The end of the last Ice Age ca. 14000–12000 BC brought instability to the Pontic–Caspian area: meltwater flew torrentially from the northern glaciers and the permafrost into the Khvalynian Sea (the Caspian Sea is a small remaining part of it). A shoreline between the Middle Volga and the Ural rivers restricted east–west movements south of the Ural Mountains (Anthony 2007).
By 11000–9000 BC water may have poured into the Black Sea (Major et al. 2006; Ryan 2007), enlarging it and creating the Sea of Azov. Although the magnitude and rapidity of this flow remains controversial (Yanko-Hombach, Gilbert, and Dolukhanov 2007), it is agreed that meltwater created unstable shores in eastern Europe (Patton et al. 2017).
Deglaciation and palaeoclimatic changes were probably more important in their potential for environmental, cultural, social and historical changes of this region, though. A significant deterioration is found first during the Younger Dryas, a severe cold spell that lasted between 10800 and 9500 BC. Then a warming trend began, with climate aridisation and reduction of overall biomass density seen in the region during the transition to the pre-Boreal period, with large group segmentation, local population dispersion, increase in population mobility, and decrease in population density (Smyntina 2016).
In the Boreal period, the Pontic–Caspian steppe became stable with an increase in climatic humidity, and a growth of biomass density. Hunters, probably incoming from eastern and western regions, settled there and population density increased (Anthony 2007).
In the Pontic steppes, Crimea shows new technology of flint blade production from a Near Eastern inspiration in the Murzak–Koba culture (ca. 10th–8th millennium BC). Reindeer hunters of the western region, in the Dniester valley, became deer hunters and riverine fishers during the Early Mesolithic. In the Dnieper–Donets steppes, bison and horse hunters of the Late Palaeolithic became deer and horse hunters of the Early Mesolithic. Early Mesolithic horse hunters also appeared in the Dniester–Prut steppes (Biagi and Kiosak 2010).
The Near East component is still visible in the Epigravettian Kukrek and Grebeniki cultures. Kukrek appeared as heir of this Near Eastern tradition in the late 8th millennium BC, and included the eastern part of the north Pontic area, expanding to the north (Biagi and Kiosak 2010).
The north-western Pontic region was thus exploited by intertwined communities distinguished by different material cultures: the non-geometric Anetivka variant of Kukrek, and the geometric Grebeniki material culture, offspring of Early Mesolithic Tsarinka flint knapping tradition, continuing thus earlier western Pontic traditions. Two basic inventions are attributed to this period: the first attempts at aurochs domestication, in the Lower Danube region, and a significant intensification of the use of wild plants, fish, and other river resources (Smyntina 2016).
The next development was the transition to the stage of food-producing economy, with two cultures appearing in the north Pontic area: the Azov culture in the east, and the Bug–Dniester culture in the west. Both have pre-pottery stages dated to around 7500–6000 BC, with the Azov culture being a continuation of the Kukrek tradition. In the Dnieper rapids—represented by the Vasylivka site—the Kukrek tradition was replaced by the Surskii culture, and then by the Middle Neolithic Dnieper–Donets I (Anthony 2006).
In the forest-steppe area, the Mesolithic is represented by the Zimovniki culture (in its different stages, since the Early Mesolithic), from north-east Azov to the Don–Volga interfluve, with a material culture that has been linked to the lithic industry of the Caucasus. This culture is probably related to the emergence of the Late Mesolithic–Neolithic Donets culture, in the Don Right Bank valley. The dispersal of these Mesolithic materials, possibly up to the Volga–Oka interfluve, attest to possible trans-regional ancient population migrations (Fedyunin 2015).
In the north Pontic forest area, the Swiderian culture had been replaced by local groups which grew from its tradition. Early west Mesolithic forest hunters from flooded areas between Britain and Scandinavia migrated to the east into Middle European lowlands, forming the Duvensee cultural unit (Maglemose culture) in the 8th–7th millennium BC. The only group to reach into the north Pontic forest-steppe region comes from the Komornica culture, from the Vistula river basin (Zalizniak 2016).
The eastward migration of west European Late Mesolithic groups, as well as the appearance of post-Maglemosian cultures, have been suggested as the result of further floodings in western Europe, specifically the flooding of Doggerland, ca. 6200 BC. In the southern part of the east European forest zone, between the Vistula and the Dnieper, Janislawice became the dominant post-Maglemosian culture. There is no influence of the Caucasus here (Zalizniak 2016).
