Isotopic analysis of archaeobotanicals to reconstruct past climates: Effects of activities associated with food preparation on carbon,hydrogen and oxygen isotope ratios of plant cellulose

The cellulose fraction of botanicals recovered from archaeologically defined strata may be suitable for stable isotope-based palaeoclimatology in much the same manner as cellulose from tree rings has been utilized. However, manipulation by humans is a distinct possibility with such specimens and constitutes a potential source of isotopic alteration early in the post-mortem history of the samples. We studied the susceptibility of plant cellulose to isotopic alteration caused by manipulations related to food processing to determine if discarded plant foods recovered from archaeological contexts are suitable substrates for isotopic palaeoclimatic studies. The carbon and hydrogen isotope ratios of cellulose nitrate and the oxygen isotope ratios of cellulose were determined for Zea mays cobs, Helianthus annus seeds, Agave americana leaves, Pachyrrhizus erosus tubers and a cellulose standard before and after a variety of treatments, including boiling, roasting, fermentation, liming, molding and carbonization. The oxygen and hydrogen isotope ratios (which are climatically sensitive in all plants) and the carbon isotope ratios (which reflect climate only in certain plants) of all samples, except for Agave, were conserved during various food-processing steps. Thus, it appears that the isotope ratios of cellulose and cellulose nitrate prepared from many archaeological food plants, whether processed or uncooked, will reflect in vivo values and can be used to reconstruct aspects of palaeoclimate. Such isotopic palaeoclimatic studies will extend the utility and value of existing collections of ecofacts by opening a unique window for the study of the relationships among climate, plants and man.     

Provenance analysis of Olivella biplicata shell beads from the California and Oregon Coast by stable isotope fingerprinting

While Olivella beads are a common component of archaeological sites in California, and were widely traded in prehistory, no method has been developed to trace individual beads to a point of origin. This study examines the potential of stable carbon and oxygen isotopes to source Olivella beads from the Pacific coast. The study shows that 1) the oxygen isotopic composition of modern Olivella biplicata shells faithfully varies with ambient sea surface temperature and local upwelling, lending themselves to sourcing studies; 2) oxygen isotope ratios in modern shells can be used to identify shells that grow north versus south of Point Conception, California; and 3) shell carbon isotope ratios may further subdivide these two regions into more spatially restricted source zones. Analyses on a small sample of 10 beads found at various archaeological sites within the interior of California suggest that all were made in southern California.     

Stable carbon- and nitrogen-isotope ratios and electron spin resonance (ESR) g-values of charred bones: changes with heating and a critical evaluation of the utility of g-values for reconstructing thermal history and original isotope ratios

Changes in the stable carbon and nitrogen isotope ratios of modern bone samples heated to a variety of times and temperatures were used to determine the effect of heating on isotope ratios and the retention of organic matter in charred bones. For organic extracts produced by slow demineralization in weak acid, δ¹³C values were unchanged, while δ¹⁵N values increased by up to 5‰ and were primarily determined by heating temperature. Changes in the electron spin resonance (ESR) g-value of whole bone and organic extracts were also measured. For organic extracts from charred bones, the g-value was well-correlated with δ¹⁵N and temperature, suggesting that g-values could be used to estimate the charring temperature and original δ¹⁵N values of charred bones. Thus, g-values from demineralized extracts could be very useful in forensic investigations where it would important to reconstruct the thermal history of burned bones. Isotope ratios and g-values of demineralized extracts from four prehistoric components at three sites that produced cremated human bone were used to test whether the same approach can be applied to archaeological materials. While carbon isotope ratios of the prehistoric samples were similar to those of uncharred specimens, nitrogen isotope ratios were increased and the g-value corrections for nitrogen isotope ratios were not effective.     

