Speleothems fill gaps in the Paleolithic of Armenia

The Armenian highlands have been a critical crossroads for hominin migration and settlement since the Early Pleistocene. However, significant gaps of unknown origin exist in the archaeological record, particularly during the MiddleUpper Paleolithic transition (~4537 ka) and the Last Glacial Maximum (2319 ka). Compounded by the lack of a high-resolution paleoclimatic framework, these gaps hinder our understanding of Neanderthal replacement by Anatomically Modern Humans and the role of climatic and environmental changes in shaping hominin population dynamics within Armenias high-relief microclimates, which may have served as local refugia. To date, the potential overlap between Neanderthals and AMH remains unresolved, as does the impact of Heinrich events and other anomalies on hominin habitability. The study proposes to use speleothems in caves as a novel archive to reconstruct paleoclimate and test hypotheses about hominin population dynamics. Reconnaissance dating of in situ speleothems will be employed to identify growth periods, paired with environmental monitoring of cave temperature, humidity, and drip rates to assess microclimatic stability. Conventional geochemical proxies, such as trace elements and stable isotopes of carbon (d13C) and oxygen (d18O) will be measured in stalagmites covering key intervals to reconstruct centennial-scale paleoclimate histories. Ancient DNA (aDNA) in speleothem calcite will then be extracted and sequenced to identify the ecological composition within and above the cave site. This approach will specifically target hominin and associated taxa, such as food and medicinal plants. Active calcite samples will be used as controls to assess preservation and contamination potential. The primary goal is to fill gaps in the Paleolithic record of Armenia by producing high-resolution paleoclimate reconstructions and testing whether climatic pressures drove cultural hiatuses in the archeological record. The study aims to determine whether cultural gaps are due to preservation bias or environmental factors, test for evidence of Neanderthal overlap with modern humans or population decline during cold Heinrich events, and to establish Armenias role as a glacial refugium for hominins and megafauna. Additionally, the project seeks to advance the use of speleothems as paleoenvironmental archives, including the development of aDNA recovery techniques. This interdisciplinary project combines paleoclimatology, archaeology, and genetics to address longstanding questions about human evolution and adaptation in the Armenian highlands. We therefore expect that even negative results may contribute to refining methodologies and expanding the potential of speleothem-based research.