Agriculture in the arid Arabian Peninsula became established during the early Bronze Age and relied, at least in eastern Arabia, on the cultivation of date palm ( Phoenix dactylifera ) and annual crops, namely barley ( Hordeum vulgare ssp. vulgare , H. vulgare ssp. distichon ) and different wheats—in particular, emmer ( Triticum turgidum ssp. dicoccon ), durum/rivet wheat ( T. turgidum ssp. durum / turgidum ), bread wheat ( T. aestivum ssp. aestivum )—and pulses, such as pea ( Lathyrus oleraceus ) and lentil ( Vicia lens ). The association of these crops with irrigation systems indicates the presence of resilient oasian agrosystems allowing the production of multiple crops over a reduced surface area thanks to water use optimization. It is also a hub connecting local agrarian producers with merchants and travellers through exchange, particularly dynamic during historical times, which can be highlighted through archaeobotanical data. At the crossroads of the Mediterranean, African and Indian Ocean spheres, the Arabian Peninsula is a relevant observatory of the diffusion processes of new Mediterranean, tropical and subtropical crops. Recent archaeobotanical finds from antique and early medieval Islamic sites show that ancient oases were ecological and economic niches hosting new plants, such as rice ( Oryza sativa ), sorghum ( Sorghum bicolor ssp. bicolor ), pepper ( Piper nigrum ) and cotton ( Gossypium arboreum/herbaceum ), some of which were probably acclimatized and cultivated locally. Their introduction should have modified the spatial, temporal and labour organizations of pre-existent agricultural systems, implying the transfer and development of new know-how. Therefore, by following an interdisciplinary approach using archaeobotany, archaeology, history and isotope geochemistry, this contribution aims to describe some of these new plants and their chronology and discuss their potential introduction into local agricultural systems.

With a view to understanding the dynamics of ancient trade and agrobiodiversity, archaeobotanical remains provide a means of tracing the trajectories of certain agricultural commodities. A prime example is cotton in Arabia, a plant that is non-native but has been found in raw seed and processed textile form at Hegra and Dadan, in the region of al-ʿUlā, north-western Saudi Arabia—sites of critical importance given their role in the trans-Arabian trading routes during Antiquity. Here, we demonstrate that the measurement of strontium isotopes from pre-cleaned archaeological cotton is methodologically sound and is an informative addition to the study of ancient plant/textile provenance, in this case, putting forward evidence for local production of cotton in oasis agrosystems and possible external supply. The presence of locally-grown cotton at these sites from the late 1st c. BCE–mid 6th c. CE is significant as it demonstrates that cotton cultivation in Arabia was a Pre-Islamic socio-technical feat, while imported cotton highlights the dynamism of trade at that time.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The prehistory of the Mediterranean region has long been a subject of considerable interest, particularly the links between human groups and regions of origin. We utilize the spatial variation in the δ2H and δ18O values of precipitation (isoscapes) to develop proxies for geographic locations of fauna and humans. Bone collagen hydrogen isotope ratios (δ2H) in cattle (and to a lesser extent, ovicaprids) across the Mediterranean reflect the isotopic differences observed in rainfall (but δ18O values do not). We conclude that δ2H in herbivore bone collagen can be used as a geolocation tracer and for palaeoenvironmental studies such as tracing past isotopic variations in the global hydrological cycle. In contrast, human bone δ2H values are relatively tightly grouped and highly distinct from precipitation δ2H values, likely due to human-specific food practices and environmental modifications. Given the inter-species variability in δ2H, care should be taken in the species selected for study.

Detailed information about the lives and deaths of children in antiquity is often in short supply. Childhood dietary histories are, however, recorded and maintained in the teeth of both juveniles and adults. Primary tooth dentinal collagen does not turn over, preserving a sequential record of dietary changes. The use of nitrogen (δ15N) and carbon (δ13C) isotope values of incrementally sampled dentin are used in the study of breastfeeding practices but evidence for the addition of weaning foods, both in terms of mode and, particularly, duration, has remained analytically inaccessible to date. Here, we demonstrate how the novel use hydrogen isotope (δ2H) values of sequentially micro-sampled dentin collagen, measured from individuals excavated from a Punic cemetery, in Sardinia, Italy, can serve as a proxy for weaning food type and duration in ancient childhood diet. The weaning rate and age, based on the decline in δ15N and δ13C values of permanent first molars and the concomitant increase in δ2H, appears to be broadly similar among six individuals. Hydrogen isotopes vary systematically from a low value soon after birth, rising through early childhood. The early post-birth values can be explained by the influence of 2H-depleted lipids from mother’s breastmilk and the later δ2H rise is consistent with, among other things, a substantial portion of boiled foodstuffs, such as the higher δ2H values observed in porridge. Overall δ2H in dentin shows great promise to elucidate infant and childhood feeding practices, and especially the introduction of supplementary foods during the weaning process.

