Medieval Britain in 1978

Abstract

ZOOARCHAEOLOGICAL ANALYSIS OF a substantial assemblage of animal bones excavated from Dudley Castle, West Midlands, suggests that a significant change in pig management occurred during the 14th century. A dramatic decrease in the relative abundance of pigs, combined with an increase in the size of post-cranial bones and teeth, and a higher proportion of neonatal individuals, raises the possibility that greater control over breeding and feeding was being exerted in this period through the emergence of enclosed husbandry practices. Carbon and nitrogen stable-isotope analysis of a sample of 41 pig mandibles from two tightly dated phases of occupation supports this interpretation. Between the late 13th century and later 14th century there was a statistically significant decrease in δ¹⁵N, but not in δ¹³C, and pig dietary diversity probably also decreased. This paper discusses several explanations for these patterns, all consistent with a major change in pig management at this time.     

Stable carbon and nitrogen isotope ratios of bone collagen: Variations within individuals,between sexes,and within populations raised on monotonous diets

The stable carbon and nitrogen isotope ratios of collagen of seven bones from each of three rabbits raised on a monotonous diet, and of two bones from each of eight female and seven male mink raised on another monotonous diet, were determined. The ranges of δ¹³C values and δ¹⁵N values were 0·5‰ and 0·6‰ for the rabbit bones and 1·0‰ and 1·4‰ for the mink bones. Uncertainties in the δ¹³C and δ¹⁵N values for prehistoric human diets estimated from the isotopic composition of collagen from the small numbers of bones which are typically available for analysis, and thus likely to be of the order of ±1‰.     

Stable isotope insights (δ18O, δ13C) into cattle and sheep husbandry at Bercy (Paris,France, 4th millennium BC): birth seasonality and winter leaf foddering

Abstract

Bercy is a prehistoric village sited by the Seine river (Paris, France), whose main period of occupation was dated to the very beginning of the 4th millennium BC. The animal subsistence economy relied heavily on cattle husbandry, complemented by other species including sheep. Cattle and sheep isotopic history (δ¹³C, δ¹⁸O) was investigated at the seasonal scale, through sequential sampling in tooth enamel, providing new insights into seasonality of birth and diet. Sheep were lambing in mid-spring, only slightly later than expected from what is observed nowadays in temperate Europe at similar latitude. Cattle were born over a period spanning approximately six months, which was an unexpected result compared with a two to three months calving period in free-ranging cattle populations. The extension of the calving period might have been related to seasonal food supplementation. Some cattle and some sheep fed on a ¹³C-depleted resource in winter, potentially leafy fodder. A direct consequence of an extended calving period would be the availability of cow milk, which would have covered the whole year at Bercy. This is important information in a context where the exploitation of cattle milk by the human community was highly suspected from the demographic management of the herd.     

Stable isotope analysis of human and animal remains from the Late Upper Palaeolithic site of Balma Guilanyà, southeastern Pre-Pyrenees,Spain

Stable isotope analysis of carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) was performed on collagen extracted from three human and five herbivore bone and tooth samples from the Late Upper Palaeolithic site of Balma Guilanyà (Catalonian Pre-Pyrenees, Spain). Contextual and palaeoecological data as well as radiocarbon dates indicate that the studied occupation phase took placed during the Bolling/Allerod interstadial (GI-1a event). The human remains were co-mingled without any anatomical association, corresponding to a minimum number of three individuals, and it was not possible to determine if the three analyzed samples are from one or more individuals. The mean isotope values obtained from the human remains are δ¹³C = −19.8‰ and δ¹⁵N = 6.7‰, while those of the large herbivores (red deer and wild goat) were −19.8‰ and 1.7‰ for δ¹³C and δ¹⁵N respectively. This indicates that the main source of protein in the diet of the Balma Guilanyà human(s) came from terrestrial herbivores. There is no zooarchaeological or isotopic evidence for the consumption of freshwater or marine resources at the site, which lies 80 km from the present Mediterranean coast. The low δ¹⁵N values observed in both human and animal samples correspond to a trend reported by other researchers working in northwestern Europe: a significant δ¹⁵N reduction in collagen from bones datable within 20,000–10,000 BP, followed by a rise to present values in the Early Holocene. This phenomenon, generally attributed to climatic and/or pedological processes, had not been previously observed in the Mediterranean region and, until now, was thought to be restricted to northern Europe.     