Two main groups developed in the area: the Tacenki group around the Kyiv Polesia, and its offshoot the Kudlaievka in the valley of the upper Dnieper and Desna, under influence from the Kukrek tradition. Similar findings in the River Donets and to the north are thought to derive from a migration of population from the Kudlaievka culture in both directions. The adaptation of Janislawice to Caucasian–Pontic traditions, including animal husbandry, happened late, and only after the expansion of this culture into the forest-steppe (Zalizniak 2016).
To the east, the Early Mesolithic forager camps (ca. 8000–7000 BC) inhabited the North Caspian depression, then filled with lakes, in a cooler and moister climate. The economy of these groups, like that of north Pontic groups, depended on equid hunting, and their camps probably represented single families or small hunting parties. Their garbage dumps contain almost exclusively bones of onagers, and their flint tool inventories mainly geometric microliths (Anthony 2006).
During the Late Mesolithic (ca. 7000–6000 BC), the North Caspian area became increasingly dry, with pollen evidence suggesting that desert conditions spread precisely during this time, with a peak dry episode ca. 6000 BC (related to the cold oscillation ca. 6200 BC in the northern hemisphere), after which humid conditions returned. Camps reached larger sizes, hunters preferred a grey flint different from the previously prevalent yellow-grey flint, and geometric microliths diminished (Anthony 2006).
Toolmaking traditions recognised in these sites include many different lowland steppe foraging groups, from the North Caspian area (Istai IV type), West Caspian steppes (Kharba type), and Azov–Crimean steppes (Kukrek and Zimovniki). When pottery-making emerged in this area, Early Neolithic cultures of this Azov–Caspian region (Surskii, Kairshak III) made pots with similar shapes and similar patterns of decoration. Because of that, Vasiliev advanced the idea that the dry Azov–Caspian steppe constituted a ‘cultural region’ during the Late Mesolithic and Early Neolithic, a network of interacting forager bands. Different from this common material culture was that one seen east of the Caspian Sea and east of the Urals, which belonged to distinct social networks (Anthony 2006).
The oldest known pottery appeared in East Asia, with findings in the Yangze Basin (20th–17th mllennium BC), and further examples in northern China (11th millennium), the Korean Peninsula (11th–10th millennium BC). In Japan, pottery was apparently introduced during the incipient Jōmon phase (16th–13th millennium BC), and was probably related to the introduction in North Asia from the east, with findings spanning ca. 15th–12th millennium BC (Piezonka 2016).
In the Trans-Baikal area, the first findings are dated ca. 13th–11th millennium BC, but it seems to have been a still-stand zone, because pottery appeared to the west only millennia later, in west Siberia and the Trans-Uralian regions. While some initial findings can be dated to the 10th–8th millennium BC, the start of a westward cultural wave can be dated only to the first half of the 8th millennium BC, with widespread findings in cultures of the North Asian regions dating to the 7th and 6th millennium BC (Piezonka 2016). On the other hand, the period between 11th-8th millennium seems to be one of expansion from east to west.
Before the arrival of farmers to the western frontier of the Pontic–Caspian steppe, pottery was produced in the Volga region by the Elshanian culture ca. 7000–6500, with the oldest pottery in Europe coming from the Samara region. This material culture was probably derived from the Eastern Asian tradition of the Late Pleistocene, which arrived through a path following Siberia and the Trans-Urals (Piezonka 2015). The earliest Trans-Uralian sites include Yurtobor and Lake Andreevskoe, in the Tobol-Ishim region, of the late Mesolithic Boborykino culture—featuring round- and flat-based bots with incised and impressed decoration—and Sumpanya in the Konda River Basin (Gibbs and Jordan 2013). The scarce sites investigated and variable dates obtained from them (ca. 12000–8000 BC) make it impossible to ascertain a precise origin of eastern European pottery, though.
From this source, the first Neolithisation wave reached hunter-gatherer groups of the Pontic–Caspian steppe, starting with the Lower Volga region (Suppl. Fig. 5), whose oldest pottery is dated ca. 6200 BC, with similarities to those of the Kairshak culture in the northern Caspian steppes, whose first sites with the oldest pottery appeared ca. 6500 BC (Vybornov 2016). From the north-western Caspian region pottery spread south- and westward into north Pontic societies, appearing in different steppe regions simultaneously ca. 6200–6000 BC, including the Bug–Dniester culture (Zaitseva et al. 2009).
