Romano-British Cambridgeshire human genomes

The Roman Imperial period saw the empire expand to new distances across Europe, including what is today the United Kingdom. While there is written evidence of high mobility into and out of Britain for the ruling and soldier classes, the impact of colonisation on local population structure is invisible in the historical record. The extent of genetic change that occurred in Britain before the Migration Period and how closely linked by genetic kinship the local populations were, remains underexplored. Here, using genome-wide data from 96 ancient individuals from Cambridgeshire, we show low levels of genetic ancestry differentiation between Romano-British sites and lower levels of runs of homozygosity over 4cM than in the Bronze Age and Neolithic. We find 14 cases of genetic relatedness within and one between sites without evidence of patrilineal dominance and one case of temporary mobility within a family unit during the Late Romano-British period. We also show that the modern patterns of genetic ancestry composition in Modern Britain emerged after the Roman period.