Long-term ecological stability in the Pleistocene central Levantine corridor revealed by enamel isotopes from Lebanon

Throughout the Pleistocene, the Levant served as a key land bridge between continents and witnessed repeated hominin dispersals, including the major expansion of modern humans out of Africa. Yet despite this strategic role, the local ecological conditions encountered by hominin populations along the central Levant remain poorly understood. Here, we analyze sequential and bulk δ¹³C and δ¹⁸O enamel values from eight herbivore species across three Lebanese archaeological sites, Naame, Nahr Ibrahim, and Ras el-Kelb, spanning ~400,000 to ~100,000 years ago, to reconstruct vegetation structure, hydrology, and seasonal temperature regimes experienced by the hominins who lived in this region. Our results show that the central Levant maintained persistently regular Mediterranean seasonality, with consistent summer-winter offsets and minimal chronological change in amplitude across multiple glacial-interglacial cycles, despite pronounced regional and global climatic oscillations. This reliable hydroclimate supported C3-dominated woodlands and mesic, heterogeneous habitats that maintained reliable resources for herbivore communities over nearly 300,000 years. Together, these findings identify the Lebanese coast as a persistent ecological refugium offering resource predictability that likely facilitated repeated hominin occupations and dispersal events through the eastern Mediterranean.