The Eurasian steppes reach from the Ukraine in Europe to Mongolia and China. Over the past 5000 years, these flat grasslands were thought to be the route for the ebb and flow of migrant humans, their horses, and their languages. de Barros Damgaard et al. probed whole-genome sequences from the remains of 74 individuals found across this region. Although there is evidence for migration into Europe from the steppes, the details of human movements are complex and involve independent acquisitions of horse cultures. Furthermore, it appears that the Indo-European Hittite language derived from Anatolia, not the steppes. The steppe people seem not to have penetrated South Asia. Genetic evidence indicates an independent history involving western Eurasian admixture into ancient South Asian peoples.
According to the commonly accepted “steppe hypothesis,” the initial spread of Indo-European (IE) languages into both Europe and Asia took place with migrations of Early Bronze Age Yamnaya pastoralists from the Pontic-Caspian steppe. This is believed to have been enabled by horse domestication, which revolutionized transport and warfare. Although in Europe there is much support for the steppe hypothesis, the impact of Early Bronze Age Western steppe pastoralists in Asia, including Anatolia and South Asia, remains less well understood, with limited archaeological evidence for their presence. Furthermore, the earliest secure evidence of horse husbandry comes from the Botai culture of Central Asia, whereas direct evidence for Yamnaya equestrianism remains elusive.
We investigated the genetic impact of Early Bronze Age migrations into Asia and interpret our findings in relation to the steppe hypothesis and early spread of IE languages. We generated whole-genome shotgun sequence data (~1 to 25 X average coverage) for 74 ancient individuals from Inner Asia and Anatolia, as well as 41 high-coverage present-day genomes from 17 Central Asian ethnicities.
We show that the population at Botai associated with the earliest evidence for horse husbandry derived from an ancient hunter-gatherer ancestry previously seen in the Upper Paleolithic Mal’ta (MA1) and was deeply diverged from the Western steppe pastoralists. They form part of a previously undescribed west-to-east cline of Holocene prehistoric steppe genetic ancestry in which Botai, Central Asians, and Baikal groups can be modeled with different amounts of Eastern hunter-gatherer (EHG) and Ancient East Asian genetic ancestry represented by Baikal_EN.
In Anatolia, Bronze Age samples, including from Hittite speaking settlements associated with the first written evidence of IE languages, show genetic continuity with preceding Anatolian Copper Age (CA) samples and have substantial Caucasian hunter-gatherer (CHG)–related ancestry but no evidence of direct steppe admixture.
In South Asia, we identified at least two distinct waves of admixture from the west, the first occurring from a source related to the Copper Age Namazga farming culture from the southern edge of the steppe, who exhibit both the Iranian and the EHG components found in many contemporary Pakistani and Indian groups from across the subcontinent. The second came from Late Bronze Age steppe sources, with a genetic impact that is more localized in the north and west.
Our findings reveal that the early spread of Yamnaya Bronze Age pastoralists had limited genetic impact in Anatolia as well as Central and South Asia. As such, the Asian story of Early Bronze Age expansions differs from that of Europe. Intriguingly, we find that direct descendants of Upper Paleolithic hunter-gatherers of Central Asia, now extinct as a separate lineage, survived well into the Bronze Age. These groups likely engaged in early horse domestication as a prey-route transition from hunting to herding, as otherwise seen for reindeer. Our findings further suggest that West Eurasian ancestry entered South Asia before and after, rather than during, the initial expansion of western steppe pastoralists, with the later event consistent with a Late Bronze Age entry of IE languages into South Asia. Finally, the lack of steppe ancestry in samples from Anatolia indicates that the spread of the earliest branch of IE languages into that region was not associated with a major population migration from the steppe.
I think the wording of the abstract is weird, but consequent with their samples and results, so probably just clickbait / citebait for Indian journalists and social networks, or maybe a new attempt to ‘show respect for the sensibilities of Indians’ related to the artificially magnified “AIT vs. OIT” controversy, that is only present in India.
Why and how exactly social complexity develops through time from small-scale groups to the level of large and complex institutions is an essential social science question. Through studying the Late Bronze Age Sintashta-Petrovka chiefdoms of the southern Urals (cal. 2050–1750 BC), this research aims to contribute to an understanding of variation in the organization of local communities in chiefdoms. It set out to document a segment of the Sintashta-Petrovka population not previously recognized in the archaeological record and learn about how this segment of the population related to the rest of the society. The Sintashta-Petrovka development provides a comparative case study of a pastoral society divided into sedentary and mobile segments.