Pots were made of a clay-rich mud collected from the bottoms of stagnant ponds, and they were formed by the coiling method and baked in open fires at 450–600º C. These pots are bottom-tappered and non-decorated in the Middle Volga (Elshanian culture); non-decorated and with scoring marks with round and flat bottoms in the North Caspian steppe; non-decorated in the Lower Don; and non-decorated or sparsely decorated in the Dvina–Lovat’ region (Zaitseva et al. 2009).
Sparsely decorated pottery (decorated with little punctures, and having a tapered bottom) dispersed north into the forest zone ca. 6000 BC or slightly earlier, from the Upper Volga and Dvina–Lovat’ regions to the east (into the Dvina–Pechora region) and west (into the eastern Baltic), reaching the Upper Volga, Serteya, and Valday cultures, and later the Narva culture. It reached the Bug–Dniester culture in the Southern Buh valley ca. 6200–6000 BC, just before the western pottery type was adopted in the Middle Dniester valley ca. 5900–5700 BC (Vybornov, Kosintsev, and Kulkova 2015).
Pottery production increases at the end of the 7th millennium and beginning of the 6th millennium, with the second stage of Elshanian pottery appearing ca. 5750–5500 BC, with pottery assemblages also found in the North Caspian region. More pottery decorated with triangular impressions can be traced to the second half of the 6th millennium in the region (Mazurkevich and Dolbunova 2015).
In the forest-steppe of the Don River region, sites appear in the upper parts of the first terrace above the floodplain, and sometimes on bedrock shores. Pottery of the Karamyshevo type appear through direct contacts with the population of the Elshanian culture, which had the skills and arrived in the Don region probably at the end of the 6th millennium BC, with Karamyshevo culture prevalent throughout the first half of the 5th millennium BC, eventually produced from sanded silty clay containing natural inclusions, like the pottery of the Middle Don culture (Smolyaninov, Skorobogatov, and Surkov 2017).
The Middle Don culture, in turn, appears to be contemporaneous with early Karamyshevo, with the southern periphery of the Upper Volga region also coincident with early stage of both, hence connecting it to the Valday and Volga-Oka groups that formed the Upper Volga culture. It is difficult to pinpoint exactly the intertribal communication networks between Upper Don River basin and those of the Upper Volga, as is the relationship to the communities of the Dnieper–Donets culture around the mid–5th millennium BC (Smolyaninov, Skorobogatov, and Surkov 2017).
A second expansion of eastern pottery reached the eastern Baltic region ca. 5500 BC, expanding from the Dnieper region to the north-west, generating the sparsely decorated Dubičiai pottery (later evolving into the Neman culture), and influencing the north European regions from the Narva to the Ertebølle cultures (Piezonka 2015).
A third expansion of eastern pottery spread from the Volga–Kama region to the east ca. 5000 BC, connected to influences from beyond the Urals, showing a more elaborately decorated ware (with bands of pits and impressions made from comb stamps), spreading north and west in the Sperrings and Säräisniemi 1 cultures (Piezonka 2015).
The successful expansion of haplogroup R1a-M459 (formed ca. 20800 BC, TMRCA ca. 16200 BC) may have been associated with waves of migration of ANE/EHG ancestry into eastern Europe from northern Eurasia. An individual from Vasylivka ca. 8700 BC, of hg. R1a1-M459 (Jones et al. 2017), supports this haplogroup as one of the prevalent Epipalaeolithic lineages of north Pontic hunters. The spread of R1b1b-V88 lineages (TMRCA ca. 9700 BC) in the North Pontic area, with the first sample found in Vasylivka ca. 7050 BC (Mathieson et al. 2018), may be linked to remnants of ancestral populations expanding westward, but they could be more directly associated with the eastward expansion of the Grebeniki tradition, of west Pontic origin, close to Balkan hunter-gatherers of the same haplogroup (see §i.3. Nostratians). A sample of hg. I2a1a-P37.2 in Vasylivka ca. 8100 BC may also represent either an earlier Epipalaeolithic population, or a recent migration of Iron Gates hunter-gatherers or post-Swiderian migrants.
Mesolithic samples from the north Pontic area are intermediate between EHG and SHG, with further contribution of WHG ancestry (Mathieson et al. 2018), which—together with their position in PCA—support close contacts of post-Swiderian and Maglemosian cultures in the region. The expansion of eastern ancestry detected in north Pontic samples (from the Middle Volga) and in a Middle Volga sample (from further east) also support westward migration waves coinciding with the expansion of hunter-gatherer pottery (see below §iii.5. Early Indo-Europeans and Uralians).
