A geostatistical approach to modelling human Holocene migrations in Europe using ancient DNA

The European continent was subject to two major migrations of peoples during the Holocene: the northwestward movement of Anatolian farmer populations during the Neolithic and the westward movement of Yamnaya steppe peoples during the Bronze Age. These movements changed the genetic composition of the continents inhabitants, via admixture and population replacement processes. The Holocene was also characterized by major changes in vegetation composition, which altered the environment occupied by the original hunter-gatherer populations. Here, we use a combination of paleogenomics and geostatistical modelling to produce detailed maps of the movement of these populations over time and space, and to understand how these movements impacted the European vegetation landscape. We find that the dilution of hunter-gatherer ancestries and the Yamnaya steppe migration coincided with a reduction in the amount of broad-leaf forest and an increase in the amount of pasture lands in the continent. We also show that climate played a role in these vegetational changes. Additionally, we find that the spread of Neolithic farmer ancestry had a two-pronged wavefront, in agreement with similar findings based on patterns of the cultural spread of farming from radiocarbon-dated archaeological sites. With thousands of ancient genomes publicly available and in production, we foresee that the integration of ancient DNA with geostatistical techniques and large-scale archaeological datasets will revolutionize the study of ancient populations movements, and their effects on local fauna and flora.