Isotopic Reconstruction of the Late Longshan Period (ca. 4200–3900 BP) Dietary Complexity before the Onset of State‐Level Societies at the Wadian Site in the Ying River Valley,Central Plains,China

During the late Longshan period (ca. 4200–3900 BP) settlements on the Central Plains of China underwent a diversification in food production technologies, which set the stage for rapid economic and social development. The introduction of novel domesticates such as rice, wheat, cattle, and sheep not only provided more food choices, but also changed ideas concerning land use, farming techniques, and the use and mobilization of large scale labor forces. To better understand the contribution that these new dietary items and practices made to shaping the late Longshan period societies, a stable isotope ratio study of humans (n = 12) and animals (n = 42) was conducted at the late Longshan period site of Wadian. The human δ¹³C and δ¹⁵N values are clustered into two distinct groups. One group of nine individuals (δ¹³C = −9.9 ± 0.7‰; δ¹⁵N = 7.5 ± 0.5‰) had a predominately C₄ diet based on millet grains with little protein input from the domestic animals. The other group of three individuals (δ¹³C = −14.3 ± 0.8‰; δ¹⁵N = 10.2 ± 0.3‰) had a mixed C₃/C₄ diet of millets and rice and were consuming sheep and cattle. The animals also displayed dietary diversity with the pigs (δ¹³C = −11.3 ± 2.5‰; δ¹⁵N = 6.9 ± 1.0‰, n = 10) and dogs (δ¹³C = −10.1 ± 1.0‰; δ¹⁵N = 7.2 ± 1.1‰, n = 7) having mostly a C₄ plant based diet (millets). In contrast, the cattle (δ¹³C = −12.8 ± 2.1‰; δ¹⁵N = 7.6 ± 0.7‰, n = 9), sheep (δ¹³C = −16.7 ± 0.9‰; δ¹⁵N = 7.6 ± 0.1‰, n = 2), and cervids (δ¹³C = −20.8 ± 0.9‰; δ¹⁵N = 5.0 ± 1.2‰, n = 10) had diets with a greater contribution from C₃ sources such as rice and wild plants. The discovery that humans and animals had different subsistence patterns indicates dietary complexity at Wadian and that rice agriculture, and cattle and sheep husbandry practices were already an important part of the local economy by the late Longshan period in the southern region of the Central Plains of China. Copyright © 2015 John Wiley & Sons, Ltd.     

Detecting the medieval cod trade: a new method and first results

This paper explores the potential of stable isotope analysis to identify the approximate region of catch of cod by analysing bones from medieval settlements in northern and western Europe. It measures the δ¹³C and δ¹⁵N values of cod bone collagen from medieval control samples collected from sites around Arctic Norway, the North Sea, the Kattegat and the Baltic Sea. These data were considered likely to differ by region due to, for example, variation in the length of the food chain, water temperature and salinity. We find that geographical structuring is indeed evident, making it possible to identify bones from cod caught in distant waters. These results provide a new methodology for studying the growth of long-range trade in dried cod and the related expansion of fishing effort—important aspects of the development of commercialisation in medieval Europe. As a first test of the method, we analyse three collections of cod bones tentatively interpreted as imported dried fish based on a priori zooarchaeological criteria. The results tentatively suggest that cod were being transported or traded over very long distances since the end of the first millennium AD.     

