a novel technique that has been applied to Maya skeletal collections, although the variation in environmental δ34S values throughout the Maya region has yet to be systematically characterized. This research presents the first Maya faunal sulfur isotope baseline based on the δ34S values of 148 archaeological faunal remains from 13 sites in the Northern and Southern Lowlands. As expected, terrestrial animals in coastal areas had elevated δ34S due to sea spray. However, those from inland sites had unexpectedly high δ34S values that varied depending on the age of the underlying limestone. Although the δ34S values of marine animals were lower than expected, similarly low values in freshwater animals permits the differentiation of freshwater and terrestrial animals at inland sites. These data demonstrate that sufficient variation in δ34S values exists in the Maya region to identify sources of protein and nonlocal animals, which speaks to prehispanic Maya animal exchange and interregional interaction. The δ34S values of 49 humans from seven Maya sites ranging from the Preclassic to Colonial periods were also interpreted using the faunal baseline. The spatial distribution of human δ34S values differed from that of the terrestrial fauna, demonstrating sociocultural variation in Maya resource procurement in addition to underlying environmental influences. A comparison of carbon and nitrogen data from the same individuals also revealed the consumption of protein from different catchments. Nonlocal δ34S values show three individuals migrated near the end of their lives, and when integrated with childhood strontium and oxygen isotope data from
tooth enamel, demonstrate a more robust means of investigating the length of residence and potentially the extent of integration into the receiving community. Finally, a case study of the prehispanic Maya from Nakum, Guatemala, demonstrates the contributions of stable sulfur isotope analysis to the interpretation of Maya subsistence strategies and migration when integrated into a multi-isotopic approach.
... In contrast, the Middle, East, and South regions are marked by lower 87 Sr/ 86 Sr ratios (Tables S1 and S2, Figures 2 and 3), which could be related to the influx of extrinsic sediment from the Cavally and Sassandra rivers (Goldstein & Jacobsen, 1987). Indeed, water-related weathering and erosion, which affect the Sr concentration in river runoff, can result in lower 87 Sr/ 86 Sr ratios in riparian environments (Capo et al., 1998;Sillen et al., 1998).While there are some inselbergs in South, and East territories, we suggest that the environmental 87 Sr/ 86 Sr ratios are possibly driven by increased weathering related to several small river systems (Figures 2b and 3;Luncz et al., 2016). Particularly in East territory, we know of well-documented offshoots of the Cavally River, which could influence the distinct pattern in 87 Sr/ 86 Sr ratios observed in this area (Hamilton et al., 2019;Poszwa et al., 2002;Poszwa et al., 2004). ...
Objectives
Chimpanzees ( Pan troglodytes ) are patrilocal, with males remaining in their natal community and females dispersing when they reach sexual maturity. However, the details of female chimpanzee dispersal, such as their possible origin, are difficult to assess, even in habituated communities. This study investigates the utility of ⁸⁷ Sr/ ⁸⁶ Sr analysis for (1) assessing Sr baseline differences between chimpanzee territories and (2) identifying the status (immigrant or natal) of females of unknown origin within the territories of five neighboring communities in Taï National Park (Côte d'Ivoire).
Materials and Methods
To create a local Sr isoscape for the Taï Chimpanzee Project (TCP) study area, we sampled environmental samples from TCP‐established territories ( n = 35). To assess dispersal patterns, 34 tooth enamel samples (one per individual) were selected from the Taï chimpanzee skeletal collection. ⁸⁷ Sr/ ⁸⁶ Sr analysis was performed on all 69 samples at the W.M. Keck Lab. The theoretical density and overlap of chimpanzee communities as well as generalized linear mixed models (GLMMs) were used to test each question.
Results
⁸⁷ Sr/ ⁸⁶ Sr ratios for natal male chimpanzees ranged from 0.71662 to 0.72187, which is well within the corresponding environmental baseline range of 0.70774–0.73460. The local Sr isoscapes fit was estimated with the root‐mean‐square error value, which was 0.0048 (22% of the whole ⁸⁷ Sr/ ⁸⁶ Sr data range). GLMMs identified significant differences in ⁸⁷ Sr/ ⁸⁶ Sr ratios between natal and unknown North community origin groups, suggesting that after 1980, females of unknown origin could be immigrants to North community ( n = 7, z ‐ratio = −4.08, p = 0.0001, power = 0.94).
Discussion
This study indicates that ⁸⁷ Sr/ ⁸⁶ This study indicates that ⁸⁷ Sr/ ⁸⁶ Sr analysis can successfully identify immigrant females in skeletal collections obtained from wild chimpanzee communities, enabling the tracking of female dispersal patterns historically. There are, however, significant limitations within the scope of this study, such as (1) the absence of reliable maps for the TCP study area, (2) limited capacity for environmental sampling, (3) small sample sizes, and (4) tooth formation in wild chimpanzees.
... However, relying solely on geologic substrates is problematic because these minerals can exhibit considerable isotopic variability within a single area, and these ratios alone do not account for other, environmental inputs from dust or water (Krom et al., 1999;Price et al., 2002). Alternatively, measuring strontium from the hydroxyapatite of local plant-consuming fauna across a limited geographic area generates a homogenized average of bioavailable strontium in a given region, from which a mean ratio, ±2 SD around this mean, provides an estimate for expected local 87 Sr/ 86 Sr ratios for human communities residing in the same area (Grupe et al., 1997;Koch et al., 1992;Price et al., 2002;Sillen et al., 1998). Further, as 87 Rb possesses a lengthy half-life (4.7 Â 10 10 years) so that almost no change in strontium isotope ratios has occurred over hundreds of thousands of years (Ezzo & Price, 2002;Faure, 1986), both archeological and modern fauna may be used to evaluate bioavailable strontium. ...
Objectives:
The Kingdom of Kush in today's northern Sudan and southern Egypt (ancient Nubia) is often depicted as a secondary state relative to ancient Egypt. More recent investigations have set aside Egyptocentric and western, colonialist perspectives of state development focused on control of land and agricultural surplus, examining Kushites through the lens of African-based models of mobile pastoralism in which power and authority were achieved through control of herds and alliance-building. Here, analyses of radiogenic strontium isotopes in human dental enamel are used to investigate diachronic shifts in mobility patterns linked to pastoralism and state development during the Kerma period (ca. 2500-1100 BCE).
Materials and methods:
From five cemetery sites around al Qinifab, Sudan, upstream of the capital at Kerma, we analyzed the strontium isotope ratios of 50 teeth from 27 individuals dating from the Early through Late Kerma phases.
Results:
Individuals from the Early and Middle Kerma phases demonstrated considerable 87 Sr/86 Sr ratio variability (mean = 0.70835 ± 0.00109), with 50% falling outside the locally bioavailable strontium range. Conversely, most Classic (0.70756 ± 0.00043) and Late Kerma (0.70755 ± 0.00036) individuals exhibited ratios consistent with the local region.
Discussion:
These changes indicate a potential transformation in subsistence strategies and social organization as early communities engaged in a more mobile lifestyle than later groups, suggesting a greater degree of pastoralism followed by declining mobility with Kushite state coalescence and a shift to agropastoralism. Because 87 Sr/86 Sr ratios from enamel reflect childhood geographic residence, these findings indicate that mobility likely involved extended family groups, and not just transhumant adults.
... The abundance of 87 Sr and of 86 Sr varies locally, depending on the age of the underlying bedrock and other factors. Plants growing on these soils take up this local Sr signature and accordingly reflect the characteristic isotope ratio, which then enters the local food chain (Bentley, 2006;Evans et al., 2010;Sillen et al., 1998). Comparing the 87 Sr/ 86 Sr of human bone with the locally occurring value recorded in modern plants, makes it possible to investigate mobility, in which the 87 Sr/ 86 Sr in the skeleton reflects the 87 Sr/ 86 Sr of the ingested food of the last decades or so in life, depending on the skeletal element and other factors (Montgomery, 2010;Price et al., 2002). ...
Urnfields were the common type of cemetery in the Late Bronze Age (LBA) and Early Iron Age (EIA) in much of Northwest Europe. Rarely are there clear social or chronological differences between burials apart from changing pottery types. The cemetery of Destelbergen stands out because of the relatively high prevalence of monumental ditches surrounding a selection of graves, indicating a certain status difference between the deceased. Strontium concentrations ([Sr]) combined with radiocarbon (14 C) dates and spatial analysis bring to light clear differences between LBA and EIA traditions. The end of the LBA went hand in hand with the abandonment of the oldest part of the cemetery, which new 14 C dates demonstrate was strict. Additionally, [Sr] reveal changing diets in individuals buried centrally within monumental ditches. In the EIA these individuals present significantly lower [Sr] than the surrounding burials, potentially the result of a diet richer in animal protein at the expense of plant-based food, a distinction not seen in LBA burials. Even though continuity and equality are reflected in the uniform burial tradition seen within urnfields, this paper's analyses unlock subtle changes in social attitudes between the LBA and EIA and suggest increasing (dietary) social differentiation in the EIA.
... Although Sr found within bedrock is the ultimate source of Sr to Earth surface systems, its 87 Sr/ 86 Sr signature can differ significantly from that of soils, surface water, and organisms due to many features at the local scale, such as variation in weathering rates for different minerals, the local soil pH, animal behavior, or possible input from aeolian sources (Bentley 2006;Chadwick et al. 1999;Stewart et al. 1998). For provenance investigations, it is most appropriate to model the "biologically available Sr" as an approximation of the Sr that is incorporated by organisms (Frei and Frei 2011;Hodell et al. 2004;Price et al. 2002;Sillen et al. 1998). ...
The impact of the climate drying during the Holocene within the Nile River Valley System (NRVS) has been the focus of recent debate in the archaeological community. It is argued that the increased contribution of aeolian material from the neighboring Sahara Desert during the last ~7,000 years has changed the isotope compositions of bioavailable Sr relative to the geological background and thus hinders provenance investigations of human remains within the NRVS. This study reports new trace element and strontium (Sr), neodymium (Nd), and lead (Pb) isotope compositions for a combined total of 125 samples consisting of human tooth enamel and various faunal samples from different time periods, and present-day botanical samples from 11 archaeological sites along the NRVS. The new isotope data combined with published data do not support a time-dependent increase in a Saharan aeolian bioavailable Sr component during the Holocene within the NRVS; in general, Sr isotope compositions for human enamel samples match those of their corresponding faunal matrices, and these define a similar range of isotope compositions over the various time periods. The Nd and Pb isotope compositions for human tooth enamel reported here also support the limited contribution of Saharan aeolian dust within the NVRS.
... In addition, atmospheric inputs in the form of wet (rainfall, sea spray) and dry (aeolian dust) deposition, glacial deposition, and agricultural fertilizers also contribute to the exchangeable Sr pool in soils (e. g., Capo et al., 1998;Hartman and Richards, 2014;Holt et al., 2021;Pett-Ridge et al., 2009;Hedman et al., 2009). Therefore, despite major influence from the substrate, the bioavailable 87 Sr/ 86 Sr in soils (and by extension, the terrestrial biosphere) does not exactly mirror the bedrock's isotopic value (Bentley, 2006), and substantial disparities in Sr isotopes among whole rocks, bulk soil, and the exchangeable fraction in soils may occur Sillen et al., 1998). The labile Sr in soils is taken up by plants and enters the food chain. ...