A sample of a Mesolithic hunter-gatherer at Lebyanzhinka in the Samara region, dated ca. 5600 BC, shows hg. R1b1a1-P297 (Mathieson et al. 2015), while R1b1a1a-M73 is found later in Donkalnis, in the Baltic region (ca. 5200 BC), belonging to the Narva culture (Mittnik, Wang, et al. 2018). Similarly, expanding Indo-Anatolians show hg R1b1a1b-M269 (see below §iv.2. Indo-Anatolians), apart from other likely local haplogroups. These lineages are compatible with the previous expansion of R1b1a1-P297 lineages with the North-Eastern Technocomplex (see §ii.1. Eurasians).
Nevertheless, the presence of R1b1a1-P297 late in the Baltic, after the resurgence of I2-M438 lineages, could also suggest a back-migration of certain groups associated with the westward expansion of hunter-gatherer pottery from the Trans-Urals into the Pontic–Caspian and north-eastern European regions. This is supported by the presence of AEA ancestry in two individuals, from Samara and Karelia (Lazaridis et al. 2018), and the appearance of haplogroup R1b1a1-P297 in Karelia ca. 5600 BC (Mathieson et al. 2015). The presence of R1b1a1-P297 lineages in Latvia since the Mesolithic until the arrival of Corded Ware does not help distinguish between continuity, resurgence, and back-migration events.
Samara and Karelia hunter-gatherers also show in ‘speculative’ estimates further contribution of El Mirón ancestry compared to the older Sidelkino sample (ca. 9300 BC), and higher than the one found in other EHG samples from Karelia, in south-eastern Europe, or in the north Pontic region during the Mesolithic or Neolithic (Lazaridis et al. 2018). This contribution is thus compatible with the expansion of populations related to northern Mesolithic Europe, and thus post-Swiderian cultures.
The ancestry of later Eneolithic individuals of the Khvalynsk culture (5th millennium BC) is also found in two Sintashta outliers from Kamenyi Ambar (ca. 2000–1650 BC), one of hg. R1b1a1-P297, the other R1b1a1a-M73 (Narasimhan et al. 2018), both probably related to local groups of the southern Urals and Trans-Urals region, remnant populations of these groups expanding hunter-gatherer pottery to the west. The same haplogroup R1b1a1a-M73 is found further east among the Botai, supporting the widespread distribution of these groups beyond the Urals (see §v.9. Pre-Tocharians and §v.8. Palaeosiberians). Like these late outliers, Khvalynsk-related individuals on the Cis-Urals probably hosted some West Siberian Hunter-Gatherer (WSHG) ancestry, and were thus most likely part of an ancestral EHG:WSHG cline from the Cis-Urals to the Trans-Urals and West Siberian region.
R1a1-M459 lineages continued probably in groups of the Pontic–Caspian region, evidenced by one individual from Deriïvka (ca. 6900 BC), a hunter-gatherer from Karelia (ca. 6300 BC), and an individual of the Khvalynsk culture from Samara (ca. 4600 BC). The expansion of R1a1a-M198 lineages (formed ca. 12000 BC, TMRCA ca. 6600 BC) and the finding of sister clade R1a1b-YP1272 (TMRCA ca. 5300 BC) in a Maikop outlier from the northern Caucasus, and in an individual from Kudruküla, Estonia (Saag et al. 2017), of the Comb Ware culture (ca. 3000 BC), suggest—together with their early split date—an early expansion of R1a1-M459 subclades from within eastern Europe, probably associated with the spread of some groups of hunter-gatherer pottery within the forest zone. the with later expansions likely associated with specific groups of hunter-gatherer pottery.
If post-Swiderian cultures are associated with the expansion of Eurasiatic languages into eastern Europe and the Trans-Urals region, the westward expansion of hunter-gatherer pottery from the Elshanian culture in the Volga–Ural region—probably originally associated with R1b1a1-P297 lineages in the Volga–Ural area, and continued after the resurgence of local R1a1a-M198 lineages mainly in the forest zone—can be linked to the expansion of Indo-Uralic from the east. The emergence of elk-head staffs (see below Figure 10) and other elk-head sculptures since the 7th millennium BC in the east European forest zone may have also been associated with this cultural expansion.