Fish bone chemistry and ultrastructure: implications for taphonomy and stable isotope analysis

This paper reviews the ultrastructure and chemistry of fish bone, with an emphasis on zooarchaeology and stable isotope analysis. On the basis of the chemical composition of the collagen and the relationships between the collagen and mineral phases, fish bone is more susceptible to biotic and abiotic degradation than mammalian bone and is therefore less likely to be recovered in archaeological deposits. The amino acid composition of fish bone differs from that of mammals, most notably with respect to hydroxyproline content. The C:N ratio of fish collagen is, however, very similar and slightly lower than mammalian collagen, and thus the traditional range of acceptable C:N ratios for archaeological bone collagen (2.9–3.6) should not be shifted or extended for fish on the basis of the amino acid composition of collagen. An extensive survey of published archaeological bone collagen C:N ratios demonstrates that fish collagen from archaeological contexts tends to have significantly higher C:N ratios than mammalian collagen. The elevated C:N ratios in fish bone collagen may be the result of abiotic degradation processes that occur within the bone after death, the presence of exogenous humic contaminants, or endogenous lipid contaminants.     

Sulphur isotope evidence for freshwater fish consumption: a case study from the Danube Gorges,SE Europe

To explore the use of sulphur isotopes as an indicator of the consumption of freshwater fish, we undertook sulphur isotope analysis on bone collagen extracted from humans and animals from five archaeological sites from the Danube Gorges region dating from the Mesolithic to the middle Neolithic periods. The results show a difference in the sulphur isotope values between freshwater and terrestrial ecosystems of 8.7‰. To reconstruct human diets, bone collagen from 24 individuals was analysed for carbon, nitrogen and sulphur isotopic values. The nitrogen isotope ratios ranged from 10.3 to 16.5‰ and the carbon isotope ratios ranged from −20.8 to −18.3‰. Low nitrogen isotope values were found for individuals with low sulphur isotope ratios reflecting the low sulphur isotopic values of the terrestrial animals. The highest human nitrogen isotope values coincided with higher sulphur isotope ratios, which are related to the higher sulphur isotope values of the freshwater fish. Intermediate human sulphur isotopic ratios between these two extremes showed mixed diets of both terrestrial and freshwater resources.     

THE POTENTIAL OF CARBONIZED GRAIN TO PRESERVE BIOGENIC 87SR/86SR SIGNATURES WITHIN THE BURIAL ENVIRONMENT*

Carbonized grains survive for millennia in many archaeological contexts. Their stable structure raises the possibility that they preserve biogenic strontium isotope signatures. This hypothesis was investigated using short‐term, laboratory experiments with modern grain immersed in Chalk solution. HCl leaching removed > 95% of secondary alteration from charred grain, and isotope ratios close to the starting value were recovered. This could not be achieved with uncharred grains. HCl leaching of archaeological carbonized grains produced comparable levels of decontamination. Although preliminary, these results suggest that strontium isotope analysis of archaeological carbonized grains from calcareous burial contexts could be used to investigate ancient trade and agriculture.     

Inter-site variability in the season of shellfish collection on the central coast of British Columbia

High-resolution stable oxygen isotope analysis of the bivalve Saxidomus gigantea from shell midden sites was applied to identify seasonal patterns of resource procurement on the central coast of British Columbia, Canada. A total of 90 archaeological shells were examined from eight distinct sites spanning a 4500-year period. Combining micro-growth pattern analysis with high-resolution stable oxygen isotope sampling allows for a precise season of collection to be determined in estuarine bivalves recovered from archaeological sites. The results of the stable oxygen isotope analysis provide insights into seasonally structured harvest of S. gigantea (butter clam), which is associated with different types of sites. The results show a variety of patterns, including multi-seasonal collection, intensive seasonal harvesting and casual, supplemental use of butter clams at different locations.     

What's in a bone? Recent advances in archaeological bone chemistry

This paper focuses on advances in archaeological bone chemistry since 1989. At that time studies generally shifted from development and application of techniques in bone chemistry to more experimental approaches. In stable isotope studies, controlled feeding experiments have been carried out to determine the routing of various dietary components into bone tissues. Biological apatite has been added to collagen as a tissue of study for stable carbon isotope analysis, providing the ability to study much older remains. Other elements have been added such as hydrogen for the study of paleoclimate and oxygen and strontium isotopes to study life history. Trace element studies have focused on methods of detecting and controlling for diagenesis, and barium has been added to the list of useful dietary indicators. Attempts to extract DNA from archaeological bone have been successful, however, this field is still in its early stages in terms of applications to understanding prehistoric biological relationships.     