Bioavailable Sr and detrital Nd isotopes are important tools for archaeological provenance. To apply Sr and Nd isotopes for provenance, regional isotope databases and baselines are generally needed. For the vast Silk Road regions of Mesopotamia, Iran, and Central Asia, detailed isotopic distribution patterns essential for determining provenance may not become available in the short term due to the severe deficiency of available data. In the present work, we investigate the geo-environmental factors controlling the Sr and Nd isotopic signatures and use published data from archaeology and Earth sciences, selected by rigorous criteria, to construct the first large-scale, semi-quantitative Sr–Nd isotope baseline for these Silk Road regions. Three isotopic zones are proposed for Central Asia: CA-1 (mountains), εNd < −7.5, ⁸⁷Sr/⁸⁶Sr > 0.7095; CA-2 (deserts), εNd = −5 to −2, ⁸⁷Sr/⁸⁶Sr ∼ 0.709; CA-3 (loess), εNd = −5 to −2, ⁸⁷Sr/⁸⁶Sr > 0.710. General isotopic signatures are suggested for Iran: εNd = −8 to −4, ⁸⁷Sr/⁸⁶Sr = 0.7075–0.7090. Three isotopic zones are proposed for Mesopotamia: MP-1 (floodplain and foothill), εNd = −6.5 to −4 (putative extended range MP-1N, εNd = −8 to −6), ⁸⁷Sr/⁸⁶Sr = 0.7080–0.7085; MP-2 (deserts), εNd < −8, ⁸⁷Sr/⁸⁶Sr > 0.7085; MP-3 (Syrian Euphrates), εNd = −5.5 to −2, ⁸⁷Sr/⁸⁶Sr = 0.7080–0.7085. Within the limitation of available data, these ranges indicate the overall trend of bioavailable Sr and detrital Nd isotopic signatures for each isotopic zone, which are controlled by their geological context, climate (e.g., precipitation), and various Earth surface processes (e.g., riverine versus aeolian transport). This baseline can be used as an essential guide for geochemical contexts to suggest or verify the provenance of plant-ash glass, serving as part of an integrative Sr–Nd isotopic approach. We illustrate the potential of this approach using two case studies. By investigating the isotopic compositions of Mesopotamian plant-ash glass, we suggest possible northern Mesopotamian origins for plant ash and silica raw materials used for Mesopotamian glass-making. By reassessing medieval plant-ash glass from San Lorenzo, Italy, we propose diverse origins including Central Asia and Mesopotamia. Additionally, as part of this isotopic approach, by examining the Nd isotope mixing lines in the context provided by the Nd isotope baseline, we reveal the occurrence of glass recycling for Islamic plant-ash glass from different production zones in association with a westward spread from Mesopotamia to the Eastern Mediterranean metropolises.
... In addition, the contribution of different minerals to the soil pool is variable due to e.g. differential weathering, Sr/Rb content and solubility (Sillen et al., 1998). For example, the contribution of Sr-rich carbonates to the local bioavailable reservoir is much larger than e.g. a more resistant to weathering Sr-rich silicate. ...
We present a novel database of environmental and geological 87Sr/86Sr values (n = 1920) from Italy, using literature data and newly analysed samples, for provenance purposes. We collected both bioavailable and non-bioavailable (i.e. rocks and bulk soils) data to attain a broader view of the Sr isotope variability of the Italian peninsula. These data were used to build isotope variability maps, namely isoscapes, through Kriging interpolations. We employed two different Kriging models, namely Ordinary Kriging and Universal Kriging, with a geolithological map of Italy categorized in isotope classes as external predictor. Model performances were evaluated through a 10-fold cross validation, yielding accurate 87Sr/86Sr predictions with root mean squared errors (RMSE) ranging between 0.0020 and 0.0024, dependent on the Kriging model and the sample class. Overall, the produced maps highlight a heterogeneous distribution of the 87Sr/86Sr across Italy, with the highest radiogenic values (>0.71) mainly localized in three areas, namely the Alps (Northern Italy), the Tuscany/Latium (Central Italy) and Calabria/Sicily (Southern Italy) magmatic/metamorphic terrains. The rest of the peninsula is characterized by values ranging between 0.707 and 0.710, mostly linked to sedimentary geological units of mixed nature. Finally, we took advantage of the case study of Fratta Polesine, to underscore the importance of choosing appropriate samples when building the local isoscape and of exploring different end-members when interpreting the local Sr isotope variability in mobility and provenance studies. Our user-friendly maps and database are freely accessible through the Geonode platform and will be updated over time to offer a state-of-the-art reference in mobility and provenance studies across the Italian landscape.
... Strontium isotope ratios ( Sr/ Sr) are an increasingly widely used tool for establishing provenience, as strontium is incorporated into plant and animal tissues without fractionation, thus recording the bioavailable sources of geological and marine strontium (i.e., the "local signature") (Bentley 2006). Although there are few studies that have directly addressed questions of human diets, Sr/ Sr is useful for reconstructing the movement of wild and domestic animals (and humans) across the landscape throughout the year, through serial analysis of tissues that grow incrementally, namely tooth enamel. 2 This information can help to reconstruct the seasonality of the food system and associated elements of social organization, but implementation of this tool requires detailed ecological knowledge (Hodgkins et al. 2020;Sillen et al. 1998). As strontium is incorporated into mineral tissues (bone apatite and tooth enamel), it can supplement geochemical insights into the subsistence economy in those contexts where collagen is not preserved. ...
Stable isotope methods are firmly established as a key tool for investigating the diets of ancient humans, offering insights into broad dietary composition at the scale of an individual’s life. African archaeology and ecosystems have played an important role in the global development of stable isotope approaches, but archaeological applications have been constrained in many African settings by poor preservation conditions for organic remains and limited institutional capacity for large analytical sampling programs. Yet growing numbers of research and training laboratories around the world, declining relative analytical costs, and increasing familiarity among archaeologists and paleoecologists with both the prospects and limitations of stable isotope approaches, all indicate that such methods will continue to increase in importance for modern archaeological practice.
Complex ecological patterning in carbon, nitrogen, and other isotopes within Africa offers a rich background for interpretation. Carbon isotopes largely reflect patterning in vegetation, with the major isotopic distinction between tropical grasses and most other plants aiding the reconstruction of broad food classes. Aquatic and terrestrial environments may also differ sharply in carbon isotope patterning, providing a tool for investigating marine food exploitation. Nitrogen isotope patterning, by comparison with carbon isotopes, is more complex and less well-characterized in many African environments but has been useful for identifying the consumption of marine resources. Other isotopes, including sulfur, strontium, oxygen, and metal isotopes, such as calcium and zinc, may offer complementary insights that can help to interpret ancient food systems.
Analyses of enamel carbon isotopes from eastern and South African hominins have demonstrated the significance of diverse dietary resources for millions of years among several groups of hominins, including the gracile and robust australopithecines and early Homo . The puzzle of extensive consumption of ¹³ C-enriched foods, especially among the eastern African robust australopithecines, has driven wide-ranging research into the dietary diversity of hominin species, targeting questions of ecological niche separation and dietary flexibility. In southern African coastal settings, stable isotope evidence for differential access to dietary resources among foraging groups has demonstrated the maintenance of more sedentary, territorial settlement systems during some periods in the Holocene. Research in these fields is ongoing, with new insights emerging from applications of alternative isotopic systems, increased sampling resolution, and sophisticated statistical modeling approaches.
... While the authors found a broad correspondence of plant and snail 87 Sr/ 86 Sr with lithological unit and previously-published soil 87 Sr/ 86 Sr data (Willmes et al., 2014, there is a closer relationship between plant and soil 87 Sr/ 86 Sr than between snails and soils. However, plants growing on heterogeneous substrates (e.g., granite) also had more variable 87 Sr/ 86 Sr than those on more homogeneous lithologies (e.g., limestone) echoing the findings of other 87 Sr/ 86 Sr bioavailability studies (e.g., Sillen et al., 1998;Hartman and Richards, 2014;Willmes et al., 2018;Aguzzoni et al., 2019). An influence of proximity to water on bioavailable 87 Sr/ 86 Sr was also determined, likely reflecting the origin of rivers on bedrocks with elevated 87 Sr/ 86 Sr. ...
... Although the regional geology and water and surface sediment samples provide a good initial indication of the expected bioavailable 87 Sr/ 86 Sr values, plant and small heterotroph samples are precise and accurate measurements of biological available strontium (Sillen et al., 1998(Sillen et al., , p.2466. ...
... In addition, the contribution of different minerals to the soil pool is variable due to e.g. differential weathering, Sr/Rb content and solubility (Sillen et al., 1998). For example, the contribution of Sr-rich carbonates to the local bioavailable reservoir is much larger than e.g. a more resistant to weathering Sr-rich silicate. ...
We present a novel database of biological and geological ⁸⁷Sr/⁸⁶Sr values (n = 1920) from Italy, using literature data and newly analysed samples, for provenance purposes. We collected both bioavailable and non-bioavailable (i.e. rocks and bulk soils) data to attain a broader view of the Sr isotope variability of the Italian territory. These data were used to build isotope variability maps, namely isoscapes, through Kriging interpolations. We employed two different Kriging models, namely Ordinary Kriging and Universal Kriging, with a geolithological map of Italy categorized in isotope classes as external predictor. Model performances were evaluated through a 10-fold cross validation, yielding accurate ⁸⁷Sr/⁸⁶Sr predictions with root mean squared errors (RMSE) ranging between 0.0020 and 0.0024, dependent on the Kriging model and the sample class. Overall, the produced maps highlight a heterogeneous distribution of the ⁸⁷Sr/⁸⁶Sr across Italy, with the highest radiogenic values (>0.71) mainly localized in three areas, namely the Alps (Northern Italy), the Tuscany/Latium (Central Italy) and Calabria/Sicily (Southern Italy) magmatic/metamorphic terrains. The rest of the peninsula is characterized by values ranging between 0.707 and 0.710, mostly linked to sedimentary geological units of mixed nature. Finally, we took advantage of the case study of Fratta Polesine, to underscore the importance of choosing appropriate samples when building the local isoscape and of exploring different end-members when interpreting the local Sr isotope variability in mobility and provenance studies. Our user-friendly maps and database are freely accessible through the Geonode platform and will be updated over time to offer a state-of-the-art reference in mobility and provenance studies across the Italian landscape.
... The radiogenic 87 Sr isotope abundance is determined after normalization of the stable isotope variations to a reference 88 Sr/ 86 Sr value, therefore the 87 Sr/ 86 Sr ratio is immune to biological and any other process up the trophic chain. Consequently, the 87 Sr/ 86 Sr ratio of an animal ultimately reflects that of the bedrock on which it feeds and is used for the reconstruction of ancient mobility (e.g., Sillen et al., 1998;Müller et al., 2003;Balter et al., 2012;Sillen and Balter, 2018;Lugli et al., 2019). ...
The reconstruction of life histories traits such as the ontogenic evolution of diet or sequences of mobility can be achieved for fossil mammals thanks to laser ablation analysis of trace elements concentration and radiogenic Sr isotope composition in dental enamel. However, a major limitation for the use of laser ablation to study fossil tooth enamel is that the analysis must be carried out on bulk sample hence prohibiting any ad hoc leaching step to remove diagenetic compounds. Biogenic and diagenetic trace elements along with the ⁸⁷Sr/⁸⁶Sr ratio must be monitored and post hoc correlation tests processed to isolate areas free of diagenesis. The present study combines a unique combination of biogenic (Sr and Ba), diagenetic (Mn and U) trace elements, major elements (Mg and Ca) and ⁸⁷Sr/⁸⁶Sr ratio time series obtained by means of laser ablation ICPMS and MC-ICPMS on a large number (n = 94) of fossil tooth enamel samples of humans and animals from a set of neighboring Neolithic sites in France. Bone fragments sampled from the same specimens are also analyzed for comparison. Trends between diagenetic and biogenic trace and major elements are first identified using inclusive data analysis. The trends are then validated at the scale of the laser ablation raster, and a protocol of data cleaning is developed to identify areas free of diagenesis. Non-significantly altered Sr/Ca, Ba/Ca and ⁸⁷Sr/⁸⁶Sr average values are thus gathered for each cleaned tooth enamel samples and are discussed, along with previously measured bone collagen δ¹³C and δ¹⁵N values, in terms of diet and mobility in the context of the Neolithic Revolution.
... Additionally, isotope analyses are increasingly undertaken. An early study looked at strontium ratios in micromammals from the Sterkfontein Valley to understand human habitat preferences (Sillen et al., 1998) and stable carbon isotope analysis of Namaqua rock rat Micaelamys namaquensis teeth was used to infer the presence of C 4 grasses at Kromdraai (Thackeray et al., 2003). Leichliter et al. (2016Leichliter et al. ( , 2017 have assessed the usefulness of carbon isotopes in micromammals for environmental reconstruction. ...
