Molecular traces of human arrival in Remote Oceania

The colonization of Remote Oceania ~3000 years ago is attributed to the Lapita people,a population originating from South East Asia. First human settlements on these islandsare associated with major landscape modifications. However, past hydroclimatic variations,which played a role in the colonization of remote islands, challenge a clear anthropogenicattribution of ecosystem changes. The archipelago of Vanuatu, with its extensive archeologicalremains of the Lapita culture, is considered a crucial location in the colonization of RemoteOceania. Here we present a sediment record retrieved near the Teouma archeological site,the earliest confirmed Lapita cemetery found in the Pacific Islands. We dated 43 macrofossilsfrom a 4 m long peat core spanning the last 5000 years. Fecal sterols associated withhuman presence become more abundant during the Lapita period as well as the later Eruetiphase. Palmitone downcore concentrations were quantified as a signature for taro, a staplecrop introduced by early settlers, and applied as a proxy for the establishment of agriculture.Elemental changes were measured with X-ray fluorescence core-scanning to track soilerosion and provenance. The hydrogen isotopic composition of plant waxes, namelylong-chain fatty acids, was measured as a proxy for hydroclimatic changes. A transitiontowards wetter climatic conditions corresponds to the initial human settlement indicated byarcheological remains and fecal sterols. Coupling human-related and climatic proxies on arecord spanning the last 5000 years allows us to reconstruct the pre-anthropogenic stateof the site, and add insights to the timing of human arrival and the consequent landscapemodifications.