Subsurface testing on the peripheries of three Sintashta-Petrovka communities suggests that a group of mobile herders lived outside the walls of the nucleated villages on a seasonal basis. During the summer, this group moved away from the village to pasture livestock farther off in the valley, and during the winter returned to shelter adjacent to the settlement. This finding illuminates the functioning of the year-round settlements as centers of production during the summer so as to provide for herd maintenance and breeding and winter shelter against harsh environmental conditions.
The question of why individuals chose in this context to form mutually dependent relationships with other families and thus give up some of their independence can be answered with a combination of two necessities: to remain a community in a newly settled ecological niche and to protect animals from environmental risk and theft. Those who were skillful at managing communal construction of walled villages and protecting people from military threats became the most prominent members of the society. These people formed the core of the chiefdoms but were not able to accumulate much wealth and other possessions. Instead, they acquired high social prestige that could even be transferred to their children. However, this set of relationships did not last longer than 300 years. Once occupation of the region was well established the need for functions served by elites disappeared, and centralized chiefly communities disintegrated into smaller unfortified villages.
Some interesting excerpts (emphasis mine):
The quintessential archaeological evidence of Sintashta-Petrovka communities takes the form of highly nucleated and fortified settlements paired with easily-recognized kurgan (burial mound) cemeteries. This pattern spread across Northern Central Eurasia in a relatively short period of about 300 years (cal. 2050–1750 BC), and the period consists of two chronological phases (Hanks et al. 2007). The earlier Sintashta phase (cal. 2050–1850 BC) is distinguished from the later Petrovka phase (cal. 1850–1750 BC) by some differences in ceramic styles and some techniques of bronze metallurgy (Degtyareva et al. 2001; Vinogradov 2013). Bronze Age subsistence patterns apparently relied on a wide variety of resources, among which meat and milk production played a major role (…). The most outstanding graves are individual male burials accompanied by weaponry (projectile weapons and chariots), the insignia of power (stone mace heads), craft tools, and a specific set of sacrificed animals (horses, cows, and dogs). (…) there were at least two adults buried with chariots and one with sacrificed horses (Epimakhov 1996b). Chariots – the most famous and spectacular material component of Sintashta-Petrovka society – are known exclusively from burial contexts. Two-wheeled vehicles represent complex technology, incorporating some crucial innovations and the investment of substantial resources. Highly developed craft and military skills were required for their production and use. Burials with chariots probably represent military elites who used them (Anthony 2009; Chechushkov 2011; Frachetti 2012:17) and played especially important social roles in Sintashta-Petrovka societies. This pattern strongly suggests that military leadership extended into the realm of ideology and general social prestige (Earle 2011:32–33).
The following sequence of archaeological cultures – based on the sample of radiocarbon dates (Epimakhov 2007a; 2010a), – is adopted: (1) the Sintashta-Petrovka phase 1 dated to cal. 2050–1750 BC and (2) the Srubnaya-Alakul’ phase 2 dated to cal. 1750–1350 BC.
(…) control of craft might have provided a source of power for elites in the fortified settlements (Steponaitis 1991). Some bronze tools, such as chisels, adzes, and handsaws seem more abundantly represented at some fortified settlements than at others, raising the possibility of a stronger focus on different craft products and some degree of exchange and interdependence between fortified settlements. (…) Zdanovich (1995:35) estimates 2500 people within the walls at Arkaim. He bases his conclusion an average house size of 140 m2 and the idea that Arkaim households consisted of an extended family of several generations, similar to Iroquois longhouse inhabitants. He also suggests that the entire population did not live in the “town” all the time, but moved around. The fully permanent residents were shamans, warriors, and craftsmen, i.e., elites and attached specialists.
