Beyond Isolation: Mitochondrial Variability and Micro-Regional Discontinuity at El Rebollar (Madrid, 7th Century CE)

Recent advances in archeogenetics offer vital biological data to complement traditional anthropological approaches. This study presents a global archeobiological and arcaheogenetics study, focused on the mitochondrial DNA (mtDNA) analysis of five individuals from the 7th-century CE church and subsequent medieval phases at El Rebollar (El Boalo, Madrid) to reconstruct population dynamics and maternal lineages. Hypervariable regions I and II were analyzed from three high-status sarcophagi adults and two subsequent perinatals. Results reveal a highly diverse population mosaic: adults harbored distinct lineages, including European haplogroups H2a2 and T1a, alongside a remarkable trans-Mediterranean signal (haplogroup L3h2) linked to the Horn of Africa. Conversely, both perinatals shared the autochthonous Iberian haplogroup HV0, confirming long-term demographic resilience of the local substrate. Pop-wide comparative analyses (AMOVA and FST distances) show significant micro-regional genetic discontinuity, isolating El Boalo from immediate peninsular neighbors while aligning it with cosmopolitan mixed sites (Pla de l’Horta, Girona) and Central Europe, but discarding direct Eastern European (Viminacium) Gothic flows. We conclude that El Rebollar’s profile reflects the accumulation and fixation of ancestral gene flows during the 5th and 6th centuries CE, challenging traditional paradigms of Late Antique rural isolation in central Iberia.