Immigration to Tikal,Guatemala: Evidence from stable strontium and oxygen isotopes

This paper presents strontium and oxygen isotopic measurements on archaeological human teeth from the ancient Maya city of Tikal, Guatemala, that illuminate the role that migration played in the history of the state. Stable strontium isotope ratios of human teeth parallel the bedrock geology of the location where foods were grown, while stable oxygen isotope ratios reflect the sources of water imbibed, and track geographic variation in the isotopic composition of rain water. Because tooth enamel forms during childhood and is not remodeled during life, we can identify foreign-born individuals at Tikal by their outlying strontium and oxygen isotope ratios. These data indicate that approximately 11–16% of the sampled Tikal skeletons spent their childhood at distant sites. Most of the migrant burials date from the Early Classic period and are high status contexts. Several royal burials demonstrate long distance movement of both males and females, and shed light on the identification of epigraphically-known individuals. Yet, both Early and Late Classic migrants are found in lower status domestic burials. Interaction with distant peers was important in the rise of the Tikal polity, however, immigration from all social tiers contributed to the city’s rapid population growth.     

Pigments and Plasters Discovered in the House of Diana (Cosa,Grosseto, Italy): An Integrated Study Between Art History,Archaeology and Scientific Analyses*

The pigments and the plasters of the Roman frescoes discovered at the House of Diana (Cosa, Grosseto, Italy) were analysed using non‐destructive and destructive mineralogical and chemical techniques. The characterization of both pigments and plasters was performed through optical microscopy, scanning electron microscopy and electron microprobe analysis. The pigments were identified by Raman spectroscopy and submitted to stable isotope analysis. The results were integrated with the archaeological data in order to determine and reconstruct the provenance, trade patterns and the employment of the raw materials used for the elaboration of the frescoes.     

Bone stable isotope studies in archaeology

Stable isotope ratios of carbon and nitrogen in bone have become increasingly frequent inclusions in archaeological reports over the past few decades. The majority of such studies has been done in North America, where the use of marine foods and the introduction of maize have been monitored. Similar questions have been addressed in Mesoamerica and South America. In Europe, stable isotope ratios have documented the shift from marine fishing and gathering to agriculture in coastal areas and the introduction of millet in parts of eastern and southern Europe. Much work remains to be done in Asia, where millet replaced early C3 plant foods and, in turn, was replaced by rice. In Africa marine adaptations, freshwater fishing, agriculture, and pastoralism all yield diagnostic isotopic signatures. We review these studies, discuss areas requiring further study, and close with discussions of areas promising interesting future developments.     

Experimental chemical degradation compared to natural diagenetic alteration of collagen: implications for collagen quality indicators for stable isotope analysis

Stable isotopic ratios from archaeological bone collagen are valid palaeodietary indicators, but depend on sufficiently well preserved molecules and several collagen quality criteria have to be fulfilled (mostly collagen wt%, C%; N%, C/N molar ratio). For a reassessment of these quality criteria, and a better understanding of the chemical degradation of bone collagen, experimentally degraded modern bones and 54 archaeological human bones were investigated. In the course of the experimental degradation, alterations of isotopic ratios were paralleled by altered collagen quality criteria. The contrary was found in the case of the archaeological specimens. This implies that the commonly used collagen quality criteria may be insufficient and do not guarantee that stable isotopic values of the gelatine extracts will still represent the original biological signal.     

Isotopic evidence for the trade and production of exotic marine mammal bone artifacts at Chavín de Huántar,Peru

This study uses stable isotope analysis to identify the possible origin and taxon of unusually large worked bone artifacts recovered from the site of Chavín de Huántar in the central highland of Peru (3200–2200 BP). The site was traditionally considered to be an ideal trading point halfway between the Pacific coast and the Amazon jungle. The archaeological specimens were discovered in a workshop area located in the La Banda sector across from the main temple, and they were analyzed for the stable isotopes of carbon, nitrogen, sulfur, and oxygen. Results indicate that the worked bone artifacts are marine in origin and are likely from a cetacean or large pinniped. Their exotic origin and elaborate work have implications about ancient production practices and exchange, and they provide benchmark data and a comparative approach for future analysis of exotic bone artifacts.     