Summarizing, excavated households represent very strongly similar architectural patterns, similar levels of wealth and prestige, little productive differentiation, and no evidence of elites amassing wealth through control of craft or subsistence production or any other mechanism (Earle 1987). These observations sharply contradict the burial record, where strong social differentiation is visible. The description above recalls the Regional Classic period elites of the Alto Magdalena whose standard of living differed little if at all from anyone else’s. Their elaborate tombs and sculptures suggest supernatural powers and ritual roles were much more important bases of their social prominence than economic control or accumulation of wealth (Drennan 1995:96–97). On the other hand, craft activities (especially metal production) are highly obvious in the Sintashta-Petrovka settlements. Defensive functions could also have played some role for the entire population. This benefit might attract people in an unstable or wild environment to spend much of their time in or near such settlements (Earle 2011:32–33). Since the construction of ditches and outer walls, as well as dwellings with shared walls, requires planning and organization, purposeful collective effort must have been a key feature of Sintashta-Petrovka communities (Vinogradov 2013; Zdanovich 1995). Sintashta-Petrovka communities thus evidence substantial investment of effort in non-subsistence activities, potentially resulting in a subsistence deficit in an economy with a heavy emphasis on herding. Altogether, this makes it plausible to think of the known Sintashta-Petrovka communities as special places where elites for whom military activities were important resided, and where metal production and possibly other crafts were carried out. It remains unclear just how a subsistence economy relying heavily on herding was managed from these substantial sedentary communities. Moving herds around the landscape seasonally is generally thought to be a part of subsistence strategy in Inner Eurasia (Frachetti 2008; Bachura 2013). In this area migration to exploit seasonal pastures is the best strategy for maintaining a regular supply of food for livestock due to shortages of capital or of labor pool to produce, harvest, and store fodder (Dyson-Hudson and Dyson-Hudson 1980:17). The recent stable isotope studies support this notion showing high likelihood that during the Bronze Age livestock was raised locally (Kiseleva et al. 2017).
The above raises the possibility that the residential remains that have been excavated within the fortifications of Sintashta-Petrovka communities represent only a portion of the population (Hanks and Doonan 2009, Johnson and Hanks 2012). It could be (along with the general lines suggested by D. Zdanovich ) that the archaeological remains of the ordinary people who made up the majority of the population, built the impressive fortifications and stoked the subsistence economy have gone largely undetected. In global comparative perspective, many societies with the features known for Sintashta-Petrovka organization consisted of elite central-place settlements and hinterland populations. In such a scenario, the “missing” portion of the Sintashta population would reside in smaller unfortified settlements scattered around in the vicinity of the fortified ones.
In terms of wealth and productive differentiation, the inside assemblage of Kamennyi Ambar demonstrates a higher degree of richness and diversity in its material assemblage, leading to the conclusion that the outside materials may represent a semi-mobile group of people who used significantly less durable materials and accumulated less possessions. As for the diversity within the inside artifact assemblage, some households at Kamennyi Ambar demonstrate more diverse artifact assemblages than others, as well as bigger sizes, that could be related to differences in productive activities and/or wealth differentiation between families. A focus on specific objects of ceramic production in House 1 suggests some degree of productive specialization, while the elite goods in House 5 clearly point out the presence of elite members of the society.
There are two possible social scenarios that explain the settlement situation during the Sintashta-Petrovka phase. The first scenario considers all three communities as simultaneous and the second scenario suggests seeing the three sites as the same community that moved around the landscape during the Late Bronze Age in order to keep the pasture grounds from degradation.
Since no remains of permanent structures were found and any people living outside the walls must have stayed in temporary shelters. If this was the case, then the outside part of the population consisted of a semi-mobile group of people who moved to live near the fortified settlement during the winter. The pattern of animal slaughtering supports this conclusion. Animal teeth found near Kamennyi Ambar and Konoplyanka demonstrate a tendency for animal butchering during the fall, throughout the winter and spring, with less evidence of summer meat consumption. Moreover, since the Bronze Age subsistence strategy relied heavily on pastoralism, herds had to be grazed during the summer and kept safe during the winter. This strongly suggests that the part of the population responsible for management of animals spent their time in the summer pastures with the livestock. During the winter the animals had to be kept in the warm and safe environment of the walled settlements (as suggested by the highest level of phosphorus on the house floors) while the herders stayed in portable shelters in close to the walls.
(…) the outsiders used a less diverse set of tools, as well as less durable materials (for example, wooden instead of metal) in their everyday life and did not accumulate much in the way of archaeologically visible possessions. On the other hand, a few stone and lithic artifacts demonstrate that craft activities were carried out using cheap and abundant raw materials. The artefact assemblages also point out that the people inside accumulated wealth in the form of material belongings and luxury goods, especially, things like metal artifacts and symbolic or military-related stone artifacts, while people outside did not do that. However, the presence of semi-precious stones could signify some kind of wealth accumulation by the segment of population outside the walls. Since there are limits to our ability to assess social relationships from material remains, it is difficult to say if the people who lived outside the walls were oppressed or less respected. Their possible concentration on herding-related activities and livestock keeping might suggest less prestigious social status. The most prominent members of the society were, nonetheless, buried with the attributes of warriors or craft specialists, not those of shepherds, suggesting that those involved in livestock management had less social prestige.
