Genetic Variation and Population Structure in Native Americans

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians-signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.

Multi-grade teaching practices in Austrian and Finnish primary schools

This article describes the teaching strategies used in multi-grade classes in five small rural primary schools in Austria and Finland on the basis of the content analysis of transcribed teacher interviews. Two main types of strategies were identified: practices that (1) aim to reduce or (2) capitalize on students’ heterogeneity. The results illustrate how differently multi-grade teaching can be realized and how it can effectively support individual student learning. The findings are discussed with regard to teacher education with the intention of increasing the awareness of the professional skills required in high-quality teaching practices in multi-grade teaching.