Who are Europeans? Both prehistoric archaeology and, subsequently, classical population genetics have attempted to trace the ancestry of modern Europeans back to the first appearance of agriculture in the continent; however, the question has remained controversial. Classical population geneticists attributed the major pattern in the European gene pool to the demographic impact of Neolithic farmers dispersing from the Near East, but archaeological research has failed to uncover substantial evidence for the population growth that is supposed to have driven this process. Recently, molecular approaches, using non-recombining genetic marker systems, have introduced a chronological dimension by both allowing the tracing of lineages back through time and dating using the molecular clock. Both mitochondrial DNA and Y-chromosome analyses have indicated a contribution of Neolithic Near Eastern lineages to the gene pool of modern Europeans of around a quarter or less. This suggests that dispersals bringing the Neolithic to Europe may have been demographically minor and that contact and assimilation had an important role.