Furthermore, Kuzmina (1994:72) cites linguistic studies demonstrating that the Sanskrit word for a permanent village earlier meant a circle of mobile wagon homes, situated together for defensive purposes for an overnight camp (Kuzmina 1994:72).
The likely population of semi-mobile herders represented some 30%–60% of the entire local community, while the other of 40%–70% were inhabitants of the walled settlement. The almost completely excavated kurgan cemetery of Kamennyi Ambar-5 (only two kurgans remain unstudied) yielded about 100 individuals, or about 2%–5% of the total of 4,896±1,960 individuals in four generations who lived at the nearby settlement for 100 years. In other words, no more than 10% of the population was entitled to be buried under the kurgan mound and this proportion can be taken as an estimate of those with elevated social status. Perhaps, these elites were kin, since analysis of the burial patterns suggests sex/age rather than wealth/prestige differentiation between buried individuals within this elite group (Epimakhov and Berseneva 2011; Ventresca Miller 2013). The remaining non-elite members of the permanently resident community, then, represented some 30%–60% of the complete local community, but did not show evidence of standards of living particularly lower than the elites eventually interred in the kurgan.
(…) The buried population in the Sintashta Cemetery is about 80 individuals or only about 2%–3% of the total estimated population. However, these few individuals were buried with extremely rich offerings, like complete chariots, decorations made of precious metals or sacrifices of six horses (equal to about 900 kg of meat), etc. With such a low proportion of the population assigned such high prestige, the Sintashta local community can easily be labeled a local chiefdom. In Pitman and Doonan’s view (2018) the social structure of the chifedom consisted of a chief and his kin at the highest level; warriors, religious specialists, and craftsmen in the middle; and the pastoral community at the bottom level.
In the Bronze Age, the people who comprised the majority of the permanent population were involved in craft activities, including extraction of copper ores, metallurgy, bone, leather, and woodwork. The most important and labor-intensive part of the economy, however, was haymaking. The evidence of hay found in the cultural layer near Kamennyi Ambar supports the idea that animals were fed during the winter. Nowadays, hay cutting is typically done in July-August, the period of most intensive grazing for animals. Thus, the part of the collective that remained in the settlement had to provide the labor force for haymaking.
In the wintertime, the herders returned to the settlements with the herds, and animals were kept inside the walls––a practice which is known archaeologically (Zakh 1995) and ethnographically (Shahack-Gross et al. 2004)––while herders stayed outside in their tents.
In sum, the Sintashta-Petrovka chiefdoms demonstrate a three-part social order. In Kuzmina’s (1994) view, this is similar to the Varna system of ancient India, that consisted of priests (Sansk. Brahmanis), rulers and warriors (Sansk. Kshatriyas), free producers (Sansk. Vaishyas) and laborers and service providers (Sansk. Shudras). In the Sintashta-Petrovka chiefdom, the elite 2%–5% of the population would have consisted of priests and warriors; 48%–55% would have been dependent producers; and 50%–60% would have been herders of lower social rank.
In the case of the Sintashta-Petrovka chiefdoms, the questions of why and how exactly social complexity developed through time and why individuals choose to integrate and give up their independence can be answered as some combination of two necessities: to persist as a larger community in the ecological niche of the newly settled region, and to protect herds from theft.
There is general agreement among researchers that the Sintashta phenomenon had no local roots and originated with a large-scale migration of pastoral communities from Eastern Europe to the marginal area of the Southern Urals. This process forced families to stay together and fueled the necessity in the walled villages for ensuring the reproduction of herds in the extreme climatic conditions of the southern Urals that are colder and dryer than the eastern Black Sea region from which the Sintashta populations are thought to have migrated (Kuzmina 1994, 2007; Anthony 2007; Vinogradov 2011, etc.). At the same time, the herds needed protection from animal and human predators. Probably, the risk of losing animals was a threat to survival that created tensions between neighboring communities, and the Neolithic hunter-gatherers who had populated the Urals before the arrival of Sintashta people could have hunted the domestic animals. Apparently, those who were talented in managing the construction of closely-packed villages surrounded by ditches and walls to protect people and livestock from threats from neighbors, and who otherwise served the community in the newly colonized zone became the most prominent members of society. Theses people formed the core of the Sintashta-Petrovka chiefdom but were not able to accumulate much personal wealth in the form of material possessions. Instead, they acquired high social prestige that could even be transferred to their children (since up to 65% of the buried elite population consists of infants [Razhev and Epimakhov 2005). In this sense, the Sintashta-Petrovka elites were simmilar to their counterparts in the Alto Magdalena of Colombia (Drennan 1995; Gonzalez Fernandez 2007; Drennan and Peterson 2008).
