Genetic characterization of horses in Early Medieval Poland

Archaeozoological assemblages at various sites contained numerous subfossil horse remains with diverse social functions, proving that horses played a significant role in military and social life during the establishment of the Slavic Polish state during the Early Middle Ages. Although historical records emphasise the importance of this animal, information about its appearance remains limited. To investigate morphometric diversity in more depth, we combined ancient DNA analyses with macroscopic and biometric methods applied in archaeozoology to 152 horses. We performed target enrichment and high-throughput sequencing of ∼ 5,000 genomic SNPs, including coat colour, genetic disorder, functional trait-associated polymorphisms, and neutral SNPs. Our results indicated a strong sex bias, with approximately 80% of the specimens genetically identified as males. The dominant coat colour was chestnut, black rarely appeared, and we could not detect any white colour. Polish medieval horses were grouped with other ancient and modern domestic horses without significant differentiation between separate populations and regions.