A Simple(R) Model to Predict the Source of Dietary Carbon in Individual Consumers

Abstract

Quantitative individual human diet reconstruction using isotopic data and a Bayesian approach typically requires the inclusion of several model parameters, such as individual isotopic data, isotopic and macronutrient composition of food groups, diet-to-tissue isotopic offsets and dietary routing. In an archaeological context, sparse data may hamper a widespread application of such models. However, simpler models may be proposed to address specific archaeological questions. As a consequence of the intake of marine foods, individuals from the first century AD Roman site of Herculaneum showed well-defined bone collagen radiocarbon age offsets from the expected terrestrial value. Taking as reference these radiocarbon offsets and using as model input stable isotope data (δ 13 C and δ 15 N), the performance of two Bayesian mixing model instances (routed and concentration-dependent model versus nonrouted and concentration-independent) was compared to predict the carbon contribution of marine foods to bone collagen. Predictions generated by both models were in good agreement with observed values. The model with higher complexity showed only a slightly better performance in terms of accuracy and precision. This demonstrates that under similar circumstances, a simple Bayesian approach can be applied to quantify the carbon contribution of marine foods to human bone collagen.

Adding Hydrogen to the Isotopic Inventory—Combining δ13C, δ15N and δ2H Stable Isotope Analysis for Palaeodietary Purposes on Archaeological Bone

“…Uncertainties for consumer data were set to 1‰ for δ 13 C and δ 15 N, and 5‰ for δ 2 H values. Diet‐to‐collagen offsets were set to 5 ± 2.2‰, 5.5 ± 0.5‰ (similar to Fernandes ) and 40 ± 10‰ for CNH, respectively. Food concentrations were set to 100% because we are using a single fraction (protein).…”

“…FRUITS is freely available and allows for the inclusion of not only isotopic evidence but also prior information available from other sources, such as archaeological records (Fernandes ). The FRUITS software is described in detail in Fernandes et al .…”

Calling all archaeologists: guidelines for terminology, methodology, data handling, and reporting when undertaking and reviewing stable isotope applications in archaeology

“…Diet‐to‐consumer isotopic offsets and routing mechanisms are quantified through controlled feeding experiments on humans or omnivorous mammals. The complexity of dietary routing mechanisms means that mixing models that account for separate signal contributions from multiple food nutrients towards consumer tissues are best employed in certain contexts …”

Testing the Use of δ2H Values for Reservoir Corrections in Radiocarbon Dating Human Bone

“…FRUITS is freely available and allows for the inclusion of not only isotopic evidence but also prior information available from other sources such as archaeological records (Fernandes et al, 2016).…”