Isotope evidence for agricultural extensification reveals how the world's first cities were fed

Abstract

This study sheds light on the agricultural economy that underpinned the emergence of the first urban centres in northern Mesopotamia. Using δC and δN values of crop remains from the sites of Tell Sabi Abyad, Tell Zeidan, Hamoukar, Tell Brak and Tell Leilan (6500-2000 cal bc), we reveal that labour-intensive practices such as manuring/middening and water management formed an integral part of the agricultural strategy from the seventh millennium bc. Increased agricultural production to support growing urban populations was achieved by cultivation of larger areas of land, entailing lower manure/midden inputs per unit area-extensification. Our findings paint a nuanced picture of the role of agricultural production in new forms of political centralization. The shift towards lower-input farming most plausibly developed gradually at a household level, but the increased importance of land-based wealth constituted a key potential source of political power, providing the possibility for greater bureaucratic control and contributing to the wider societal changes that accompanied urbanization.

Effectiveness of different pre‐treatments in recovering pre‐burial isotopic ratios of charred plants

“…However, a main disadvantage of ABA protocols is that they cause large sample losses particularly for powdered samples, and increase the risk of laboratory contamination. 11,16 Pre-treatment alternatives to an ABA protocol have been employed including acid-only protocols, 5,[21][22][23][24][25] acid-only or base-acid protocols following infrared pre-screening, 11 and no pre-treatment. 26,27 Statistical comparison of isotopic ratios from untreated and acid-only pre-treated archaeological samples of single charred grains from the Iron Age site of Danebury Hillfort (UK) showed no significant difference in either δ 13 C or δ 15 N values.…”

“…Pre‐treatment alternatives to an ABA protocol have been employed including acid‐only protocols, acid‐only or base–acid protocols following infrared pre‐screening, and no pre‐treatment . Statistical comparison of isotopic ratios from untreated and acid‐only pre‐treated archaeological samples of single charred grains from the Iron Age site of Danebury Hillfort (UK) showed no significant difference in either δ 13 C or δ 15 N values .…”

Quantifying Land Use in Past Societies from Cultural Practice and Archaeological Data

“…The calculation of fallow land, in cultures where this was practised, is founded on the amount of land required for cereal crops, where the available records attest to its usage. The proportion of land under fallow is dependent on sociocultural and environmental factors, such as the intensiveness/extensiveness of agriculture and soil fertility (e.g., [18]) and can be provided independently, or linked to societal complexity as expressed in textual accounts and the archaeological record. The employment of crop rotation substantially reduces the amount of cropland required by a population through increased intensity of land use and the reuse of cropland, for example, a Roman three-field rotational strategy with cereals, legumes and fallow [32].…”

“…At the scale of individual settlements, or more generally for certain regions and periods, intensive research (e.g., [16]) combined with experimental techniques (e.g., [17][18][19]) and ethno-archaeological studies of pre-mechanised farming (e.g., [20]) have led to the development of inventories and scenarios of land use. The detailed analysis of Neolithic land use in the Central European context performed by Gregg [21], is among the most comprehensive examples of a quantification of land use in a prehistoric society.…”

Open for Competition: Domesticates, Parasitic Domesticoids and the Agricultural Niche

“…These include many early Pre-Pottery Neolithic sites in the Levant, inferred from site locations (Scott 2017: 66;Sherratt 2007), and the decrue rice agricultural systems of China in use prior to evolution of domesticated, non-shattering rice (Fuller, Weisskopf and Castillo 2016;Weisskopf et al 2015). But as cultivation expanded, and crops became morphologically closer to domesticated forms, thus more demanding, intensive management of soil conditions became necessary, as inferred for rice based on early field systems and associated phytolith indicators (Fuller and Qin 2009;Weisskopf et al 2015), and for early Near Eastern/ European wheat and barley based nitrogen isotopes from archaeological grains (Bogaard et al 2013;Styring et al 2017). …”