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Compound-specific amino acid carbon-isotope compositions have shown particular promise for elucidating dietary behaviors in complex environmental contexts, and may also be able to mitigate the effect of many of the limitations inherent to palaeodietary reconstructions. Here, we investigate the efficacy of compound-specific amino acid isotopic proxies in characterizing the consumption of different dietary protein sources using amino acid carbon-isotope compositions for humans and fauna from Rössberga (Early to Middle Neolithic), Köpingsvik (Mesolithic and Middle Neolithic), and Visby (Medieval Period), Sweden. We also assess the explanatory capabilities of an isotopic mixing model when used with essential amino acid carbon-isotope compositions of humans and local fauna. All three isotopic proxies distinguished among humans from the three sites consistently and informatively, and were able to enhance the broad interpretations made using bulk isotopic compositions. The mixing model palaeodietary reconstruction revealed considerable diversity in relative protein source contributions among individuals at both Köpingsvik and Visby. Comparing the mixing model for bulk carbon- and nitrogen-isotope compositions to the model for essential amino acid isotopic compositions further demonstrated the likelihood of underestimation and overestimation of marine protein consumption for both aquatic-dominant and mixed marine-terrestrial diets when using bulk isotopic compositions.

While the use of radiogenic strontium isotope values to examine paleomobility is increasingly common in the Andes, and beyond, many questions about baseline variability remain. To better understand baseline radiogenic strontium isotope compositions in the Andes, we present new 87Sr/86Sr values from Peruvian soil samples. Modern soil samples were collected from agricultural fields from the following areas in central and southern Peru: Arequipa, Atico, Camana, Chala, Cusco, Ica, Ilo, Lima, Mejia, Moquegua, Nazca, Ocona, Palpa, Pisco, Puno, Tacna, and Yauca. Samples were partially dissolved to better approximate the bioavailable strontium. Radiogenic strontium isotope values from the partially dissolved soil samples range from 87Sr/86Sr = 0.70202 to 0.71894 and, for all soil samples, have a mean of 87Sr/86Sr = 0.70773 ± 0.00166 (1σ, n = 114). In general, the 87Sr/86Sr values measured for soil samples collected from modern agricultural fields reflect the expected 87Sr/86Sr values based on bedrock geology. Comparing our new soil data with published radiogenic strontium isotope data for bedrock, soil, water, and faunal samples provides constraints on the regions in the Andes that can, and cannot, be distinguished through radiogenic strontium isotope analysis.