Environmental conditions during the early Pleistocene peopling of Sunda; Geological Society of America, 2007 annual meeting

A sequence of estuarine, lacustrine and fluvial deposits with intercalated paleosols in Central Java, Indonesia provides information on the local and regional environments occupied by Homo erectus as this species entered Southeast Asia during the early Pleistocene. The first human immigrants to the southern part of the Sunda subcontinent encountered a low relief estuary margin dominated by moist grasslands with savanna in the driest landscape positions. By 1.5 Ma large bedload stream systems filled the estuary as savanna and open woodland expanded across the lowland. The morphology of paleosols and delta (super 13) C values of soil organic matter and soil carbonates suggest a long-term change toward regional drying, or increased duration of the annual dry season through the early Pleistocene. We propose that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread out of Africa to Southeast Asia.