Radiocarbon chronology and environmental context of Last Glacial Maximum human occupation in Switzerland

Central Europe during the Last Glacial Maximum (LGM) was dominated by polar desert and steppe-tundra biomes. Despite this, a human presence during this time period is evident at several locations across the region, including in Switzerland, less than 50 km from the Alpine ice sheet margin. It has been hypothesised that such human activity may have been restricted to brief periods of climatic warming within the LGM, but chronological information from many of these sites are currently too poorly resolved to corroborate this. Here we present a revised chronology of LGM human occupation in Switzerland. AMS radiocarbon dating of cut-marked reindeer (Rangifer tarandus) bones from the sites of Kastelhöhle-Nord and Y-Höhle indicates human occupation of Switzerland was most likely restricted to between 23,400 and 22,800 cal. BP. This timeframe corresponds to Greenland Interstadial 2, a brief warming phase, supporting the hypothesis that human presence was facilitated by favourable climatic episodes. Carbon, nitrogen and sulphur stable isotope analysis of the fauna provides palaeoenvironmental information for this time period. These findings contribute to our understanding of human activity in ice-marginal environments and have implications for understanding cultural connections across central Europe during the LGM

Deglacial landscapes and the Late Upper Palaeolithic of Switzerland

The presence of people in Switzerland in recently deglaciated landscapes after the Last Glacial Maximum represents human utilisation of newly available environments. Understanding these landscapes and the resources available to the people who exploited them is key to understanding not only Late Upper Palaeolithic settlement in Switzerland, but more broadly human behavioural ecology in newly inhabited environmental settings. By applying bone collagen stable isotope analysis (δ13C, δ15N and δ34S) to faunal remains from Late Upper Palaeolithic localities in Switzerland, we investigate animal ecology and environmental conditions during periods of human occupation. High and relatively uniform δ34S values indicate that landscapes north of the Jura Mountains provided comparatively stable environmental conditions, while lower and more variable δ34S values on the Swiss Plateau suggest a dynamic landscape with diverse hydrological and pedological conditions, potentially linked to regionally different patterns of permafrost thaw. This contrasts with the archaeological record that appears relatively uniform between the two regions, suggesting people were employing similar subsistence behaviours across a range of environmental settings. The pattern of change in δ15N across the deglacial period appears consistent between areas that remained ice-free throughout the LGM and those that were glaciated. Most notable is a period of exclusively low δ15N values between 15,200 and 14,800 cal. BP, which could relate a regional expansion of floral biomass in response to environmental change