Local population structure in Cambridgeshire during the Roman occupation

Ancient DNA studies have shown that the Roman occupation of Britain (43-410 CE) was associated with significant changes in ancestry composition, particularly an increase in continental European ancestry. However, the demographic processes underlying these changes remain poorly understood. Here we present a detailed analysis of local population structure in Cambridgeshire during the Roman period using ancient DNA from 52 individuals from 6 sites spanning the 1st-5th centuries CE. We find evidence for substantial population heterogeneity within Roman Cambridgeshire, with some sites showing high levels of continental ancestry while others retain primarily Iron Age British ancestry profiles. Isotope analysis suggests that many high-continental-ancestry individuals were likely first-generation migrants. Our results indicate that Roman-era demographic change in Britain was geographically variable and involved ongoing migration rather than a single admixture event. These findings provide new insights into the complex demographic processes that shaped Roman Britain.