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Post by Admin on Oct 14, 2019 18:34:32 GMT
3. Discussion The gene pool of modern Europeans has been shaped by a number of prehistoric events and migrations. The CWC horizon represents one of the major demographic processes in the northern areas of Europe as this is associated with the first occurrence of steppe-related ancestry. Our results have implications for our view on the demographic development associated with the CWC in general, and the Scandinavian variety of the BAC specifically.  People buried in CWC contexts display a genetic ancestry component that was not present in northern and central Europe prior to the third millennium BCE. This ancestry component, often called ‘steppe ancestry’, probably traces back to the ‘Yamnaya expansion’ of herders associated with the Yamnaya Culture that dispersed into Eastern Europe from the Pontic–Caspian steppe around 3000 BCE [1,2,32]. This component makes up the largest proportion of the genetic ancestry in all sequenced BAC/CWC individuals around the Baltic Sea: from the modern-day countries Estonia, Latvia, and Lithuania in the east; Poland and Germany in the southwest; and Denmark and Sweden in the northwest (figure 1b). One important observation is that the earliest CWC individuals analysed to date had the highest proportion of steppe ancestry (greater than 90%), while this proportion decreased in later individuals (figure 2). This suggests a gradual process of admixture between incoming groups and local groups, such as the FBC groups in northern Europe that traced most of their genetic ancestry to Anatolian Neolithic farmers. This process was driven by incoming males mixing mainly with local females [5,7,45,46]. The admixture process is evident across the entire distribution of the CWC, even in regions such as the eastern Baltic coast where no FBC groups or genetically related groups have been found. Consequently, farmer-related ancestry must have arrived in the eastern Baltic region via migrations more recent than 2500 BCE [7–9]. Possibilities include a generally large exchange network across the entire CWC horizon or specific migrations into the eastern Baltic region. Potential source regions for the latter could be modern-day Poland or Sweden, where FBC groups predating the arrival of the CWC are found. The paternal lineages found in the BAC/CWC individuals remain enigmatic. The majority of individuals from CWC contexts that have been genetically investigated this far for the Y-chromosome belong to Y-haplogroup R1a, while the majority of sequenced individuals of the presumed source population of Yamnaya steppe herders belong to R1b [1,2]. R1a has been found in Mesolithic and Neolithic Ukraine [1,31,32]. This opens the possibility that the Yamnaya and CWC complexes may have been structured in terms of paternal lineages—possibly due to patrilineal inheritance systems in the societies [47,48]—and that genetic studies have not yet targeted the direct sources of the expansions into central and northern Europe.  The Scandinavian Middle Neolithic megalithic tombs are associated with the FBC. However, their reuse, indicated by artefacts common to the BAC and later periods, has been noted [17]. The oll007 individual, buried in the FBC-associated Öllsjö megalithic tomb, but radiocarbon dated to the time period of the BAC, is genetically very similar to individuals from BAC contexts (e.g. Bergsgraven and Viby). Thus, although archaeologically the reuse of megalithic tombs was assumed earlier [17], our study may be the first direct link (using genetics) showing that indeed FBC-associated megalithic tombs were used as burial places also for the people of the BAC. This could possibly also extend to the Danish Single Grave Culture (SGC) [49], as RISE61 [2], a male buried in the Kyndeløse passage grave and with a radiocarbon date overlapping with the BAC/CWC/SGC time period, also displays some steppe ancestry. The BAC replaces the FBC in the southern parts of Scandinavia and was previously assumed to have been a cultural adaptation of existing groups [12,17]. We show in multiple individuals from different parts of Scandinavia that these groups (BAC) were part of the general CWC horizon, i.e. they too are the result of admixture of different groups tracing parts of their ancestry to European hunter–gatherers, Anatolian Neolithic farmers, and Yamnaya steppe herders. This implies that BAC groups were not the direct descendants of any of the groups that lived in the area previously or even contemporaneously—i.e. the groups associated with FBC or the PWC. We also note that the BAC group does not have a particular genetic connection with other eastern Baltic groups such as the Combed Ceramic Culture. The mixed ancestry of individuals in BAC contexts is evident across all autosomal analyses, as well as in mitochondrial