Long-term archaeological perspectives on new genomic and environmental evidence from early medieval Ireland

摘要

Using archaeological data, this paper investigates past population trends in Ireland as a response to recent genomic studies that have identified admixture signals in the genomes of Irish people caused by historically-recorded migration events. Among these was Norse settlement in the 9th -10th Centuries CE, which has a greater than expected signal in the contemporary population of the island. Here, we contextualise these discoveries using a large database of recently discovered archaeological sites with radiocarbon dates that we have analysed using Kernel Density Estimation techniques. We argue that the Viking migrations occurred following a 300-year period of population decrease in Ireland. This new, data-driven synthesis of the archaeological record contrasts with previous accounts of early medieval Ireland as a period of ever-growing expansion and progression. However, this new interpretation is also aligned to evidence for economic and environmental change, including recent discoveries concerning the soil nitrogen cycle and agricultural intensification. We compare historical evidence for Viking migrations to later episodes of migration between Britain and Ireland, where more details are known about the size of the incoming groups, ultimately wishing to confront the opinion that past population sizes cannot be fathomed for cultures without documentary records. Through comparison with historic analyses and census records, we make broad estimates of absolute population size in Ireland since prehistoric times, including during these demographic events, and argue that much value is added to genomic evidence for migration when these points in time are contextualised in terms of evolving population trends.