1. Two genetically distant groups of Slavic populations were revealed: One encompassing all Western-Slavic, Eastern-Slavic, and few Southern-Slavic populations (north-western Croats and Slovenes), and one encompassing all remaining Southern Slavs. According to the authors most Slavic populations have similar Y chromosome pools — R1a. They speculate that this similarity can be traced to an origin in the middle Dnieper basin of Ukraine during the Late Glacial Maximum 15 kya.
2. However, some southern Slavic populations such as Bulgarians, Serbs and Macedonians are clearly separated from the tight DNA cluster of the rest of the Slavic populations. According to the authors this phenomenon is explained by "…contribution to the Y chromosomes of peoples who settled in the Balkan region before the Slavic expansion to the genetic heritage of Southern Slavs…."