A second migration of Neanderthals into the Russian Altai Region took place 70 − 60,000 years ago. Traces of the first migration have been found in Middle Paleolithic deposits in Denisova Сave (sample Denisova 5, MIS5). Late and early Neanderthals likely did not meet in the Altai due to a chronological gap, unlike late Neanderthals and Denisovans who left hybrid offspring (Slon et al. 2018). Remains of Late European Neanderthals have thus far been found only in Chagyrskaya and Okladnikov caves. In regional context, these caves preserve evidence of the Sibiryachikha variant of the Altai Middle Paleolithic. These caves are the easternmost manifestation of the Micoquian/KMG assemblages brought by Late Neanderthals from Central and Eastern Europe (Kolobova et al. 2020).
Until recently, these two caves yielded the only evidence of Late Neanderthal occupation of the Altai Region. Chagyrskaya Cave has been classified as a consumption camp, primarily geared toward hunting and processing bison and horses. A complete behavioral sequence of stone and bone tool manufacturing has been identified at the site (Kolobova et al. 2019), which seems to have been regarded by Neanderthals as a safe haven where they brought their children (Kolobova et al. 2020). Published data on Okladnikov Cave also support the interpretation that it was used as a permanent shelter and consumption site of horses and bison (Krause et al. 2007).
Since a behaviorally complex array of Micoquian/KMG sites has been observed in Europe, associated with various on-site activities and Neanderthal mobility (Chabai 2004; Uthmeier 2012; Richter 2016; Wiesner 2021), the two Altai sites constitute pieces of a much larger puzzle. Post-depositional destruction of open-air Neanderthal sites due to colluvial or alluvial processes, and insufficient archaeological study of the region may explain why this is so.
The discovery of Verkhnyaya Sibiryachikha Cave, located near Okladnikov Сave in the Russian Altai Mountains, has helped fill critical gaps in our knowledge of late Neandertal behavior (Fig. 1, a, c). Verkhnyaya Sibiryachikha Cave was first recognized as an archaeological site in 2020, although the cave itself was known much earlier.
In 2020–2021, a 3 × 1 m pit was excavated in the cave’s central chamber to a depth of 1.2 m (Fig. 1, b). Five stratigraphic units were identified in the profile (Fig. 2, a). Layer 1 is modern sediment, including significant amounts of rubbish and small domestic livestock waste up to 0.1 m thick; Layer 2 is brownish loamy sand with a high content of fine clastic material up to 0.3 m thick; Layer 3 is a grayish brown silt with a significant proportion of coarse and medium clastic material up to 0.7 m thick; Layer 4.1 is reddish-pale silt with limestone debris up to 0.15 m; Layer 4.2 is pale silt with coarse clastic material up to 0.3 m thick.
A total of 2,154 non-human paleontological remains have been found at Verkhnyaya Sibiryachikha of which 14.7% are identifiable as belonging to at least 27 mammal species. In Layers 3 and 4, the species composition, their ratios, and the suite of preserved bone remains are typical of cave taphocenoses formed due to the activity of large predators, primarily cave hyenas. The faunal assemblage from Layers 3 and 4 is dramatically dominated by species adapted to open spaces (87.8%). The portion preferentially inhabiting forest-steppe habitats is 7.4%; forest environments (beaver, brown bear, lynx) 2%; and rocky biotopes (Siberian ibex) 2.7%. Lynx and beaver remains suggest the presence of small wooded areas, perhaps riverine gallery forests and floodplain woodlands. A significant portion of the Verkhnyaya Sibiryachikha Cave bones exhibit traces of digestive corrosion.
Single small fragments of burnt bones from Layers 3 and 4, along with artifacts, indicate episodic, short-term human visits to the cave.
A single proximal bladelet fragment with a straight profile was found in Layer 2 (Fig. 2, b), and a medial fragment of a blade with a straight profile and bidirectional negatives was recovered at the top of Layer 3 (Fig. 2, c), while a leaf-shaped retouched point made on a primary flake was found together with a flake at the bottom of Layer 3 (Fig. 2, d, e).
Preliminary AMS 14C dating of bones yielded ages of 27,890 ± 347 (GV 3074) and 28,764 ± 369 (GV 3073) for Layer 2. Bones recovered from lower Layer 3 near the tool, are dated to 40,952 ± 2479 (GV 3076) and 44,255 ± 3737 (GV 3075) (Fig. 2, a).