Improvements in excavation methods, dating, analytical techniques and statistical applications have all led to a substantial increase in recoverable environmental evidence from micromammals. Because these animals are so small the information they provide is on a smaller geographical scale than that afforded by most other lines of evidence. However, with increasing amounts of data and greater interpretational precision in all spheres, the chances are improving of being able to mesh information from different scales. Blombos, Pinnacle Point and Klasies River on the southern coast of South Africa have clearly demonstrated that micromammalian data can contribute to multidisciplinary interpretations of past conditions, in this case during MIS 5 and 6. Little attention has been paid to the generally small samples from Iron Age sites but the presence of the House rat Rattus rattus may provide important information about human movements and may also contribute to our understanding of the Anthropocene once this has been formally defined. Micromammals have not yet been used as chronostratigraphic indicators in southern Africa but it may be possible to develop biochronologies using them and to incorporate this material into African Land Mammal Ages.
... Therefore, 87 Sr/ 86 Sr in soils, vegetation, and fauna generally reflect the original 87 Sr/ 86 Sr values of the bedrock (Capo et al., 1998). However, studies on biologically available 87 Sr/ 86 Sr indicate that heterogeneous 87 Sr/ 86 Sr in rock, sediment and soil samples of some regions can be due to additional strontium sediment sources, introduced by fluviatile transport or by fertilizers (Sillen et al., 1998;Price et al., 2002;Maurer et al., 2012). ...
The Gomphotheriidae family belongs to the Proboscidea order. Gomphotheres were elephant-like mammals whose representatives inhabited North America from the Middle Miocene to the late Pleistocene. In this work, a gomphothere remains from Santiago Tepeticpac (Tlaxcala, Mexico) are described. The comparative study with
other Proboscidea, mainly from different localities of Mexico and South America, mostly Argentina and Brazil, allowed to identify them as Cuvieronius genus. The microwear signature together with carbon and oxygen stables isotopes showed that this animal was a mixer feeder and inhabited open zones with patches of wooded flora. These analyses also indicated the presence of high abrasiveness components and C4 plants (grasslands) and medium to low wearing elements as well as C3 vegetation (forest) in the site. The strontium isotopic signature implies that this gomphothere lived in the Puebla-Tlaxcala Valley. The paleoenvironmental inferences would show regional conditions.
... Therefore the range of biologically available 87Sr/86Sr values needs to be established for each geological type in an area. The most convenient method is to measure plants growing on the various geological formations (Sillen et al. 1998;Copeland et al. 2016). Because the mass difference between 87Sr and 86Sr is small, there is little biological fractionation with trophic level. ...
At the ancient Shona centre of Great Zimbabwe (1200–1700 CE ), cattle ( Bos taurus ) were centrally important for economic, social, and symbolic purposes. ⁸⁷ Sr/ ⁸⁶ Sr for modern plants collected in southern Zimbabwe vary from 0.7054 to 0.8780 and ranges differ between some geological substrates. ⁸⁷ Sr/ ⁸⁶ Sr in serial samples of Bos taurus tooth enamel provides information on where animals consumed at Great Zimbabwe were raised and how herds were managed. The majority of animals sampled were born and remained for their first year of life in a region some 40–120 km south of Great Zimbabwe. Few animals came from geological substrates like that of Great Zimbabwe itself, and none from areas underlain by basalts (> 120 km south of Great Zimbabwe). Earlier hypotheses of transhumance are not supported. These findings will help to build a fuller picture of the role of local commodities (in this case, cattle) in the economic networks that supported the rise and florescence of Great Zimbabwe as a major centre of power.
... Trace metal stable isotopes have been used to explore a variety of questions relevant to human evolution including mobility (strontium [Sr]; Ericson, 1985;Sillen, Hall, Richardson, & Armstrong, 1998;Bentley, 2006;Faure & Powell, 2012), diet (zinc [Zn] ;Jaouen, Beasley, Schoeninger, Hublin, & Richards, 2016;Bourgon et al., 2020), and sex (iron (Fe), copper (Cu) ;Jaouen et al., 2012). In humans, Fe and Cu stable isotopes have been shown to differ significantly in females relative to males in blood (Fe: Walczyk & von Blanckenburg, 2002;Cu: Albarède, Telouk, Lamboux, Jaouen, & Balter, 2011) and bone (Jaouen et al., 2012), but not in tooth enamel (Jaouen, Herrscher, & Balter, 2017). ...
Objectives
Here, we examine (1) if the sex‐related differences in iron (Fe) and copper (Cu) isotope ratios, represented as δ⁵⁶Fe and δ⁶⁵Cu values, respectively observed in humans exist in bulk occipital bone and incisors of male and female non‐human primates, and (2) if the variation of Fe and Cu isotope ratios, known to vary in human blood as a factor of age are similar in non‐human primate bone.
Materials and Methods
Isotope ratios were measured from the skeletal elements of 20 rhesus macaques (Macaca mulatta) with known life history traits. The metals were purified by column chromatography and their isotope ratios measured by MC‐ICP‐MS. Data were analyzed using generalized additive models (GAM).
Results
When accounting for age and sex independently, we found a significant relationship between δ⁶⁵Cu values and occipital bone, but not in incisors. There were no significant relationships observed between δ⁵⁶Fe values, occipital bone, or incisors. Similarly, there were no significant relationships observed between δ⁵⁶Fe values, δ⁶⁵Cu values, and age.
Discussion
We suggest that Cu and Fe isotope ratios have the potential to be useful supplementary tools in future research in biological anthropology, but additional studies are needed to further verify the relationship between sex, age, δ⁶⁵Cu, and δ⁵⁶Fe values in primates.
... This indicates, that the sandstone group of proxy data could be further divided into subgroups, but these groups would still show overlapping ranges, and would not define geographically discernible entities (Fig 3). The high variability of strontium isotope ratios in the areas dominated by gneiss, granites, and clastic sedimentary rock expected due to the nature of their composition, which has been shown in several other studies [36,[62][63][64]. Despite a comparatively narrow range of proxy-data from limestone dominated areas, the bioavailable Sr isotope signatures from this group largely exceeds the range expected for Cretaceous-to Tertiary limestone-derived Sr components ( 87 Sr/ 86 Sr~0.708-0.709; ...
The Bronze Age of Sweden's southernmost region, Scania, is complex and intriguing. One could say that Scania represented in many ways a gateway for people, ideas and material culture connecting continental Europe with Sweden. Shedding light on the dynamics of human mobility in this region requires an in depth understanding of the local archaeological contexts across time. In this study, we present new archaeological human data from the Late Bronze Age Simris II site, located in an area of Scania showing a dynamic environment throughout the Late Bronze Age, thus likely involving various forms of mobility. Because the characterization of solid strontium isotope baselines is vital for delineating human mobility in prehistory using the strontium isotope methodology, we introduce the first environmentally based multi-proxy (surface water-, plant- and soil leachates) strontium isotope baselines for sub-regions of Scania. Our results show, that the highly complex and spatially scattered lithologies characterising Scania does not allow for a spatially meaningful, geology-based grouping of multi-proxy data that could be beneficial for provenance studies. Instead, we propose sub-regional baselines for areas that don't necessarily fully correspond and reflect the immediate distribution of bedrock lithologies. Rather than working with a Scania-wide multi-proxy baseline, which we define as 87Sr/86Sr = 0.7133 ± 0.0059 (n = 102, 2σ), we propose sub-regional, multi-proxy baselines as follows: Area 1, farthest to the north, by 87Sr/86Sr = 0.7184 ± 0.0061 (n = 16, 2σ); Area 2, comprising the mid and western part of Scania, with 87Sr/86Sr = 0.7140 ± 0.0043 (n = 48, 2σ); Area 3-4, roughly corresponding to a NW-SE trending zone dominated by horst-graben tectonics across Scania, plus the carbonate dominated south western part of Scania with 87Sr/86Sr = 0.7110 ± 0.0030 (n = 39, 2σ). Our results also reflect that the complexity of the geology of Scania requires systematic, high density, statistically sound sampling of multiple proxies to adequately constrain the baseline ranges, particularly of those areas dominated by Precambrian lithologies. The averaging effect of biosphere Sr in surface water might be beneficial for the characterization of baselines in such terranes. Our sub-regional, area-specific baselines allow for a first comparison of different baseline construction strategies (single-proxy versus multi-proxy; Scania-wide versus sub-regional). From the Late Bronze Age Simris II site, we identified six individuals that could be analysed for Sr isotopes, to allow for an interpretation of their provenance using the newly established, environmental strontium isotope baselines. All but one signature agrees with the local baselines, including the 87Sr/86Sr value we measured for a young individual buried in a house urn, typically interpreted as evidence for long distance contacts. The results are somewhat unexpected and provides new aspects into the complexity of Scandinavian Bronze Age societies.
... ), sediments transported outside their areas of origin by erosion, rivers and streams, and glaciers Serna et al. 2020;Widga et al. 2017), non-local strontium ratios carried in river and stream waters(Sillen et al. 1998), and airborne and atmospheric inputs such as aeolian dust, volcanic ash, rainfall, and sea spray(Burton and Hahn 2016;Capo et al. 1998;Chadwick et al. 2009;Evans et al. 2010;Hartman and Richards 2014;Hoogewerff et al. 2019; Serna et al. 2020). ...
The use of bioavailable strontium in different environments to provenance biological materials has become increasingly common since its first applications in ecology and archaeology almost four decades ago. Provenancing biological materials using strontium isotope ratios requires a map of bioavailable strontium, commonly known as an isoscape, to compare results with. Both producing the isoscape and using it to interpret results present methodological challenges that researchers must carefully consider. A review of current research indicates that, while many archives can be analyzed to produce isoscapes, modern plant materials usually provide the best approximation of bioavailable strontium and can be used alone or combined with other archives if applying machine learning. Domain mapping currently produces the most accurate, most interpretable isoscapes for most research questions; however, machine learning approaches promise to provide more accurate and geographically wide-ranging isoscapes over time. Using strontium isotope analysis for provenancing is most successful when combined with other isotopes and/or trace elements as part of a likelihood approach. Strontium isoscapes that are both appropriate and sufficiently high resolution to answer specific research questions do not exist for most parts of the world. Researchers intending to incorporate strontium analysis into their research designs should expect to conduct primary sampling and analysis to create appropriate isoscapes or refine existing ones, which should themselves not be uncritically utilized. When sampling, it is essential to collect appropriate metadata; these metadata and the results of the analyses should be archived in one of several online databases to maximize their usefulness. With increasing amounts of primary data and the likely increased availability of machine learning approaches to mapping, strontium analysis will continue to improve as a method of provenancing.
... From my dissertation research on elemental strontium, I was aware that total and available soil Sr/Ca could differ enormously, so suggested an empirical approach at the Pleistocene site of Swartkrans, in the Sterkfontein Valley. The discoveries available in 87 Sr/ 86 Sr plants in this region bore little resemblance to that of whole rock substrates, and that 87 Sr/ 86 Sr varied more with hydrology (riparian vs. dry habitats) than geological maps may have been lucky accidents (Sillen et al., 1998), but illustrated rather profoundly the potential distance between existing theory and the real world which in many cases may not be serious, but in others might fatally undermine the unwary. ...
The stable isotope ratio ⁸⁷Sr/⁸⁶Sr has been shown to have extraordinary potential for documenting the movement and life-histories of humans and other animals, both in history and prehistory. Thirty years of expanding applications has taken the method from a niche (if not fringe) approach to a normal part of archeological and paleobiological enquiry; indeed a “Golden Age.” The technique is inherently interdisciplinary, because in addition to those archeologists and paleobiologists wishing to apply it, most applications require informed input from ecologists, geochemists, and calcified tissue biologists. This perspective explores how such interdisciplinarity is both a strength and an impediment to further advancement.
