Hardwood ash nixtamalization may lead to false negatives for the presence of maize by depleting bulk δC in carbonized residues

Among the multiple proxies for detecting maize in precontact economies is the use of δ¹³C analysis of carbonized residues from ceramic cooking vessels. Although maize horticulture was widely established in Eastern North America (ENA) by A.D. 1000, there are carbonized residues from ceramic assemblages after this date that lack the elevated δ¹³C values indicative of the presence of maize. This may be due to the true absence of maize, or other factors including the masking of maize. Prior experimental research by Hart et al. demonstrated that the addition of C₃ plants or consumers to two part mixes with maize can mask maize presence even when maize is the dominant ingredient. Here we investigate the effect of alkali processing of maize (nixtamalization) on δ¹³C using the widespread ENA process of boiling maize kernels with wood ash, a C₃ product, to create hominy. Our experiments test whether or not the process of hardwood ash nixtamalization can mask the presence of maize in adhering carbonized residues by depleting δ¹³C values, and whether there is a reciprocal δ¹³C enrichment effect on the hardwood ash employed in nixtamalization. Overall, there is substantial δ¹³C depletion of residues when maize is cooked with hardwood ash, and hardwood ash cooked with maize shows the reciprocal enrichment. Therefore, the depleted values after the adoption of maize may be false negatives due to the nixtamalization process.     

Non-linear relationship between bulk δC and percent maize in carbonized cooking residues and the potential of false-negatives in detecting maize

Bulk δ¹³C values on charred cooking residues adhering to pottery sherd interior surfaces have been used as a source of information on the histories of maize in various locations in the western hemisphere. This approach is based on an assumption of a linear relationship between the percent maize in the resource mix cooked in a pot and δ¹³C. Previous experiments suggest that this relationship is non-linear, and maize may not be identified from bulk δ¹³C values even when it contributed substantially to the resource mix. A second round of experiments, presented here, indicates that the mobilization of carbon from maize and C₃ resources over time is the critical variable in residue formation and the resulting bulk δ¹³C value. This is influenced by the form of maize being cooked.     

Chemical,elemental, and isotopic effects of acid concentration and treatment duration on ancient bone collagen: an exploratory study

Demineralization of bone for collagen extraction is most commonly performed using dilute hydrochloric acid (HCl) despite the fact that little data exists on the effects of differing acid concentration or treatment time on the quantity and quality of collagen extracts and that hydrochloric acid is extremely effective at hydrolyzing peptide bonds. Data on yield, elemental composition, and isotopic signature from bone collagen obtained from multiple extractions performed on two large ancient human bone samples from prehistoric Puerto Rico indicate that there is no meaningful difference between acid treatments ranging from 0.05 to 0.2 M concentration and 24–120 h of treatment. As such, a shorter course of demineralization using more concentrated acid would appear to produce quality results in a shorter time.     

Stable isotope analysis of prehistoric populations from the cemeteries of the Middle and Lower Dnieper Basin,Ukraine

This paper presents the results of new stable isotopes (carbon and nitrogen) analysis of human, faunal and fish remains from thirteen cemeteries from the Middle and Lower Dnieper Basin, Ukraine. The results are integrated with earlier analyses, undertaken solely on human samples, in order to provide a comprehensive overview of subsistence across the Upper Palaeolithic through to Eneolithic periods in this region. This is the first time that a combined sample of human, faunal and fish remains has been studied in order to interpret subsistence strategies across these periods in Ukraine. The total dataset comprises 113 samples of human, faunal and fish remains, 59 of which include new analyses of faunal and fish remains that have not previously been made available for study (Table 1). The analysis of the faunal and fish remains allows for a consideration of trophic levels which indicates that the consumption of freshwater fish occurs from the Epipalaeolithic period onwards. Whilst the majority of the cemeteries and the individuals therein cluster in relatively tight groups, there is a significant offset between the human and faunal samples due to the consumption of freshwater resources. The fish samples analysed in the study appear to exhibit a relatively random distribution when compared to the other samples analysed. In general, freshwater resources remain significant through until the end of the Neolithic period and into the Eneolithic period at the sites investigated.     