haplogroups, but the paternal haplogroups stand out to some extent, showing a deviant, more extreme, pattern. This Y-chromosome pattern is, however, consistent with a male sex-biased migration and admixture process among the Yamnaya, and later CWC, groups [7,39,45,50]. As the individuals of the BAC complex cannot be modelled as direct genetic descendants of FBC or PWC groups, a migration into Scandinavia of people with a large proportion of steppe ancestry must have taken place. We were not able to find unambiguous evidence for a specific source population by testing all other individuals associated with the CWC that have been genomically investigated as potential ancestors. The Scandinavian BAC group has more Neolithic farmer ancestry than pre-2600 BCE individuals in CWC contexts from the southern or eastern Baltic coast, suggesting that they mixed with an FBC group. This process could have happened in Scandinavia or before arriving in Scandinavia. On the one hand, the CWC people were mainly bound to travels on land, which would favour migration from central Europe into modern-day Denmark and Sweden (e.g. [16]). On the other hand, there is evidence for technological exchange (pottery craft) crossing the Baltic Sea in this time period [20,51], which may or may not be associated with gene flow. Finally, the genetic data from BAC contexts are still limited, and the patterns of gene flow that we observe are consistent with both a single migration event into Scandinavia and with a continuous process with an extensive network of social and technological exchange. Future studies will refine our understanding of the social, geographical, and temporal dynamics during this important period in European prehistory. Published:09 October 2019 doi.org/10.1098/rspb.2019.1528 |
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Post by Admin on Apr 15, 2020 21:34:41 GMT
Mitochondrial genomes reveal an east to west cline of steppe ancestry in Corded Ware populations Anna Juras, Maciej Chyleński, Edvard Ehler, Helena Malmström, Danuta Żurkiewicz, Piotr Włodarczak, Stanisław Wilk, Jaroslav Peška, Pavel Fojtík, Miroslav Králík, Jerzy Libera, Jolanta Bagińska, Krzysztof Tunia, Viktor I. Klochko, Miroslawa Dabert, Mattias Jakobsson & Aleksander Kośko Scientific Reports volume 8, Article number: 11603 (2018) Abstract From around 4,000 to 2,000 BC the forest-steppe north-western Pontic region was occupied by people who shared a nomadic lifestyle, pastoral economy and barrow burial rituals. It has been shown that these groups, especially those associated with the Yamnaya culture, played an important role in shaping the gene pool of Bronze Age Europeans, which extends into present-day patterns of genetic variation in Europe. Although the genetic impact of these migrations from the forest-steppe Pontic region into central Europe have previously been addressed in several studies, the contribution of mitochondrial lineages to the people associated with the Corded Ware culture in the eastern part of the North European Plain remains contentious. In this study, we present mitochondrial genomes from 23 Late Eneolithic and Bronze Age individuals, including representatives of the north-western Pontic region and the Corded Ware culture from the eastern part of the North European Plain. We identified, for the first time in ancient populations, the rare mitochondrial haplogroup X4 in two Bronze Age Catacomb culture-associated individuals. Genetic similarity analyses show close maternal genetic affinities between populations associated with both eastern and Baltic Corded Ware culture, and the Yamnaya horizon, in contrast to larger genetic differentiation between populations associated with western Corded Ware culture and the Yamnaya horizon. This indicates that females with steppe ancestry contributed to the formation of populations associated with the eastern Corded Ware culture while more local people, likely of Neolithic farmer ancestry, contributed to the formation of populations associated with western Corded Ware culture. Introduction The forest-steppe north-western Pontic region of the middle Dniester and Prut interfluve was a place of contact and exchange routes between human populations inhabiting the drainages of the Black and Baltic Seas from around 4,000 to 2,000 BC1. During this time, the region was occupied by forest-steppe populations attributed to the Eneolithic (3350–3200 BC)1 and the succeeding Bronze Age groups associated with the Yamnaya - Pit Grave (dated to 3,100/3,050–2,800 BC)2, the Catacomb (2,600–2,200 BC), the Babyno (2,200–1,700/1,600 BC) and the Noua (1,600–1,200/1,100 BC) cultures3,4. Although there were cultural differences between these populations, they all shared a similar nomadic lifestyle, pastoral economy and barrow burial rituals5. Some of the rounded burial mounds founded by Eneolithic people were reused by