... During the last few decades, strontium isotope ratios ( 87 Sr/ 86 Sr) have proven to be a powerful tracer of provenance not only for geological applications but also in a wide variety of studies including archaeology (e.g., Bentley et al., 2003;Evans et al., 2006;Montgomery, 2010;Rich et al., 2015;Szczepanek et al., 2018), hydrology (e.g., Christian et al., 2011;Hogan et al., 2000;Négrel et al., 2004;Zieliński et al., 2018), forensics (Beard and Johnson, 2000;West et al., 2009), ecology (e.g., Chamberlain et al., 1996;Hegg et al., 2013;Hoppe and Koch, 2007;Sillen et al., 1998), water supply (Chesson et al., 2012;Leung and Jiao, 2006), and food authenticity (e.g., Crittenden et al., 2007;Rodrigues et al., 2011;Rossmann et al., 2000;Voerkelius et al., 2010). Regardless of the purpose of research, the usage of Sr isotopes as a provenance tracer requires knowledge of spatial variations in 87 Sr/ 86 Sr values within the environment at a local and regional scale, preferably in the form of accurate reference maps. ...
This study presents first isoscape maps of strontium isotope signatures and their spatial variation in Poland, based on ~900 samples of rocks, sediments, surface water, and flora. This dataset is supplemented by ⁸⁷Sr/⁸⁶Sr ratios predicted for several carbonate rock units. High, radiogenic Sr isotope ratios (>0.72), related to the Pleistocene glacial deposits, are omnipresent throughout the country and are also found in the Sudetes and the Holy Cross Mountains, where igneous and clastic Palaeozoic rocks are widely exposed. The lowest Sr signatures (<0.71) occur predominantly in the Silesian-Małopolska and Lublin uplands and are related to exposures of Palaeozoic, Mesozoic, and Neogene carbonate rocks. The large variation of ⁸⁷Sr/⁸⁶Sr ratios in the environment across the country is chiefly driven by the diversity in the geological substrate, and locally, it is also influenced by anthropogenic contamination. Strontium isoscapes for the geological substrate and surface waters differ from each other, in terms of the range of ⁸⁷Sr/⁸⁶Sr values and their distributional pattern. The differences result primarily from mixing processes in the geosphere (weathering), hydrosphere, and biosphere that control Sr inputs from various natural sources present in the environment. On the other side, they are also created by anthropogenic contamination of surface water and presumably of soils. This situation has important implications for future archaeological provenance and migration studies, as isoscapes for surface water and vegetation cannot be directly used to estimate the local ⁸⁷Sr/⁸⁶Sr baselines for past human populations. Therefore, caution is required when modern Sr data of surface water and plants are used in archaeological research. ⁸⁷Sr/⁸⁶Sr values of the geological substrate, which may be affected by anthropogenic contamination to a lesser extent than water, soil, and vegetation, are favoured for the baseline estimation for historical times.
... Strontium-87 is the product of the radioactive decay of Rubidium-87 ( 87 Rb), so Sr isotope ratios ( 87 Sr/ 86 Sr) vary between different types of bedrock, depending on the initial Rb-Sr ratio and time since deposition: the amount of 87 Sr in relation to 86 Sr increases with bedrock age as 87 Rb decays to 87 Sr (Faure and Powell, 1972). 87 Sr/ 86 Sr values as high as 0.9000 may be observed in some granites, for instance in the Mourne Mountains in Northern Ireland (Meighan et al., 1988) and in South Africa (Sillen et al., 1998). Younger geological formations often have values below 0.7060, and those with very low initial Rb/Sr ratios, such as basalt, typically have values of 0.7027-0.7040 ...
Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood – in the rare instances it does survive – is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo ⁸⁷Sr/⁸⁶Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad’s Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous ⁸⁷Sr/⁸⁶Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that ⁸⁷Sr/⁸⁶Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, ⁸⁷Sr/⁸⁶Sr values may extend outside of the mixing line between the wood’s endogenous strontium and the water. These results indicate the need for extreme caution when attempting to determine the provenance of waterlogged wood.
... Heterogeneous lithological units such as granite are expected to have a higher variability in their 87 Sr/ 86 Sr ratio than more homogeneous units, which may also be reflected in more variable bioavailable strontium values (Sillen et al., 1998;Willmes et al., 2018). Variability in sample 87 Sr/ 86 Sr ratio between lithological groups was compared using robust Levene test because 87 Sr/ 86 Sr ratio values did not follow a normal distribution. ...
Establishing strontium isotope (87 Sr/ 86 Sr) geographical variability is a key component of any study that seeks to utilize strontium isotopes as tracers of provenance or mobility. Although lithological maps can provide a guideline, estimations of bioavailable 87 Sr/ 86 Sr are often necessary, both in qualitative estimates of local strontium isotope "catchments" and for informing/refining isoscape models. Local soils, plants and/or animal remains are commonly included in bioavailability studies, although consensus on what (and how extensively) to sample is lacking. In this study, 96 biological samples (plants and snails) were collected at 17 locations spanning 6 lithological units, within a region of southwest France and an area with a high concentration of Paleolithic archaeological sites. Sampling sites aligned with those from a previous study on soil bioavailable strontium, and comparison with these values, and the influence of environmental and anthropogenic variables, was explored. Data confirm a broad correspondence of plant and snail 87 Sr/ 86 Sr values with lithological unit/soil values, although the correlation between expected 87 Sr/ 86 Sr values from lithology and bioavailable 87 Sr/ 86 Sr ratios from biological samples was higher for plants than for snails. Grass, shrub and tree 87 Sr/ 86 Sr values were similar but grasses had a stronger relationship with topsoil values than trees, reflecting differences in root architecture. Variability in 87 Sr/ 86 Sr ratios from all plant samples was lower for sites located on homogeneous geological substrates than for those on heterogeneous substrates, such as granite. Among environmental and anthropogenic variables, only an effect of proximity to water was detected, with increased 87 Sr/ 86 Sr values in plants from sites close to rivers originating from radiogenic bedrock. The results highlight the importance of analyzing biological samples to complement, inform and refine strontium isoscape models. The sampling of plants rather than snails is Britton et al. 87 Sr/ 86 Sr Bioavailability Map of S-W France recommended, including plants of varying root depth, and (if sample size is a limitation) to collect a greater number of samples from areas with heterogeneous geological substrates to improve the characterizations of those regions. Finally, we call for new experimental studies on the mineralized tissues of grazers, browsers, frugivores and/or tree leaf feeders to explore the influence of 87 Sr/ 86 Sr variability with soil profile/root architecture on 87 Sr/ 86 Sr values of locally-feeding fauna.
... Heterogeneous lithological units such as granite are expected to have a higher variability in their 87 Sr/ 86 Sr ratio than more homogeneous units, which may also be reflected in more variable bioavailable strontium values (Sillen et al., 1998;Willmes et al., 2018). Variability in sample 87 Sr/ 86 Sr ratio between lithological groups was compared using robust Levene test because 87 Sr/ 86 Sr ratio values did not follow a normal distribution. ...
Establishing strontium isotope (⁸⁷Sr/⁸⁶Sr) geographical variability is a key component of any study that seeks to utilize strontium isotopes as tracers of provenance or mobility. Although lithological maps can provide a guideline, estimations of bioavailable ⁸⁷Sr/⁸⁶Sr are often necessary, both in qualitative estimates of local strontium isotope “catchments” and for informing/refining isoscape models. Local soils, plants and/or animal remains are commonly included in bioavailability studies, although consensus on what (and how extensively) to sample is lacking. In this study, 96 biological samples (plants and snails) were collected at 17 locations spanning 6 lithological units, within a region of south-west France and an area with a high concentration of Paleolithic archaeological sites. Sampling sites aligned with those from a previous study on soil bioavailable strontium, and comparison with these values, and the influence of environmental and anthropogenic variables, was explored. Data confirm a broad correspondence of plant and snail ⁸⁷Sr/⁸⁶Sr values with lithological unit/soil values, although the correlation between expected ⁸⁷Sr/⁸⁶Sr values from lithology and bioavailable ⁸⁷Sr/⁸⁶Sr ratios from biological samples was higher for plants than for snails. Grass, shrub and tree ⁸⁷Sr/⁸⁶Sr values were similar but grasses had a stronger relationship with topsoil values than trees, reflecting differences in root architecture. Variability in ⁸⁷Sr/⁸⁶Sr ratios from all plant samples was lower for sites located on homogeneous geological substrates than for those on heterogeneous substrates, such as granite. Among environmental and anthropogenic variables, only an effect of proximity to water was detected, with increased ⁸⁷Sr/⁸⁶Sr values in plants from sites close to rivers originating from radiogenic bedrock. The results highlight the importance of analyzing biological samples to complement, inform and refine strontium isoscape models. The sampling of plants rather than snails is recommended, including plants of varying root depth, and (if sample size is a limitation) to collect a greater number of samples from areas with heterogeneous geological substrates to improve the characterizations of those regions. Finally, we call for new experimental studies on the mineralized tissues of grazers, browsers, frugivores and/or tree leaf feeders to explore the influence of ⁸⁷Sr/⁸⁶Sr variability with soil profile/root architecture on ⁸⁷Sr/⁸⁶Sr values of locally-feeding fauna.
Between the sixth and fifteenth c. CE, a vast expanse of central and southern Sudan belonged to the kingdom of Alwa, ruled from the urban metropolis of Soba. Renewed investigation of the city unearthed a small cemetery in the northern part of the site. The heterogeneity of burial practices raised some questions as to the cultural and religious affinities of the deceased and suggested potential multiculturalism of the local urban population. We applied isotopic analyses to investigate the origins of the people buried at Cemetery OS and their concomitant ways of life. Non-concordance of ⁸⁷Sr/⁸⁶Sr and δ¹⁸O values with local hydro-geological background speaks to the mixing of water sources as a result of residential mobility. The concordance of human and faunal strontium and oxygen results, combined with elevated δ¹³C values corresponding to almost exclusive reliance on C4 produce, points to the possibility of seasonal movement of people with their herds between the Nile valley and the adjacent grasslands. Despite the turn of the medieval Nubian economy towards settled agriculture, by revealing the granular specificities of human adaptation in challenging ecosystems, our results produce the first insight into the enduring diversification of economic production, even in urbanized settings, and persisting participation of local peoples in agro-pastoral symbiosis.
The archaeological site of Ghazali (northern Sudan) provides a rare opportunity to investigate the dynamics of mixed economies and mobility on the fringes on the Nile valley at the time of Christian expansion in Nubia. Thanks to its particular hydrological conditions, Sudan has a long history of diverse groups pursuing different economic activities, with agricultural communities settled along the fertile Nile valley and various mobile pastoralists groups occupying vast areas of the adjacent deserts. Ghazali represents an early medieval Nubian rural site with an extensive funerary zone. Somewhat removed from the Nile valley, Ghazali extends along the western bank of a large wadi , Wadi Abu Dom, running across the Bayuda desert, dated ca. 7th–13th century CE . Multi-isotopic analysis of human tooth enamel from Cemeteries 1, 3, and 4 was used to explore patterns of mobility among these communities. Ten enamel samples were subjected to ⁸⁷ Sr /86 Sr analysis, while 24 individuals were studied for their δ ¹⁸ O values. ⁸⁷ Sr/ ⁸⁶ Sr and δ ¹⁸ O values were very heterogeneous, suggesting that the Ghazali community, as a whole, benefited from a variety of water sources, perhaps including significant contributions from groundwater wells. We suggest that this adds further support for the reconstruction of a mixed practice of agriculture and animal herding in the neighbouring Bayuda desert. These data add to growing evidence for diverse and flexible mixed economies in eastern Africa that provided food security even under the most challenging of conditions.
