The driving force behind the transition from a foraging to a farming lifestyle in prehistoric Europe (Neolithization) has been debated for more than a century [1-3]. Of particular interest is whether population replacement or cultural exchange was responsible [3-5]. Scandinavia holds a unique place in this debate, for it maintained one of the last major hunter-gatherer complexes in Neolithic Europe, the Pitted Ware culture [6]. Intriguingly, these late hunter-gatherers existed in parallel to early farmers for more than a millennium before they vanished some 4,000 years ago [7, 8]. The prolonged coexistence of the two cultures in Scandinavia has been cited as an argument against population replacement between the Mesolithic and the present [7, 8]. Through analysis of DNA extracted from ancient Scandinavian human remains, we show that people of the Pitted Ware culture were not the direct ancestors of modern Scandinavians (including the Saami people of northern Scandinavia) but are more closely related to contemporary populations of the eastern Baltic region. Our findings support hypotheses arising from archaeological analyses that propose a Neolithic or post-Neolithic population replacement in Scandinavia [7]. Furthermore, our data are consistent with the view that the eastern Baltic represents a genetic refugia for some of the European hunter-gatherer populations.

The skeletal remains from the Middle Neolithic (2750-2300 BC) burial ground at Ajvide, Gotland, are analyzed in order to explore musculoskeletal patterns and to attempt to trace general as well as three specific prehistoric activities (archery, harpooning, and kayaking) that are likely to have been performed in this marine setting of fishing, hunting, and gathering. Scoring of muscular and ligament attachments is performed using the scoring method of Hawkey and Merbs ([1995] Int. J. Osteoarchaeol. 5:324-338) for muskuloskeletal stress markers (MSM). The skeletal material consists of 24 male and 15 female adult individuals divided into three age groups: young (<24 years), middle (25-39 years), and old (>40 years). Thirty upper body MSM sites, on both the left and right sides, are scored and form the basis of the study. Results show that males most frequently have higher mean MSM scores than females. Bilateral asymmetry was noted as low in both sexes. Age proved to be a contributing factor to increased MSM scores, with a greater age-related increase in females. MSM patterns were analyzed statistically in muscle groups associated with the three investigated activities. Significant positive correlations were observed in male individuals in muscle groups associated with archery and to some extent harpooning, an indication that these activities would mainly have been performed by men. Correlations in kayaking muscles were not evidently consistent with the kayaking motion. Furthermore, the costoclavicular ligament, often referred to in connection with "kayaker's clavicle," showed no positive statistical correlation with the kayaking muscles.

The occurrence of osteoarthritis (OA) as an indicator of physical activity was explored in two Middle Neolithic samples from Gotland (c. 3400-2300 BC) in the Baltic Sea: Ajvide (n ¼ 46) and Vä sterbjers (n ¼ 32). The difficulty in diagnosing OA is recognised and only eburnation was used as a definite criterion for OA. The relationship between eburnation lesions and Musculoskeletal Stress Markers (MSM) was investigated particularly in relation to age, but also with reference to patterns of sex, body side and site. Results show that increasing prevalence of eburnation as well as increased MSM scores was highly correlated with age. In the combined sample, females exhibited higher frequencies of eburnation, while total MSM mean scores were higher in males. Significantly higher MSM mean scores were also found in those individuals with eburnation lesions. Vä sterbjers exhibited higher frequencies of eburnation as well as higher mean MSM scores, which in part may be explained by the difference in age distribution at the two sites. However, the differences in both eburnation and MSM patterns between the sexes, and between age groups as well as between the two sites indicate that other factors also have to be considered. These may include genetic predisposition and possibly activity, although, a direct link (other than age) between eburnation and MSM was difficult to discern.

Atypical wear and oral lesions were studied in the dental remains from the Middle Neolithic Pitted Ware Culture site Ajvide on the island of Gotland in the Baltic Sea. Teeth (n = 764) from 17 males and 11 females were examined microscopically to document unusual wear, assess wear patterns and oral lesions as evidence of habitual behavior, and determine their effect on the oral health of this population. Five atypical wear types were observed: occlusal facets, occlusal excessive load, labial vertical striae, labial horizontal striae, and interproximal striae. Three oral lesions were recorded: chipping, periapical lesions, and dental tilting. Results indicate that teeth were used in a habitual manner at Ajvide, based on the morphology and regularity of the patterns of atypical wear. Differences were observed between the sexes, indicating gender-related differences in the habitual use of teeth. Some wear categories showed a significant correlation with age, signifying increased or accumulated wear with age. Statistically significant positive correlations were found in the molars between occlusal excessive load wear and periapical lesions as well as tilting. Other apparent links were also observed between chipping and vertical striae as well as excessive load, although these were not significant. This suggests a relationship between dental wear and dental pathologies at this site, suggesting that habitual use of teeth indirectly affected the general oral health at the site. Wear patterns, furthermore, seem to mirror both frequent activities as well as single events.