Stable Isotope Record of Human and Sheep Enamel Carbonate from the Ancient Middle Euphrates Valley (Syria)

Stable isotope analyses of human tooth enamel have allowed us to reconstruct the isotope composition of dietary carbon, changes in the oxygen isotope composition of drinking water and the possible migration of humans in ancient Terqa and Tell Masaikh (SE Syria). δ¹⁸O_carbonate values of human tooth enamel from the interval comprising the Neo‐Assyrian to the modern Islamic periods (from 900 BC to AD 1949) generally mirror the isotope composition of Euphrates water, which is believed to have been a major drinking water source. Lower δ¹⁸O_carbonate values of human Bronze Age apatite are linked to a different hydrologic system that was present in the Middle Euphrates valley at that time (2650–1700 BC). Higher δ¹⁸O_carbonate values of some individuals in the Neo‐Assyrian (900–700 BC) and Islamic periods (AD 600–1200) may indicate human migration from the interior of the Near East. Low δ¹³C_carbonate values (−11.3 to −12.4‰) of human tooth enamel from the interval comprising the Early Bronze to the Islamic periods (from 2650 BC to AD 1200) indicate C₃ plants as a predominant source of dietary carbon. Changes in human dietary customs in SE Syria (with inferred usage of C₄ plants) occurred in the modern Islamic period only (AD 1850–1949). Oxygen and carbon isotope data of sheep enamel show the usage of water bodies characterised by an enhanced evaporation rate during the Neo‐Assyrian time (900–700 BC) and grazing sheep herds on drier areas during the Islamic and the modern Islamic periods (after AD 600). Copyright © 2015 John Wiley & Sons, Ltd.     

REFINING ESTIMATES FOR THE SEASON OF SHELLFISH COLLECTION ON THE PACIFIC NORTHWEST COAST: APPLYING HIGH‐RESOLUTION STABLE OXYGEN ISOTOPE ANALYSIS AND SCLEROCHRONOLOGY

Stable oxygen isotopes from estuarine bivalve carbonate from Saxidomus gigantea were analysed combined with high‐resolution sclerochronology from modern and archaeological shells from British Columbia, Canada, to determine the seasonality of shellfish collection from the archaeological site of Namu. The combination of high‐resolution sclerochronology and a micro‐milled sampling strategy for δ¹⁸O analysis permits a precise estimate of archaeological seasonality, because seasonal freshwater influxes and changes in temperature have dual effects on the δ¹⁸O value of the shell. Sclerochronological analysis identifies the timing and duration of growth that is temporally aligned to stable oxygen isotope results, since δ¹⁸O_shell appears to be strongly influenced by seasonal inputs of very low δ¹⁸O snowmelt‐water from adjacent coastal mountain ranges. The results show that shellfish were collected year‐round at this site over a 4000‐year period, and these data combined with other zooarchaeological lines of evidence support the interpretation of year‐round occupation.     

THE USE OF OXYGEN ISOTOPES IN SHEEP MOLARS TO INVESTIGATE PAST HERDING PRACTICES AT THE NEOLITHIC SETTLEMENT OF ÇATALHÖYÜK,CENTRAL ANATOLIA

This paper presents a pilot study designed to test the use of oxygen isotopes for investigating aspects of early herding practices in the Neolithic of western Asia, using the site of Çatalhöyük in central Anatolia as a case study. Time‐sequenced δ¹⁸O values in dental enamel of archaeological sheep are assessed for post‐depositional diagenetic effects and compared with seasonal δ¹⁸O meteoric water values in the region today. The evidence is used to indicate the environmental conditions in which individual sheep spent their first year, enabling management of breeding and birthing seasons, and movement to seasonal pastures, to be investigated.     

The Seasonal Mobility Model for Prehistoric Herders in the South-western Cape of South Africa Assessed by Isotopic Analysis of Sheep Tooth Enamel

