The Scythians: Who Were They?

Population genetic analysis
The studied Conqueror group very likely represent real populations, as 24 of the 29 samples came from 4 nearby cemeteries (Karos 1,2,3 and Kenézlő) with identical archaeological and anthropological groupings and the studied Magyarhomorog individuals were also categorized as belonging to the same early Conqueror elite. The Avar group was assembled from several different cemeteries of a wider timespan, thus they cannot represent the Avar period population of the Carpathian Basin, however their relatively homogenous Hg distribution indicate that the Avar elite embodied the same east Eurasian sub-population throughout their reign, so it appeared to be meaningful to include them in the analysis.

In order to find the most similar populations to our studied ones, we compared the Hg distribution of the Avar and Conqueror elite to that of 78 modern Eurasian populations (Supplementary Table S4) and represented their relations on MDS plot displayed on Fig. 5. Only one individual was included in the analysis from first degree relatives. In order to increase resolution, we separately calculated the frequencies of each sub-Hg-s which are present in our samples, while frequencies of all other subclades were combined as listed in Supplementary Table S4. Similar Hg distributions are mapped into neighboring positions on the MDS plot, which clearly separates populations according to their geographic locations. Along the x axis east Eurasian populations map to the right while Europeans are compressed at the left. Along the y axis Siberian populations are sequestered at the top, while East Asian ones at the bottom of the graph. The Avars are obviously mapped to the Siberian side with smallest weighted Euclidean distances from Koryaks (KRY), Teleuts (TEL), Khantys (KHT), Komis, (KOM) and Dolgans (DLG). The Conquerors are positioned between eastern Europeans, Central Asians and Siberians but their exact relations are hard to make out because of the crowding at the European side.

Figure 5



In order to better discern the position of the Conquerors we redraw the MDS plot without the eastern Asian and Siberian populations (Fig. 6). Though having removed subset of the data MDS imaging in two-dimensions inevitably rearranged the remaining components, but the general organization of the population clusters remained unchanged: Western-Northern Europeans map to the left, Central-eastern European and Balkan people around the middle, Central Asians to the top right, and Caucasus-Middle East populations to bottom right. Conquerors remained between Central Asians and eastern Europeans, with smallest weighted Euclidean distances from Bashkirs (BSH), Hungarians (HUN), Tajiks (TJK), Estonians (EST), Kazakhs (KAZ), Uzbeks (UZB) and Slovaks (SVK).

Figure 6



MDS plot of Y-chromosomal Hg distribution of 58 European and Central Asian populations including Conquerors (arrow). Population three letter codes are given in Supplementary Table S4.

The considerable frequency of Hg N1a in Conquerors and especially in Avars facilitates another analysis in which the frequency distribution of their N1a subbranches can be compared to that of all Eurasian populations carrying this Hg, which is described in22. The N1a database of22 contains several relevant Eurasian populations missing from Supplementary Table S3, moreover the Y dataset of Supplementary Table S4 has a low resolution of N1a subclades, thus this analysis is expected to provide additional information. We combined the N1a dataset published in22 with our data as presented in Supplementary Table S5 and performed Principal Component Analysis (PCA) as shown on Fig. 7.

Figure 7



PCA also separates populations according to their geographical positions, as identical colors appear in the same segments of the graph. The Avars map to the top right corner, close to eastern Siberian Chukchis (CHK), Yukaghirs (YUK), Eskimos (ESK) and Transbaikalian Buryats (BUR). The Conquerors (CONQ) map to the middle of the graph, very close to eastern European Belarusians (BLR), Ukrainians (UKR), Russians (RUS) and Polish (POL), not far from Volga-Uralic region Bashkirs (BSH), Volga Tatars (TAT), Komi Permians (KOMP) and Mordvins (MRD), also surrounded by Central Asian groups; Karanogays (KNO), Karakalpaks (KARA), Uzbeks (UZB) as well as Crimean Tatars (TATC), Mongols (MON), Selkups (SEL) and Dolgans from Taymyr (DLGT).

Ancient genomic time transect from the Central Asian Steppe unravels the history of the Scythians

Science Advances 26 Mar 2021:
Vol. 7, no. 13, eabe4414
DOI: 10.1126/sciadv.abe4414

Abstract

The Scythians were a multitude of horse-warrior nomad cultures dwelling in the Eurasian steppe during the first millennium BCE. Because of the lack of first-hand written records, little is known about the origins and relations among the different cultures. To address these questions, we produced genome-wide data for 111 ancient individuals retrieved from 39 archaeological sites from the first millennia BCE and CE across the Central Asian Steppe. We uncovered major admixture events in the Late Bronze Age forming the genetic substratum for two main Iron Age gene-pools emerging around the Altai and the Urals respectively. Their demise was mirrored by new genetic turnovers, linked to the spread of the eastern nomad empires in the first centuries CE. Compared to the high genetic heterogeneity of the past, the homogenization of the present-day Kazakhs gene pool is notable, likely a result of 400 years of strict exogamous social rules.



Fig. 1 Geographic location and dates of the newly reported ancient genomes.

