Arabian hydroclimate and hominin population dynamics over the last ~500,000 years

Despite the discovery of an extensive Arabian archaeological record over the last decade, the environmental context of hominin dispersals remains poorly understood due to the absence of proximate and continuous palaeoenvironmental records across the Pleistocene. Here, we reconstruct a multi-proxy, high-resolution Arabian dust record from the western equatorial Indian Ocean spanning the last 500 thousand years (kyr) to investigate the role of orbital-scale hydrological variations in regulating Arabian hominin populations. Climate variability, as delineated by a dust index, reveals a clustering of archaeological phases around eccentricity maxima, simultaneous with protracted wetter periods in the Arabian Peninsula. This reinforces the view that hominin presence in Arabia was driven by enhanced monsoon precipitation during pluvial epochs, referred to here as Green Arabia periods (GAPs). These results, coupled with hunter-gatherer demographic data, point to dramatic hominin population expansions during GAPs. Hominin occupation was not linked exclusively to major GAPs, however. Brief phases with high-intensity rainfall, manifested by transient high dust contents and associated with enhanced physical erosion and increased availability of wind-erodible particles, also favoured hominin expansions within some glacial periods.