Stable isotope palaeodietary study of humans and fauna from the multi-period (Iron Age,Viking and Late Medieval) site of Newark Bay,Orkney

We report here on stable carbon and nitrogen isotope measurements of human and faunal bone collagen from the Iron Age, Viking Age, and Late Medieval site of Newark Bay, Orkney, Scotland. We found a wide range of results for humans in both δ¹³C (−15.4‰ to −20.3‰) and δ¹⁵N (8.6‰–15.6‰) values. The enriched carbon and nitrogen values indicate the consumption of significant amounts of marine protein, which is very unusual for post-Mesolithic (e.g. 4000 cal BC) UK and European populations. Also of interest is a statistically significant difference in δ¹³C (t = −2.48, p = 0.011) and δ¹⁵N (t = −2.44, p = 0.011) values, and therefore diets, between adult males and females at this site, with males (δ¹³C = −17.8 ± 1.2‰, δ¹⁵N = 13.2 ± 1.6‰) having, on average, a higher proportion of marine protein than females (δ¹³C = −18.9 ± 1.1‰, δ¹⁵N = 11.8 ± 1.8‰). The weaning age of the sub-adults was difficult to interpret due to the large isotopic variation in the adult females, but nearly all individuals between birth and 1.25 years have elevated δ¹⁵N values indicating that they were breastfed to some extent.     

Forensic Ar/Ar dating: a provenance study of Middle Stone Age obsidian artifacts from Ethiopia

Obsidian sourcing based on geochemistry is widely applied to reconstruct commerce patterns and dissemination of early hominid groups. Due to problems concerning potential intra-source variability or homogeneity of a geological source over large areas, parameters additional to this classical approach are desirable. Here we present the first ⁴⁰Ar/³⁹Ar investigation of Middle Stone Age (MSA) obsidian artifacts (i.e. debitage pieces) for this purpose, as well as of potential geological obsidian sources from Ethiopia. With the present pilot study we demonstrate that ⁴⁰Ar/³⁹Ar geochronology represents a reliable and powerful tool for archaeological provenance studies complementary to the geochemical approach and more recently applied techniques like fission track counting or Mössbauer spectroscopy. Two independent sets of debitage and potential source rock samples were dated by the ⁴⁰Ar/³⁹Ar method. Debitage pieces from the Kulkuletti excavation site and obsidian samples from the nearby obsidian outcrop Worja (central Ethiopia) exhibit basically identical age ranges as well as similar Ca/K and Cl/K ratios, supporting the debitage/source rock relationship previously inferred on geochemical grounds. A second small set of geochemically characterized debitage samples from the Porc Epic cave and potential source rocks from an obsidian outcrop at Kone (Eastern Ethiopia) however have different ⁴⁰Ar/³⁹Ar ages and Ca/K and Cl/K ratios. These results contradict the previous conclusion about a debitage/source rock relationship of the Porc Epic and Kone samples made on the basis of geochemistry [A. Negash, M.S. Shackley, Archaeometry 48 (2006) 1]. Additional sampling at the Kone outcrop as well as of other obsidian occurrences in the greater area is needed to unambiguously pinpoint the origin of these obsidian tools.     

Diversity in foddering strategy and herd management in late Bronze Age Britain: An isotopic investigation of pigs and other fauna from two midden sites

Abstract

Middens of the southern British late Bronze and Iron Age are vast accumulations of cultural debris that can be explained as refuse dumps linked with large periodic feasting events. A distinctive feature of these sites is that their faunal assemblages invariably comprise a considerably higher proportion of pig remains than contemporaneous settlement sites. This paper presents results from a programme of stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis of fauna from two major midden sites, Llanmaes in South Wales and Potterne in Wiltshire. The research aim is to reconstruct husbandry strategies and foddering regimes, particularly concerning pigs, to better understand how the challenges of raising large herds were met. Analysis produced exceptionally wide-ranging results for pigs and other domesticates at both sites, particularly in terms of δ¹⁵N values, demonstrating that diverse foddering strategies were employed. Diversity in the late Bronze Age pig foddering regimes indicates that the Neolithic husbandry practices (focusing on woodland fodder) had not been abandoned, but that new husbandry methods (consumption of household waste) were also being practised, which subsequently became more widely established in the Iron Age. The heterogeneity of signatures suggests that animals may have been husbanded in a piecemeal fashion at a local, household level. This in turn hints that fauna may have been brought to these sites from households across the surrounding landscape, rather than being husbanded by specialist producers in the vicinity of the middens.     

Studies on amerindian dogs, 1: Carbon isotopes in relation to maize in the diet of domestic dogs from early Peru and Ecuador

Work initiated purely as a dating project in support of a craniometric and morphological investigation of domestic dogs from early Peru has proved to have much wider implications. The stable carbon isotoperatios (¹³C/¹²C) of hair samples from ten dogs show that maize formed a significant part of their diet. Radiocarbon dates for these remains have confirmed that they belong to the period well after the cultivation of maize was first established. Stable carbon isotope measurements can thus be used to test for the presence of maize as a dietary constituent at earlier sites even where there is otherwise only indirect evidence for its cultivation. Collagen from animal or human bone is a suitable alternative to hair for this purpose and the method has been successfully applied to collagen dating to c. 3000 BC from the Valdivia culture site of Real Alto, Ecuador, as well as to a series of early Peruvian dogs.