Early Neolithic diet and animal husbandry: stable isotope evidence from three Linearbandkeramik (LBK) sites in Central Germany

The first appearance of the Neolithic Linearbandkeramik (LBK) in Central Germany occurred during the 6th millennium BC. However, though LBK sites are abundant in the German loess areas, there are only a few studies that reconstruct the diet of these first farmers using biochemical methods. Here we present the largest study undertaken to date on LBK material using stable isotope analysis of carbon and nitrogen to reconstruct human diet and animal husbandry strategies. We analyzed the bone collagen of 97 human individuals and 45 associated animals from the sites of Derenburg, Halberstadt and Karsdorf in the Middle Elbe–Saale region of Central Germany. Mean adult human values are ?19.9 ± 0.4‰ for δ¹³C and 8.7 ± 0.8‰ for δ¹⁵N. The δ¹³C values are typical for terrestrial, temperate European regions, whereas the δ¹⁵N values fall within an expected range for farming societies with a mixed diet consisting of products from domestic animals and plants. The consumption of unfermented dairy products is unlikely as there is direct palaeogenetic evidence of lactose intolerance available for one of the sites. There are no clear indications for dietary differences in sex. Young children under three years of age are enriched in δ¹⁵N due to breastfeeding indicating that weaning likely occurred around the age of three years. The fauna exhibit mean δ¹³C values of ?20.9 ± 0.8‰ and mean δ¹⁵N values of 7.0 ± 0.9‰ respectively. Variation in the δ¹³C and δ¹⁵N in the domestic animals is probably caused by different livestock managements.     

Raising Practices of Neolithic Livestock Evidenced by Stable Isotope Analysis in the Wei River Valley,North China

Although a patchwork of projects shows a process of agriculture intensification in North China during the Neolithic, the impact of cereal farming on animal husbandry and their mutual interaction remain cloudy. This study reports bone collagen δ¹³C and δ¹⁵N of humans and animals from Wayaogou (ca 6.5–6.0 kyrs bp ) and Dongying (ca 5.9–5.6 kyrs bp , 4.6–4.0 kyrs bp ) to explore temporal trend of livestock raising and particularly the importance of millet fodder to stock raising practices in the Wei River valley, North China. The isotopic evidence overall shows that millet products increased in human and domestic animal diets during the mentioned chronological span. δ¹³C values of pigs and dogs at Dongying are higher than those at Wayaogou, implying that the importance of millet nutrients increased to animal husbandry diachronically. Interestingly, δ¹³C results of domestic cattle of Dongying late phase (−14.1 ± 1.1‰, N = 5) are more enriched than Wayaogou wild Bos (−17.8 ± 0.3‰, N = 3), indicating that millet fodder had taken a significant place in early cattle husbandry. Besides, differences between Bos species of the two periods also imply that δ¹³C values of bone collagen constitute a potential indicator for tracing the origin of cattle husbandry in North China. In addition, domestic sheep at Dongying produced similar isotope data to wild ovicaprid at Wayaogou, suggesting that they possibly had grazed for the most in grassland and therefore experienced a different lifestyle from cattle. Copyright © 2014 John Wiley & Sons, Ltd.     

Historical ecology of late Holocene sea otters (Enhydra lutris) from northern British Columbia: isotopic and zooarchaeological perspectives

We examined the isotopic composition (δ¹³C and δ¹⁵N) of sea otter (Enhydra lutris) bone collagen from ten late Holocene (ca. 5200 years BP–AD 1900) archaeological sites in northern British Columbia (BC), Canada. Because sea otters are now extinct from much of this region and have not fully recolonized their former range (e.g. Haida Gwaii and most of northern BC) these data represent an important first step towards better understanding sea otter foraging ecology in BC. The isotopic data suggest a diet composed primarily of benthic invertebrates, with a very low reliance on epibenthic fish. There is very low isotopic and thus inter-individual dietary variability in Holocene BC sea otters during the late Holocene. Furthermore, zooarchaeological abundance data suggest that otters represented a widespread and significant focus of aboriginal hunting practices on the northern BC coast during the mid- to late-Holocene. The consistent reliance on a small number of low-trophic level prey and limited dietary variability in Holocene BC sea otters may reflect top-down impacts on otter populations by aboriginal peoples. As part of our assessment of sea otter diet, we review trophic discrimination factors (Δ¹³C and Δ¹⁵N) for bone collagen from published literature and find marked variability, with mean values of +3.7 ± 1.6 for Δ¹³C (n = 21) and +3.6 ± 1.3 for Δ¹⁵N (n = 15).     