RATIONALEDifferent thermal conversion reactor packings result in distinct δ2 H values in nitrogen-containing materials, such as bone collagen. An older 'traditional' glassy carbon packing method causes incomplete conversion of N-containing samples into H2 gas, resulting in altered δ2 H values compared with the complete conversion of hydrogen obtained with a chromium-packed reactor. Given that δ2 H values from collagen are gaining importance in palaeoecological and archaeological studies, a determination of the relationship between δ2 H values produced with a glassy-carbon-packed and a chromium-packed reactor is needed.METHODSWe obtained δ2 H values (normalized on the VSMOW-SLAP scale) from both glassy-carbon-packed (GP) and chromium-packed (Cr) reactor configurations from bone collagen (n = 231) from a variety of archaeological sites, using a High-Temperature Conversion Elemental Analyzer (TC/EA) coupled to a Delta Plus XP isotope ratio mass spectrometer.RESULTSδ2 H values from both methods are linearly correlated (r2  = 0.934) and yield the following interconversion equation, δ2 H(Cr) = 1.054 δ2 H(GP) + 11.6‰ (95% conf. slope 1.020-1.090, intercept 10.6-12.6), and a mean difference of δ2 H(Cr) - δ2 H(GP) = 10.1‰ (1 sd 5.2, 1 se 0.3, n = 231).CONCLUSIONSWe recommend adopting this interconversion between δ2 H values produced with a glassy-carbon-packed and chromium-packed reactor for bone collagen only, with appropriate propagation of uncertainty.

Ecologists, archaeologists and paleontologists have generously used the natural abundance of stable nitrogen isotopes (δ 15 N) to assess trophic relationships among consumers from both past and present ecosystems. The basis for trophic δ 15 N studies dates to the 1980's and the empirical observations of Minagawa and Wada documenting a stepwise increase in 15 N, primarily in aquatic environments. Moving to terrestrial environments, numerous difficulties have been reported in using δ 15 N values of consumers to determine food web relationships for a variety of reasons: complexity of the food sources (including the differential bioavailability of nitrogen); the unknown isotopic composition of primary producers; impact of aridity on plant nitrogen isotopes; and the offset in δ 15 N between the consumer and the consumed.

Strontium isotopes are used in archaeology, ecology, forensics, and other disciplines to study the origin of artefacts, humans, animals and food items. Strontium in animal and human tissues such as bone and teeth originates from food and drink consumed during life, leaving an isotopic signal corresponding to their geographical origin (i.e. where the plants grew, the animals grazed and the drinking water passed through). To contextualise the measurements obtained directly on animal and human remains, it is necessary to have a sound baseline of the isotopic variation of biologically available strontium in the landscape. In general, plants represent the main source of strontium for humans and animals as they usually contain much higher strontium concentrations than animal products (meat and milk) or drinking water. The observed difference between the strontium isotope composition of geological bedrock, soils and plants from the same locality warrants direct measurement of plants to create a reliable baseline. Here we present the first baseline of the biologically available strontium isotope composition for the island of Ireland based on 228 measurements on plants from 140 distinct locations. The isoscape shows significant variation in strontium isotope composition between different areas of Ireland with values as low as 0.7067 for the basalt outcrops in County Antrim and values of up to 0.7164 in the Mourne Mountains. This variability confirms the potential for studying mobility and landscape use of past human and animal populations in Ireland. Furthermore, in some cases, large differences were observed between different types of plants from the same location, highlighting the need to measure more than one plant sample per location for the creation of BASr baselines.