the succeeding cultural entities of the Early Bronze Age1, while other kurgans shared a mix of characteristics from both the Late Eneolithic and the Early Bronze Age funeral rites1,4. According to some researchers6,7,8,9, the Yamnaya culture originated in the Volga-Ural interfluve and spread across the Pontic-Caspian steppe between 3,300–2,800 BC. This cultural expansion led to the development of a less homogenous group of cultural entities belonging to the so-called Yamnaya Cultural-Historical Area/Unity10,11, hereafter reffered to as ‘the Yamnaya horizon’12. People associated with the eastern Yamnaya culture spread across the steppe to the east of Don River. With no settlements identified in this area, they were thought to be more mobile because of their supposed nomadic profile of economy stimulated by environmental conditions of Kuban – North Caspian steppes13. On the other hand, Yamnaya settlements were found more frequently in the forest-steppe Pontic regions, to the west of Don River, probably due to favorable environmental conditions12. One of the most widely debated issues, which emerged in connection to studies on the Yamnaya horizon, was the relationship between the people associated with the Yamnaya and the Central European final Neolithic cultures, in particular the Corded Ware culture (dated to 2800–2300 BC)14. Archaeological records point to some similarities between the Corded Ware culture and the steppe, including shared practices such as the barrow structures and burial rituals2. Adoption of a herding economy based on mobility through the use of wagons and horses, was also proposed as a common trait associated with both the Yamnaya and Corded Ware cultures12. These observations led some researchers to suggest a possible Yamnaya migration toward the Baltic drainage basin15 or a massive westward expansion of the steppe pastoralist people, representing the “barrow culture”, into the North European Plain12,16. However, specific burial customs of the Yamnaya people, such as the scarcity of grave goods, the presence of ochre, and the building of specific wooden roof or floor structures, generated opposing arguments emphasizing the significant differences between the Corded Ware and steppe cultures2. Recent ancient DNA (aDNA) studies suggest that the large-scale migration of steppe populations associated with the Yamnaya horizon contributed to the formation of the final Neolithic central European populations14,17,18. Moreover, people associated with the Yamnaya horizon have been shown to be an admixed population with ancestry from Eastern hunter-gatherers and Caucasus hunter-gatherers14,17,19,20. Ancient DNA data indicate that the Neolithic populations from Central Europe already had the ‘Caucasus’ genetic component from the eastern steppes around 2,500 BC. Presence of this genetic component was used as an argument for the expansion of people from the Pontic-Caspian region into the central Europe14,17. X chromosome sequence data suggest that it was primarily males who participated in these migrations21,22 and contributed to the formation of the people associated with the Corded Ware culture14,17. Based on the X chromosome data obtained mainly from western Corded Ware-associated individuals, it was estimated that, for every female, ~4–15 males migrated from the steppe21. Subsequently, the Yamnaya genetic component spread across Bronze Age Europe and West Asia14. Although questions concerning the migrations of nomadic people have been addressed by a number of studies19,23,24, the contribution of mitochondrial lineages associated with the Yamnaya horizon to the formation of people associated with the Corded Ware culture from the eastern part of the North European Plain, especially from the region of modern Poland, remains contentious. To investigate the maternal relationship between these two groups, we generated complete mitochondrial genomes from the representatives of Late Eneolithic and Early Bronze Age populations from the north-western Pontic region, including Yamnaya groups and individuals associated with the Corded Ware culture from the eastern part of the North European Plain.  Figure 1 Location of archaeological sites used in this study. Extent of the Corded Ware culture (CWC) region and the Yamnaya horizon (YAM) are marked in yellow and orange, respectively. Groups of Corded Ware culture, including western (CWW), eastern (CWPlM) and Baltic (CWBal), and groups of Yamnaya horizon including western (YAW) and eastern (YAE), are marked in circles. Numbers represent archaeological sites from which analyzed individuals came from: (1) Držovice; (2) Malżyce; (3) Książnice; (4) Hubinek; (5) Klembivka; (6) Porohy; (7) Pidlisivka; (8) Prydnistryanske. The map was created using QGIS 2.12.247. Ancient DNA was extracted from the Corded Ware culture individuals excavated in south-eastern Poland (N = 12) and Moravia (N = 3). Late Eneolithic (N = 5) and Bronze Age human remains (N = 25) originated from western Ukraine and came from the Yampil barrow cemetery complex located in the north–western region of the Black Sea. Bronze Age individuals were associated with different archaeological cultures, including Yamnaya (N = 14), Catacomb (N = 2), Babyno (N = 4) and Noua (N = 5). The sampling localities are shown in Fig. 1. Detailed information about sampled individuals can be found in Table 1, Supplementary Information Text (Materials) and Supplementary Table S1. |