Horticulturists and oxygen ecozones in the tropical and subtropical forests of Southeast South America

We analyse the isotopic values (δ¹³C, δ¹⁵N) of the diet of pre-Columbian horticulturalist populations from tropical and subtropical areas of southeastern South America, belonging to the Guarani and Taquara archaeological units. The data indicate different trends in each one (T?=?4.21; P?=?0.0004), showing a mixed diet with maize consumption in the Guarani samples (δ¹³C_co?=??15.5?±?1.8‰; δ¹³C_ap ?10.4?±?0.8‰) and a depleted one in the Taquara ones (δ¹³C_co ?18.2?±?1.7‰; δ¹³C_ap ?11.9?±?0.9‰), with a significant internal dispersion in both populations. The first population has higher nitrogen values (δ¹⁵N 11.1?±?0.6‰) compared to the Taquara samples (δ¹⁵N 9.3?±?1‰), suggesting a more carnivorous diet. The recognition of these pre-Columbian mixed diets involves the identification of maize cultivation on the Atlantic side of the southernmost area of South America (Parana Delta, 34° SL). Through the analysis of δ¹⁸O we have identified two isotopic ecozones, the first along the Paraná River Valley, with an average value of δ¹⁸O ?3.7?±?0.5‰ (CV?=?13.5%; CI?=??3.83 / ?3.16), and the second one, located in the Planalto of southern Brazil (Araucaria Forest), with a mean value of δ¹⁸O ?1.5?±?0.3‰ (CV?=?16.5%; CI?=??1.69 / ?1.29). The isotopic data (δ¹³C, δ¹⁵N and δ¹⁸O) suggest human movements between these two ecozones.     

Preliminary evidence for medieval Polish diet from carbon and nitrogen stable isotopes

In this pilot study, stable carbon and nitrogen isotopes from bone collagen and apatite of skeletons from the 11th and 12th century cemetery in Giecz, Poland are interpreted. Isotope values from a small number of fish and animal bones from the same archaeological site are also examined. The goal of this research is to provide preliminary evidence of diet for a group of medieval Polish peasants, with particular emphasis on sex-based differences in diet. Results of isotope analyses suggest diet of this early medieval population was omnivorous and terrestrial-based. Fish bones sampled exhibit low δ¹³C ratios, and in half of the cases are significantly enriched in ¹⁵N, indicating they are freshwater species. Human bones do not reflect these signatures, suggesting freshwater fish were not a significant source of dietary protein at Giecz. The ¹³C_coll from some human bones is enriched beyond what might be expected from an exclusively C₃ diet. Associated mammal bones do not exhibit similarly elevated δ¹³C_coll ratios, suggesting enrichment among humans is not due to consumption of animals foddered on C₄ plants. Two possible sources of ¹³C_coll enrichment are marine fish in diet and direct consumption of a C₄ plant, such as millet. The δ¹³C values obtained from bone apatite of a small subset of humans suggest that millet contributes to ¹³C_coll enrichment, although at least three individuals may have also consumed small amounts of marine fish. Sex-based differences in δ¹⁵N ratios indicate that men consumed relatively more animal products (meat or dairy) than did women. There is also a correlation between δ¹³C_coll and δ¹⁵N values in skeletons of men that is absent in women. These carbon and nitrogen isotope data are the first reported for any Polish population and contribute to a more complete picture of dietary adaptation and social organization in medieval Europe.     