However, this situation did not last longer than 300 years, since after the initial phase of colonization of the Southern Urals was over, the need for social services provided by an elite disappeared and centralized chiefly communities disintegrated into the smaller unfortified villages of the Srubnaya-Alakul’ period.
As I have said many times already (see e.g. here) the outsider pastoralists, forming originally the vast majority of the population, were most likely Pre-Proto-Indo-Iranian speakers of haplogroup R1b-Z2103, and their elite groups (whose inheritance system was based on kinship) probably incorporated gradually Uralic-speaking families of haplogroup R1a-Z93, whose relative importance increased gradually, and then eventually expanded massively with the migrations of Andronovo and Srubna, creating a second Y-chromosome bottleneck that favoured again Z93 subclades. The adaptation of Pre-Proto-Indo-Iranian to the Uralic pronunciation, and the adoption of PII vocabulary in neighbouring Proto-Finno-Ugric bear witness to this process.
Previous research at KA-5 was carried out by A. V. Epimakhov in 1994–1995 and 2002–2003 and resulted in the excavation of three Sintashta culture barrows (kurgans) that produced 35 burial pits and a reported 100 skeletons (Epimakhov, 2002, 2005; Epimakhov et al., 2005; Razhev and Epimakhov, 2004). Seven AMS radiocarbon dates on human remains from the cemetery yielded a date range of 2040–1730 cal. BC (2 sigma), which placed the cemetery within the Sintashta phase of the regional Bronze Age (Hanks et al., 2007). Twelve recently obtained AMS radiocarbon dates, taken from short-lived wood and charcoal species recovered from the Kamennyi Ambar settlement, have provided a date range of 2050–1760 cal. BC (2 sigma). Importantly, these dates confirm the close chronological relationship between the settlement and cemetery for the Middle Bronze Age phase and discount the possibility of a freshwater reservoir effect influencing the earlier dating of the human remains from the Kamennyi Ambar 5 cemetery (Epimakhov and Krause, 2013).
Sintashta cemeteries frequently yield fewer than six barrow complexes and the number of skeletons recovered represents a fraction of the total population that would have inhabited the settlements (Judd et al., 2018; Johnson and Hanks, 2012). Scholars have suggested that only members of higher status were afforded interment in these cemeteries and that principles of social organization structured placement of individuals within central or peripheral grave pits (Fig. 2) (Koryakova and Epimakhov, 2007: 75–81). In comparison with other Sintashta cemeteries that have been excavated, KA-5 provides one of the largest skeletal inventories currently available for study.
The KA-5 (MBA), Bestamak (MBA) and Lisakovsk (LBA) datasets exhibited a wide range of δ13C and δ15N values for both humans and herbivores (Figs. 5 and 6 & Table 8). This diversity in isotopic signals may be evident for a variety of reasons. For example, the range of values may be associated with a broad spectrum of C3 and C4 plant diversity in the ancient site biome or herbivore grazing patterns that included more diverse environmental niche areas in the microregion around the sampled sites. Herders also may have chosen to graze animals in niche areas due to recognized territorial boundaries between settlements and concomitant patterns of mobility. Importantly, data from Bolshekaragansky represents humans with lower δ15N values that are more closely associated with δ15N values of the sampled domestic herbivores (Fig. 6). When the archaeological evidence from associated settlement sites is considered, Bolshekaragansky, Bestamak, Lisakovsk and KA-5 have been assumed to represent populations that shared similar forms of pastoral subsistence economies with significant dietary reliance upon domesticated herbivore meat and milk. Human diets have δ13C values closely related to those of local herbivores in terms of the slope of the trendline and range of values (Fig. 6). Comparatively, the cemetery of Bolshekaragansky (associated with the Arkaim settlement) reflects individuals with trend lines closer to those of cattle and caprines and may indicate a stronger reliance on subsistence products from these species with less use of wild riverine and terrestrial resources. The site of Čiča is significantly different with elevated human δ15N isotopic values and depleted δ13C values indicative of a subsistence regime more closely associated with the consumption of freshwater resources, such as fish. The stable isotopic data in this instance is strongly supported by zooarchaeological evidence recovered from the Čiča settlement and also is indicative of significant diachronic changes from the LBA phases through the Iron Age (Fig. 6).