Isotopic analyses have become an important tool in archaeological and bioarchaeological research. This chapter provides an overview of the application of both stable and radiogenic isotopic analyses to the reconstruction of past human behavior. We present an overview of the main isotope systems commonly used within this context, i.e. carbon, nitrogen, sulfur, oxygen, and strontium. We then provide a discussion of the most common tissues from which isotope ratios are obtained and highlight the importance of considering scales of analysis in research design and data interpretation. Finally, we present the general categories of social research questions for which isotopic studies have been particularly productive, such as studies of paleodiet and life-history, human-animal interactions, and human mobility and migration. Within these general categories, we discuss the individual contributions to the volume.KeywordsIsotope analysisScale of analysisIsotopic archaeologyInterpreting isotopes
The region of present-day Angola was one of the main areas from which millions of enslaved Africans were abducted and forced to migrate to the Americas during the transatlantic slave trade. Strontium isotope (87Sr/86Sr) analysis is a useful tool in reconstructing large-scale human movements across geologically distinct landscapes in archaeological and forensic contexts. However, the absence of environmental 87Sr/86Sr reference data from Angola hinders the use of 87Sr/86 Sr analysis in provenance studies related to Angola, especially in identifying the geographic origin of enslaved people in the African Diaspora. Here, we measured 101 plant samples from most, yet not all, major geological units to draft the first bioavailable 87Sr/86 Sr map (isoscape) for Angola using a machine learning framework. Our results suggest that the 87Sr/86 Sr ratios in Angola span a large range from 0.70679 to 0.76815 between the different geological units. Specifically, the high average 87Sr/86Sr ratios of 0.74097 (±0.00938, 1 SD) found in the Angola Block of central Angola, are distinctly more radiogenic than any previously published bioavailable 87Sr/86 Sr ratios for western Central and West Africa. However, these match the 87Sr/86Sr ratios previously published for human enamel samples from four historic slavery contexts in the Americas. We demonstrate that our strontium isoscape of Angola greatly improves the ability to assess the possible origins of enslaved African individuals discovered outside of Africa and encourage the future use of emerging African isoscapes in the study of life histories within the slave trade.
This introduction to the volume includes a short history of isotopic proveniencing, a discussion of mass spectrometers as essential instruments in these studies, a brief summary of the major features of the various methods, and an introduction to the papers that follow. It is my hope that this introduction will provide a background that will allow the contributed papers to have more impact.KeywordsHistoryMass spectrometersIsotopic proveniencingStrontiumLeadSulfurOxygen
A review of ideas about the spread of agriculture from the Near East into Europe introduces a bioarchaeological investigation of the question. Strontium isotope analysis is used to make an important point about the transition to agriculture, rather large datasets are available from two areas where the transition to agriculture is well defined and where there are a substantial number of burials—in the Danube Gorges between Serbia and Romania and in Southern Scandinavia. This paper will discuss each area separately prior to a more general synthesis of the results. The moral of the story has to do with mobility and sedentism.KeywordsDanube GorgesSouthern ScandinaviaStrontiumIsotopic proveniencingSpread of agricultureArchaeology
This chapter has two goals: (1) to review and synthesize the preceding papers in an evaluation of what we have learned and (2) to make a series of suggestions and recommendations based on the papers in this volume and some years of experience in the field. The focus of this section will be on strontium and oxygen. Topics for recommendations include terminology, pretreatment, measuring bioavailable, isoscapes, mixing models, databases, life history, publication, determining local, place of origin, oxygen, and carbon.KeywordsSynthesisPretreatmentBioavailableOxygen
Isoscapes
Stable isotope ratio analysis revolutionized research on present and past diets and ecology, particularly when combined with information from other sources. In South Africa, geochemist John Vogel worked with archaeologist Nik van der Merwe, and together they published one of the earliest papers on the use of carbon stable isotopes determining the timing of maize introduction into North America. For collagen synthesis, enzymatic control determines the magnitude of the fractionation; this is a case of kinetic isotope fractionation. The majority of the world's active cycling carbon is sequestered in the ocean as dissolved carbonate. In archaeological applications of isotopic diet reconstructions, carbon isotope ratios differ not only with foods consumed, but among different consumer tissue types. Hydrogen is ubiquitous in the geosphere and the huge relative mass difference between its two stable isotopes means that hydrogen exhibits the largest fractionations among the light stable isotopes.
The isotopic signatures of human tissues can provide valuable information on geographic origin for medicolegal investigations involving unidentified persons. It is important to understand the impact of diagenetic processes on isotopic signatures, as alterations could result in incorrect estimation of geographic origin. This study examines alterations in isotope signatures of different tissues of five human body donors studied throughout decomposition at the Forensic Anthropology Research Facility (FARF), San Marcos, TX. Two body donors were buried, two were placed in open pits, and one was first allowed to naturally mummify and then buried. Remains were recovered after a period of 7–34 months. The preplacement and post-recovery Sr–Pb isotope data of scalp hair, bone (iliac and tibia), and tooth enamel and dentine were compared. The hair samples record significant shifts in Sr-Pb isotope compositions, with hair keratin Pb isotope composition shifting towards the Pb signature of local soil samples. Hair keratin Sr isotope compositions were altered by the burial environment and possibly also by the lab sample cleaning method. The spongy iliac bone samples show inconsistencies in the recoverability of the preplacement Sr–Pb isotope signatures. The post-placement signatures of the buried donors show slight elevation over preplacement signatures. The post-placement signatures of donors placed in open pits are significantly elevated. The tibia and dental samples record the most consistent isotopic data with the least alteration. These more densely mineralised elements show good recoverability of the preplacement isotope signatures in burials and open pits and are thus deemed better targets for forensic investigative purposes.
The crusades were arguably the largest migration events that involved medieval Europeans. A range of archaeological and textual methods have been used in the past in order to try to understand the process of migration and settlement in the Frankish states in the eastern Mediterranean. Archaeological methods include identifying the building plans of European-style houses in the Latin East, and finding European items such as coins, brooches and belt buckles in burials. Textual approaches using manuscripts from the Frankish East include the spelling of words in texts indicating the accent of the author, the use of words particular to specific European regions, the names of Europeans in lists of settlers, and mention of European toponymic bynames among those recorded in documents. Here we also introduce recent results of an archaeological method that had not previously been applied to crusade-related migration: the analysis of oxygen and strontium isotopes in teeth from excavated human skeletal remains. This technique has been applied to crusader-period burials at Caesarea and the farming village of Parvum Gerinum, both in the kingdom of Jerusalem, in order to identify which individuals were probably born in the East and which had spent their childhood in Europe. The results suggest that the majority of those tested from the cemeteries of Caesarea were born in Europe; and we have been able to identify the specific region of origin for a proportion of those migrants.
The archaeological record is a combination of what is seen by eye, as well as the microscopic record revealed with the help of instrumentation. The information embedded in the microscopic record can significantly add to our understanding of past human behaviour, provided this information has not been altered by the passage of time. Microarchaeology seeks to understand the microscopic record in terms of the type of information embedded in this record, the materials in which this information resides, and the conditions under which a reliable signal can be extracted. This book highlights the concepts needed to extract information from the microscopic record. Intended for all archaeologists and archaeological scientists, it will be of particular interest to students who have some background in the natural sciences as well as archaeology.
Isotopic analysis has seen significant use in archaeological sciences to date objects, determine their origin, and depict ancient human dietary habits. However, the potential of this technique for provenance studies of ancient silks remains underdeveloped. In this study, we applied Sr isotopic ratios to the provenance tracing of silkworm cocoons. We investigated the ⁸⁷Sr/⁸⁶Sr ratios of cocoons from seven Chinese provinces to determine their regional differences. The ⁸⁷Sr/⁸⁶Sr ratios of mulberry leaves and cocoons in Shandong and Sichuan were analyzed and silkworms were cultured at four sampling locations in Hangzhou, Zhejiang, to determine isotopic signature relationships between mulberry leaves and cocoons. Those results showed that the ⁸⁷Sr/⁸⁶Sr signature of cocoons not only reflected regional differences, but also was related to the type of soil in each sampling location from which the samples were collected. It is suggested that the Sr isotope ratios was able to be an effective tool for the provenance tracing of cocoons. The Mann–Whitney test result indicated no significant differences in isotopic ratios between mulberry leaves and cocoons. In other words, mulberry leaves may predict mean isotopic values in the cocoons. No clear evidence of Sr isotopic fractionation was found in our control experiments. However, mulberry leaves and cocoons from Sichuan did not show significant correlation between them, overall reducing the predictive power of the ⁸⁷Sr/⁸⁶Sr ratios of mulberry leaf for provenance studies of cocoons. Finally, in order to improve the accuracy of Sr isotope ratios for the provenance tracing of cocoons, more ⁸⁷Sr/⁸⁶Sr data should be complemented and the relationship needs to be established between Sr isotope information in more kinds of proxies and cocoons.
As people, animals and materials are transported across increasingly large distances in a globalized world, threats to our biosecurity and food security are rising. Aotearoa New Zealand is an island nation with many endemic species, a strong local agricultural industry, and a need to protect these from pest threats, as well as the economy from fraudulent commodities. Mitigation of such threats is much more effective if their origins and pathways for entry are understood. We propose that this may be addressed in Aotearoa using strontium isotope analysis of both pests and products. Bioavailable radiogenic isotopes of strontium are ubiquitous markers of provenance that are increasingly used to trace the origin of animals and plants as well as products, but currently a baseline map across Aotearoa is lacking, preventing use of this technique. Here, we have improved an existing methodology to develop a regional bioavailable strontium isoscape using the best available geospatial datasets for Aotearoa. The isoscape explains 53% of the variation (R ² = 0.53 and RMSE = 0.00098) across the region, for which the primary drivers are the underlying geology, soil pH, and aerosol deposition (dust and sea salt). We tested the potential of this model to determine the origin of cow milk produced across Aotearoa. Predictions for cow milk (n = 33) highlighted all potential origin locations that share similar ⁸⁷ Sr/ ⁸⁶ Sr values, with the closest predictions averaging 7.05 km away from their true place of origin. These results demonstrate that this bioavailable strontium isoscape is effective for tracing locally produced agricultural products in Aotearoa. Accordingly, it could be used to certify the origin of Aotearoa’s products, while also helping to determine if new pest detections were of locally breeding populations or not, or to raise awareness of imported illegal agricultural products.
How do the environments and social structures that we create and modify to suit our needs affect the individuals that live and work within those environments? Bioarchaeology and political ecology provide novel means by which to understand how the environments we create, both social environments and our modifications of the natural environment, can affect the body and individuals’ health disproportionately. This dissertation uses osteological analyses, historic records, trace element analysis (arsenic, barium, and lead), and isotopic analyses (various lead isotopes as well as strontium 87/86) to evaluate how different types of anthropogenic environments can be retained within and have an effect upon the body. Key in this dissertation is how anthropogenic environments and industrial practices transformed environments during the Industrial Revolution in England, and how individuals’ interaction with their environments depended upon elements of their biosocial identity and the inequality present within society, both of which ultimately dictate what environments individuals can access. Accordingly, the anthropogenic processes that transformed environments in England and which were prevalent during the industrial period were a systemic threat that had far reaching consequences throughout the country, and possibly the world.
This dissertation studies two archaeological collections of individuals from England during the Industrial Revolution. Neither collection is extreme in being either completely industrial and urban, or completely rural and agrarian. Instead, these collections fall within the mid-range of industrialization, though one is larger and more industrialized than the other. The more industrial population was buried at St. Hilda’s parish in South Shields, a large industrial town with a variety of industries that include nearby coal mines and the construction of ships and steam engines. The more agrarian population was buried at St. Peter’s church in Barton-upon-Humber, a small market town focused on agriculture. These collections were chosen, as was this time period, because they represent populations of individuals who lived during dramatic environmental change, but before environmental and occupational legislation was passed to prevent pollution and job-related hazards. Therefore, this dissertation focuses on the extent to which individuals were exposed to the pollutants present in their environments, and how this exposure occurred disproportionately based on aspects of their identity and the regions in which they lived.