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Post by Admin on Apr 16, 2020 8:00:13 GMT
Results Ancient mitochondrial genomes Out of the 45 analyzed samples, we successfully obtained 23 mtDNA genomes, belonging to individuals associated with the Corded Ware culture (N = 11), and with the Late Eneolithic (N = 3) and Bronze Age (N = 9) from western Pontic region (Table 1 and Supplementary Table S1). Eleven of the mtDNA genomes were retrieved from the Illumina shotgun screening data with the depth-of-coverage (DoC) ranging between ca. 5.4× to 64×. The remaining twelve mtDNA genomes were retrieved from the hybridization capture enrichment followed by PGM Ion Torrent sequencing, and yielded DoC ranging between 11× to 194×. Nucleotide misincorporation patterns assessed using MapDamage showed characteristic aDNA damage involving C-T and G-A transitions at the 5′ and 3′ ends of DNA fragments, respectively (Supplementary Fig. S26). Schmutzi estimations conducted for each individual showed low levels of contaminations (1–3%) (Supplementary Table S1). Additionally, we found no contamination in the extraction blanks and PCR negative controls. The mitochondrial DNA data are deposited in GenBank under accession numbers MH176332, MH176333, MH17635-MH176355. In general, the individuals associated with the Corded Ware culture and the Yamnaya horizon were assigned to mtDNA lineages common among modern-day west Eurasian groups (hgs H, I, J, T, U2, U4, U5, W, X). Individuals associated with the Eneolithic and Yamnaya cultures were assigned to hgs U2e1a1, U5a2b, H2a1 and U5a1i1, U4c1, W3a1, W3a1a, respectively (Table 1 and Supplementary Table S1). Other Bronze Age individuals from the western Pontic region belonged to hg X4 (two individuals associated with Catacomb culture) and J2b1a, J1c2m, H1e (three individuals associated with Babyno culture). Individuals associated with the Corded Ware culture were assigned to hgs H (H6a, H15a1, H2a2, H1e), U4 (U4b1a1a, U4a2f), W5b, U5a1b, I4a and T2e (Table 1 and Supplementary Table S1). Genetic distances between ancient populations The PCA results described 50.62% of the variability and were combined with the k-means clustering (with the k value of 5 as the best representation of the data, at the average silhouette of 0.2608) (Figs 2 and S27). Based on these results individuals associated with the western and eastern Yamnaya horizon (YAE and YAW in Fig. 2) were grouped within a cluster consisting of populations from central Eurasia and Europe (blue cluster) including people associated with eastern Corded Ware culture (CWPlM) and Baltic Corded Ware culture (CWBal). This cluster did not contain any populations linked with early Neolithic farmers (red), or hunter-gatherers (green and yellow). On the other hand, k-means clustering linked the western Corded Ware culture-associated population (CWW) with Near East and Neolithic farmer ancestry groups from western and central Europe.  Figure 2 PCA based on mitochondrial DNA haplogroup frequencies with k-means clustering. The two principal components explained 50.62% of the total variance. Loading vectors, representing mitochondrial haplogroup contributions, are highlighted as grey arrows. Populations are grouped into four clusters according to k-means. Population abbreviations are as follows: BABA – Bronze Age Balkans; CAT – Catacomb Culture; CWPlM – Corded Ware Culture from Poland and Moravia; CWBal – Baltic Corded Ware Culture; IAK – Iron Age Kazakchstan; IASI – Iron Age Syberia – Aldy Bel Culture; SCA – Scytho-Siberian Pazyryk (Altai); SCR – Rostov-Scythians, Samara; SCU – Scythians from Moldova and Ukraine; TAG – Tagar Culture; GAC – Globular Amphora Culture; YAW – western Yamnaya horizon population from Ukraine and Bulgaria; YAE – eastern Yamnaya horizon population; BAC - Baalberge Culture; BANE - Bronze Age Near East; BEC - Bernburg Culture; CHAHu – Chalcolithic Hungary; CWW – Corded Ware Culture west; CHABA - Chalcolitic Balkans; EBAG - Early Bronze Age Germany; FBC – Funnel Beaker Culture; IAG – Iron Age Germany; MNG – Middle Neolithic Germany; LBK – Linear Pottery Culture; LDN – Late Danubian Neolithic; MIC - Minoans; NEBA - Neolithic Balkans; PPNE - Pre-Pottery Near East; SCG - Schöningen group; SMC - Salzmünde Culture; AND – Andronovo Culture; BASI – Bronze Age Siberia; PWC – Pitted Ware Culture; HGE – eastern hunter-gatherers; NEUk- Neolithic Ukraine; HGS – southern hunter-gatherers; HGBal – Baltic hunter-gatheres; HGC – central huther-gatherers. Detailed descriptions and references of comparative populations are provided in Supplementary Table S2. The k-means clustering on t-SNE results was consistent with the PCA results, although the approach to dimension reduction of the t-SNE algorithm is completely different than that of the PCA. Scatterplot of populations colored according to the k-means k = 7 (average silhouette 0.5158) (Fig. 3) represented the main components of European genetic ancestry. Individuals associated with western Corded Ware culture (CWW in Fig. 3) clustered with the early Neolithic Farmer ancestry group (dark green), while people associated with CWPlM from this study and CWBal showed greater affinity to the eastern European cluster (dark blue) which included mostly steppe populations associated with the Yamnaya horizon, Srubnaya, and western Scythians. Another clearly defined cluster was the central-western Asia group (red) with Andronovo, Catacomb and Siberian populations. Iron Age central Asia cluster (light green) consisted mostly of Altai and Russian Scythians and populations from Siberia and Kazakhstan. The strong hunter-gatherer ancestry cluster (light blue) included the hunter-gatherers and Neolithic populations with major hunter-gatherers component associated with the Neolithic Ukraine and the Scandinavian Pitted Ware culture. The last two clusters comprised of populations linked with the post-Linear Pottery culture from central Europe and other Middle and Late Neolithic groups from Europe (yellow and purple).  Figure 3 Pairwise mtDNA-based FST54 values (Supplementary Table S4), visualized on MDS using the raw non-linearized FST (stress value = 0.099) (Fig. 4), also supported the PCA results and indicated that western and eastern Yamnaya horizon groups (YAW and YAE) were closer to people associated with the eastern Corded Ware culture (CWPlM) (FST = 0.00; FST = 0.01, respectively; both p > 0.05) and Baltic Corded Ware culture (CWBal) (FST = 0.00; FST = 0.00, respectively; both p > 0.05), than to populations associated with the western Corded Ware culture (CWW) (FST = 0.047 and FST = 0.059, respectively; both statistically significant p < 0.05). Western and eastern Yamnaya horizon groups also showed close genetic affinity to the Iron Age western Scythians (SCU) (FST = 0.0022 and FST = 0.006, respectively, both p > 0.05). The most distant populations to the Yamnaya horizon groups were western hunter-gatherers (HGW) (FST = 0.23 and FST = 0.15, p < 0.001; see Supplementary Table S4). |
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Post by Admin on Apr 16, 2020 19:51:35 GMT
 Figure 4 The FST-based MDS reflected the general European population history in the post-LGM period as the three highest FST scores were detected between western hunter-gatherers (HGW) and people associated with Linear Pottery culture (LBK) (FST = 0.33, p < 0.001), between eastern hunter-gatherers (HGE) and Baltic hunter-gatherers (HGBal) (FST = 0.35, p < 0.05), and between western (HGW) and eastern hunter-gatherers (HGE) (FST = 0.36, p < 0.05) (Fig. 4 and Supplementary Table S4). The Yamnaya horizon groups (YAE and YAW) were placed centrally between northern hunter-gatherers (HGN) and Neolithic farmers (LDN), in direct proximity to the Bronze and Iron Age populations from Eastern Europe (SCU, BARu, SRU) and close to individuals associated with eastern and Baltic Corded Ware culture (Fig. 4). We investigated the within- and between-group variability using an AMOVA analysis. Concentrating on the eastern and western Corded Ware groups, we found the best variability distribution when the individuals associated with the western Corded Ware culture (CWW in Supplementary Table S5) were grouped together with the Middle Neolithic/Bronze Age Central Europe groups, while individuals associated with the eastern and Baltic Corded Ware culture (CWPlM, CWBal), and Yamnaya horizon groups (YAW and YAE) clustered together with the eastern Europe populations (from the Middle Neolithic-Bronze Age) (4.68% of variability among groups, 3.04% among populations within groups). Discussion By analyzing ancient mitochondrial genomes, we show that people from the eastern and western Corded Ware culture were genetically differentiated. Individuals associated with the eastern Corded Ware culture (from present day Poland and the Czech Republic) shared close maternal genetic affinity with individuals associated with the Yamnaya horizon while the genetic differentiation between individuals associated with the western Corded Ware culture (from present-day Germany) and the Yamnaya horizon was more extensive. This decreasing cline of steppe related ancestry from east to west likely reflect the direction of the