Formation processes, fire use, and patterns of human occupation across the Middle Palaeolithic (MIS 5a-5b) of Gruta da Oliveira (Almonda karst system, Torres Novas, Portugal).

Summary

# Editorial Summary: Fire Use and Occupation Patterns in Middle Palaeolithic Portugal Gruta da Oliveira preserves a 6.5-metre-thick archaeological deposit spanning approximately 71,000–93,000 years ago (Marine Isotope Stages 5a and 5b), offering exceptional stratigraphic resolution for understanding Neanderthal site use and behaviour during the Middle Palaeolithic. Sedimentological analysis reveals that cave infilling resulted primarily from slope wash and gravitational processes, with climatic fluctuations driving alternating pulses of stadial accumulation (marked by open-country fauna including rhino, horse and ibex) and interstadial hiatuses featuring carbonate formation—allowing the researchers to reconstruct environmental conditions and human occupation intensity across multiple millennia. Human occupation was consistently intermittent, creating opportunities for carnivore activity between visits; notably, the predator guild shifted from wolf and lion dominance (85,000–93,000 years ago) to brown bear and lynx prevalence (71,000–78,000 years ago). Peak residential use occurred during layers 20–22 (c. 90,000–92,000 years ago) and layer 14 (c. 76,000–78,000 years ago), both yielding dense, hearth-focused concentrations of stone tools and burnt bone, providing robust evidence that Middle Palaeolithic Neandertals employed fire systematically and routinely rather than opportunistically. These occupation and fire-use patterns mirror those documented 50,000 years later in Upper Palaeolithic and Solutrean cave sites, suggesting behavioural continuity across this critical temporal transition and reinforcing the necessity of moving beyond simplistic narratives of cultural rupture in the archaeological record.

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