Prior to osteological and sample analyses, it was predicted that the population from St. Hilda’s would have experienced greater pollutant exposure and adverse health outcomes than the population from St. Peter’s, and that this could be seen in the concentration of key trace elements in their bones. It was also predicted that men from St. Hilda’s should have greater concentrations of trace elements in their bones compared to women due to the more hazardous nature of men’s work during this time period. Furthermore, it was predicted that as a consequence of the concentrations of trace element pollutants in individual’s bones, the population from St. Hilda’s would have experienced a greater variety of negative health outcomes associated with exposure.
The findings of this dissertation do not support all of these predictions, however. There were no differences in stature between the two populations, indicating that either there was some buffer in South Shields that protected the individuals from St. Hilda’s from the causative factors of decreased stature, or that there were similar hazards in both South Shields and Barton-upon-Humber. There were also a significantly greater number of older women among the population from St. Hilda’s compared to St. Peter’s, further reinforcing this finding. In regard to the pollutants present in both environments, there were harmful concentrations of different trace element pollutants in the skeletal samples from both populations (lead among those from St. Peter’s, and barium and arsenic among those from St. Hilda’s), and women from St. Hilda’s show significantly higher levels of arsenic and barium in their bodies compared to men. Furthermore, the men from St. Peter’s had significantly greater skeletal concentrations of lead compared to the men from Sr. Hilda’s.
The findings of this dissertation contradict the assumptions that the countryside and more rural environments provided safe and clean escapes from industrial cities and towns, and that women experienced fewer hazards in terms of pollutant exposure compared to men. Instead, there was continuity in environments throughout England during the Industrial Revolution such that the major changes and processes that occurred in industrial cities affected the entire country. A more agrarian town like Barton-upon-Humber was not immune to the pollutants and harmful effects of industry. However, living in a larger and more industrial town like South Shields was not entirely harmful to its population, either. Potential routes of exposure to pollutants and toxic compounds include not only occupational exposure, but also exposure as a result of burning coal in the home and workplace for heat, energy, and to cook food, as well as the use of goods made with toxic compounds – “silent killers” that could be found in homes throughout the country.
The ecology and behaviour of woolly and Columbian mammoths and mastodons have been extensively studied. Despite this, their patterns of mobility, and particularly the question of whether or not they migrated habitually, remains unclear. This paper summarises the current state of knowledge regarding mobility in these species, reviewing comparative datasets from extant elephant populations as well as isotopic data measured directly on the ancient animals themselves.
Seasonal migration is not common in modern elephants and varies between years. Nonetheless, non-migratory elephants can still have considerable home ranges, whose size is affected mainly by habitat, seasonal availability of water and food, and biological sex. Strontium isotope analyses of woolly mammoths, Columbian mammoths, and mastodons demonstrate plasticity in their migratory behaviour as well, probably in response to spatio-temporal variations in ecological conditions. However, biological sex is difficult to establish for most proboscidean fossils and its influence on the results of Sr analyses can therefore not be assessed. Advances in intra-tooth sampling and analytical methods for strontium isotope analysis have enabled research on intra-annual movement, revealing nomadic behaviour in all three species. Sulfur isotopes have been analysed from woolly mammoth remains numerous times, but its methodology is not yet developed well enough to inform on past proboscidean mobility in as much detail as strontium studies.
The inter- and intra-individual variation in migratory behaviour in mammoths and mastodons implies that their role in the subsistence strategies of Palaeolithic people may have fluctuated as well. Further assessment of hominin-proboscidean predator-prey interactions will require a more detailed understanding of proboscidean habitual mobility in specific contexts and places. Strontium isotope studies based on multi-year enamel sequences from multiple individuals have the potential to provide this insight.
Strontium isotopes facilitate the study of human paleogeography and have widened the scope of archaeological enquiries on mobility. We present an approach based on strontium isotopes (⁸⁷Sr/⁸⁶Sr) to study the mobility of hunter–gatherer societies from northwestern Patagonia (Neuquén, Argentina). The analysis is developed on the basis of a macro-regional geological framework that guides the sampling and interpretation of results. We also present results for fauna to begin building a landscape of bioavailable strontium to be utilized in the interpretation of results from human samples. These first results conform to general expectations and show the most radiogenic ⁸⁷Sr/⁸⁶Sr values for the oldest geological provinces, while low values are recorded for recent substrates. Additionally, we provide results for human samples from archaeological sites spanning the last 4000 years, a period during which a number of important socio-demographic changes occurred. The results in human samples indicate overall isotopic fidelity to the values recorded in the local geology, suggesting a relatively restricted spatial scale of mobility during the late Holocene. This discussion is situated in a biogeographic research framework assessing topographic variation and landscape seasonality, and contributes toward understanding the movements of people, flow of material objects, and circulation of information in the Patagonian Andes.
The Osmore Drainage of southern Peru has a long and rich history of human occupation. While the utility of stable oxygen and radiogenic strontium isotope values in identifying paleomobility between this region and population centers in the Bolivian altiplano has been well established, many questions about intra-regional mobility remain. To better understand how these methods can be used to detect localized residential mobility, we present new δ¹⁸Omw(VSMOW) and ⁸⁷Sr/⁸⁶Sr values from water, soil, plant, and faunal samples. Samples were collected primarily from traditionally farmed agricultural fields in the upper, middle, and lower Osmore Drainage. Results are indiscernible between the upper and middle drainage, while marine contribution to the lower drainage produces distinct values. We discuss the methodological limitations and implications of our results for the use of stable oxygen and radiogenic strontium isotope analyses for intra-regional paleomobility studies in the Osmore Drainage.
Strontium isotope ratios ( ⁸⁷ Sr/ ⁸⁶ Sr) allow researchers to track changes in mobility throughout an animal's life and could theoretically be used to reconstruct sex-biases in philopatry and dispersal patterns in primates. Dispersal patterns are a life-history variable that correlate with numerous aspects of behaviour and socio-ecology that are elusive in the fossil record. The present study demonstrates that the standard archaeological method used to differentiate between ‘local’ and ‘non-local’ individuals, which involves comparing faunal isotopic ratios with environmental isotopic minima and maxima, is not always reliable; aspects of primate behaviour, local environments, geologic heterogeneity and the availability of detailed geologic maps may compromise its utility in certain situations. This study instead introduces a different methodological approach: calculating offset values to compare ⁸⁷ Sr/ ⁸⁶ Sr of teeth with that of bone or local environments. We demonstrate this method's effectiveness using data from five species of primates, including chimpanzees, from Kibale National Park, Uganda. Tooth-to-bone offsets reliably indicate sex-biases in dispersal for primates with small home ranges while tooth-to-environment offset comparisons are more reliable for primates with larger home ranges. Overall, tooth-to-environment offsets yield the most reliable predictions of species' sex-biases in dispersal.
The Archaeology of Human Bones provides an up to date account of the analysis of human skeletal remains from archaeological sites, introducing students to the anatomy of bones and teeth and the nature of the burial record. Drawing from studies around the world, this book illustrates how the scientific study of human remains can shed light upon important archaeological and historical questions. This new edition reflects the latest developments in scientific techniques and their application to burial archaeology. Current scientific methods are explained, alongside a critical consideration of their strengths and weaknesses. The book has also been thoroughly revised to reflect changes in the ways in which scientific studies of human remains have influenced our understanding of the past, and has been updated to reflect developments in ethical debates that surround the treatment of human remains. There is now a separate chapter devoted to archaeological fieldwork on burial grounds, and the chapters on DNA and ethics have been completely rewritten. This edition of The Archaeology of Human Bones provides not only a more up to date but also a more comprehensive overview of this crucial area of archaeology. Written in a clear style with technical jargon kept to a minimum, it continues to be a key work for archaeology students.
The Pitted Ware Culture emerged during the Neolithic around 3400 BCE in east-central Sweden and quickly spread south and west to various parts of southern Scandinavia. For the next millennium these groups exhibited less interest in agricultural activity and a general return to the hunting and gathering of wild animals and plants with a focus on seals in some coastal areas. Pitted Ware Culture arrived in northeastern Denmark after 3100 BCE. One of the most important sites of this period was at Kainsbakke, on the peninsula of Djursland. One deep pit at the site contained unusual numbers of bear, red deer, European elk, and boar remains. This study focuses on the isotopic proveniencing of some of these animal remains to evaluate their origins. Confirmation of the import of some of the animals, probably from western Sweden, suggests possible shared ritual activity at the central Kainsbakke site. This evidence also confirms the navigating skills of Neolithic peoples in northern Europe.
Strontium and oxygen isotopes provide a useful method for provenancing bioapaties, such as teeth and bone. In order for this approach to be successful, regional baseline bioavailable isotope data are required; however, few databases are currently available in Australia. This study measured stable oxygen and bioavailable strontium isotope ratios from low mobility fauna sampled from the major geological and physiographic provinces in Adelaide, South Australia in order to create a database for this region.
Bioavailable strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) obtained from the predominantly siliciclastic metasediments of the Neoproterozoic Adelaide Geosyncline have a range of 0.7122 ± 0.0001 to 0.7202 ± 0.0001. Cainozoic samples (dominantly terrestrial fluvial/lacustrine and marine carbonate sediments) from the Adelaide Plains have values in the range of 0.7098 ± 0.0002 to 0.7121 ± 0.0001. Samples from the alluvial fan sediments near the Eden-Burnside Fault at the boundary between these regions have values of 0.7131 ± 0.0001 to 0.7143 ± 0.0001. Stable oxygen isotope results range from − 9.5 to − 4.5‰ δ¹⁸OC (VPDB) and do not appear to vary systematically based on elevation, temperature, rainfall or humidity.
These results demonstrate that strontium isotopes are potentially a useful tool for provenance studies within the Adelaide area. Oxygen is probably a more appropriate tool for discriminating seasonality rather than location within the study region.
This research also suggests that rats are better suited for mapping strontium isoscapes than koalas, and that, while (non-systematic) offsets appear to exist between laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) and thermal ionisation mass spectrometry (TIMS) data, this effect is considerably less than the variation between geological provenances in the region.
The soluble and exchangeable ions for a soil profile from the Roonka archaeological site. Lower Murray Basin, South Australia, are compared with the total elemental content of the soils. Since the chemical composition of post-mortem ionic substitution phases and secondary minerals in archaeological bone will depend on the availability of ions to the soil solution under field conditions, it is suggested that models addressing diagenesis in bone employ soluble and exchangeable ions rather than total elemental soil data.
THE isotopic composition of carbon and nitrogen as well as of strontium
in animal bone is related to the environment in which the animal
lived1-6. It can be assumed that this is also the case for
lead isotopes. In theory, therefore, we have a way of pinpointing the
origin of elephant ivory, which may be of value in conservation. Here we
report that by analysing the isotope ratios of these elements, a clear
distinction between several different populations of the African
elephant can be made.
The isotopic ratio of strontium-87 to strontium-86 shows no detectable variation in present-day ocean water but changes slowly
over millions of years. The strontium contained in carbonate shells of marine organisms records the ratio of strontium-87
to strontium-86 of the oceans at the time that the shells form. Sedimentary rocks composed of accumulated fossil carbonate
shells can be dated and correlated with the use of high precision measurements of the ratio of strontium-87 to strontium-86
with a resolution that is similar to that of other techniques used in age correlation. This method may prove valuable for
many geological, paleontological, paleooceanographic, and geochemical problems.
Amino acid analyses of undecalcified samples of fossil crocodile and rhinoceros enamel and dentin from mature teeth revealed that the total protein content of these mineralized fossil tissues varied from ~0.01–0.007% by weight. Except in one instance, amino acid analyses of the enamel proteins revealed them to be free of collagen and to have an amino acid composition similar to the proteins obtained from the enamel of mature modern vertebrates. Molecular sieving of the acid soluble enamel proteins demonstrated that the components consisted principally of small peptides and free amino acids, as in the enamel of modern vertebrates.
Based on the presence of hydroxyproline (hyp) and hydroxylysine (hyl), collagen was detected in undecalcified mature dentin of fossil rhinoceros, but not in undecalcified crocodile dentin. It was only by sequential extraction procedures that the presence of collagen in the dentin of fossil crocodile was established, emphasizing the utility and importance of analyzing the soluble components in specific extracts of the fossil. Based on these data and the concentrations of hyp and hyl in the material solubilized by the various solvents, the dentin of fossil rhinoceros contained considerably more collagen per weight and as a percentage of the total protein in the dentin than did the dentin of fossil crocodile.
