Lithic Insights from Yuku Rockshelter: 17,000 Years of Cultural and Environmental Change in the New Guinea Highlands

Thomas Prince1*, Anne Ford2, Glenn Summerhayes2, and Dylan Gaffney1

1University of Oxford, United Kingdom; 2University of Otago, New Zealand; *tp518@cantab.ac.uk

The New Guinea Highlands were among the most challenging environments colonised by Homo sapiens in the Late Pleistocene. Climate change and increasing human modification of the landscape reshaped these montane rainforests across the Pleistocene-Holocene transition, yet long-term behavioural responses to these shifts remain poorly understood. Yuku rockshelter, excavated by Sue Bulmer in 1959, preserves a sequence spanning the Last Glacial Maximum to the present and provides a rare opportunity to examine technological organisation in an understudied region of the Western Highlands. Here, we present the results of an attribute analysis of the Yuku stone tool assemblage, investigating how changes in site use, subsistence, and mobility are reflected in lithic technology. The results demonstrate an enduring reliance on expediently flaked locally sourced river cobbles supplemented by a broader dynamic toolkit including slate implements, grindstones, and waisted axes. Some aspects of technological organisation changed over time in response to a changing landscape, yet others persisted. The assemblage therefore demonstrates selective technological change within a stable expedient framework, suggesting that highland populations adapted to environmental and subsistence shifts without restructuring their core technological system.