Carbon Isotope Ratios Of Collagen Research Articles

Early Colonial Diet in El Japón, Xochimilco, Mexico: Examining dietary continuity through stable isotope analysis of bone collagen and bioapatite.

Early colonial documents from central Mesoamerica detail raising and planting of European livestock and crops alongside native ones. The extent to which Indigenous people, especially of the rural commoner class, consumed newly introduced foods is less known. This gap in knowledge is addressed through stable isotope analysis and comparison to published archaeological botanical, human, and faunal data. Stable isotope analysis of bone collagen and bioapatite is applied to 74 skeletal samples of Indigenous human remains representing Colonial period individuals from El Japón-a farming hamlet in the Xochimilco area-to provide insight into long-term individual dietary practices in the context of a rapidly transforming Mesoamerican world. Carbon isotope ratios in collagen (δ13Ccollagen) average -8.10/00 VPDB (SD 0.55), while δ15N averages 8.90/00 AIR (SD 0.50). δ13Cbioapatite averages -2.90/00 VPDB (SD 0.60). Modest increase in carbon isotopic diversity is observed among more recent males from El Japón when compared to earlier males and females. Based on the isotopic results, it is estimated that the individuals of El Japón consumed maize or other C4 plants as a central source of carbohydrates. Dietary protein was largely supplied through domestic maize-fed fauna but potentially supplemented by wild terrestrial and aquatic fauna and fowl. Similarity in skeletal isotopic composition between precontact Mesoamericans from other sites and El Japón individuals of both earlier and later stratigraphy is interpreted as continuity in local diets and foodways despite potentially available European alternatives. Colonial taxation demands on preexisting agricultural regimes may have incentivized maize production, thus indirectly contributing to the maize-centered aspect of local foodways.

Trophic level and macronutrient shift effects associated with the weaning process in the postclassic Maya

The weaning process was investigated at two Maya sites dominated by Postclassic remains: Marco Gonzalez (100 BC-AD 1350) and San Pedro (1400-AD 1650), Belize. Bone collagen and bioapatite were analyzed from 67 individuals (n < or = 6 years = 15, n > 6 years = 52). Five isotopic measures were used to reconstruct diet and weaning: stable nitrogen- and carbon-isotope ratios in collagen, stable carbon- and oxygen-isotope ratios in bioapatite, and the difference in stable carbon-isotope values of coexisting collagen and bioapatite. Nitrogen-isotope ratios in infant collagen from both sites are distinct from adult females, indicating a trophic level effect. Collagen-to-bioapatite differences in infant bone from both sites are distinct from adult females, indicating a shift in macronutrients. Oxygen-isotope ratios in infant bioapatite from both sites are also distinct from adult females, indicating the consumption of breast milk. Among infants, carbon- and nitrogen-isotope ratios vary, indicating death during different stages in the weaning process. The ethnohistoric and paleopathological literature on the Maya indicate cessation of breast-feeding between ages 3-4 years. Isotopic data from Marco Gonzalez and San Pedro also indicate an average weaning age of 3-4 years. Based on various isotopic indicators, weaning likely began around age 12 months. This data set is not only important for understanding the weaning process during the Postclassic, but also demonstrates the use of collagen-to-bioapatite spacing as an indicator of macronutrient shifts associated with weaning.

Status and gender differences in diet at Mound 72, Cahokia, revealed by isotopic analysis of bone

Cahokia Mound 72 contains 272 human burials dating to the Lohmann and early Stirling phases (ca. 1050–1150 AD) of the Mississippian period. Substantial status- and gender-related differences in burial style are apparent. Some burials are associated with large quantities of prestigious grave goods, suggesting high status. Mass graves of young adult females with skeletal indicators of poor health suggest low status and nutritional stress. Nitrogen isotope ratios of bone collagen show that high status individuals ate much more animal protein, but carbon isotope ratios of collagen suggest these individuals ate only ca. 10% less maize than lower status individuals. Apatite carbon isotopes show low status females ate ca. 60% more maize than high status individuals, which confirms the large nitrogen isotope difference of females in mass graves. These results indicate high and low status individuals had significantly different diet compositions and nutritional qualities. The stable isotope evidence supports paleopathological data for status-related differences in health, and dental morphological data for presumed genetic differences in origin. These data also provide insights into the nutrition- and health-related dimension of regional hierarchical organization of settlements and social inequality of this complex chiefdom in the greater Cahokia region.

Preparation and characterization of bone and tooth collagen for isotopic analysis

Criteria are presented for the identification of diagenetic alteration of carbon and nitrogen isotope ratios of bone and tooth collagen prepared by a widely used method. Measurements of collagen concentrations in tooth and bone, atomic C:N ratios, and carbon and nitrogen concentrations in collagen of 359 historic and prehistoric African humans, and modern and prehistoric East African non-human mammals are described. Carbon isotope ratios of collagen lipids from four bones are also presented. Compared to bone, whole teeth have significantly lower collagen concentrations, lower carbon and nitrogen concentrations in collagen, and similar C:N ratios. Carbon and nitrogen concentrations and C:N ratios are relatively constant over a wide range of collagen concentrations. However, prehistoric specimens with very low collagen concentrations have highly variable C:N ratios, very low carbon and nitrogen concentrations in collagen, and stable carbon and nitrogen isotope ratios unlike collagen. At the transition from well-preserved to poorly preserved collagen the most reliable indicator of collagen preservation is the concentration of carbon and nitrogen in collagen. Concentrations of C and N drop abruptly by an order of magnitude at this transition point. These attributes provide simple criteria for assessing sample quality. Since collagen preservation can vary greatly within prehistoric sites, these attributes should be reported for each specimen. Use of purification procedures that remove acid- and base-soluble contaminants and particulate matter (carbonates, fulvic acids, lipids, humic acids, sediments and rootlets) are recommended. Wider adoption of these procedures would insure comparability of results between laboratories, and permit independent and objective evaluation of sample preservation, and more precise dietary, climatic, and habitat interpretations of collagen isotopic analyses.