The second half of the first millennium ce in Central and Eastern Europe was accompanied by fundamental cultural and political transformations. This period of change is commonly associated with the appearance of the Slavs, which is supported by textual evidence^1,2 and coincides with the emergence of similar archaeological horizons^3–6. However, so far there has been no consensus on whether this archaeological horizon spread by migration, Slavicisation or a combination of both. Genetic data remain sparse, especially owing to the widespread practice of cremation in the early phase of the Slavic settlement. Here we present genome-wide data from 555 ancient individuals, including 359 samples from Slavic contexts from as early as the seventh century ce. Our data demonstrate large-scale population movement from Eastern Europe during the sixth to eighth centuries, replacing more than 80% of the local gene pool in Eastern Germany, Poland and Croatia. Yet, we also show substantial regional heterogeneity as well as a lack of sex-biased admixture, indicating varying degrees of cultural assimilation of the autochthonous populations. Comparing archaeological and genetic evidence, we find that the change in ancestry in Eastern Germany coincided with a change in social organization, characterized by an intensification of inter- and intra-site genetic relatedness and patrilocality. On the European scale, it appears plausible that the changes in material culture and language between the sixth and eighth centuries were connected to these large-scale population movements.

The purpose of the present study was an assessment of differences between boys and girls in the process of emergence of primary teeth. This paper also provides updated data on the timing and sequence of primary tooth emergence in Polish children. The research were conducted in the years 2004–2008, and covered 865 children (437 boys and 428 girls) aged 3 to 36 months from all nursery and randomly selected “Healthy Child Clinics” in Lodz (central Poland). The first and last primary tooth emerged, on average: in boys at 6.24 months and 24.75 months respectively; in girls at 7.07 months and 24.21 months respectively. All incisors and the first upper molars erupted significantly earlier in boys. Typical order of teeth emergence – central incisor, lateral incisor, first molar, canine, second molar – was observed in 86.36 % of boys and in 89.47 % of girls. The interdependence between the morphological and the dental criterion of biological maturity during the completion of primary teeth was very strong in both sexes (stronger in boys). The regression equations for the estimation of the number of erupted primary teeth based on child's chronological age, body height and body mass were proposed separately for boys and for girls.