A pattern of seasonal mobility between the coast and the hinterland by Khoekhoe pastoralists in the south-western Cape of South Africa was documented at the time of European contact. Because the region is characterized by a mosaic of geological substrates of various ages and vegetation types with different proportions of C₃ and C₄ plants, this mobility model for prehistoric herders can be tested by analysis of carbon, oxygen and strontium isotope ratios in domestic bovid tooth enamel. Isotopic analysis was performed on archaeological sheep, cattle, eland and steenbok teeth from the Late Stone Age site of Kasteelberg on the Vredenburg Peninsula. Sequential sampling of enamel provided a chronological record of the isotopic composition of diet during tooth formation. Results from carbon and oxygen isotope analysis of archaeological and modern steenbok teeth show seasonal variation in the δ¹³C of local pastures in the vicinity of the site (up to 2·9‰ in a single individual), which could be due to seasonal change in proportions of C₃ and C₄ plants and/or seasonal variation in the δ¹³C of C₃ plants. A pattern of seasonal change of 0·9–3·5‰ in the δ¹³C of tooth enamel is also observed in the sheep teeth. This amplitude of variation could be due to local seasonal changes, thus it is not possible, from the δ¹³C values, to infer whether the sheep were moving seasonally. Results from ⁸⁷Sr/⁸⁶Sr analysis of two sheep suggest that one individual stayed all year round on the coast, whereas the other had grazed in the interior for part of its life. Both δ¹³C and ⁸⁷Sr/⁸⁶Sr values measured in a cow tooth suggest that this animal spent part of its life in the interior, even though it died at Kasteelberg. Results on this cow also suggest longer residence within habitats rather than seasonal mobility. A clear pattern of seasonal mobility between the coast and the interior has not been shown for prehistoric pastoralists. However, the pattern of mobility attested in historical times might have developed only later in prehistory, when cattle pastoralism developed in the region.     

Oxygen isotope seasonality in a temperate estuarine shell midden: a case study from CA-ALA-17 on the San Francisco Bay,California

Seasonality determination using stable oxygen isotope (δ¹⁸O) analyses in archaeological mollusk shell has been largely limited to aquatic settings where one of the two factors that control shell δ¹⁸O – water δ¹⁸O (or salinity) and temperature – is assumed to be constant. Open coastal marine environments reflect the former situation, and tropical estuaries constitute the latter. In an effort to expand stable isotope seasonality to an ecological setting where neither variable remains constant, we present a model of annual shell δ¹⁸O cycle of aragonite deposition derived from instrumental data on salinity and temperature from San Francisco Bay, California. The predicted range of modeled shell δ¹⁸O is consistent with observed δ¹⁸O values in prehistoric and modern shells when local conditions are considered. Measurements of δ¹⁸O taken at 0 mm and 2 mm from the terminal growth margin were made on 36 archaeological specimens of Macoma nasuta from a late Holocene hunter-gatherer site CA-ALA-17, and season of collection was inferred using the shell δ¹⁸O model. We conclude that shellfish exploitation occurred through the year with the exception of fall, which may indicate scheduling conflicts with acorn harvesting or other seasonally abundant resources elsewhere. The model supports the feasibility of stable isotope seasonality studies in temperate estuaries, provided that instrumental records are available to quantify the relevant water conditions at appropriate spatial and temporal scales.     

Preservation assessment of Miocene–Pliocene tooth enamel from Tugen Hills (Kenyan Rift Valley) through FTIR,chemical and stable-isotope analyses

We investigated fossil tooth enamel of mammals and crocodiles from two Mio-Pliocene East-African formations (Lukeino and Mabaget Fms) using infrared spectroscopy and chemical and stable-isotope analyses. Infrared spectra indicate that the fossil enamel contains biological apatite (bioapatite), without significant secondary carbonate contaminations. Several empirical infrared indexes were used to analyze the crystal–chemical characteristics of enamel. Fossil enamel has less organic matter, water and structural carbonate of apatite than modern enamel with which it was compared. Fossil apatite has a better crystallinity than bioapatite. The calcium/phosphorus mass ratio and the fluorine content of fossil apatite show intermediate values between bioapatite and geological fluorapatite. The samples also display significant crystal-chemical variations, depending on the vertebrate group (mammals vs. reptiles) and the taphonomic context (Lukeino Fm vs. Mabaget Fm). In spite of these changes, no relationship was observed between the chemical contents (carbonate and fluorine) and the stable-isotope ratios of carbonate (δ¹³C and δ¹⁸O) in fossil enamel. Preservation of the palaeoenvironmental signals is strongly supported by the fact that the stable-isotope composition of the three investigated fossil mammalian taxa (deinotheres, equids and hippos) is consistent with their ecological features. For instance, typical C₃- and C₄-plant isotope compositions are reflected in the deinotheres and equids, respectively, and amphibious hippos display lower δ¹⁸O values than terrestrial herbivores, as expected.     