steppe migration. It also indicates that more people with steppe-related ancestry, likely both females and males, contributed to the formation of the population associated with the eastern Corded Ware culture. Similarly, closer genetic affinity to populations associated with Yamnaya horizon can be observed in Baltic Corded Ware groups, which confirms earlier indications of a direct migrations from the steppe not only to the west but also to the north, into the eastern Baltic region18,19,55. The mitochondrial data further suggests that with increased distance from the source populations of the steppe, the contribution of local people increase, which is seen as an increase of maternal lineages of Neolithic farmer ancestry in individuals associated with the western Corded Ware culture. Among the analyzed samples, we identified two Catacomb culture-associated individuals (poz220 and poz221) belonging to hg X4. They are the first ancient individuals assigned to this particular lineage. Haplogroup X4 is rare among present day populations and has been found only in one individual each from Central Europe, Balkans, Anatolia and Armenia56,57. Moreover, we have reported mtDNA haplotypes that might be associated with the migration from the steppe and point to genetic continuity in the north Pontic region from Bronze Age until the Iron Age. These haplotypes were assigned to hgs U5, U4, U2 and W3. MtDNA hgs U5a and U4, identified in this study among Yamnaya, Late Eneolithic and Corded Ware culture-associated individuals, have previously been found in high frequencies among northern and eastern hunter-gatherers19,23,28,55,58,59. Moreover, they appeared in the north Pontic region in populations associated with Mesolithic (hg U5a)45, Eneolithic (Post-Stog) (hg U4)24, Yamnaya (hgs U5, U5a)24, Catacomb (hgs U5 and U5a)24 and Iron Age Scythians (hg U5a)60, suggesting genetic continuity of these particular mtDNA lineages in the Pontic region from, at least, the Bronze Age. Hgs U5a and U4-carrying populations were also present in the eastern steppe, along with individuals from the Yamnaya culture from Samara region14,17, the Srubnaya23 and the Andronovo from Russia14. Interestingly, hg U4c1 found in the Yamnaya individual (poz224) has so-far been found only in two Bell Beaker- associated individuals61 and one Late Bronze Age individual from Armenia14, which might suggest a steppe origin for hg U4c1. A steppe origin can possibly also be assigned to hg U4a2f, found in one individual (poz282) but not reported in any other ancient populations to date, and to U5a1- the ancestral lineage of U5a1b, reported for individual poz232, which was identified not only in Corded Ware culture-associated population from central and eastern Europe55,61 but also in representatives of Catacomb culture from the north Pontic region24, Yamnaya from Bulgaria and Russia17,46, Srubnaya23 and Andronovo62-associated groups. Hg U2e, reported for Late Eneolithic individual (poz090), was also identified in western Corded Ware culture-associated individual23 and in succeeding Sintashta14, Potapovka and Andronovo23 groups, suggesting possible genetic continuity of U2e1 in the western part of the north Pontic region. Hgs W3a1 and W3a1a, found in two Yamnaya individuals from this study (poz208 and poz222), were also identified in Yamnaya-associated individuals from the Russia Samara region17 and later in Únětice and Bell Beaker groups from Germany61,63, supporting the idea of an eastern European steppe origin of these haplotypes and their contribution to the Yamnaya migration toward the central Europe. The W3a1 lineage was not identified in Neolithic times and, thus, we assume that it appeared in the steppe region for the first time during the Bronze Age. Notably, hgs W1 and W5, which predate the Bronze Age in Europe, were found only in individuals associated with the early Neolithic farmers from Starčevo in Hungary (hg W5)64, early Neolithic farmers from Anatolia (hg W1-T119C)23, and from the Schöningen group (hg W1c)61 and Globular Amphora culture from Poland (hg W5)45. This study is the first to present mitochondrial genome data from the population associated with Corded Ware culture from the south-eastern part of present-day Poland. As this area is geographically close to the steppe region, it provides us with a better picture of the early steppe migration between 3,000 and 2,500 BC. Although our results indicate a contribution of females as well as males to the formation of populations associated with eastern Corded Ware culture, more detailed studies of X chromosome data are needed to clearly resolve female and male migrations, especially between the western Pontic steppe and the eastern part of the North European Plain. Conclusions Ancient mitochondrial genome data from the western Pontic region and, for the first time, from the south-eastern part of present