Widespread evidence of Middle Stone Age (MSA) presence in Equatorial Guinea (West-Central Atlantic Africa)

Understanding the evolutionary history of humans in the rainforest ecosystems of West Central Africa remains a challenge, despite the region's significance for understanding both the biological and cultural history of Homo sapiens. The relative scarcity of archaeological and chronological references in African rainforests further complicates their integration into a broader evolutionary framework. Since 2014, 11 archaeo-paleontological campaigns have been conducted in Equatorial Guinea to uncover evidence of early human settlements in West Central Africa. These surveys identified 449 Quaternary outcrops, 50 of which yielded Paleolithic stone tools. Technological analysis reveals recurring patterns in Equatorial Guinea, particularly the widespread use of centripetal flaking techniques, either bifacial or unifacial, for flake production. Other methods include blade production and bipolar-on-anvil flaking. Retouched tools are characterized by large cutting and heavy-duty tools, such as handaxes, cleavers, and wedges, alongside bifacial points. Retouched flakes, including scrapers and denticulates, are rare, but some backed elements were identified despite their scarcity. A clear distinction emerges between coastal and inland sites. Coastal sites show greater raw material diversity and Acheulean-like morphotypes, absent in inland regions. The origins of these differences remain uncertain but may reflect geological, functional, ecological, or population history factors. The assemblages share features with the Middle Stone Age (MSA), including bifacial points, prepared core technologies, and laminar knapping. Acheulean morphotypes and heavy-duty tools, typical of the final phases of Mode 2, coexist with MSA characteristics, aligning the industries with the Lupemban technocomplex. This technocomplex appears to aggregate Mode 2 morphotypes, such as handaxes and cleavers, and Mode 3 flake production techniques and morphotypes, potentially indicating a degree of cultural continuity over at least 250 ka. However, preliminary dating places these industries within the Upper Pleistocene, with geological evidence suggesting poor preservation of sedimentary records predating the last glacial cycle.