As with modern dentin, EDTA and dilute acid solubilize the noncollagenous proteins and peptides found in fossil enamel and dentin, some of which contain O-phosphoserine [Ser(P)], an amino acid unique to mineralized connective tissues. Similar to recent reported findings from fossil bone, less of the original content of the noncollagenous proteins, including those phosphorylated, is degraded and removed from the enamel and dentin during fossilization than the percentage of dentinal collagen and the nonphosphorylated domains of the enamel proteins which are removed. This selective resistance to degradation and removal of the noncollagenous proteins, including phosphoproteins, may reflect the strong interaction of these proteins with the mineral phase of fossilized tissues. The amount and close packing of the inorganic crystals may also inhibit the interaction of the proteins in the interior of the enamel and dentin with the geochemical environment.
Stable-isotopic analyses of human bone, now an established aid to dietary reconstruction in archaeology, represent the diet as averaged over many years. Separate analysis of different skeletal components enables changes in diet and place of residence to be tracked, giving a fuller life-history for long-dead individuals.
Strontium isotopes can be used as biogeochemical tracers in the study of human and animal ecology. Strontium isotopes are characteristic of the local geology, and they pass through the food chain with significant fractionation. The local geology can be characterized by strontium isotope analysis (reported as a simple ratio of isotope abundances) of the soils and plants that form the catchment or home range of the species under study. Soil (Dasch 1969) and plants (Hurst and Davis 1981) are in isotopic equilibrium with local source rock and share similar isotopic ratios for strontium. Dietary strontium is incorporated in tissues and stored for different periods of time depending on the strontium turnover rates of the specific tissues. Accordingly, strontium isotope analysis of permanent teeth, gut contents, and muscle and bone tissues, all having different turnover rates, may provide important data in studying animal migration and local movement, particularly if animals move between regions with heterogeneous geology.
Under conditions of normal calcium metabolism, Sr/Ca ratios have been shown to reflect the trophic level of contemporary and recent terrestrial fauna. A procedure is investigated for the analysis of biogenic and diagenetic apatite in vertebrate fossils, on the basis of solubility differences among carbonate, hydroxy-, and fluorapatites. When applied to the 2Ma BP fauna of the Omo Basin (Ethiopia), distinct characterization of the herbivore, omnivore, and carnivore fauna in conformity with trophism was descerned, in spite of anomalous Sr/Ca of one highly specialized carnivore, Homotherium. Possible metabolic and/or taphonomic explanations of this anomaly are discussed, and future basic research into the solubility profile procedure is outlined.-from Author
A Dictionary of South African English on Historical Principles is the fullest ever study of the English language in South Africa. The result of 25 years of work, this dictionary has been researched and written according to historical principles. However, as well as recording examples of South African English going back to the sixteenth century, the dictionary also provides an insight into the dramatic political and cultural changes in South Africa's history by examining the country's ever changing language right up to the present day. Research into language has involved the contributions of hundreds of individual South Africans, as well as extensive research into all other forms of the written and spoken language. Diverse and informative entries include robot (a traffic light), bakkie (a small truck), bond (a mortgage), and brinjals (aubergines). The dictionary includes such areas as children's slang, the vocabulary of soldiers, the mines, local music terms, the townships, food, and a detailed look at the complex language of apartheid. English words originating from all the country's groups are recorded, including words from Dutch/Afrikaans, the Malayo-Indonesian languages, the Indian, Khoisan, Nguni, and Sotho languages.
Strontium isotope ratios and strontium concentrations in bone and tooth enamel are used to investigate patterns of residential mobility and migration in the late prehistoric (14th century) period in the mountain province of east-central Arizona. This area is of interest because of significant questions concerning the movement of people into and within the region and because of the number of late prehistoric sites with well-studied burial populations. Grasshopper Pueblo is the main focus of analysis, with additional information from the site of Walnut Creek.A pilot strontium isotope study of bone and tooth enamel of first molars from the Grasshopper and Walnut Creek regions has demonstrated intriguing variability in strontium isotope compositions of human samples and indicates a significant probability of the success of the investigations proposed here. This initial work indicates that there are measurable and meaningful differences between bones and tooth enamel from the same individuals, among individuals from the same site, and between communities in the study area.
Dietary adaptations of early hominids are generally understood to have played a crucial role in hominid evolution. The dietary habits of Australopithecus robustus are of special interest because the robust masticatory apparatus and characteristic dental features point to a distinctive dietary niche. Suggestions have ranged anywhere between carnivory and specialist herbivory, but current consensus has focused mainly on small hard items within the context of a vegetarian diet, and more particularly, frugivory. Few studies have challenged this perspective, although the results of a recent Sr/Ca study of A. robustus at Swartkrans were found to be inconsistent with herbivory. Here we address the question of A. robustus diet using 13C/12C ratio analysis of structural carbonate in tooth enamel, which has been shown to retain biogenic isotopic composition over long periods, contra earlier arguments based on bone apatite. Results for A. robustus, compared with other fauna from Swartkrans, show a mixed diet including both C3 and C4 foods. Since the C4 contribution must derive from consumption of grass or grazing animals, the data do not support either a specialist frugivorous or graminivorous niche for A. robustus; rather, they suggest a more generalized or omnivorous diet.
In experiments on marine animal fossils that had been buried in terrestrial sediments, Nelsonet al.(1986,Geochimica et Cosmochimica Acta50:1941-1949) reported that the strontium (Sr) of prehistoric bone had nearly completely exchanged with that of the burial environment, and therefore cannot be used for paleodietary reconstruction. However, Sealyet al.(1991,Journal of Archaeological Science18:399-416), using a solubility profile procedure, reported that it was possible to remove diagenetic Sr and obtain biologically meaningful Sr. Nevertheless, the Nelsonet al.study is often cited as evidence that a biological signal is irretrievable.Here infra-red spectrometry, XRD spectrometry and elemental analyses were used to compare the effects of the Nelsonet al.protocol with the solubility profile protocol on the crystal structure and crystallinity of the bone and fossil specimens. The results show that the procedures used by Nelsonet al., which include a preliminary ashing step, result in severe recrystallization of apatite both before and during the leaching step, which deleteriously affects any attempt to recover biological Sr. By contrast no observable recrystallization takes place in the solubility profile procedure.The results imply that the conclusions reached by Nelsonet al.are primarily artefacts of the specific methods used in their study, rather than due to any inherent mechanism of diagenesis.
Strontium isotope analysis of the tooth enamel of 69 adults from Grasshopper Pueblo reveals aspects of the settlement of and immigration to the area during the late 13th and 14th centuries. Depending on the range of local strontium isotope compositions, non-local residents vary from one-third to more than half of the individuals analysed. Based on associated archaeological evidence, it is likely that the latter figure is more accurate. The majority of locals are associated with Room Block 2 and the Great Kiva. Individuals associated with Room Blocks 1 and 3 tend to be immigrant, and this is also the case of the two individuals analysed from Room Block 5, a room block which has been thought to represent an immigration to the site. There are both locals and immigrants in the outliers, and the temporal data indicates that immigration continued throughout the occupation of the pueblo. Immigrants originate largely from two geologic areas: those underlain by Precambrian rocks located to the west and south of Grasshopper, or from areas underlain by Phanerozoic sedimentary rocks to the north and immediately east of Grasshopper. Ten individuals buried with diagnostic artefacts were analysed in the sample, and they represent both local and non-local origins, supporting earlier notions that the diagnostic artefacts symbolized sodalities which cross-cut ethnic and social boundaries.
Strontium isotope ratios () in human and animal bone are inherited, via foodstuffs, from rocks in the areas in which an individual lived. If such an area includes more than one rock type with differing , or is coastal region with terrestrial different from that of the sea, then bone strontium isotope ratio measurements provide a measure of the relative importance of foods from each isotopic zone. In the southwestern Cape of South Africa, marine and coastal terrestrial areas (covered by marine sands) should yield foods with close to the marine average, while the Cambrian and pre-Cambrian shales and sandstones of the hinterland ought to be enriched in 87Sr (from radioactive decay of 87Rb during the considerable time elapsed since they were laid down). Analyses of modern animal bones show that these patterns do prevail, furnishing us with a new means of reconstructing prehistoric diets.Preliminary measurements on archaeological human material recovered from coastal shell-midden sites apparently reflect heavy reliance on coastal foods. However, these bones have been shown to be contaminated with diagenetic marine strontium from the shells in the middens. Experiments on faunal specimens show that diagenetic strontium can be removed by repeated washing in acetic acid/sodium acetate buffer. Mineral with similar to the burial environment dissolves first, while subsequent washes remove strontium with different . For two coastal human skeletons, however, the marine/coastal terrestrial nature of the isotopic signature remains. Further experimental work is required in order to establish the limits of the technique; however, a combination of the solubility profile method and strontium isotope analysis promises to provide a powerful tool for reconstructing palaeodiets.
RECENT international efforts to conserve the African elephant Loxodonta africana prompted us to seek an appropriate method for determining the area from which individual tusks were derived. Trace element analysis of ivory has indicated the potential of chemical analysis for source identification1, but recent isotopic studies of African mammals2–5 suggest another approach. Stable carbon isotope ratios (13C/12C) in elephant bone collagen clearly reflect the mixture of C3 foliage and C>4 grasses in the diet, and are directly proportional to the density of C3 browse2. Furthermore, nitrogen isotope ratios (15N/14N) in bone collagen of African mammals are related to rainfall or water stress3–5. Strontium isotopes (87Sr/86Sr) in bone or ivory can be expected to reflect local geology6,7. Here we report on a study of ivory and bone samples from different regions of Africa demonstrating the feasibility of trivariate isotopic analysis to identify the area in which an elephant lived, thus providing a potentially powerful tool for the control of illegal trading in ivory.
To optimize conservation and restoration strategies for fish stocks it
is important to identify the rearing habitats that produce the most successful
individuals. However, tracking millions of migratory fish through multiple
life stages seems to be impossible using conventional techniques. Using differences
in the ratio of stable isotopes of strontium (Sr), found naturally in stream
water, we have been able to distinguish juvenile Atlantic salmon (Salmo
salar) from eight of ten rearing sites studied in Vermont streams. This
demonstrates the potential for using environmental signals to determine the
rearing stream from which salmon originate, and should help to guide restoration
activities.
Reconstructions of hominid foraging activities at Koobi Fora must account for an uneven distribution of Plio-Pleistocene archaeological sites and hominid fossils. Near the 1·64 million year old stratigraphic level of the Okote Tuff complex, stone raw materials and tools are abundant in fluvial contexts at the Karari Ridge. In contrast, hominid fossils are abundant but stone raw materials are absent and tools are rare in fluvial and shallow, ephemeral lake margin contexts at Ileret and at the Koobi Fora Ridge. As the distance to the nearest source of stone raw materials increases, from local abundance at the Karari Ridge to 5 km at Ileret and to at least 15 km at the Koobi Fora Ridge, the archaeological visibility of hominid activities, as defined by sites with stone tools, decreases to essentially zero. Cut marks made with large stone tools during Butchery occur on more than 66 fossil bones from Ileret and especially from the Koobi Fora Ridge. In the absence of associated stone tools, those define a new kind of stone age site. The fossils with cut marks represent diverse skeletal parts and taxa, especially hippopotamus, and occur over several square km as isolated specimens, as associated elements of one carcass, and as concentrations of conjoining pieces and multiple carcasses. Some of the defleshing cut marks occur on intact limb elements that were not utilized for marrow. Early Homo erectus probably carried large stone tools during their foraging visits to these sub-regions, using the tools in butchery but rarely discarding them. Alternative hominid foraging strategies along the ancestral Omo River and taphonomic processes of site formation are discussed.