BULK STABLE LIGHT ISOTOPIC RATIOS IN RECENT AND ARCHAEOLOGICAL RESINS: TOWARDS DETECTING THE TRANSPORT OF RESINS IN ANTIQUITY?*

We have applied and refined methods for the determination of bulk hydrogen, carbon and oxygen isotope ratios in modern and archaeological resins. The modern resins have a wide range of isotopic values and vary within the same tree, between individual trees, with species and location. For all isotopes measured, there is a general trend of increasing depletion of the heavier isotope with increasing altitude. There is also a linear trend between depletion of δD and δ¹³C values with increasing latitude; this trend is less clear for oxygen, but is related to the meteoric water line. Two case studies using archaeological resins known or suspected to have been transported in antiquity have been investigated to determine whether isotopic signatures can assist in pinpointing the geographical origin of the resin: Pistacia sp. resin from Canaanite amphorae imported into Egypt from known geographical locations in the eastern Mediterranean during the Late Bronze Age, and Roman amphorae sherds lined with Pinus sp. resin from sites ranging from Britain to the eastern Mediterranean. These results show separate groupings between the two resin types (pine/pistacia) and between the modern/archaeological resins. Some archaeological samples are distinct from the others and the modern resins show differences between geographical areas. However, there are no clear patterns relating the different Canaanite fabrics or the suggested manufacturing site of the Roman amphorae.     

云南剑川海门口遗址饱水古木降解的微观构造分析

文中采用扫描电镜(SEM)和透射电镜(TEM)对海门口遗址饱水古木进行降解机理分析。结果表明:古木细胞次生壁收缩严重并与胞间层分离;胞间层保存较完好,呈连续网状。说明古木纤维素和半纤维素降解相对严重,木质素降解相对较轻。古木主要是受细菌降解,通过SEM和TEM均可见明显的细菌腐朽特征。细菌首先侵入细胞腔,再通过S3层侵入细胞壁内部。细胞壁内由于降解而产生的空隙在几十到几百纳米之间。饱水古木也受到了一定程度的真菌降解,但这类真菌主要降解古木内淀粉等物质,对细胞壁物质降解能力差,主要是使古木变色。     

Multi-isotope fingerprints (O,Sr and Pb) in archaeological animal bone bioapatite: Similarity search and the suitability for provenance analysis in a geologically complex Alpine region

Multi-isotope fingerprints in the bioapatite of archaeological skeletons are mostly superior over single isotope analyses for provenance studies. Gaussian mixture model (GMM) clustering is a novel tool for a similarity search among multidimensional data sets and at the same time permits the evaluation of the structural importance of particular isotopic ratios in the data set. We applied three GMM clustering experiments on multi-isotope fingerprints—stable strontium (Sr), lead (Pb) and oxygen (O) isotopic ratios—established in 217 archaeological animal bones excavated along a specific transect across the European Alps. This reference region had been in use since prehistoric times by humans who crossed the Alps from north to south, and vice versa. The resulting clusters permit a spatial assignment of the specimens with a very high probability, in particular with regard to the geological complexity of the region. A combination of Sr with Pb stable isotopes led to an optimal differentiation between the southern and northern Alpine forelands that cannot be distinguished from each other by ⁸⁷Sr/⁸⁶Sr ratios alone, while the contribution of δ¹⁸O is not particularly high. The isotopic mapping and subsequent cluster analysis is suitable for the analysis of archaeological human finds and the reconstruction of the direction of transalpine mobility and trade.     