Isotopic evidence of dietary variability in subadults at the Usu-moshiri site of the Epi-Jomon culture,Japan

This study reconstructs adult and subadult diets of a hunter-gatherer population of the Epi-Jomon culture (approximately 2300–1700 years BP) in Japan, using the stable isotopic analysis of carbon and nitrogen. The results suggest that the Usu-moshiri adults were highly dependent on marine resources such as seals for their dietary protein intake and that no significant dietary differences existed between the sexes. Among subadults we found two types of diet on the basis of different isotopic signatures. One group consisted of individuals with δ¹³C values below than those of the adult female mean minus two standard deviations and δ¹⁵N values lower than those of subadults in the other groups. These low-δ¹³C subadults indicated relatively less enriched δ¹⁵N values by 3.5 years of age at the latest. They probably consumed more ¹³C-depleted foods during weaning than in the ordinary adult diet. In the other high-δ¹³C group, their enriched δ¹⁵N values start to decline by four years of age and fall within the two-standard-deviations range of the total adult mean around five to six years of age. Isotopic values of children in this high-δ¹³C group suggest that they would have been fed ordinary adult diets during weaning. Perinates could also be divided into two groups on the basis of the similar patterns in their carbon and nitrogen isotope ratios. Our results indicate variabilities in the diets of subadults, and similar variabilities were also seen in ethnographic studies of the Ainu populations.     

Dietary changes and millet consumption in northern France at the end of Prehistory: Evidence from archaeobotanical and stable isotope data

Diachronic changes of dietary human habits between the Neolithic and the Bronze Age are mainly identified through archaeological artefacts and archaeozoological and archaeobotanical studies. This paper aims to demonstrate the importance of a multi-disciplinary approach for palaeodietary studies and to identify the food changes between Neolithic and Bronze Age human groups in northern France. These changes are probably linked to the introduction of new crops, such as millet, and the use of stable isotope analysis on bones and teeth proves to be an effective method for assessing the role of this specific cereal in the diet and the economy. Stable isotope analyses were performed on bone and tooth collagen and apatite from eight humans and five domestic animals from a Late Bronze Age site (LBA; Barbuise; 15th–13th c. BC; Aube). The studied corpus is compared with isotopic data from human and animal bones from a nearby Neolithic site (Gurgy; 5th mill. BC; Yonne) and regional Neolithic to Iron sites located in northern France. Moreover, Barbuise data are supplemented by information from an important archaeobotanical study carried out on 21 LBA and Early Iron Age sites in the region. Neolithic and LBA human collagen isotopic ratios (δ¹³C, δ¹⁵N) differ statistically, as do those of some animals. Carbon isotopic ratios of human apatite corroborate collagen results indicating the consumption of ¹³C enriched food by LBA humans and animals compared to Neolithic samples. The high number of occurrences of plant remains in the Bronze Age settlements near the site points to the consumption of C₄ plants, such as millet, and would account for these results.     

Investigating the dietary life histories and mobility of children buried in St Gertrude Church cemetery,Riga, Latvia, 15th–17th centuries ad*

Carbon and nitrogen isotope profiles were obtained from incremental dentine analysis of 19 non-adults from a cemetery in Riga, Latvia. The research compared the life histories and diet between people buried in two mass graves and the general cemetery. The δ¹³C profiles of several children from the mass graves were similar but did not resemble the patterns seen in children from the general cemetery, suggesting that they probably represented a different population group. The rise in δ¹⁵N values towards the end of the life of four individuals from one mass grave suggests they were victims of an historically documented famine.     

Stable isotope data from the early Christian catacombs of ancient Rome: new insights into the dietary habits of Rome's early Christians

This study reports on the first attempt that determines the diet of a small but conceivably representative section of Rome's early Christian community by means of δ¹³C and δ¹⁵N measurements on collagen extracted from twenty-two samples of human bone. Samples derive from the Liberian Region in the catacombs of St. Callixtus on the Appian Way—an area that has been radiocarbon dated to the period from the mid-3rd through early 5th century AD. Comparing our results to those produced for several other sites, we argue that this population's typical diet included freshwater fish. We also briefly discuss breastfeeding and the freshwater reservoir effect, to then explore the dietary, art historical, and possible sociological ramifications of our results.     

