Climate-inferred distribution estimates of mid-to-late Pliocene hominins

International audience ; During the mid-to-late Pliocene (ca. 4–3 Ma), several hominin species were present in central Sahel, eastern andsouthern Africa. The potential for the discovery of hominin remains from this interval is limited by the availabilityof exposed Pliocene deposits and the ability to investigate them. As a result, most discoveries have beenmade in the Afar region of Ethiopia and in the Lake Turkana basin, thus unveiling only a portion of Pliocenehominins' probable geographical presence. In this study we provide a continental view of geographic areaspotentially accessible to these hominins. To do so, we estimate the climatic envelope suitable for mid-to-latePliocene hominin presence, using the earth system model IPSL-CM5A and the Maxent habitat suitability algorithm.Our analysis reveals high habitat suitability for these hominin species in semi-arid regions where annualthermal amplitude and mean annual precipitation are moderate, mostly corresponding to tropical xerophyticshrublands. Our habitat model estimates geographically continuous, suitable climatic conditions for homininsbetween central Sahel and northeastern Africa, but not between eastern and southern Africa. This discontinuitysuggests that southern African and eastern African hominins were separated by an environmental barrier thatcould only be crossed during particularly favourable periods or by undertaking long-range dispersal overclimatically hostile habitats. Under climate conditions of northern hemisphere summer at perihelion this climaticbarrier is not present. In contrast, the Turkana basin, the Laetoli region, and a large part of southern Africaremain suitable for all precession angles, suggesting that these areas may have functioned as refugia. The constantpresence of these stable areas combined with the periodic establishment of corridors for dispersion canpotentially explain hominin diversity in eastern Africa.