Isolation and female migration between Neolithic farmers and foragers on the Island of Gotland
Two genetically distinct archaeological groups, Neolithic farmers (4000 - 2600 BCE) and foragers (3300 – 2300 BCE) coexisted on the Island of Gotland for >500 years. Their interaction has long been debated, with some scholars suggesting that it was the same population practicing different ways of life. We generated and analyzed genome-sequence data of six individuals from the megalithic Ansarve burial (3500-2600 BCE) and investigated ancestry, admixture, and disease among both farmers and foragers on Gotland. The Ansarve individuals were genetically related to other European Neolithic farmer groups, demonstrating a different demographic history from the foragers on the island. They were also more closely related to each other, showing isolation on the island. The Ansarve genomes show some admixture with foragers, but this admixture happened mainly prior to their coexistence on Gotland. Interestingly, some of the forager's genomes display recent gene-flow from female farmers, suggesting exogamy of farmer females into the forager communities on the island.