Sedimentary biomarkers of human presence and taro cultivation reveal early horticulture in Remote Oceania

Abstract

Remote Oceania was among the last places settled by humans. However, the timing of initial human settlements and the early introduction of horticulture remain debated. We retrieved a sediment core close to Teouma, the oldest cemetery in Remote Oceania that reveals evidence of initial settlement, horticulture practice, and concurrent climatic conditions on the island of Efate, Vanuatu. Sedimentary biomarkers indicating human presence (coprostanol and epicoprostanol), and taro cultivation (palmitone), increase simultaneously, attesting to the early introduction of horticulture by first settlers. The precipitation signal preserved in leaf waxes shows that the initial settlement occurred during a period of increasing wetness—climatic conditions favourable for the establishment of horticulture. The timing of these events is constrained by a high-resolution radiocarbon chronology that places the first unequivocal trace of human activity and horticulture at 2800 years ago. These findings advance our understanding of human history in the Pacific.