Environmental Drivers of Hominin Persistence in Middle Pleistocene Sundaland: Evidence from Java

Eduard Pop1,2*, Mega Hafsari2,3, Tom Veldkamp4, Putu Yuda Haribuana5, Jeroen van der Lubbe6, Benyamin Perwira Shidqi7, Jeroen Schoorl8, Sukiato Khurniawan9, Fred Spoor10,11, Dama Qoriy Arjanto12, Josephine Joordens1,2,13, Indra Sutisna14, Harold Berghuis2, Sander Hilgen1, Olafianto Drespriputra5, Pratiwi Yuwono15, Wout Krijgsman16, Nia Marniati E. Fajari5, Thijs Smink8, and Sofwan Noerwidi5

With its rich Homo erectus record, Java provides a key archive for understanding hominin adaptation in low-latitude Sundaland, yet the Middle Pleistocene remains poorly resolved. This interval, marked globally by intensified climatic variability and faunal turnover, lacks well-constrained palaeoanthropological and palaeoenvironmental records across the region. New data from the Sogen locality in the Solo Basin help bridge this gap. A ~57 m thick succession documents the transition from Early Pleistocene mostly laharic deposition to a Middle Pleistocene floodplain system characterised by carbonate-rich palaeosols, indicating seasonally dry conditions. Cyclic sedimentation and preliminary stable isotope data suggest potential sensitivity to glacial–interglacial climate forcing. Fossils with affinities to the Trinil HK fauna and associated lithic artefacts occur in close relation to palaeosol interfaces, while combined palaeomagnetic, pIRIR, and US/ESR dating constrain these phases of hominin presence to ~700–400 ka. The upper part of the sequence records a shift to wetter conditions, expressed in lacustrine deposition and the disappearance of pedogenic carbonates. This transition may reflect internal basin dynamics, but its timing also coincides with increased Sunda Shelf flooding, suggesting a broader environmental change affecting habitat structure and connectivity. These results, considered alongside nearby Early and Late Pleistocene records such as Sangiran and Ngandong, provide a framework for evaluating long-term ecosystem dynamics, faunal development, and hominin occupation across the Kendeng Zone within a broader Sundaland context. Sogen thus contributes a critical Middle Pleistocene reference point for understanding how climatic and landscape-scale processes structured evolutionary trajectories in Southeast Asia.