Elemental analyses of mammalian bone (e.g., strontium-calcium ratios, or Sr/Ca) distinguish between herbivores and carnivores; however, the relationships among herbivores are unclear. To study this question, a modern faunal sample from the Nagupande Tsetse Control Area (Zambezi drainage, Northwestern Zimbabwe) was used. This collection has the advantage of well-established geographical controls in addition to a varied fauna, which includes both bovids and suids.
The grazing/browsing dietary status of each species was ascertained by means of isotopic analysis of carbon. Clear differences were seen in the δ13C of grazing and browsing animals; a specialized grazer was found to have significantly lower Sr/Ca than less specialized grazers and browsers.
In this study it was also possible to examine differences in Sr/Ca by sex; female warthogs were found to have significantly lower Sr/Ca than males. The variation in certain animal groups was found to be abnormal.
Implications for reconstruction of prehistoric human diets using trace-element techniques are discussed.
Faunal and human bones from the Natufian and Aurignacian levels of Hayonim Cave, Israel, were analyzed for calcium, strontium, and phosphate, in order to investigate the efficacy of strontium measurements for determining the proportion of meat in human diets. This site in the western Galilee was appropriate for a test of the technique since a)herbivore and carnivore fauna were present in numbers from two different time periods, b) well-characterized human skeletons were also present in at least one of these levels, and c)the diets of the individuals examined were basically well understood. On the basis of Sr/Ca values, a large difference was observed between Natufian herbivore bones and carnivore bones in the manner predicted by the diets of these species. Sr/Ca values for the adult humans from the same level fell midway between the herbivore and carnivore ranges. However, a different pattern was observed for Aurignacian fauna; no difference could be found between Sr/Ca ratios of herbivore and carnivore bones. The findings suggest that, in certain circumstances, the technique may provide important new paleodietary information. However, at any given site or level, both herbivore and carnivore fauna should be analyzed before conclusions about human diets are drawn from it.
Isotopic analysis of skeletons excavated during the 1950s has confirmed that they are the remains of shipwreck victims: slaves on board the Portuguese slaving brig Pacquet Real when it sank on 18 May 1818. Twenty-five slaves drowned and the remaining 133 became Prize Negroes at the Cape. The isotopic signatures are consistent with values expected for people living in an African village eating a terrestrially based diet. Analyses of different skeletal elements, i.e., teeth, long bone, and rib, are shown to be a valuable tool in tracing change or consistency in diet during a person''s life, because different skeletal elements form at different stages of life and, subsequently, remodel at different rates. A comparison of isotope ratios from different skeletal elements indicates a change in diet in all these individuals, probably coincident with their enslavement. Variation between individuals in the isotopic composition of diets eaten early in life is sufficiently large to deduce heterogeneous origins for the group.
Paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured values reflect in vivo values. To test for postmortem alteration, we measured , , and ratios and Sr concentrations in modern and prehistoric (610 to 5470 yr old) bones of animals with marine or terrestrial diets from Greenland.Bones from modern terrestrial feeders have substantially lower Sr concentrations and more radiogenic ratios than those from modern marine feeders. This contrast was not preserved in the prehistoric samples, which showed almost complete overlap for both Sr concentration and isotopic composition in bones from the two types of animals. Leaching experiments, X-ray diffraction analysis and infrared spectroscopy indicate that alteration of the Sr concentration and isotopic composition in prehistoric bone probably results from nearly complete exchange with groundwater. Oxygen isotope ratios in fossil apatite carbonate also failed to preserve the original discrimination between modern terrestrial and marine feeders. The C isotope ratio of apatite carbonate did not discriminate between animals with marine or terrestrial diets in the modern samples. Even so, the ranges of apatite δ13C values in prehistoric bone are more scattered than in modern samples for both groups, suggesting alteration had occurred. δ13C and δ15N values of collagen in modern bone are distinctly different for the two feeding types, and this distinction is preserved in most of the prehistoric samples.Our results suggest that postmortem alteration of dietary tracers in the inorganic phases of bone may be a problem at all archaeological sites and must be evaluated in each case. While collagen analyzed in this study was resistant to alteration, evaluation of the possibility of diagenetic alteration of its isotopic composition in bones from other contexts is also warranted.
Previous study of the strontium calcium ratio (Sr/Ca) of robust australopithecine skeletons from the Transvaal site of Swartkrans indicated that this Pleistocene hominid was an omnivore, suggesting that models for niche differentiation amongst contemporaneous hominids based on trophic level (i.e. Homo sp. = omnivore vs. A. robustus = herbivore) may be incorrect. In this study, we report that relatively elevated Sr/Ca is found in Homo sp. when compared to Australopithecus robustus skeletons from Swartkrans (ca. 1·8 ma BP). Examination of 87 Sr/86Sr in the same skeletons reduces the possibility that the result is due to different substrate sources of Sr. Foods with elevated Sr/Ca in the general area of Swartkrans are mainly geophytes, suggesting that the early Homo niche may have included relatively intensive exploitation of underground plant resources.
The controversy about the validity of using bone and tooth mineral (biological apatite) as an alternative sample material to collagen for stable carbon isotope analyses is briefly reviewed. Some of the apparent contradictions may have arisen as a result of the effects of different pretreatment methods, as well as the choice of tissue. Experimental results are presented which document the isotopic and mineralogical effects of 1 m acetic acid pretreatment on modern and fossil biological apatites. The data show that this procedure has marked effects on modern mineral. Prolonged reaction in 1 m acetic acid leads to recrystallization of bone apatite to brushite (dicalcium phosphate-dihydrate), suggesting that this treatment must be used cautiously for recent archaeological materials. Recrystallization was not observed for older fossil material; changes are rather due to elimination of calcite and the more soluble apatite crystallites. The results indicate that enamel provides the most consistent results. Accordingly, only enamel was used for an applied study of the diets of 1·8 Ma extinct primates from Swartkrans Cave, South Africa.
Strontium-calcium ratios (Sr/Ca) are normally reduced at higher trophic levels in foodwebs, due to discrimination against strontium in favour of calcium by animals. This phenomenon has not generally been applied to the study of fossil foodwebs and the diets of early hominids because of diagenetic changes which obscure or obliterate biological Sr/Ca. The examination of compartments of fossil apatite having differing solubility, however, is a promising method for independently measuring biological and diagenetic Sr/Ca. In this study, Sr/Ca in Member I fossils from the site of Swartkrans were examined using a solubility profile procedure. Sr/Ca relationships observed among Swartkrans fauna match those seen in modern African foodwebs, suggesting that biological Sr/Ca accounts for the observed variation.When specimens of the fossil hominid Australopithecus robustus were examined, Sr/Ca values were inconsistent with that of a root, rhizome or seed-eating herbivore, suggesting that the diet of this species was more diverse than previously believed, and almost certainly included the consumption of animal foods.
Strontium-calcium ratio (Sr/Ca) and stable carbon isotope ratio (13C/12C) analyses of bone and enamel apatites may be used for reconstructing predator-prey relationships in vertebrate fossil assemblages. The approach is based on the rationale that 13C/12C in predator apatite closely resemble those of their prey, while Sr/Ca is predictably reduced in specific predator-prey pairs. As an example, we compare the relationship of the extant leopard, Panthera pardus, and its preferred prey in modern foodwebs, with the relationship of fossil leopards (from the Member 1 fossil faunal assemblage at Swartkrans Cave), and their likely prey. The results suggest that Swartkrans Member I leopards depended heavily on Papio baboons, with some lesser contribution from Hyrax (Procavia sp.). The approach has considerable potential for elucidating the preferred prey of extinct predators such as sabertooth cats.
Strontium has been shown to vary within trophic levels in natural foodwebs so that previous criteria used to identify biogenic strontium in fossils, namely consistent differences between herbivores and carnivores, may be inappropriate. In this article, two alternative approaches are explored. These include first, experimental studies of the behaviour of synthetic apatites in the solubility profile system, and second, solubility profile studies of fossils from the Pleistocene site of Swartkrans. The synthetic apatite studies show that simple mixtures of apatites dissolve discretely in the system. Study of Swartkrans specimens reveals that, while diagenetic Sr is clearly present, some recoverable Sr varies in a manner similar to that seen in modern African foodwebs, and is therefore unlikely to be of diagenetic origin.
By comparing the Sr isotopic composition of migratory fossil salmon, which lived in the ocean but died in continental regions, to the well established marine Sr isotopic record, the age of the continental deposit could be determined with high accuracy. This approach to marine-continental correlation and dating requires (1) that marine-resident salmon bear a marine 87Sr/86Sr value in their bones or teeth, and (2) that the original 87Sr/86Sr value of fossils is not overprinted by diagenesis. The vertebrae of modern, hatchery-reared salmon exhibit Sr isotopic variations indicative of freshwater to marine migration during bone growth. Modern marine 87Sr/86Sr values were preserved in growth layers formed later in life. Marine-phase growth layers in the bones and teeth of the late Miocene migratory salmon,Oncorhynchus rastrosus, were subjected to stepwise selective leaching to separate biogenic hydroxyapatite from diagenetic calcium carbonate and recrystallized hydroxyapatite. Although the procedure yielded leachates with Sr/Ca and Ca/P values characteristic of apatite, the leachates had 87Sr/86Sr values consistently less radiogenic than values for late Miocene seawater ( ⊃ 0.7087. The fossils were substantially contaminated by Sr from the hosting clastic sediments. Specimens in continental deposits differed in 87Sr/86Sr value from host sediments by 0.0002 to 0.0200, supporting the conclusion that these salmon were migrants from marine waters. However, because the original Sr isotopic composition of fossil bones and teeth cannot be determined with confidence, archaeological, paleobiological and stratigraphic applications of this technique may be limited.
The initial rates of dissolution of synthetic apatites were determined using the rotating disc method. The reactivities of carbonated apatites in acidic media were directly related to their carbonate content. This appeared to be due, in part, to a decrease in the apparent activation energy for dissolution of carbonated apatites. Structurally incorporated fluoride in carbonated apatites at levels up to 1,000 μg/g did not influence the dissolution rates, whereas fluoride at a concentration of 1 μg/ml in the buffer solution reduced the dissolution rates by 20–30%. Apatite dissolution under the experimental conditions was intermediate between transport control and surface chemical control. After 10 min, diffusion processes within the apatite pellets were found to influence the overall dissolution rate.Copyright © 1983 S. Karger AG, Basel
Apatites containing CO3 and/or F were synthesized and exposed to acid buffer. The extent of dissolution was determined (as mMCa/ml buffer solution) and the apatites characterized by X-ray diffraction, IR absorption, and chemical analyses before and after acid exposure. Results showed that: (i) the extent of dissolution was directly proportional to the CO3 contents but that the simultaneous presence of F in the apatite minimized the adverse CO3 effect; (ii) the extent of dissolution during the second exposure was much less than during the first exposure; (iii) the lattice parameters, crystal-Unity and CO3 and F contents of the apatites differed before and after exposure to the acid buffer, i.e., larger a-axis, initial decrease then increase in crystallinity, lower carbonate and higher fluoride contents of apatites after acid exposure. Results from this study suggest that the vulnerability of synthetic and biological apatites to acid dissolution is largely due to their carbonate constituent and that the caries process may involve a combination of dissolution of carbonate-rich/fluoride-poor apatites and reprecipitation of carbonate-poor/fluoride-rich enamel apatites and that the reprecipitated apatite is rendered more resistant to acid dissolution.Copyright © 1983 S. Karger AG, Basel
Strontium-87/strontium-86 ratios indicate the sources of strontium in samples of natural waters, vegetation, and soil material taken from watersheds in the Sangre de Cristo Mountains of New Mexico. More than 75 percent of the strontium in the vegetation is ultimately derived from atmospheric transport and less than 25 percent from the weathering of the underlying rock. Much of the airborne strontium enters the watersheds by impacting on coniferous foliage, but deciduous foliage apparently traps little, if any, strontium-bearing aerosol. The strontium and presumably other nutrients are continuously recycled in a nearly closed system consisting of upper soil horizons, forest litter, and the standing crop of vegetation.
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