In the region surrounding the brackish Baltic Sea, the water itself of course served as an excellent medium for mobility, but the Baltic was also of immense importance for subsistence, offering a wealth of resources for the provision of food, clothing, artefact production and fuel, to name just a few examples. The material analysed in this study originates from Öland, a c. 140km long island in the Baltic Sea (Figure 1). It is a narrow island, less than 20km across, in close proximity to mainland Sweden. The bedrock comprises primarily sedimentary rocks such as Ordovician limestone, with some Cambrian and Ordovician shales. Its current shape and relative closeness to the mainland have only changed marginally since the Mesolithic (Svensson 2001; for a chronological division of archaeological periods in southern Scandinavia, see Table 1), and while the natural boundaries of the island itself delimit the area of investigation, the proximity to the mainland still promotes contacts and mobility of people as well as animals. Furthermore, the calcareous soils on the island provide favourable preservation conditions for skeletal material.
|Period||Approximate date (cal BC)|
|Early Bronze Age||1800-1100|
|Late Bronze Age||1100-500|
Öland is one of the few places in eastern Sweden where megalithic tombs occur. The erection of megalithic tombs such as dolmens and passage graves, clearly associated with the Funnel Beaker culture (the TRB), took place over vast areas of northern Europe during the Early and Middle Neolithic, around the middle of the fourth millennium BC (Midgley 2008). In Sweden, about 525 dolmens and passage graves are known (Sjögren and Price 2013), at least 255 of which are concentrated in the Falbygden area (Figure 1), located in the interior of the Swedish mainland, where a limited area of young sedimentary bedrock, primarily limestone, is surrounded by much older, Precambrian, igneous rock. The megaliths outside of the Falbygden area occur mainly along the coasts of the provinces of Bohuslän, Halland and Scania, with a few notable exceptions: the Alvastra dolmen in the province of Östergötland (located only a few kilometres from the Alvastra pile dwelling), a dolmen on the island of Gotland, and three passage graves and a dolmen in Resmo parish on Öland (Figure 1).
The Middle Neolithic in Southern Scandinavia (c. 3300-2300 BC) is characterised by the presence of archaeological remains associated with three different, partly coeval, material cultures. The Funnel Beaker Culture is the first farming culture in this region. It is followed in the archaeological record by the Battle Axe Culture (a regional version of the Corded Ware Culture), traditionally perceived as pastoralists. Chronologically partly overlapping with these two cultures is the Pitted Ware Culture (PWC), mainly found at coastal sites and perceived as marine hunter-gatherers. A primary focus for discussion in Scandinavian research on the Middle Neolithic concerns whether these differences in material culture can be attributed to different groups of people, or if the differences mainly reflect different activities of the same group (Lidén and Eriksson 2007 and references cited therein).
The overall importance of food and diet - not only for survival, but also for the construction of identity and culture - makes it crucial for archaeological understanding of cultural differences and change. In a previous study, we therefore used δ13C and δ15N data in order to reconstruct dietary patterns at several sites on Öland, chronologically including primarily the Neolithic and Early Bronze Age (Eriksson et al. 2008). In our study it became evident that in fact there were differences in diet between the Funnel Beaker Culture and the Pitted Ware Culture on Öland. The two major sites analysed were the passage grave in Resmo, and the Pitted Ware habitation and burial site in Köpingsvik (for more detailed information about the sites, see e.g. Papmehl-Dufay 2006; Eriksson et al. 2008). All analysed individuals were directly radiocarbon dated, revealing that the megalithic tomb in Resmo was in use during three phases. The first phase, c. 3500-2900 BC, can be attributed to the TRB presence on the island, and the diet during this period is characterised by a mixture of marine and terrestrial protein sources. During the following phase, c. 2900-1900 BC, the dietary components are still the same, but substantial inter- and intra-individual differences in the proportions of marine vs terrestrial protein are evident in the stable isotope data. The third phase, c. 1900-1000 BC, is characterised by a seemingly complete reliance on terrestrial (probably domesticated) resources (see further Eriksson et al. 2008). At the Köpingsvik site, located less than 50km from Resmo, the majority of the analysed individuals overlapped chronologically with Resmo Phases 1 and 2, c. 3300-2500 BC, displaying a diet dominated by marine mammal protein. At a third site, the Torsborg gallery grave complex, ranging in date from the Middle Neolithic to the Early Bronze Age, c. 2900-1400 BC, the dietary patterns correspond to their chronological equivalents at Resmo during Phases 2 and 3, respectively. Thus, while the Middle Neolithic Torsborg diet was characterised by various mixtures of terrestrial and marine resources with substantial intra-individual differences, the Late Neolithic/Early Bronze Age diet was homogeneous and solely dependent on terrestrial resources.
The notion of two separate Middle Neolithic groups of people in this region - rather than different endeavours by only one group - is further supported by DNA studies. The genetic analysis of human remains associated with the Funnel Beaker Culture on the Swedish mainland on the one hand, and with the Pitted Ware Culture on Gotland and Öland on the other, suggests that these two material cultures represent two different genetic populations (Linderholm 2008; Malmström et al. 2009; 2010; Skoglund et al.2012; 2014).
Following the cultural diversity of the Middle Neolithic and the more homogeneous Late Neolithic, we observe a boom in the archaeological record at the onset of the Bronze Age, including e.g. artefacts, settlement patterns and burial customs. These changes coincide chronologically with changes in δ13C and δ15N values observed on Öland. Our question is whether this can be explained in terms of increased contacts and interaction between different geographical regions and/or cultural groups. Here, we investigate the level of mobility and contacts during the Neolithic and Early Bronze Age by means of stable sulphur isotope analysis.
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