Mountain adaptation of caprine herding in the eastern Pyrenees during the Bronze Age: A stable oxygen and carbon isotope analysis of teeth

Abstract

Pastoral activities in the northeastern Pyrenees increased substantially during the Bronze Age, raising the question of the modalities of occupations in zones where the snow cover limited access to grasslands for a significant part of the year. The present study explores how stable isotope analysis may characterize the adaptation of husbandry to mountain environments through herding strategies, including the vertical mobility of livestock. It also addresses the broader issue of the occupation of territories by Bronze Age communities in the Western Mediterranean area, focusing on possible links between coastal plains and mountainous areas. For this purpose, sequential stable carbon and oxygen isotope analyses were conducted on caprines' teeth from the mountain site of Llo (Pyr en ees-Orientales, 1630 m asl, Middle Bronze Age) and the permanent coastal site of Portal-Vielh (H erault, 0 m asl, Late Bronze Age). An exploratory analysis was also conducted on modern sedentary and transhumant ewes to investigate the effect of altitudinal mobility on enamel oxygen isotope values. The range of d 18 O values measured in modern and archaeological caprines raised in mountain zones was lower than the one measured in the lowland caprines, while no significant difference could be observed in the range of d 13 C values. Co-variations between d 13 C and d 18 O sequences reveal the most information. The positive correlation observed in all instances at low elevation sites was not the leading pattern at Llo, where a variety of schemes could be observed, including opposite d 13 C and d 18 O sequences. This opposition could not be explained by a reversal of the d 18 O cycle due to vertical mobility. Other causes could involve changes in the pattern of variation of d 13 C values, potentially linked to human responses to the local constraints, including vertical mobility and/or foddering. Portal-Vielh delivered a fully lowland signal. At Llo, although a full adaptation to a mountain environment seems clear, the question of the vertical mobility of the livestock cannot be resolved at the moment. Most importantly, Llo was characterized by a high inter-individual variability in the co-variation of d 13 C and d 18 O profiles, reflecting great plasticity of the husbandry practices on the inter-annual scale. This could have been a key to the adaptation to these marginal environments. The apparent disjunction between the coastal and mountain settlements, as far as herd trajectory is concerned, must be reaffirmed by further investigations in a larger number of sites.

Oxygen isotopes in bioarchaeology: Principles and applications, challenges and opportunities

“…Indeed, a multitude of other factors can impact the seasonal amplitude of δ 18 O in herbivore tooth enamel and intra-group variability in addition to movement. Confounding factors that may produce similar isotopic patterns in non-mobile animals and mobile animals are, for instance: the ingestion of water sources with buffering effects, such as lakes, rivers or groundwater (as suggested by Dufour et al, 2014;Henton et al, 2014); intra-group variability in drinking water source (Knockaert et al, 2017); or differences in feeding behaviour in animals ingesting large proportions of leaf water in arid or semi-arid environments (Blumenthal et al, 2017;Levin et al, 2006;Makarewicz and Pederzani, 2017). At the same time, considerable challenges are associated with defining the range of 'local' variation to be expected in a stationary animal, a problem also encountered in provenancing studies and research investigating human residential mobility (see sections 4.4.2 and 4.4.3).…”

Close management of sheep in ancient Central Asia: evidence for foddering, transhumance, and extended lambing seasons during the Bronze and Iron Ages

“…Combined oxygen and carbon isotope measurements from sequentially sampled teeth have been increasingly used to investigate livestock management strategies across a range of environments (Britton, Müldner, and Bell 2008;Makarewicz 2017;Makarewicz, Arbuckle, and Öztan 2017;Tornero et al 2016b;Knockaert et al 2017;Makarewicz and Pederzani 2017). Sequences of δ 18 O and δ 13 C values along the tooth crown have clarified seasonal vertical mobility of wild sheep feeding in Alpine environments (Tornero et al 2016a) and, when compared to the isotopic composition of other herbivorious species, in early domesticated sheep and goat in mountainous terrains east of the Jordan Valley (Makarewicz 2017).…”

“…The carbon isotope composition of herbivore tooth bioapatite is determined by the carbon isotopic composition of ingested plants (Ambrose and Norr 1993;Lee-Thorp, Sealy, and Van Der Merwe 1989;Tieszen and Fagre 1993). Shifts in the δ 13 C values of sequentially sampled herbivore teeth are useful for establishing dietary change on seasonal scales (Balasse et al 2002;Britton et al 2009;Makarewicz, Arbuckle, and Öztan 2017;Makarewicz and Pederzani 2017;Knockaert et al 2017). The carbon isotope compositions of plants are influenced by aridity, salinity, water availability and altitude.…”

“…In particular, we investigate seasonal husbandry practices involving the manipulation of sheep dietary intake, birth season, and movement (e.g. Balasse et al 2003;Britton, Müldner, and Bell 2008;Balasse et al 2012;Tornero et al 2013;Tornero et al 2016b;Knockaert et al 2017;Makarewicz, Arbuckle, and Öztan 2017). Carbon isotope sequences were used to investigate dietary intake and infer mobility by taking advantage of variation in floral biomes to track movement in the landscape (e.g.…”

Size diversity in Swiss Bronze Age cattle

“…Previous studies have proposed plausible factors that could have had an impact on animal morphologies and caused size variations, such as livestock diet (Breuer, Rehazek, & Stopp, ), which was linked to climate (Davis, ) or altitude (Knockaert et al, ), breeding strategies (Duval, Horard‐Herbin, & Lepetz, ; Trixl, Steidl, & Peters, ), idiosyncratic choices of husbandry (Cucchi et al, ), introduction of new animal forms (Gaastra, ; MacKinnon, ), transalpine mobility, and migration of humans together with their livestock (Grupe, Hölzl, Mayr, & Söllner, ), or selection of specific sex, such as small female cattle (Manning, Timpson, Shennan, & Crema, ). Because body size and sex are strongly correlated (Davis et al, ) and sex ratio provides a hint of cattle exploitation, computation of sex ratios of cattle populations was considered necessary.…”