Settlement continuity, changing economy, and palaeoecology: Comparing Viking Haithabu and medieval Schleswig
Final Report Abstract
Viking Haithabu and its successor, the medieval town of Schleswig, were important international trade centres. Human finds spanning a period of approximately 400 years represent the bodily relics of the former inhabitants who witnessed the rise and fall of these trade centres, and contemporary animal bone finds can be exploited for the reconstruction of economic change. These skeletal series are of extraordinary scientific importance and historical value, since they represent a population continuum spanning from Viking to medieval times at one and the same place during a pivotal phase in the development of occidental society that witnessed significant changes in social and political structure as well as the diversification of subsistence strategies. The isotopic analysis performed in the course of this project revealed detailed insights into changing life style and economy which could not have been obtained by osteological analysis alone. In the course of this research project, isotope mixing models were tested for bioarchaeological finds and proved very valuable for the solution of isotopic distributions which could not have been solved in the traditional way. Collagen 13C and 15N isotopic ratios resulted in a classical “mixing muddle” which could only be solved by the application of mixing models individual by individual. While marine food was preferred by the majority of individuals investigated from the prosperous trading sites (Viking Haithabu and the early phase of medieval Schleswig), a much higher number of individuals relied on protein acquired from domestic mammals when Schleswig lost its importance. This way, a change in subsistence economy could be reconstructed that accompanied the rise and decline of an early trade centre, whereby the change in major protein source did not impair overall protein supply. Moreover, ontogenetic trends of collagen 15N in immature skeletons revealed early weaning of babies during the prosperous phases of the settlements, in contrast to prolonged nursing in the following phases. Early weaning is indicative of a growing population since it bears the risk of early child death, but at the same time drastically reduces birth spacing per mother. This way, weaning practice constitutes an effective means for population regulation. The different age trends in 15N therefore mirror how the decline of Schleswig’s economic activity resulted in a changed reproduction strategy (Grupe et al., in press). The number of immigrated humans and imported animals was assessed by 87Sr/86Sr isotopic ratios in dental enamel (humans) and/or bone apatite (animals). The definition of the local isotopic range was performed by the application of ecological models for tracing the Sr-flux through ecosystems (Grupe et al. 2011). While a high percentage of primarily non-local humans at the burial sites is rather easily explained by the unusual surplus of males which is not improbable for busy trade centres, a very high proportion of animals was obviously also imported, which is compatible with the little agrarian hinterland of the sites. In terms of economic change, it became clear from isotope analyses in relation to archaeozoological finds that at Viking Haithabu, domesticated mammals played a major role in supplying raw material and work power, while dietary protein was mainly derived from aquatic vertebrates, especially fish, which could be caught in close proximity to the site. The decline in trading activities was accompanied by a significantly heavier reliance on domestic mammals as a protein source (which is in agreement with the dietary reconstruction, see above). Vertebrate food webs demonstrated changing catchment sites for certain species in the course of 400 years and the occupation of ecological niches by species (such as fish otter and white tailed eagle) from which they have been displaced in modern times. Mixing models led to the definition of foodweb end members which are of no importance for humans and therefore lacking in the archaeofaunal assemblage (Becker & Grupe 2012).
Publications
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2009: A brackish water aquatic foodweb: trophic levels and salinity gradients in the Schlei fjord, in Viking and medieval times. Journal of Archaeological Science 36, 2125-2144
Grupe G, Heinrich D, Peters J
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Das Nahrungsnetz im wikingerzeitlichen Haithabu und mittelalterlichen Schleswig: Aufstieg und Fall eines Handelszentrums. In: Metalla, Sonderheft 2: A. Hauptmann, H. Stege (Hrsg.): Archäometrie und Denkmalpflege 2009. Bochum 2009, pp 96-98
Vohberger M, Doppler S, Finkböck S, Heck K, Grupe G, von Carnap-Bornheim C, Peters J
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Rekonstruktion eines archäologische Brackwasserökosystems mit Hilfe stabiler S-, O- und S-Isotope für das wikingerzeitliche Haithabu und das mittelalterliche Schleswig. In: Metalla, Sonderheft 2: A. Hauptmann, H. Stege (Hrsg.): Archäometrie und Denkmalpflege 2009. Bochum 2009, pp 59- 61
Doppler S, Vohberger M, von Carnap-Bornheim C, Peters J, Grupe G
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2010. Biodiversity of archaeological fauna in the estuarine palaeoecosystem of the Schlei Fjord, Northern Germany. Isotopic evidence. Documenta Archaeobiologiae 8: 21-70
Doppler S, Vohberger M, von Carnap-Bornheim C, Heinrich D, Joris P, Grupe G
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2010. Fishing with the Vikings: Vertebrate food webs and isotopic mixing models in a brackish water ecosystem at Viking Haithabu and medieval Schleswig. Bulletin de la Société Suisse d’Anthropologie 16, 23-34
Grupe G, Doppler S, Vohberger M, Peters J
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2011. Teamplayer oder Gegenspieler? Der zweifache Nutzen von Archäozoologie und Isotopenanalyse – Haithabu und Schleswig neu bewertet. Beiträge zur Archäozoologie und Prähistorischen Anthropologie 8: 9-27
Becker, C. and Grupe, G.
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Stable strontium isotope mapping for provenance studies in archaeology – different material, different signals? Bulletin de la Société Suisse d’Anthropologie, Vol. 17. 2011, pp.67-76.
Grupe G, von Carnap-Bornheim C, Söllner F
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Archaeometry meets archaeozoology: Viking Haithabu and medieval Schleswig reconsidered. Journal of Anthropological and Archaeological Science, Vol. 4. 2012, Issue 4, pp. 241-262.
Becker C, Grupe G
