Ecogeographic connectivity shaped the earliest hominin presence and access route in the Iberian Peninsula

The Iberian Peninsula hosts key archaeological sites, in particular Orce and Atapuerca, that help us understand the earliest hominin settlement of the westernmost part of Eurasia and its ecological context. However, Early Pleistocene ecogeographical connectivity in the Iberian Peninsula has not been previously investigated. In this study, the likelihood that hominins transited a specific area during the Early Pleistocene is investigated via a novel algorithm based on a least-squares fitted plane. Our results show for the first time that, during the early and first half of the middle Pleistocene, the Iberian Peninsula was a region with high ecogeographic connectivity and evenly distributed core areas, and that it was likely to have been a highly habitable region, with no specific ecogeographic pattern of habitability (coastal vs. inland; North vs. South; etc.). It was also found that hominins occupied regions with temperate or Mediterranean climates, but not extreme subtypes, showing a high capacity to adapt to different habitats, although these always included warm and humid conditions. Furthermore, connectivity analyses and comparisons of faunal assemblages suggest that the most likely entry route to the Iberian Peninsula was from the north, whereas entering by crossing the Strait of Gibraltar was unlikely.