ORIGINAL RESEARCH article
Front. Environ. Archaeol.
Sec. Archaeological Isotope Analysis
Volume 4 - 2025 | doi: 10.3389/fearc.2025.1510394
This article is part of the Research TopicStable Isotope Analysis of Archaeobotanical RemainsView all 9 articles
Differences in the isotopic composition of individual grains and aggregated seed samples affect interpretation of ancient plant cultivation practices
Provisionally accepted
- 1University of California, San Diego, La Jolla, California, United States
- 2University of Kiel, Kiel, Germany
- 3University of Wisconsin-Madison, Madison, Wisconsin, United States
- 4University of Washington, Seattle, Washington, United States
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The stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope analysis of charred archaeological grains provides a remarkably precise scale of information: the growing conditions under which a plant was cultivated in a single field and season. Here we investigate how the measurement of single individual grains or aggregate 'bulk' samples for carbon and nitrogen isotopes impacts how we characterize variation and, consequently, our interpretations of ancient cultivation practices. Using experimentally grown barley (Hordeum vulgare var. nudum), this work investigates δ 13 C and δ 15 N intra-panicle variation between both uncharred and charred individual grains from four plants. We found limited intra-and interpanicle isotopic variation in single grain isotope values, ca. 0.5‰ in δ 13 C and ca. 1‰ in δ 15 N, reemphasizing the degree to which grains are representative of their local growing conditions. To explore the interpretive impact of aggregate versus single-grain isotopic sampling, we measured charred barley recovered from a single storage context excavated from Trench 42 (ca. 1900 BCE) at Harappa. Aggregate samples of a random selection of Trench 42 barley demonstrated remarkable intersample homogeneity, with a less than 0.5‰ difference in δ 13 C and δ 15 N values, demonstrating aggregate samples capture well a representative isotopic average of a single depositional context. However, the measurement of single grains revealed moderate 2-3‰ variation in δ 13 C and an outstandingly wide isotopic variation of ca. 8‰ in δ 15 N values, indicating the degree to which growing conditions varied beyond what the isotope ratios from aggregate samples indicated. These results highlight how decisions in the selection and measurement of archaeological charred grains for isotopic analysis impact data resolution, with profound consequences for understanding past agricultural diversity.
Keywords: charred grain, carbon isotope, nitrogen isotope, Plant husbandry, Indus valley civilization
Received: 12 Oct 2024; Accepted: 21 Apr 2025.
Copyright: © 2025 James, Winter-Schuh, Kenoyer, d'Alpoim Guedes and Makarewicz. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Cheryl Makarewicz, University of Kiel, Kiel, Germany
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