Interpreting Past Human Diets Using Stable Isotope Mixing Models—Best Practices for Data Acquisition

Journal of Archaeological Method and Theory - Using stable isotope mixing models (SIMMs) to quantify past diets is becoming increasingly common in archaeology. This study highlights important...     

Patterns of Diagenesis in Bone II: Effects of Acetic Acid Treatment and the Removal of Diagenetic CO3

Archaeological bones of varying preservation have been treated with 0·1 M acetic acid in order to investigate the effect on structural and chemical alterations caused by diagenesis. Acetic acid is commonly used as a “cleaning agent” for removing diagenetic carbonate from bone and enamel, in an attempt to recover original, biogenic signals for use in dietary and¹⁴C dating studies.Diagenetic parameters were measured before and after treatment on a range of archaeological bones with good and bad preservation. Histological preservation defined the behaviour of the correlating parameters, where correlation coefficients between carbonate content and crystallinity, microporosity and macroporosity increased significantly after treatment. For histologically well preserved material, acetic acid is effective at returning carbonate content to around that of modern bone. Where bone is extensively damaged by micro-organisms, “loose” diagenetic material can be removed, but a fraction largely composed of hypermineralized bioapatite remains, which, we believe, cannot be reliably used to obtain accurate biological signals.     

„Das Gewässer als Ganzes betrachten“

Ohne Zusammenfassung     

Maize,beans and the floral isotopic diversity of highland Oaxaca,Mexico

Oaxaca, Mexico has been inhabited by humans for over 10,000 years. From the time of earliest habitation, this environment provided a wide floral subsistence to its human inhabitants, notably documented at the cave site of Guila Naquitz. Light stable isotopes, primarily carbon and nitrogen, have been used in dietary and environmental reconstructions throughout Mexico and Central America. We report a large isotopic study of wild and market plants from Oaxaca that demonstrates 1) overlapping δ¹³C values of C4 plants, including maize, and plants that utilize the Crassulacean Acid Metabolism (CAM) pathway for biosynthesis, 2) the existence of a significant C4 grass biomass, 3) the lack of isotopic separation in the δ¹⁵N of legumes and non-leguminous plants and 4) the increase in the nitrogen isotopic composition of crop plants relative to wild plant averages. These four observations are potential complicating factors in interpretations involving the origins and spread of maize agriculture, the relative amount of maize in the diet and assessments of trophic level or meat contributions to the human diet.