(…) The isotopic results from KA-5, and recent botanical and archaeological studies from the Kamennyi Ambar settlement, have not produced any evidence for the production or use of domesticated cereals. While this does not definitively answer the question as to whether Sintashta populations engaged in agriculture and/or utilized agricultural products, it does call into serious question the ubiquity of such practices across the region and correlates well with recent archaeological, bioarchaeological, and isotopic studies of human and animal remains from the Southwestern Urals region and Samara Basin (Anthony et al., 2016; Schulting and Richards, 2016). The results substantiate a broader spectrum subsistence diet that in addition to the use of domesticated animal products also incorporated wild flora, wild fauna and fish species. These findings further demonstrate the need to draw on multiple methods and datasets for the reconstruction of late prehistoric subsistence economies in the Eurasian steppes. When possible, this should include datasets from both settlements and associated cemeteries.
Variability in subsistence practices in the central steppes region has been highlighted by other scholars and appears to be strongly correlated with local environmental conditions and adaptations. More comprehensive isotopic studies of human, animal and fish remains are of fundamental importance to achieve more robust and empirically substantiated reconstructions of local biomes and to aid the refinement of regional and micro-regional economic subsistence models. This will allow for a fuller understanding of key diachronic shifts within dietary trends and highlight regional variation of such practices. Ultimately, this will more effectively index the diverse social and environmental variables that contributed to late prehistoric lifeways and the economic strategies employed by these early steppe communities.
Social organization of Sintashta-Petrovka
Interesting to remember now the recent article by Chechushkov et al. (2018) about the social stratificaton in Sintashta-Petrovka, and how it must have caused the long-lasting, peaceful admixture process that led to the known almost full replacement of R1b-L23 (mostly R1b-Z2103) by R1a-Z645 (mostly R1a-Z93) subclades in the North Caspian steppe, coinciding with the formation of the Proto-Indo-Iranian community and language (read my thoughts on this after Damgaard et al. 2018).
Here is another relevant excerpt from Chechushkov et al. (2018), translated from Russian:
The analysis suggests that the Sintashta-Petrovka societies had a certain degree of social stratification, expressed both in selective funeral rituals and in the significant difference in lifestyle between the elite and the immediate producers of the product. The data obtained during the field study suggest that the elite lived within the fortifications, while a part of the population was outside their borders, on seasonal sites, and also in stationary non-fortified settlements. Probably, traces of winter settlements can be found near the walls, while the search for summer ones is a task of a separate study. From our point of view, the elite of the early complex societies of the Bronze Age of the Eurasian steppe originated as a response to environmental challenges that created risks for cattle farming. The need to adapt the team to the harsh and changing climatic conditions created a precedent in which the settled collectives of pastoralists – hunter-gatherers could afford the content and magnificent posthumous celebration of people and their families who were not engaged in the production or extraction of an immediate product. In turn, representatives of this social group directed their efforts to the adoption of socially significant decisions, the organization of collective labor in the construction of settlement-shelters and risked their lives, acting as military leaders and fighters.
Thus, in Bronze Age steppe societies, the formation, development and decline of social complexity are directly related to the intensity of pastoralism and the development of new territories, where collectives had to survive in part a new ecological niche. At the same time, some members of the collective took upon themselves the organization of the collective’s life, receiving in return a privileged status. As soon as the conditions of the environment and management changed, the need for such functions was virtually eliminated, as a result of which the privileged members of society dissolved into the general mass, having lost their lifetime status and the right to be allocated posthumously.
Regarding the special position of the Chicha-1 samples in the change of diet and economy during the Iron Age, it is by now well known that haplogroup N must have arrived quite late to North-East Europe, and possibly not linked with the expansion of Siberian ancestry – or linked only with some waves of Siberian ancestry in the region, but not all of them. See Lamnidis et al. (2018) for more on this.
