A New Perspective on the Arrival of the Eastern Mediterranean Genetic Influx in Central Italy Before the Onset of the Roman Empire

Abstract

Italian genetic history was profoundly shaped by the Romans. While the Iron Age Central Italian gene pool was comparable to that of other coeval Central/Western European regions, during the Imperial age, it was significantly influenced by Eastern Mediterranean ancestries. To explain this genetic shift, it has been proposed that people from eastern provinces of the Empire migrated toward its political center: Rome and its surroundings. In this study, by presenting a new Roman Republic individual (1.25×) and comparing it to other published Republican samples, we propose a novel perspective for the presence of the Eastern Mediterranean ancestry in the Imperial gene pool. We show that the spread of this genetic ancestry may have taken place earlier than previously thought, during the Late Republican period, therefore predating the onset of the Empire by ∼200 years. The diffusion of this ancestry occurred due to early East-to-West movements, either because Eastern Mediterranean regions were under Roman political influence since the Late Republican period or even as a result of internal movements from Southern Italy where several Greek and Phoenician settlements were established during the 1st millennium BCE.

Keywords: Central Italy; Eastern Mediterranean; Roman Republic; ancient DNA; archaeogenetics.

Fig. 1.

a) Geographic location of Villa Falgari, where the individual BSP71 was discovered. b) Timeline of the Roman Republic and the first years of the Empire. Two sigma-calibrated radiocarbon dating of the sample BSP71 from Villa Falgari and the time period of some of the main wars and annexations of the Republic are indicated below the timeline.

Fig. 2.

a) PCA plot with the newly reported individual and a subset of the used relevant ancient (colored) and modern (gray) samples from the literature (see Fig. S1 for the plot with all the samples included in the analysis). The main Italian IA and Imperial clusters are indicated, together with the IA individuals with Eastern Mediterranean ancestry. b) Unsupervised admixture analysis (K = 4), on the left, Italian IA and Imperial individuals are represented; on the right, populations representative of the main European genetic ancestries.

Fig. 3.

a) Comparisons of qpAdm results (Table S6) and the position of targets along the PC1 of the PCA (Fig. 2; Fig. S1). The four plots show different two-source qpAdm models where one of the sources is always Italy_IA_Republic.SG as a proxy of the typical IA/Republican gene pool, while the other is represented by different Eastern Mediterranean populations (shown on the y axes). When the sources Anatolia_Aegean_Aydin_BA.SG, Anatolia_Central_Gordion_IA.SG, and Lebanon_EjJaouze_Phoenician.SG are used, Italy_TarquiniaMonterozzi_IA_oLevant.SG and Italy_IA_VillaFalgari cannot be modeled and so they are not reported in the respective plots (Table S6). However, they can be modeled as deriving their ancestry entirely from these Eastern Mediterranean sources (see the one source qpAdm models in Table S7). b) Contribution of the four main sources that contributed to the peopling of Europe (Serbia Mesolithic, Anatolia Neolithic, Steppe Bronze Age, and Iran Neolithic) in Central Italian individuals from 900 BCE to 300 CE, modeled with qpAdm analysis. Component proportions are on the y axes and time on the x axes of the single plots. LOESS smooth lines indicate the trend of the component proportions over time (0.95 confidence interval represented by gray area). A sharp increase of the Iran Neolithic source can be observed starting from ∼200 BCE.