day Poland, show close genetic affinities between populations associated with the eastern Corded Ware culture and the Yamnaya horizon. This indicates that females had also participated in the migration from the steppe. Furthermore, greater mtDNA differentiation between populations associated with the western Corded Ware culture and the Yamnaya horizon points to an increased contribution of individuals with a maternal Neolithic farmer ancestry with increasing geographic distance from the steppe region, forming the population associated with the western Corded Ware culture. Among the analyzed samples, we identified, for the first time in ancient populations, two Catacomb culture-associated individuals belonging to the now-rare mtDNA hg X4. Juras, A., Chyleński, M., Ehler, E. et al. Mitochondrial genomes reveal an east to west cline of steppe ancestry in Corded Ware populations. Sci Rep 8, 11603 (2018). |
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Post by Admin on May 2, 2020 19:55:52 GMT
Corded Ware cultural complexity uncovered using genomic and isotopic analysis from south-eastern Poland
Anna Linderholm, Gülşah Merve Kılınç, Anita Szczepanek, Piotr Włodarczak, Paweł Jarosz, Zdzislaw Belka, Jolanta Dopieralska, Karolina Werens, Jacek Górski, Mirosław Mazurek, Monika Hozer, Małgorzata Rybicka, Mikołaj Ostrowski, Jolanta Bagińska, Wiesław Koman, Ricardo Rodríguez-Varela, Jan Storå, Anders Götherström & Maja Krzewińska
Scientific Reports volume 10, Article number: 6885 (2020)
Abstract
During the Final Eneolithic the Corded Ware Complex (CWC) emerges, chiefly identified by its specific burial rites. This complex spanned most of central Europe and exhibits demographic and cultural associations to the Yamnaya culture. To study the genetic structure and kin relations in CWC communities, we sequenced the genomes of 19 individuals located in the heartland of the CWC complex region, south-eastern Poland. Whole genome sequence and strontium isotope data allowed us to investigate genetic ancestry, admixture, kinship and mobility. The analysis showed a unique pattern, not detected in other parts of Poland; maternally the individuals are linked to earlier Neolithic lineages, whereas on the paternal side a Steppe ancestry is clearly visible. We identified three cases of kinship. Of these two were between individuals buried in double graves. Interestingly, we identified kinship between a local and a non-local individual thus discovering a novel, previously unknown burial custom.
Introduction
The Neolithic Stone Age of continental Europe saw important demographic changes and population events which in recent years have been demonstrated by numerous archaeogenomic studies1,2,3,4,5,6. The genetic ancestry, affinity and admixture processes between human groups have been traced by analyses of individuals from different time periods and geographical contexts which contextually are associated to cultural complexes with differing lifeways, burial customs and material culture expressions. The identification of the demographic event and successive development associated with the Neolithization of Europe demonstrated the importance of mobility and migration in the process of population turnover and transition towards changed lifeways (e.g.7,8,9). The process took different paths in different areas of Europe which is evident in the admixture patterns between the hunter-gatherer (HG) and the farming groups but also between farming and pastoralist groups, depending on the time period. The significant transitional process around 3000 cal BCE and the appearance of the (Pontic Steppe) Yamnaya cultural complex in eastern Europe is associated with a wave of migration from East that had marked impact on the demographic (a Steppe ancestry component), cultural and social as well as linguistic development in the third Millennium BCE1,10.
The appearance of the Yamnaya (around 3100-3000 BCE) complex in southern Europe roughly coincides with the appearance of the Corded Ware complex (CWC) (around 2900-2800 BCE) further to the North. Earlier archaeogenomic analyses have shown that the CWC individuals, exhibit Steppe ancestry1,10,11,12. Contemporaneous individuals analysed from this region (i.e. central Europe) have however shown a varying degree of Steppe ancestry1,10. This component has not been demonstrated among individuals associated with the Globular Amphora culture11,13,14. Although our knowledge about the demographic prehistory in continental Europe has increased immensely over the last five years1,2,3,4,5,6 the regional resolution of the events is insufficient and, thus, our understanding of the social processes is still lacking. The population dynamics and interpretations of the archaeogenomic data of the Yamnaya and the Corded Ware complexes and their relationships have been intensely debated and reviewed (see e.g.15,16,17,18).