Also, the high prevalence of haplogroup N among Fennic and Siberian (Samoyedic) peoples is not related: while the latter reflects probably the native (Palaeo-Siberian) population that acquired their Uralic branch during the MLBA expansions associated with Corded Ware groups, the former points to the expansion of Fennic peoples into Saamic territory (i.e. after the Fenno-Saamic split) as the most likely period of expansion of N1c1-L392 subclades (see known recent bottlenecks among Finns, and on Proto-Finnic dialectalization).
Probably related to these late incomers are the ancient DNA samples from the Sargat culture during the Iron Age, which show the arrival of N subclades in the region, replacing most – but not all – R1a lineages (see Pilipenko et al. (2017)). Regarding the site of Chicha-1, the following are relevant excerpts about the cultural situation that could have allowed for such stepped, diachronic admixture events in Northern Eurasia, from the paper Stages in the settlement history of Chicha-1: The Results of ceramic analysis, by Molodin et al. (2008):
The stratigraphic data allows us to make the following inference: originally, the settlement was inhabited by people bearing the Late Irmen culture. Later, the people of the Baraba trend of the Suzgun culture arrived at the site (Molodin, Chemyakina, 1984: 40–62). The Baraba-Suzgun pottery demonstrates features similar to what has been reported from the sites of the transitional Bronze to Iron Age culture in the pre-taiga and taiga zones in the Irtysh basin (Potemkina, Korochkova, Stefanov, 1995; Polevodov, 2003). The major morphological types are slightly and well-profiled pots with a short throat. (…)
During the following stage of development of the site, the Chicha population increased with people who practiced cultures others than those noted in earlier collections. The ceramic materials from layer 5 provide data on possible relationships. In addition to migrants from northwestern regions practicing the Suzgun culture, there were people bearing the Krasnoozerka culture. Available data also suggests that people from the northern taiga region with the Atlym culture visited the site.
However, people from the west and southwest represent the greatest migration to the region under study. In all likelihood they moved from the northern forest-steppe zone of modern Kazakhstan and practiced the Berlik culture. The spatial distribution analysis of the Chicha-1 site suggests that the Berlik population was rather large. The Berlik people formed a single settlement with the indigenous Late Irmen people and apparently waged certain common economic activities, but preserved their own ethnic and cultural specificity (Molodin, Parzinger, 2006: 49–55). Judging by the data on the chronological sequence of deposited artifacts, migration took place roughly synchronously, hence Chicha-1 became a real cultural and economic center.
(…) In sum, the noted distribution of ceramics over the culture-bearing horizons suggests that beginning with layer 5, traditions of ceramic manufacture described above were practiced, hence the relevant population inhabited the site. Apparently, there were two predominant traditions: the local Late Irmen cultural tradition and the Berlik tradition, which was brought by the immigrants. The Late Irmen people mostly populated the citadel, while the Berlik immigrants inhabited the areas to the east and the north of the citadel.
The stratigraphic data also suggest that the Early Sargat ceramics emerged at the site likely as a part of the Late Irmen tradition (…) Early Sargat ceramics is apparently linked with the Late Irmen tradition. Artifacts associated with the Sargat culture proper have been found in several areas of Chicha-1 (e.g., in excavation area 16). However, the Sargat people appeared at the site after it had been abandoned by its previous inhabitants, and had eventually become completely desolated. This happened no earlier than the 6th cent. BC, possibly in the 5th cent. BC (in fact, the radiocarbon dates for that horizon are close to the turn of the Christian era).