Palaeoenvironmental and chronological investigations of the Magdalenian sites of Goyet Cave and Trou de Chaleux (Belgium), via stable isotope and radiocarbon analyses of horse skeletal remains

Trou de Chaleux and Goyet are caves situated less than 30 km apart in Belgium that contain stratified Magdalenian artefacts and butchered faunal remains. Published radiocarbon dates suggest that both sites were contemporaneously occupied during to the Late-glacial interstadial. It has previously been suggested that the Trou de Chaleux Late-glacial faunal remains might be slightly older than those at Goyet Cave, and that Trou de Chaleux has two phases of occupation during the Late-glacial interstadial. However, the limited number of radiocarbon dates currently available makes it impossible to determine whether the sites are truly contemporaneous, and the assessment of their absolute chronologies is complicated by a plateau in the calibration curve. In this paper, bone collagen δ¹³C and δ¹⁵N signatures of horse bones from the two sites are used to reconstruct local palaeoenvironments. We hypothesise that if occupations at the two sites were contemporaneous, the horse collagen δ¹³C and δ¹⁵N isotope signatures from both sites will be similar, since comparable carbon and nitrogen isotopic values would reflect similar diets, ecologies and environments. To provide clear dating parameters, new AMS radiocarbon determinations are also presented. Results show that horse collagen δ¹³C and δ¹⁵N isotope signatures at the two sites are different, indicating that the populations were not subject to similar diets, ecologies and environments. The new radiocarbon dates confirm that the horse bones from Trou de Chaleux date to the Late-glacial interstadial, but they also show that in Goyet Cave Horizons 1 and 2, older horse remains dating to ca. 32?000–27?000 ¹⁴C yr BP are mixed with Late-glacial horse remains. The δ¹⁵N values of the Goyet Cave horse bones radiocarbon dated to the Pleniglacial are substantially higher than those that have Late-glacial radiocarbon dates. Therefore, we now hypothesise that the majority of the horse bones isotopically analysed from Goyet Cave Horizon 1 are Pleniglacial in age. Statistical analysis of the radiocarbon dates indicates that the Late-glacial occupation at the two sites was contemporaneous, and that while there may appear to be two phases of occupation at Trou de Chaleux, this may be an artefact of the radiocarbon calibration curve.     

Dietary reconstruction in Migration Period Central Germany: a carbon and nitrogen isotope study

This study presents bone collagen carbon and nitrogen isotope data from the Migration Period cemeteries (fifth/sixth century AD) of Obermöllern and Rathewitz in Central Germany. The human average δ ¹³C ratios of ?19.8?±?0.3 ‰ and δ ¹⁵N ratios of 9.6?±?0.9 ‰ (n?=?43) reflect a mixed diet in a temperate C3-based ecosystem without significant difference between the two sites. The average offset between human and faunal δ ¹³C and δ ¹⁵N values indicates a significant contribution of plant food to the human diet that has different isotope ratios from the forage of the animals. It furthermore suggests the influence of land management on the δ ¹⁵N values. One adult male from Obermöllern stands out due to his elevated nitrogen isotope ratio, body height, grave goods, and burial position. The collagen isotope data of this study are comparable with data from other central European sites and confirm rather stable communities with moderate variation in the environmental conditions of arable land.     

Calving seasonality at Pool,Orkney during the first millennium AD: an investigation using intra-tooth isotope ratio analysis of cattle molar enamel

The identification of dairying is essential if we are to understand economies of the past, particularly in northwest Europe, where a high degree of lactose tolerance suggests that fresh milk has long been a significant food product. This paper explores a possible link between economic focus and seasonality of calving. Although cattle (Bos taurus) can breed throughout the year, animals living in temperate regions with minimal or no human management tend to breed seasonally, their breeding behaviour being strongly influenced by the availability of food. In order to achieve a year-round supply of fresh milk in the past, it is likely that multiple-season calving was necessary, which would have required additional husbandry effort. Alternatively, for meat-focussed economies or those based on storable dairy products, a strategy of single-season calving in spring may have been favoured to maximise the utilisation of spring and summer vegetation. Cattle birth seasonality is investigated through isotope ratio analysis (δ¹⁸O, δ¹³C) of tooth enamel. Results for cattle from Pool, Orkney dating to the latter part of the first millennium AD suggest that calving occurred during at least three seasons implying that the continuous provision of fresh milk was of economic importance.     