Around 5400 BCE farming was introduced in central Poland which coincided with the appearance of the Linear Pottery culture (LBK) complex marking the transition to the Early Neolithic period. The HG population living in a neighbourhood of the LBK area upheld their lifeways and for almost a millennium the dispersal of the Neolithic lifeways halted. However, there were evidently contacts between the farming and HG groups seen in admixture patterns11. These relations are clearly visible in the Brześć Kujawski group (of the Lengyel complex) found in the region of Kuyavia which for a long time was the northern limit of the (post LBK) farming communities11,19.
During the next millennium, from around 4000 BCE, i.e. the Middle Eneolithic, the Funnel Beaker culture (TRB) emerges and the Eneolithic lifeways dispersed to the Northern parts of central Europe, including parts of Scandinavia, and now to most of the Polish area. Individuals from TRB contexts in Poland exhibit admixture with the HG-populations which were mostly linked to the west European HG group (WHG) (e.g.11). Around 3100 BCE the TRB manifestations in Poland decline with the appearance of the Baden culture and the Globular Amphora culture (GAC, c.3400/3100-c.2800 BCE) which replaced the earlier TRB complex in many areas of Poland. The GAC was a rather short-lived phenomenon and after 2800 BCE the Corded Ware Complex (CWC) manifestations became dominant, and continued for another 500 years before that complex disappears11,20.
Individuals of the GAC and CWC have very different ancestry. Individuals from CWC contexts in Poland exhibit a marked input from the eastern Yamnaya Steppe pastoralist whereas the individuals of the GAC complex hardly exhibit any Steppe ancestry11,13,19. Around 2400 BCE the Bell Beaker culture (BBC) complex enters this region, from the southwest, and yet another major genetic component is added to the local population5,21. In south-eastern Poland, the BBC disappears around 2200 BCE22,23. The development in Poland clearly shows the extent of admixture that has taken place in continental Europe and the importance of mobility in the demographic and social developments10,11. (Supplementary Information - The Corded Ware and the Bell Beaker societies in the Małopolska uplands).
By identifying mtDNA, Y-chromosomal DNA and nuclear DNA; ancestry, origin and admixture can be ascertained24,25,26,27. It has been shown that Yamnaya pastoralists contributed Y chromosome R1a and R1b haplogroups to continental Europe almost entirely replacing the previously wide-spread G2a haplogroup1,2. The mtDNA contribution of Yamnaya to CWC individuals is associated with the appearance of U2 and W haplogroups. This large-scale contribution, close to complete replacement is very evident among CWC individuals that have retained very little genetic ancestry from the Mesolithic HG and Early Neolithic farmer groups. The study of individuals associated with the CWC complex detected ancestry and admixture patterns with the HG groups, individuals of the Steppe culture groups such as Afanasievo and Yamnaya complexes. Moving forward in time evidence of admixture with individuals of the succeeding BBC complex appears, suggesting that this region of prehistoric Europe was an important social arena and melting pot of human genetics from both the east and the west5. Archaeogenomic analyses have the best possibilities to decipher demographic processes and the individuals associated to the CWC complex provide important clues to the development in the 3rd Millennium BCE.
One of the most characteristic features of the CWC complex are the funeral rituals that quickly spread over a large part of the Central Europe28. Attempts have been made to identify and understand the migration patterns within this vast cultural complex, and whether there were regional subgroups or other kinds of subdivisions11,12,20,29. To identify and to understand how different subgroups of the Corded Ware complex interacted with each other and the surrounding populations, an in-depth analysis of individuals representing this cultural complex during a highly important period in prehistory (2800-2300 BCE) is of great importance29. The present study goes deeper by also examining kinship of the individuals, which will aid the understanding of the intricate networks and social structures of the CWC subgroups28. By further investigating the genomic signatures among the regional CWC population in south-eastern Poland, a more complete yet complex image will emerge with several admixture events from different cultural groups.
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