The fast-acting "pulse" of Heinrich Stadial 3 in a mid-latitude boreal ecosystem

High-resolution ecosystem changes pacing the millennial climate variability at the Middle to Upper Palaeolithic transition in NE-Italy

Observation of high-resolution terrestrial palaeoecological series can decipher relationships between past climatic transitions, their effects on ecosystems and wildfire cyclicity. Here we present a new radiocarbon dated record from Lake Fimon (NE-Italy) covering the 60-27 ka interval. Palynological, charcoal fragments and sediment lithology analysis were carried out at centennial to sub-centennial resolutions. Identification of the best modern analogues for MIS 3 ecosystems further enabled to thoroughly reconstruct structural changes in the vegetation through time. This series also represents an "off-site" reference record for chronologically well-constrained Palaeolithic sites documenting Neanderthal and Homo sapiens occupations within the same region. Neanderthals lived in a mosaic of grasslands and woodlands, composed of a mixture of boreal and broad-leaved temperate trees analogous to those of the modern Central-Eastern Europe, the Southern Urals and central-southern Siberia. Dry and other grassland types expanded steadily from 44 to 43 ka and peaked between 42 and 39 ka, i.e., about the same time when Sapiens reached this region. This vegetation, which finds very few reliable modern analogues in the adopted Eurasian calibration set, led to the expansion of ecosystems able to sustain large herds of herbivores. During 39-27 ka, the landscape was covered by steppe, desert-steppe and open dry boreal forests similar to those of the modern Altai-Sayan region. Both Neanderthal and Sapiens lived in contexts of expanded fire-prone ecosystems modulated by the high-frequency climatic cycles of MIS 3.

Early Alpine occupation backdates westward human migration in Late Glacial Europe

Before the end of the Last Glacial Maximum (LGM, ∼16.5 ka ago)¹ set in motion major shifts in human culture and population structure,² a consistent change in lithic technology, material culture, settlement pattern, and adaptive strategies is recorded in Southern Europe at ∼18-17 ka ago. In this time frame, the landscape of Northeastern Italy changed considerably, and the retreat of glaciers allowed hunter-gatherers to gradually recolonize the Alps.^3-6 Change within this renewed cultural frame (i.e., during the Late Epigravettian phase) is currently associated with migrations favored by warmer climate linked to the Bølling-Allerød onset (14.7 ka ago),^7-11 which replaced earlier genetic lineages with ancestry found in an individual who lived ∼14 ka ago at Riparo Villabruna, Italy, and shared among different contexts (Villabruna Cluster).⁹ Nevertheless, these dynamics and their chronology are still far from being disentangled due to fragmentary evidence for long-distance interactions across Europe.¹² Here, we generate new genomic data from a human mandible uncovered at Riparo Tagliente (Veneto, Italy), which we directly dated to 16,980-16,510 cal BP (2σ). This individual, affected by focal osseous dysplasia, is genetically affine to the Villabruna Cluster. Our results therefore backdate by at least 3 ka the diffusion in Southern Europe of a genetic component linked to Balkan/Anatolian refugia, previously believed to have spread during the later Bølling/Allerød event. In light of the new genetic evidence, this population replacement chronologically coincides with the very emergence of major cultural transitions in Southern and Western Europe.