Bromine in teeth and bone as an indicator of marine diet

Nitrogen isotope ratios in tissues are often used to aid in the reconstruction of the marine component of diets in past populations. Elevated δ¹⁵N values normally found with high trophic level marine resource consumption can, however, also be mimicked by physiological conditions (breastfeeding, pathological states affecting nitrogen balance), climate (aridity), and anthropogenic environments (manuring). This paper presents a pilot study testing whether bromine concentrations can provide a tool for teasing apart possible causes of variation in nitrogen isotope ratios. Blind analyses of bromine in archaeological samples correctly identified individuals derived from coastal vs. inland regions and high vs. low marine consumption time periods. Thus, bromine can provide an important supplement to other isotopic analyses of diet.     

Tracing the source of Late Neolithic Spondylus shell ornaments by stable isotope geochemistry and cathodoluminescence microscopy

Determination of the source of Spondylus objects is essential for the interpretation of Late Neolithic exchange systems and the social role of shell ornaments. We performed stable isotope analysis combined with cathodoluminescence microscopy study on ornaments (beads, bracelets) made of Spondylus shells excavated at the Aszód-Papi földek archaeological site in Hungary, to define their origin. For comparison Spondylus finds from Neolithic sites of Greece, modern Spondylus shells from the Aegean and the Adriatic, as well as fossil Spondylus and Ostrea shells from the Carpathian Basin were also examined. Oxygen isotope composition of Spondylus finds from Aszód ranges between ?1.9 and 2.1‰ and overlaps with the oxygen isotope range of shell objects from other Neolithic sites. Modern Spondylus shells from the Aegean and the Adriatic show overlapping δ¹⁸O values with one another and with the Neolithic objects; while recent shells of the Black Sea clearly are separate isotopically from the Mediterranean ones and most of archaeological artefacts. Spondylus shells from the Aszód site have Mediterranean origin; their source can be the Aegean or the Adriatic. Based on a former strontium isotope study the use of fossil Spondylus shells is excluded as raw material used for ornaments, however, in recent years the use of fossil shells was reintroduced. The shell ornaments from Aszód-Papi földek and the fossil oyster shells collected from the Carpathian Basin exhibit some overlapping oxygen isotope values; however, cathodoluminescence microscopy indicates that the Spondylus objects retained their original aragonite material. Diagenetic calcite, which occurs typically in the fossil shells, was not detected in the ornaments suggesting that the studied objects were made of recent shells. Calcitic parts observed in some Spondylus objects are not related to fossilisation.     

Mixed results of seven methods for organic residue analysis applied to one vessel with the residue of a known foodstuff

Several methods of archaeological organic residue analysis were applied to a single unglazed and unseasoned ceramic vessel that had absorbed residues of heated camel milk. Sections of the wall of this vessel were sent to eleven archaeological laboratories. Seven reported their results before the identity of the residue was revealed, during the 70th Annual Meeting of the Society for American Archaeology. Methods included stable carbon and nitrogen isotope ratio analysis, protein analysis and lipid analysis. These laboratory techniques provide a biochemical analysis of the residue in a ceramic matrix, the archaeological interpretation of which can be rather difficult. The exact source of the residue was not identified by any laboratory, but it is evident that residue analysis can provide valuable information, especially when combined with additional archaeological and historical data. We therefore support a close cooperation of those working in this field to develop it to its full potential.     

Fast or feast: reconstructing diet in later medieval England by stable isotope analysis

In this pilot-study, which was designed to assess the range of isotopic variation in English medieval populations, we present the results of stable isotope analysis of carbon and nitrogen of human and animal bone collagen from three later medieval sites in Northern England.The isotopic values observed for the rural hospital of St. Giles by Brompton Bridge (N. Yorks.), the Augustinian Friary at Warrington and a mass-grave with casualties from the Battle of Towton (N. Yorks.) are significantly different from those reported for other archaeological populations in Britain, namely by their very enriched δ¹⁵N ratios which are combined with almost entirely terrestrial carbon signals. We discuss possible explanations for the unusual human data and argue on grounds of the available faunal data, that a mixed diet of terrestrial, marine and freshwater resources is most likely. This may indicate the significant impact of the medieval fasting regulations on everyday subsistence. We conclude that stable isotope analysis can complement the available historical information on diet in the Middle Ages.