Nikolay Sirakov’s research while affiliated with Bulgarian Academy of Sciences and other places

The dispersal of Homo sapiens across Eurasia during MIS 3 in the Late Pleistocene is marked by technological shifts and other behavioral changes, known in the archaeological record under the term of Initial Upper Paleolithic (IUP). Bacho Kiro Cave in north Bulgaria, re-excavated by us from 2015 to 2021, is one of the reference sites for this phenomenon. The newly excavated lithic assemblages dated by radiocarbon between 45,040 and 43,280 cal BP and attributed to Homo sapiens encompass more than two thousand lithic artifacts. The lithics, primarily from Layer N1-I, exist amid diverse fauna remains, human fossils, pierced animal teeth pendants, and sediment with high organic content. This article focuses on the technological aspects of the IUP lithics, covering raw material origin and use-life, blank production, on-site knapping activities, re-flaking of lithic implements, and the state of retouched lithic components. We apply petrography for the identification of silicites and other used stones. We employ chaîne opératoire and reduction sequence approaches to profile the lithics techno-typologically and explore the lithic economy, particularly blade production methods, knapping techniques, and artifact curation. Raw material analysis reveals Lower Cretaceous flints from Ludogorie and Upper Cretaceous flints from the Danube region, up to 190 km and 130 km, respectively, from Bacho Kiro Cave, indicating long-distance mobility and finished products transport. Imported lithic implements, were a result of unidirectional and bidirectional non-Levallois laminar technology, likely of volumetric concept. Systematic on-anvil techniques (bipolar knapping) and tool segmentation indicate re-flaking and reshaping of lithic implements, reflecting on-site curation and multifaceted lithic economy. A limited comparison with other IUP sites reveals certain shared features and also regional variations. Bacho Kiro Cave significantly contributes to understanding the technological and behavioral evolution of early Homo sapiens in western Eurasia.

Understanding Palaeolithic hominin subsistence strategies requires the comprehensive taxonomic identification of faunal remains. The high fragmentation of Late Pleistocene faunal assemblages often prevents proper taxonomic identification based on bone morphology. It has been assumed that the morphologically unidentifiable component of the faunal assemblage would reflect the taxonomic abundances of the morphologically identified portion. In this study, we analyse three faunal datasets covering the Middle to Upper Palaeolithic transition (MUPT) at Bacho Kiro Cave (Bulgaria) and Les Cottés and La Ferrassie (France) with the application of collagen type I peptide mass fingerprinting (ZooMS). Our results emphasise that the fragmented component of Palaeolithic bone assemblages can differ significantly from the morphologically identifiable component. We obtain contrasting identification rates between taxa resulting in an overrepresentation of morphologically identified reindeer (Rangifer tarandus) and an underrepresentation of aurochs/bison (Bos/Bison) and horse/European ass (Equus) at Les Cottés and La Ferrassie. Together with an increase in the relative diversity of the faunal composition, these results have implications for the interpretation of subsistence strategies during a period of possible interaction between Neanderthals and Homo sapiens in Europe. Furthermore, shifts in faunal community composition and in carnivore activity suggest a change in the interaction between humans and carnivores across the MUPT and indicate a possible difference in site use between Neanderthals and Homo sapiens. The combined use of traditional and biomolecular methods allows (zoo)archaeologists to tackle some of the methodological limits commonly faced during the morphological assessment of Palaeolithic bone assemblages.

Artefacts made from stones, bones and teeth are fundamental to our understanding of human subsistence strategies, behaviour and culture in the Pleistocene. Although these resources are plentiful, it is impossible to associate artefacts to specific human individuals¹ who can be morphologically or genetically characterized, unless they are found within burials, which are rare in this time period. Thus, our ability to discern the societal roles of Pleistocene individuals based on their biological sex or genetic ancestry is limited2–5. Here we report the development of a non-destructive method for the gradual release of DNA trapped in ancient bone and tooth artefacts. Application of the method to an Upper Palaeolithic deer tooth pendant from Denisova Cave, Russia, resulted in the recovery of ancient human and deer mitochondrial genomes, which allowed us to estimate the age of the pendant at approximately 19,000–25,000 years. Nuclear DNA analysis identifies the presumed maker or wearer of the pendant as a female individual with strong genetic affinities to a group of Ancient North Eurasian individuals who lived around the same time but were previously found only further east in Siberia. Our work redefines how cultural and genetic records can be linked in prehistoric archaeology.

Kozarnika cave is a renowned prehistoric site in the Balkans, which contributes significantly to our understanding of the human past due to its rich assemblages associated with the Lower to Upper Palaeolithic. Various dating methods have been employed to unravel the timing of human occupations in Kozarnika. Radiocarbon dating was used to unfold the time frame for the Kozarnikian lithic tradition uncovered in the Upper Palaeolithic sequence of the cave, and palaeomagnetic dating assigned the Brunhes–Matuyama reversal to the layer beneath the Lower Palaeolithic assemblages. In this study, we employed luminescence-dating methods, including a body of different signals to date sediment layers from the top to the bottom of the sequence covering the period of ca 30 to 700 ka. Our investigations revealed that the Kozarnikian tradition in layers 5a-c falls between 30 and 35 ka. Following that, we suggest that the Middle Palaeolithic period initiated between 250 and 309 ka and lasted until 40–53 ka. More importantly, we have updated the age of the Neanderthal radius discovered in the Mousterian assemblages to 201 ± 17 ka. Our dating resulted in a period of ca 300–700 ka for the Lower Palaeolithic assemblages in the cave. Although this age range fits perfectly with the palaeomagnetic boundary <780 ka established for Kozarnika, the possibility of reaching the threshold of luminescence dating cannot be ruled out. Thus, at this stage, this age range may represent the minimum age for the Lower Palaeolithic.

