In a genetic study published in "Proceedings of the Royal Society B" in January 2015, the mtDNA of thirteen PCW individuals from Öland and Gotland was extracted. The four individuals from Öland carried H1f, T2b, K1a1 and U4a1. Of the ten individuals from Gotland, four carried U4, two carried U5 haplotypes, two carried K1a1, and one carried HV0. The results indicated that the Pitted Ware culture was genetically distinct from the Funnelbeaker culture, and closely genetically related to earlier Mesolithic hunter-gatherers of Scandinavia and Western Europe. It was found that the Pitted Ware culture left a genetic imprint on Scandinavians, although this number is certainly not more than 60%.