New Statistical Approaches to Intra‐individual Isotopic Analysis and Modelling of Birth Seasonality in Studies of Herd Animals

This paper introduces improved methods for statistically assessing birth seasonality and intra‐annual variation in δ¹⁸O from faunal tooth enamel. The first method estimates input parameters for use with a previously developed parametric approach by C. Tornero et al. The second method uses a non‐parametric clustering procedure to group individuals with similar time‐series data and estimate birth seasonality. This method was successful in analysing data from a modern sample with known season of birth, as well as two heterogeneous archaeological data sets. Modelling indicates that the non‐parametric approach estimates birth seasonality more successfully than the parametric method when less of the tooth row is preserved. The new approach offers a high level of statistical rigour and flexibility in dealing with the time‐series data produced through intra‐individual sampling in isotopic analysis.     

EXAMINING CHILDHOOD DIETS AT KAMINALJUYU,GUATEMALA, THROUGH STABLE ISOTOPIC ANALYSIS OF SEQUENTIAL ENAMEL MICROSAMPLES*

Stable carbon and oxygen isotope ratios of tooth enamel provide a means to examine nutritional changes during childhood. To date, such studies have used large enamel samples, often spanning the developmental period of the tooth. This paper reports the results of small samples drilled from first molars and premolars of human teeth from Kaminaljuyu, a Classic period city in highland Guatemala. Carbon isotopes show considerable increase between cuspal and cervical enamel for both teeth, indicating an increase in maize consumption during childhood. Oxygen isotope trends are more variable, and suggest some seasonal fluctuation. While the oxygen isotope data confirm the identification of foreign skeletons among the samples, they illustrate a need for caution when sampling teeth due to variable δ¹⁸O composition of enamel within a tooth.     

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.     

Seasonality and season of birth in early Eneolithic sheep from Cheia (Romania): methodological advances and implications for animal economy

Cheia (early 5th millennium cal BC) is a prehistoric village in the Dobrodgea province in Romania. Its occupation is attributed to the Early Eneolithic period or Hamangia III phase. The exploitation of animal resources is heavily dominated by husbandry. Although cattle are dominant, they were complemented by caprines, mainly sheep, exploited for tender meat (as highlighted by a 6–12 months age class peak in the mortality profile). Sheep reproduction patterns were investigated through stable isotope analyses in order to characterize the annual rhythms of slaughtering for tender meat acquisition while informing a more general picture on sheep demographical management and animal husbandry at the settlement. Results from δ¹⁸O analysis on second and third molar enamel were modeled and compared with modern reference populations. Sheep births took place over less than four months, from late winter to early summer. From this it could be concluded that tender meat could be provided most of the year, excepted over short period in early summer. Finally, comparison of datasets obtained on the M2 and M3 suggests that the M2 presents a more accurate representation of birth seasonality due to lower inter-individual variability in the chronology of tooth growth.     

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.     

Distinguishing sheep and goats using dental morphology and stable carbon isotopes in C4 grassland environments

Distinguishing between sheep and goats in C₄ grass environments using new dental morphology criteria and enamel bioapatite stable carbon isotope ratios (δ¹³C) was tested on 35 modern individuals from the Central Rift Valley of Kenya. Two morphological criteria on the second and third lower molars, one of which had been previously partially described by Halstead et al. [Journal of Archaeological Science 29 (2002) 545], were found to be highly reliable in this population. Identification of species using carbon isotope ratios is made possible in some circumstances by differences in the feeding behavior of sheep, which are mainly grazers, and goats, which are mainly browsers. In environments where C₄ grasses predominate, sheep include a higher proportion of C₄ plants in their diet, and thus have higher δ¹³C values than goats. In the present study, the annual range and seasonal variation of carbon isotope ratio of diet of sheep and goats was measured from intra-tooth sequential analysis. Although the ranges of goat and sheep δ¹³C values overlap, those higher than −3.4‰ all belong to sheep; values lower than −5.2‰ all belong to goats. There is no overlap of the mean δ¹³C values by tooth, which range from −11.8‰ to −4.2‰ for goats, and from −3.1‰ to −1.3‰ for sheep. These results suggest that carbon isotope analysis of bone collagen and/or apatite will also distinguish sheep from goats in tropical C₄ grasslands. Application of the δ¹³C criteria to archaeological material must be restricted to C₄-dominated environments, and where potential access to C₃ plants (mobility, foddering) can be assessed. The utility of these morphological and isotopic criteria for differentiating sheep and goat breeds in other regions remains to be evaluated.     