Three early medieval Irish communities within a 30-km radius in Co. Meath, Ireland, have been examined using multiple isotopes ( Sr-87/Sr-86, delta O-18, delta C-13, delta(15) N) to elucidate human and domesticated animal subsistence and provenance. Existing( 87)Sr/ Sr-86 data from geochemical mapping of contemporary soils, plants and streamwater were compared to human and animal tooth enamel Sr-87/ Sr-86 to assess potential past human migration, in combination with delta O-18 from bone collagen. Oxygen isotope (delta O-18) values of human bone collagen are notably invariable, 10.0 +/- 0.6%o (n = 36), for the three archaeological sites: Collierstown, Johnstown and Raystown. Fauna (sheep, pigs, cats and a dog) delta O-18(collagen) from Raystown are distinctly grouped between and among certain species, the first instance to our knowledge of such a result. The aggregate faunal data demonstrate that delta(18)O(collagen )values of faunal remains should not be used to infer local delta O-18 ranges for humans. Nitrogen isotope (delta N-15) values for both domesticated animal (9.8 +/- 1.79 , 60) and adult human (12.0 +/- 0.8%o) bone collagen are tightly constrained suggesting a similar source of protein in the diet of humans. A mean carbon isotope (delta C-13) value of - 21.0 +/- 0.4%o for adult humans indicates overwhelming terrestrial sources of foodstuffs. Strontium isotope ratios (Sr- 87/ Sr-86) from human dental enamel range from 0.7085-0.7110 (n = 25). Two individuals (R841 and R854), both from Raystown, are statistical outliers based on their Sr-87/Sr-86 and delta C-13 values and are likely migrants to the locality where they were buried. We note that one of these putative migrants met a particularly violent end.

Geochemical mapping of biosphere variation has wide application to geological, environmental, forensic and archaeological research. The extent to which trace elements may be used to complement strontium isotopes (Sr-87/Sr-86) for biosphere characterisation is unclear and uncertainties exist regarding the most suitable sample media for this purpose. Here, the variation in Sr-87/Sr-86 and trace elements, with focus on the rare earth elements and yttrium (REE + Y), are measured in soil leachates, vegetation and streamwaters. These independent tracers are employed to define geochemical reservoirs and quantify soil-plant-water interactions in a geologically diverse and archaeologically significant area of Ireland, County (Co.) Meath. This integrated isotope and element approach produces the first combined dataset for this temperate environment. Biological absorption coefficients (BAC) are used to assess bio-uptake of selected elements. The REE + Y exhibited greatest utility in revealing soil parameter controls on bio-uptake, such as reduced availability from preferential retention of Ce on Fe/Mn-oxyhydroxide surfaces, as well as revealing a preferential uptake of Y relative to HREE. High Y/Ho ratios (65.3-465) are exhibited in ash trees (Fraxinus excelsior L.), regardless of geological setting, indicating a potential species-specific preference. However, aerial portions of ash trees do not directly reflect the REE in the bioavailable portion of the soil, indicating selectivity from the soil reservoir or fractionation during plant uptake and/or intra-plant distribution. Streamwater REE patterns have a consistent and seawater-like pattern probably inherited from marine carbonate bedrock, surficial marine carbonate-derived fill, agricultural fertiliser or a combination of all three, and thus were not site lithology diagnostic. By contrast, distinct variation in sources of Sr-87/Sr-86 to streamwaters is evident and reflects small-scale differences in underlying bedrock. The Sr-87/Sr-86 range of vegetation for the study area is 0.7081-0.7130. Soil and streamwater samples collected at proximal locations to the vegetation demonstrated a range of 0.7086-0.7133 for soil leachates and 0.7081 to 0.7107 for streamwaters. Statistically significant (p < .05) differences between the spatial distribution of 87 Sr/ 86 Sr in plants and certain underlying bedrock/Quaternary sediment were identified, even in a region without an extreme range in Sr-87/Sr-86 values. Careful selection of appropriate soil leaching protocols is necessary for an informative estimate of the natural ranges that exist within the pedosphere, supporting the notion that plant material is the most suitable sample medium for mapping bioavailable Sr. The high degree of spatial variability in Sr-87/Sr-86 and differences between reservoirs can only be accurately represented by relatively high-density sampling of plants. These data complement both national and European-wide initiatives to produce large-scale Sr-87/Sr-86 biosphere maps.