(A) Map showing the locations of the 39 archaeological sites where the 117 individuals were retrieved and (B) their respective dates in years BCE/CE. The dates reported are 14C-calibrated (2-sigma) ranges for the sites comprehending at least one individual directly radiocarbon-dated; if more individuals are dated, we report the lowest and the highest values across all of them. If for a site, no individuals are dated, we report the date ranges based on the archaeological context (data file S1). The sites are colored according to their cultural affiliation. This same culture-based color code (top right) is maintained for all the figures in the main text and the Supplementary Materials.

INTRODUCTION

The transition to the Iron Age (IA) marks one of the most important events in the history of Eurasia. At the turn of the first millennium BCE, changes in the archeological record attest to the rise of several nomad cultures across the steppe, from the Altai to the western fringe of the Pontic-Caspian region (1). These cultures are often collectively referred to as Scythians based on the common features found in their mortuary contexts (2). Compared to the preceding Bronze Age (BA) populations, the Scythians went through a transition from a sedentary to a nomadic cattle-breeding lifestyle, showed an increase in warfare and advancements in military technologies (e.g., new types of iron weapons and horseback riding techniques, such as introducing the use of a saddle), and the establishment of hierarchical elite-based societies (3).

Previous genomic studies have detected large-scale genetic turnovers (and therefore substantial human migrations) in the BA steppe, which eventually resulted in the formation of a homogeneous and widespread Middle and Late BA (LBA) gene pool that characterized the sedentary herders of the western and central steppe (“steppe_MLBA”) (4–7). The reasons that prompted the rapid decline of these MLBA cultures and the rise of the Scythians are still poorly understood. Scholars have pointed out, among the most relevant factors, the climatic humidification (8) and socioeconomic pressures from the neighboring farming civilizations, i.e., the ones linked to the Bactria Margiana Archaeological Complex (“BMAC”) (3). Three competing hypotheses have been debated regarding the origins of the Scythians: a Pontic-Caspian origin, supported by their assumed Iranian languages, a Kazakh Steppe origin supported by the archaeological findings, and a multiple independent origin from genetically distinct groups that adopted common cultural traits (2). The limited number of genomes so far retrieved from the IA steppe nomads provides a glimpse of their genetic diversity but is far from being sufficient to characterize complex patterns of admixture between various eastern and western Eurasian gene pools (9–12).

From an archaeological perspective, the earliest IA burials associated with nomad-warrior cultures were identified in the eastern fringes of the Kazakh Steppe, in Tuva and the Altai region (ninth century BCE) (13). Following this early evidence, the Tasmola culture in central and north Kazakhstan is among the earliest major IA nomad warrior cultures emerging (eighth to sixth century BCE) (13). These earlier groups were followed by the iconic Saka cultures located in southeastern Kazakhstan and the Tian Shan mountains (sixth to second century BCE), the Pazyryk culture centered in the Altai mountains (fifth to first century BCE-CE), and the Sarmatians that first appeared in the southern Ural region (sixth to second century BCE) and later are found westward as far as the northern Caucasus and eastern Europe (fourth BCE to fourth CE) (1, 14–17). The nomad groups also influenced their sedentary neighbors, such as the ones associated with the Sargat cultural horizon (fifth to first century BCE) located in the northern forest-steppe zone between the Tobol and Irtysh rivers (3, 18).

After the IA, the Kazakh Steppe served as a center for the expansion of multiple empires, such as the Xiongnu and Xianbei chiefdoms from the east (19) and the Persian-related kingdoms from the south (e.g., Kangju) (20). These events brought the demise of the eastern Scythian cultures, but the demographic turnovers associated with this cultural transition remain poorly understood (20). Furthermore, forms of nomadic lifestyle persisted in the Kazakh Steppe throughout the centuries. A key event in the recent history of the nomad populations happened in the 15th to 16th century CE when all the tribes living in the territory of present-day Kazakhstan were organized and grouped into three main hordes (Zhuzs): Elder Zhuz, Middle Zhuz, and Junior Zhuz located in southeast, central/northeast, and west Kazakhstan, respectively (21, 22). This division was a political and religious compromise between different nomadic tribes, which were spread across Central Asia and had to protect themselves from external threats after the collapse of the Golden Horde. This set the basis for the foundation of the Kazakh Khanate (1465 to 1847 CE). Today, Kazakh groups in Kazakhstan still maintain their tribal affiliations and revere their nomadic history preserving some aspects of its culture (21). One of these traditions is the “Zheti-ata,” which consists of keeping track of the family tree up to seven generations by paternal line to avoid marriage between kins (23).

To understand the genetic structure of the different IA nomadic cultures as well as the demographic events associated with their origins and decline, we successfully generated genome-wide data from 111 ancient human individuals retrieved from 39 different archaeological sites across the Kazakh Steppe (Kazakhstan, Kyrgyzstan, and Russia) and one individual retrieved from a Hun elite burial located in present-day Hungary (text S1). Our dataset densely covers a time span ranging from the eighth century BCE to the fourth century CE and also includes three individuals from the medieval period (Fig. 1 and text S1). We also produced new genome-wide data from 96 modern-day Kazakh individuals belonging to several tribes affiliated to the three major Kazakh hordes (Zhuzh) covering the entire territory of present-day Kazakhstan to better understand how recent historical events have shaped the genetic structure of present-day nomads.