Was the Maikop culture the PIE homeland?

Genomic History of Neolithic to Bronze Age Anatolia, Northern Levant, and Southern Caucasus

Summary
Here, we report genome-wide data analyses from 110 ancient Near Eastern individuals spanning the Late Neolithic to Late Bronze Age, a period characterized by intense interregional interactions for the Near East. We find that 6th millennium BCE populations of North/Central Anatolia and the Southern Caucasus shared mixed ancestry on a genetic cline that formed during the Neolithic between Western Anatolia and regions in today’s Southern Caucasus/Zagros. During the Late Chalcolithic and/or the Early Bronze Age, more than half of the Northern Levantine gene pool was replaced, while in the rest of Anatolia and the Southern Caucasus, we document genetic continuity with only transient gene flow. Additionally, we reveal a genetically distinct individual within the Late Bronze Age Northern Levant. Overall, our study uncovers multiple scales of population dynamics through time, from extensive admixture during the Neolithic period to long-distance mobility within the globalized societies of the Late Bronze Age.



Introduction
Since the beginnings of agriculture, the Near East has been an influential region in the formation of complex and early state-level societies and has drawn considerable research interest in archaeology since the 19th century (Killebrew and Steiner, 2014, McMahon and Steadman, 2012). Developments in the field of ancient DNA (aDNA) over the last decade have shed light onto questions related to the process of Neolithization. Near Eastern farmers from South-Central Anatolia, the Southern Levant, and Northwestern Iran were descended from local foragers, and the transition from foraging to farming in these areas was shown to have been a biologically continuous process with only minor gene flow among them (Broushaki et al., 2016, Feldman et al., 2019, Lazaridis et al., 2016).

Almost two millennia later, this situation had changed. In contrast to these Early Holocene populations, Chalcolithic/Eneolithic and Bronze Age populations from Western and Central Anatolia, the Southern Levant, Iran (Zagros), and the Caucasus show less genetic differentiation from each other, suggesting that these later periods were characterized by an extensive process of gene flow spanning a large area (Allentoft et al., 2015, de Barros Damgaard et al., 2018, Haber et al., 2017, Harney et al., 2018, Jones et al., 2015, Lazaridis et al., 2016, Lazaridis et al., 2017, Wang et al., 2019). However, the spatiotemporal scope of this process is poorly understood because of the lack of ancient genomes from areas that bridge these distant regions (i.e., Central and Eastern Anatolia) that, in turn, requires denser sampling. To date, the spatial distribution of features attributed to the “Neolithic package” across Anatolia suggests a heterogeneous multiple-event process that correlates with broader geographical zones (Özdoğan, 2014). However, whether population movement played a prominent role in the formation of these zones within Anatolia remains an open question.

Throughout Western Asia, archaeological evidence for the movement of peoples, material, and/or ideas is well documented (Figure 1). In the Southern Caucasus, archaeological research indicates relations with Northern Mesopotamia during the Late Neolithic (Halaf and Samarra cultures) (Badalyan et al., 2010, Nishiaki et al., 2015), and in Eastern Anatolia, a network of cultural connections marked by several expansive events, mostly related to the Mesopotamian world, is attested. These include an early intrusion of the South Mesopotamian Ubaid culture into Upper Mesopotamia as far as the Taurus mountains of Southeastern Anatolia during the 5th millennium BCE (Frangipane, 2015a, Carter and Philip, 2010). It was followed, in the Southern Caucasus, by a strong influence at this time from Upper Mesopotamia during the late 5th–mid 4th millennium (Lyonnet, 2007, Lyonnet, 2012). From the middle to the end of the 4th millennium, another Southern Mesopotamian influence (the so-called “Middle and Late Uruk expansion”) reached Upper Mesopotamia and the upper stretches of the Euphrates and Tigris river valleys in Eastern Anatolia (Allen and Rothman, 2004). At the same time, during the second half of the 4th millennium BCE, the Kura-Araxes culture, which is generally thought to originate in the Southern Caucasus, expanded outward around 3000–2900 BCE, spreading westward to Eastern Anatolia and the Northern and Southern Levant (Palumbi, 2017, Palumbi and Chataigner, 2014) and eastward to Iran (Rothman, 2011). Evidence of these events comes from numerous excavations and is especially apparent in the long and extensively excavated sequence of occupations at Arslantepe in the Malatya plain of Eastern Anatolia. In the Northern Levant, material connections with Northern Mesopotamia start appearing in the 4th millennium BCE and have been attributed to either extensive cultural contacts or population movements.