Temporal variation in coat colour (genotypes) supports major changes in the Nordic cattle population after Iron Age.

Variation in coat colour genotypes of archaeological cattle samples from Finland was studied by sequencing 69 base pairs of the extension locus (melanocortin 1-receptor, MC1R) targeting both a transition and a deletion defining the three main alleles, such as dominant black (E(D) ), wild type (E(+) ) and recessive red (e). The 69-bp MC1R sequence was successfully analysed from 23 ancient (1000-1800 AD) samples. All three main alleles and genotype combinations were detected with allele frequencies of 0.26, 0.17 and 0.57 for E(D) , E(+) and e respectively. Recessive red and dominant black alleles were detected in both sexes. According to the best of our knowledge, this is the first ancient DNA study defining all three main MC1R alleles. Observed MC1R alleles are in agreement with calculated phenotype frequencies from historical sources. The division of ancient Finnish cattle population into modern Finnish breeds with settled colours was dated to the 20th century. From the existing genotyped populations in Europe (43 breeds, n = 2360), the closest match to ancient MC1R genotype frequencies was with the Norwegian native multicoloured breeds. In combined published genotype data of ancient (n = 147) and genotypes and phenotypes of modern Nordic cattle (n = 738), MC1R allele frequencies showed temporal changes similar to neutral mitochondrial DNA and Y-chromosomal haplotypes analysed earlier. All three markers indicate major change in genotypes in Nordic cattle from the Late Iron Age to the Medieval period followed by slower change through the historical periods until the present.