Population genomics, demography, and circum-Baltic connectivity of Early Medieval southwestern Finland.

Ancient inland southwestern Finland shows continuous population genetics over a millennium, while coastal areas experienced significant genetic shifts since the Early Medieval period.

• Why it matters: Understanding these demographic changes fills a critical gap in early Finnish history, especially given scarce contemporary sources and archaeological evidence.
• What they did: Genomic data from 34 ancient individuals and modern Finns were analyzed to reconstruct ancestry, demographic patterns, and circum-Baltic relatedness, revealing shifts in population structure and connectivity.
• The result: Findings demonstrate long-term population continuity inland and a major genetic shift in coastal populations linked to medieval emigration, expanding the understanding of regional demographic and cultural dynamics.