We tested the hypothesis that the purported unstable climate in the South Urals region during the Middle Bronze Age (MBA) resulted in health instability and social stress as evidenced by skeletal response.The skeletal sample (n = 99) derived from Kamennyi Ambar 5 (KA-5), a MBA kurgan cemetery (2040-1730 cal. BCE, 2 sigma) associated with the Sintashta culture. Skeletal stress indicators assessed included cribra orbitalia, porotic hyperostosis, dental enamel hypoplasia, and tibia periosteal new bone growth. Dental disease (caries, abscess, calculus, and periodontitis) and trauma were scored. Results were compared to regional data from the nearby Samara Valley, spanning the Early to Late Bronze Age (EBA, LBA).Lesions were minimal for the KA-5 and MBA-LBA groups except for periodontitis and dental calculus. No unambiguous weapon injuries or injuries associated with violence were observed for the KA-5 group; few injuries occurred at other sites. Subadults (<18 years) formed the majority of each sample. At KA-5, subadults accounted for 75% of the sample with 10% (n = 10) estimated to be 14-18 years of age.Skeletal stress markers and injuries were uncommon among the KA-5 and regional groups, but a MBA-LBA high subadult mortality indicates elevated frailty levels and inability to survive acute illnesses. Following an optimal weaning program, subadults were at risk for physiological insult and many succumbed. Only a small number of individuals attained biological maturity during the MBA, suggesting that a fast life history was an adaptive regional response to a less hospitable and perhaps unstable environment
The low frequencies of violence-related trauma contrast sharply to the epidemic of skeletal violence observed during the Iron Age (8th-2nd centuries BC) at other regional sites, notably Aymyrlyg (Murphy, 2003). The paucity of weapon-related injuries among the Bronze Age groups may be the outcome of many factors. While weapons and chariots did exist, they could have had multi-functional contexts aside from warfare. Individuals killed in warfare may not be present if bodies were abandoned on battlefields or disposed of where the individual died. Alternatively, warfare may have involved the capture of humans in addition to material resources, such as herds or weapons, leaving no skeletal trace of physical violence (Martin, Harrod, & Fields, 2010; Wilkinson, 1997). Trauma analysis is further complicated by the lack of soft tissue, which is the target for those attempting to kill or immobilize their opponent (Judd, 2008; Judd & Redfern, 2012), and it is possible that violence-related injuries or burns sustained from metallurgy were absent because only the soft tissue was affected. The skeletal evidence for trauma is minimal at KA-5 and its contemporary sites, which may be partially attributed to the less than desirable preservation of the collections. Based on the skeletal material available, internal or external social tensions resulting in altercations are not supported.
The lack of material or skeletal evidence for warfare has encouraged a more optimistic interpretation of Steppe community relations living with environmental instability. Herding camps, such as that at Peschanyi Dol, provided evidence for assorted groups utilizing the site based on the clay sources of ceramic sherds found in the camp’s trash pit (Anthony, Brown, Kuznetsov, & Mochalov, 2016a). Anthony et al. (2016a, 2016b) suggested that herders shifted according to a schedule that permitted several settlements to use prime camp sites. They proposed a cooperative region-wide organization of groups that worked together in three key activities: mining, summer herding, and winter wolf-dog rituals (Anthony et al., 2016a). A similar regional social arrangement may have existed in the KA-5 vicinity and accords with the livestock management models proposed by Stobbe and colleagues (2016).
Using the available sampling, and based on the absence of skeletal stress markers (in combination with the high subadult mortality among Sintashta samples), the study concludes that the available data cannot support the traditional view that MBA was a period of social strife.
Since other Samara Valley samples do not follow a similar trend with Sintashta, a homogeneous, long-term relationship with the environment is suggested for this culture, independent of climatic shift or unpredictability.
My limited, speculative proposal of how this lineage replacement took place was based precisely on this traditional description of partially isolated, warring communities:
The process by which this cultural assimilation happened in the Sintashta-Petrovka region, given the presupposed warring nature of their contacts, remains unclear. It is conceivable, in a region of highly fortified settlements, to think about alliances of different groups against each other, akin to the situation found in Bronze Age Europe: a minority of Abashevo chiefs and their families would dominate over certain fortified settlements and wage war against other, neighbouring tribes.
After a certain number of generations, the most successful settlements would have replaced the paternal lineages of the region – with only a slight drift to steppe admixture observed in PCA compared to Corded Ware –, while the majority of the population in these settlements – including females, commoners and slaves – retained the original Poltavka culture. R1b1a1a2a2-Z2103 lineages were mostly replaced in the region by haplogroup R1a1a1b2-Z93, as demonstrated by the later expansion of its subclades with Andronovo and Srubna cultures, and by present-day distribution of R1a1a1b2-Z93 lineages in Eurasia.
Now we see more proof for a likely bottleneck in a more peaceful (or, rather, cooperative) region, as recently described by Anthony. In fact, if you take a look at the sampling of the paper (which is obviously not randomised), Potapovka – coeval with Sintashta, but genetically more similar to the earlier Yamna and Poltavka – follows a less steep demographic distribution than Sintashta, with succeeding Srubna (which shows a marked shift toward the Corded Ware cluster) maintaining a similar demographic pattern…
I guess the answer is probably between both positions, war and environment; the main issue is which one was the most important contributing factor. If we judged the whole picture solely by the samples studied in this paper, the answer would be the environment.