Refining oxygen isotope analysis in the Nasca region of Peru: An investigation of water sources and archaeological samples

The development of complex societies, irrigation agriculture and sociopolitical transitions are of interest to researchers working in the Nasca region on the south coast of Peru. Occupied for thousands of years, many questions regarding the circumstances of these changes in the area are being investigated. Oxygen isotope analysis provides a method for exploring residential mobility of past peoples during these transitions. This study presents new δ¹⁸O data from water sources that would have been used by the ancient inhabitants, providing important information regarding the oxygen isotope variability in the region and the necessary baseline data for migration studies in this region. Our results suggest that the isotopic composition of water sources in the Nasca region is not highly variable. In addition, archaeological human tooth enamel samples from the sites of La Tiza and Pajonal Alto are analysed. The δ¹⁸O_c results of the human enamel samples confirm the local nature of the burial population, as suggested by previous strontium isotope analysis (⁸⁷Sr/⁸⁶Sr). Copyright © 2010 John Wiley & Sons, Ltd. This article was published online on 13 January 2010. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 15 January 2010.     

Oxygen and strontium isotopes as provenance indicators of fish at archaeological sites: the case study of Sagalassos,SW Turkey

In this paper, we investigate the potential use of oxygen and strontium isotope ratios (δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr) measured in archaeological fish enamel as provenance indicators. δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr were measured in a suite of archaeological carp remains recovered from the Anatolian townsite of Sagalassos dated to the Early Byzantine period (AD 450–650) and compared to that of modern fish, river and lake waters from the Anatolian region. We used sequential leaches in weak acetic acid to remove diagenetic Sr from fossil tooth enamel, monitoring the effectiveness of this approach by measuring the Sr/Ca ratios of the leachates via an isotope dilution thermal ionization mass spectrometry method (ID-TIMS). δ¹⁸O_p values mostly excluded a riverine origin. ⁸⁷Sr/⁸⁶Sr ratios of one fish overlapped with the ⁸⁷Sr/⁸⁶Sr signatures of two lakes in the Anatolian region, and at least one lake (Gölcük) could be removed as a candidate owing to a very distinctive ⁸⁷Sr/⁸⁶Sr signature not found in any of the fish remains. Most of the tooth samples analyzed could not be assigned a precise geographical origin since the ⁸⁷Sr/⁸⁶Sr ratios measured in enamel did not match that of any of the local lakes selected as potential origin. This result suggests that carp may have originated from lakes that have not yet been sampled, although this conclusion is not supported by other archaeological evidence. Alternatively, the lack of correspondence between lakes and fish Sr isotope ratios highlights several possible sources of uncertainties including spatial heterogeneity in ⁸⁷Sr/⁸⁶Sr ratio within a lake, the contribution of dietary strontium to the ⁸⁷Sr/⁸⁶Sr ratio of fish tooth enamel, and post-mortem alteration of the tooth Sr isotope signal during fossilization. In spite of the high precision of the strontium isotope analyses and the wide range of variation in the surface waters of the Anatolian lakes and rivers, this method may remain limited to distinguishing between lakes situated in regions of bedrock of very distinct age and geology until these sources of uncertainty are more fully investigated.     

OXYGEN AND CARBON ISOTOPE ANALYSIS OF HUMAN DENTAL ENAMEL FROM THE CARIBBEAN: IMPLICATIONS FOR INVESTIGATING INDIVIDUAL ORIGINS

This study explores the potential of carbon and oxygen isotope data from human enamel carbonate (n = 50) to contribute to mobility studies in the Caribbean. Most oxygen and carbon isotope results display limited variation, with substantial overlap between islands. However, a few individuals from El Chorro de Maíta, Cuba possess relatively low δ¹⁸O and high δ¹³C. Two of these individuals were previously identified as possible non‐Antillean immigrants on the basis of strontium isotopes, and bioarchaeological and mortuary evidence. The carbon and oxygen isotope results provide additional evidence supporting the proposed non‐local origins of these individuals and contribute to explorations of their potential natal origins.     

MARINE RESOURCES IN THE MESOLITHIC AND NEOLITHIC AT THE GROTTA DELL’UZZO (SICILY): EVIDENCE FROM ISOTOPE ANALYSES OF MARINE SHELLS*

Oxygen isotopes in shell carbonate samples from the marine rocky‐shore intertidal gastropod Monodonta turbinata (Born) are investigated in both modern analogue specimens and in archaeological specimens from the Grotta dell’Uzzo (Sicily). Variations in shell edge values of δ¹⁸O in living specimens collected monthly over two years are closely correlated with monthly seawater temperatures measured at the time of collection, showing that the species can be used for palaeoseasonality studies. Analyses of shell edge δ¹⁸O values in archaeological specimens, from Mesolithic through to early Neolithic phases at the Grotta dell’Uzzo, enabled the inference of various seasons of collection of shellfish and how such seasonality varies between the different phases of occupation. Interesting similarities and differences exist between the seasons of marine shellfish exploitation and the seasons inferred from the vertebrate zooarchaeological assemblages. A major inference drawn from the analyses and discussion is that the exploitation of all marine resources (fish and shellfish) increased in the later Mesolithic and early Neolithic periods.     

