Environnements glaciaires des sociétés du Paléolithique moyen à supérieur en Méditerranée sud-occidentale depuis 200 000 ans.

Homo neanderthalensis was present in Western Europe since at least 200,000 years before present (ka BP), across two glacial–interglacial cycles and until its extinction around 40 ka BP, which coincided with the expansion of the first Homo sapiens populations on the continent. The main hypotheses proposed to explain Neanderthal decline involve a direct or indirect responsibility of Sapiens, as well as abrupt climatic changes that occurred during the last glacial period, within Marine Isotope Stage (MIS) 3. Climate in Europe during this time experienced a succession of warm (interstadial) and cold (stadial) phases at a sub-millennial scale (Dansgaard–Oeschger cycles), as well as several extremely cold and arid events linked to massive iceberg discharges in the North Atlantic (Heinrich stadials, HS). While HS4 (~39.9–38.2 ka BP), contemporaneous with the last Neanderthal occupations, is well known thanks to several marine archives retrieved off the Iberian margin, earlier analogous events are less well documented, hindering our ability to understand long-term Neanderthal population dynamics in the face of persistent environmental instability. This thesis therefore aims at reconstructing rapid environmental changes during the last 200,000 years (MIS 7–1) in order to explore their potential impact on Neanderthal populations up to their extinction. The palynological study of the marine sediment core ODP 976 in the Alboran Sea (southwestern Mediterranean) revealed the history of vegetation in a key region often described as a climatic refugia for human populations during the Pleistocene. A quantitative approach based on pollen assemblages was used to reconstruct the changes in annual and seasonal climatic parameters (temperature and precipitation) over the last 200 ka BP using multiple methods (MAT, WA-PLS, RF, BRT). Finally, a synthesis of archaeological sites associated with Neanderthals in Western Mediterranean Europe enabled an assessment of the spatial and temporal dynamics of Neanderthal populations through time. The results show that the southwestern Mediterranean region was highly sensitive to North Atlantic cold events over the past 200,000 years, exhibiting particularly arid conditions and a predominance of steppe and semi-desert vegetation during HS events. The penultimate glacial period (MIS 6, ~190–129 ka BP) was characterized by cold and dry climate and subdued climatic oscillations compared to MIS 4-3 (~70-30 ka BP). HS11, occurring during Glacial Termination 2, stands out for its duration (~6000 years), its intensity, and its complex structure, at a key moment when Lower Palaeolithic lithic industries were definitively abandoned. Several abrupt cooling events were recorded during the last interglacial period (MIS 5, 129–71 ka BP), though they were less intense than those of MIS 4–3. The most extreme events experienced by Neanderthals in the region correspond to HS11 (~132 ka BP), HS6 (~61 ka BP), HS5 (~48 ka BP), and HS4 (~39 ka BP). Finally, the increasing climatic instability marking the progressive glaciation inception may have influenced the diversification of Neanderthal behaviours during MIS 4 and 3, and may have favoured repeated population contractions into glacial refugia. Despite limited chronological data, the synthesis supports a potential vulnerability of Neanderthal populations to HS6, HS5, and HS4, which may have played a role in their extinction. This study contributes to establishing a high-resolution paleoenvironmental reference sequence describing environmental variability in the Western Mediterranean.