Based upon archaeological materials and available preliminary dates, we conclude that Verkhnyaya Sibiryachikha Cave was occasionally visited by people several times in the Late Pleistocene. The discovery of a blade and bladelet in Layer 2 and at the top of Layer 3 supports an Upper Paleolithic age for the deposits.
The only artifact we can confidently attribute both culturally and chronologically is a retouched point. Verkhnyaya Sibiryachikha Cave is located only 170 m from Okladnikov Cave, a key site of the Siberian Micoquian/KMG (Sibiryachikhа) variant (Derevianko and Markin 1992; Kolobova et al. 2020). Primary knapping is based on radial (Levallois Centripetal) and orthogonal cores for flake production. Plano-convex bifaces, including Keilmesser types, convergent scrapers of various shapes, and retouched points are characteristic of the tool assemblage. Convergent scrapers and points, often made on primary flakes, are characterized by ventral and dorsal thinning (Fig. 3, a, b, d, e).
New dating results of Neanderthal bones from Okladnikov Cave Layers 2 and 3, coinciding with U-series ages, indicate that the cave was inhabited 40,000–44,000 BP and earlier (Skov et al. 2022). Therefore, we note a chronological overlap between Cultural Layers 3 and 2 at Okladnikov Сave and Layer 3 at Verkhnyaya Sibiryachikha Cave.
The morphology of the abovementioned point, which is intensively retouched and dorsally thinned, indicates that it belongs within the Okladnikov Cave industry. Micoquian/KMG (Sibiryachikhа) technocomplexes are typified by retouched points exhibiting various types of ventral and dorsal thinning, including those made on primary flakes (Fig. 3, a, b, d, e). These tools constitute from 9-11.5% of all tools in the Okladnikov Cave assemblages (Kolobova et al. 2023). In Chagyrskaya Cave Layer 6c/1, retouched points account for 14% of tools. To the contrary, such tools are also not typical of the Denisova/Kara-Bom variant of the Altai Middle Paleolithic. Retouched points (published as Levallois or Mousterian points) are present only in two Middle Paleolithic layers at Denisova Cave (East Chamber, 1.7–3.2% of all tools) and were often made on Levallois or elongated flakes (Shunkov et al. 2023). This also applies to other sites of the Denisova variant (Fig. 3, f, g, h).
Taphonomic data suggest Verkhnyaya Sibiryachikha Cave was a den where hyenas brought their prey from nearby steppe biomes. Simultaneously, the cave was occasionally visited by ancient humans. We interpret one such episode as a visit made by late Neanderthals living at Okladnikov Cave. Evidence of this visit provides new, previously unavailable data about the behavior of Late Neanderthals in the immediate vicinity of the Okladnikov Cave base camp: apparently, Neanderthals were exploring areas close to their main occupation site. Verkhnyaya Sibiryachikha Cave may have been used as a game observation point for hunters pursuing prey in the river valley, since it is located above the base camp.
Considering the Micoquian/KMG origin of the Okladnikov Cave lithic complex, several examples of the close, mutually-beneficial location of synchronic sites have been found in comparable topographic settings in other regions, such as Kabazi II (a kill and butchery site) and Kabazi V (a campsite) in western Crimea (Uthmeier and Chabai 2018). The same applies to Sesselfelsgrotte (Richter 1997) and Klausennische (ca. 300 m opposite each other in the Altmühl Valley (Richter et al. 2000), and Großes Schulerloch(Beck 2006) and Abri I am Schulerloch (Böhner 2000, 2008) in south Germany (Richter 2016). In the case of Okladnikov and Verkhnyaya Sibiryachikha caves, just as at the European sites, we infer Neanderthal exploration of nearby areas, albeit less intensively, which may have been influenced by a shortage of stone raw materials at Okladnikov Cave (Derevianko et al. 2015; Kolobova et al. 2023).
At Verkhnyaya Sibiryachikha Cave, we found only two artifacts in a layer synchronic with the habitation of late Neanderthals there, but their cultural and chronological contexts greatly increase their scientific significance. Late Neanderthals in the Russian Altai Region apparently practiced the same behaviors as their European relatives. Several examples of such similarities in subsistence strategies have already been reported (Salazar-García et al. 2021), which may indicate there were no significant changes in the behavior of the Neanderthal population that migrated eastward into Siberia.