Reconstructing Diet of the Early Qin (ca. 700–400 BC) at Xishan,Gansu Province,China

Here we report the bone collagen carbon and nitrogen isotopic results of humans (n = 33) and animals (n = 58) to reconstruct the dietary practices of an early Qin population dating to the Zhou Dynasty (Late Western–Early Eastern period ca. 700–400 BC ) at the Xishan site in Gansu Province, China. The humans have a very large range of δ¹³C (−23.3‰ to −7.1‰) and δ¹⁵N (4.3‰ to 10.9‰) values which reflects extraordinarily diverse diets and included individuals with predominately C₃ as well as those with exclusive C₄ diets. This wide span of isotopic results produced a subtle linear trend (R² = 0.62) in the human data, which paralleled the animals across the C₃ and C₄ environmental gradient. However, the majority of the individuals had a predominately C₄ diet based on millet with δ¹⁵N results only slightly elevated above the animals, except for the pigs and cattle. This is evidence that many of the animals were likely used for their secondary products, labour or as sacrificial offerings and that pork and beef were the main sources of animal protein for the population. High status individuals had elevated δ¹⁵N values (10.2 ± 0.6‰) compared to medium (8.9 ± 0.3‰) and lower status (8.8 ± 0.8‰) individuals, possibly related to increased animal protein in the diet. Differences related to gender were also found with females having elevated δ¹³C (−11.2 ± 1.9‰) and δ¹⁵N (9.4 ± 0.8‰) values compared to the males (δ¹³C = −14.1 ± 4.2‰; δ¹⁵N = 7.9 ± 1.9‰), but these results necessitate caution given the large number of individuals that could not be sexed. The results of this study support the view that the early Qin people were a more sedentary society focused on millet agriculture and animal husbandry, and that they were influenced by the pre‐existing populations of the central Gansu region. Copyright © 2015 John Wiley & Sons, Ltd.     

Geochemistry and origin of natural gases dissolved in brines from gas fields in southwest Japan

Previous geochemical studies indicated that most natural gases dissolved in brines in Japan are of microbial origin, consisting of methane produced via carbonate reduction. However, some of those from gas fields in southwest Japan contain methane relatively enriched in ¹³C, whose origin remains to be clarified. To address this issue, chemical and isotopic analyses were performed on natural gases and brines from the gas fields in Miyazaki and Shizuoka prefectures, southwest Japan. Methane isotopic signatures (δ¹³C ≈ ?68‰ to ?34‰ VPDB; δ²H ≈ ?183‰ to ?149‰ VSMOW) suggest that these gases are of microbial (formed via carbonate reduction) or of mixed microbial and thermogenic origin. The relatively high δ²H‐CH₄ values and their relationship with the δ²H‐H₂O values argue against the possibility of their formation via acetate fermentation. The δ¹³C‐CO₂ values (≈?5‰), together with the slope of the correlation between δ²H‐CH₄ and δ¹³C‐CH₄ (Δδ²H‐CH₄/Δδ¹³C‐CH₄ ≈ 1), contradict the possibility of their formation via carbonate reduction followed by partial oxidation by methanotrophs. The ³He/⁴He ratios of the gases from Miyazaki (≈0.11–1.3 Ra) and their low correlation with δ¹³C‐CH₄ values do not support an abiogenic origin. It is inferred therefore that the high δ¹³C‐CH₄ values of natural gases dissolved in brines from gas fields in southwest Japan are indications of the contribution of thermogenic hydrocarbons, although whether abiogenic hydrocarbons contribute significantly to the gases from Shizuoka requires further investigation. This study has clarified that, for the future exploration of natural gases in southwest Japan, we should adopt the strategies for conventional thermogenic gas accumulations, such as checking the content, type and maturity of organic matter in the underlying sedimentary rocks.