The expansion of Homo sapiens and our interaction with local environments, including the replacement or absorption of local populations, is a key component in understanding the evolution of our species. Of special interest are artifacts made from hard animal tissues from layers at Bacho Kiro Cave (Bulgaria) that have been attributed to the Initial Upper Paleolithic. The Initial Upper Paleolithic is characterized by Levallois-like blade technologies that can co-occur with bone tools and ornaments and likely represents the dispersal of H. sapiens into several regions throughout Eurasia starting by 45 ka or possibly earlier. Osseous artifacts from the Initial Upper Paleolithic are important components of this record and have the potential to contribute to our understanding of group interactions and population movements. Here, we present a zooarchaeological, technological, and functional analysis of the diverse and sizable osseous artifact collection from Bacho Kiro Cave. Animal raw material sources are consistent with taxa found within the faunal assemblage including cervids, large bovids, and cave bears. A variety of bone tool morphologies, both formal and informal, indicate a diverse technological approach for conducting various on-site activities, many of which were focused on the processing of animal skins, likely for cold weather clothing. Technological flexibility is also evident in the manufacture of personal ornaments, which were made primarily from carnivore teeth, especially cave bear, though herbivore teeth and small beads are also represented. The osseous artifacts from Bacho Kiro Cave provide a series of insights into the bone technology and indirectly on the social aspects of these humans in southeast Europe, and when placed within the broader Initial Upper Paleolithic context, both regional and shared behaviors are evidently indicating widespread innovation and complexity. This is especially significant given the location and chronology of the site in the context of H. sapiens dispersals.

Bone surface modifications are crucial for understanding human subsistence and dietary behaviour, and can inform about the techniques employed in the production and use of bone tools. Permission to destructively sample such unique artefacts is not always granted. The recent development of non-destructive proteomic extraction techniques has provided some alternatives for the analysis of rare and culturally significant artefacts, including bone tools and personal ornaments. The Eraser Extraction Method (EEM), first developed for ZooMS analysis of parchment, has recently been applied to bone and ivory specimens. To test the potential impact of the EEM on ancient bone surfaces, we analyse six anthropogenically modified Palaeolithic bone specimens from Bacho Kiro Cave (Bulgaria) through a controlled sampling experiment using qualitative and 3D quantitative microscopy. Although the overall bone topography is generally preserved, our findings demonstrate a slight flattening of the microtopography alongside the formation of micro-striations associated with the use of the eraser for all bone specimens. Such modifications are similar to ancient use-wear traces. We therefore consider the EEM a destructive sampling approach for Palaeolithic bone surfaces. Together with low ZooMS success rates in some of the reported studies, the EEM might not be a suitable approach to taxonomically identify Pleistocene bone specimens.

The behavioral dynamics underlying the expansion of Homo sapiens into Europe remains a crucial topic in human evolution. Owing to poor bone preservation, past studies have strongly focused on the Initial Upper Paleolithic (IUP) stone tool record. Recent excavations and extensive radiocarbon dating at Bacho Kiro Cave (Bulgaria) pushed back the arrival of IUP H. sapiens into Europe to ca. 45,000 years ago. This site has exceptional bone preservation, and we present the study of 7431 faunal remains from across two IUP layers (I and J) and one Middle Paleolithic layer (K). We identified a shift in site use and occupation intensity through time, marked by increased find density and human modifications in Layer I. Alongside a decrease in carnivore presence and seasonality data demonstrating human presence in all seasons, this indicates a more frequent or prolonged occupation of the site by IUP groups. Contrarily, the dietary focus across the IUP and Middle Paleolithic layers is similar, centered on the exploitation of species from a range of habitats including Bos/Bison, Cervidae, Equidae, and Caprinae. While body parts of large her-bivores were selectively transported into the site, the bear remains suggest that these animals died in the cave itself. A distinct aspect of the IUP occupation is an increase in carnivore remains with human modifications, including these cave bears but also smaller taxa (e.g., Canis lupus, Vulpes vulpes). This can be correlated with their exploitation for pendants, and potentially for skins and furs. At a broader scale, we identified similarities in subsistence behavior across IUP sites in Europe and western Asia. It appears that the first IUP occupations were less intense with find densities and human modifications increasing in succeeding IUP layers. Moreover, the exploitation of small game appears to be limited across IUP sites, while carnivore exploitation seems a recurrent strategy.

Kozarnika cave is a renowned prehistoric site in the Balkans. It contributes significantly to our understanding of the human past due to its rich assemblages associated with the Lower to Upper Palaeolithic periods. The cave was first mentioned in the prehistoric survey carried out before 1933. Years after, in 1996, the site was excavated systematically by Bulgarian-French researchers [1]. ▶ Various chronological dating methods have been employed alongside the excavation to unravel the timing of humans’ occupation in Kozarnika. ▶ This study presents our contribution of employing luminescence-dating methods (OSL, IRSL, pIRIR, VSL, IR-RF) to unravel the reliable timeframes for several geological units and archaeological assemblages. A vast body of techniques has been put together, enabling us to date sediment samples containing the assemblages attributed earlier to the Upper, Middle, and Lower Palaeolithic periods [2,3]. ▶ Our results show that the inhabitants of Kozarnika occupied that region from ca 30 to 600 ka, showing general accordance with the previous dating.