In situ oxygen isotope micro-analysis of faunal material and human teeth using a SHRIMP II: a new tool for palaeo-ecology and archaeology

A Sensitive High Resolution Ion MicroProbe (SHRIMP II) has been used to make high spatial resolution in situ micro-analyses of oxygen isotopes in fish otoliths, and teeth from fossil herbivores and a Neanderthal. Large intra-tooth variations in the oxygen isotopic composition (up to 9‰) were observed in the enamel of herbivores from the Neanderthal fossil site of Payre, consistent with preservation of seasonal cyclicity. The range of isotopic compositions observed in Neanderthal tooth enamel was much smaller (∼3‰), possibly the result of a longer enamel maturation time averaging out variability. An archaeological otolith from a Preceramic site in Northern Peru exhibited marked changes in δ¹⁸O over life, due either to the fish occasionally migrating from the sea to a lower salinity habitat, or to short-lived rises in sea water temperature. A fish otolith from Australia's Willandra Lakes World Heritage Area showed clear seasonal variations, but also a general trend towards isotopically heavier and more saline water, as indicated by higher δ¹⁸O and Sr/Ca values resulting from increased evaporation. The results of these case studies are compared to results of oxygen isotope analysis using more conventional methods and demonstrate the ability of the SHRIMP II to provide precise high spatial resolution in-situ oxygen isotope analyses of a variety of biogenic materials. This approach has major advantages over conventional methods. It can provide rapid, micro-scale isotopic analyses of sub-permil precision without the need for chemical preparation of the sample.     

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.     

IN‐SITU ELEMENTAL AND Sr ISOTOPE INVESTIGATION OF HUMAN TOOTH ENAMEL BY LASER ABLATION‐(MC)‐ICP‐MS: SUCCESSES AND PITFALLS*

Trace element and Sr isotope data were obtained by laser ablation‐ and solution mode‐(MC)‐ICP‐MS analysis for tooth enamel from remains excavated at the New Kingdom period Egyptian colonial and Nubian cemetery site of Tombos (Sudan). Elemental abundances determined by both methods of ICP‐MS analysis yielded comparable values; however, ⁸⁷Sr/⁸⁶Sr values obtained by laser ablation were higher compared to their solution mode counterparts. This discrepancy is related to the production of a molecular interference—Ca + P + O (overlaps ⁸⁷Sr); hence the higher ⁸⁷Sr/⁸⁶Sr values recorded during ablation analyses. Laser ablation studies of enamel may provide relatively precise ⁸⁷Sr/⁸⁶Sr values rather quickly but cannot be used for accurately deciphering historical population migrations.     

Oxygen isotopes in cellulose identify source water for archaeological maize in the American Southwest

Maize (Zea mays) was a primary food crop for aboriginal societies of the arid American Southwest. Water used for maize production in these arid zones could have come from precipitation and runoff during the summer monsoon, from perennial streams and springs, or from stored soil water fed by snowmelt. The oxygen stable isotope ratio (δ¹⁸O) of summer and winter precipitation on the Colorado Plateau naturally differ by more than 10‰ providing a powerful tool for distinguishing winter- from summer-derived water sources used in cultivation of maize. We investigated whether variation in δ¹⁸O of potential source waters is preserved in the δ¹⁸O of cellulose (δ¹⁸O_cellulose) of maize cobs by growing four aboriginal and one modern maize variety in pots irrigated with water of known δ¹⁸O composition. The δ¹⁸O_cellulose values of cobs ranged from 26.8 to 36.4‰ (averaged within varieties) and were highly correlated with δ¹⁸O values of the source irrigation water (−15.8 to −8.2‰). Cob δ¹⁸O_cellulose from five archaeological sites on the Colorado Plateau in southeastern Utah ranged from 27.3 to 34.6‰, closely matching the range of values observed in experimental plants. A δ¹⁸O_cellulose model developed originally for tree rings was parameterized and applied to the archaeological maize cobs. The model indicated that monsoonal precipitation accounted for 0–20% of the moisture for archaeological cob samples from a site adjacent to a perennial stream and 43–98% for samples from an upland site, more distant from a perennial water source. These results reveal the potential for using δ¹⁸O_cellulose to investigate prehistoric irrigation practices and source water used for maize production in the American Southwest.