Modelling Neanderthals’ dispersal routes from Caucasus towards east

PLOS ONE RESEARCH ARTICLE Modelling Neanderthals’ dispersal routes from Caucasus towards east Elham Ghasidian ID1,2,3,4*, Anooshe Kafash5, Martin Kehl3,4, Masoud Yousefi5, Saman Heydari-Guran1,2,3,4 1 Neanderthal Museum, Mettmann, Germany, 2 DiyarMehr Institute for Palaeolithic Research, Kermanshah, Iran, 3 Institute for Prehistoric Archaeology, University of Cologne, Koln, Germany, 4 Institute of Geography, University of Cologne, Cologne, Germany, 5 Department of Environmental Science, Faculty of Natural Resources, University of Tehran, Tehran, Iran * a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Ghasidian E, Kafash A, Kehl M, Yousefi M, Heydari-Guran S (2023) Modelling Neanderthals’ dispersal routes from Caucasus towards east. PLoS ONE 18(2): e0281978. https://doi.org/ 10.1371/journal.pone.0281978 Editor: Tzen-Yuh Chiang, National Cheng Kung University, TAIWAN Received: September 16, 2022 Accepted: February 5, 2023 Published: February 23, 2023 Copyright: © 2023 Ghasidian et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The study of the cultural materials associated with the Neanderthal physical remains from the sites in the Caucasus, Central Asia and Siberian Altai and adjacent areas documents two distinct techno-complexes of Micoquian and Mousterian. These findings potentially outline two dispersal routes for the Neanderthals out of Europe. Using data on topography and Palaeoclimate, we generated computer-based least-cost-path modelling for the Neanderthal dispersal routes from Caucasus towards the east. In this regard, two dispersal routes have been identified: A northern route from Greater Caucasus associated with Micoquian techno-complex towards Siberian Altai and a southern route from Lesser Caucasus associated with Mousterian towards Siberian Altai via the Southern Caspian Corridor. Based on archaeological, bio- and physio-geographical data, our model hypothesises that during climatic deterioration phases (e.g. MIS 4) the connection between Greater and Lesser Caucasus was limited. This issue perhaps resulted in the separate development and spread of two cultural groups of Micoquian and Mousterian with an input from two different population sources of Neanderthal influxes: eastern and southern Europe refugia for these two northern and southern dispersal routes respectively. Of these two, we focus on the southern dispersal route, for it comprises a ‘rapid dispersal route’ towards east. The significant location of the Southern Caspian corridor between high mountains of Alborz and the Caspian Sea, provided a special biogeographical zone and a refugium. This exceptional physio-geographic condition brings forward the Southern Caspian corridor as a potential place of admixture of different hominin species including Neanderthals and homo sapiens. Data Availability Statement: All relevant data are within the paper. Funding: This research was funded by Deutsche Forschungsgemeinschaft (German Research Foundation) – Project no. 414357211 to Elham Ghasidian. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. 1. Introduction During the last few decades, great progress has been made in several domains, particularly palaeogenetics, which have revealed the complex ancestry of early Eurasians. This progress— including the identification of a “ghost lineage” of Eurasians in the Middle East—is providing important new biogeographical hypotheses [1]. Recent molecular and morphological research PLOS ONE | https://doi.org/10.1371/journal.pone.0281978 February 23, 2023 1 / 24 PLOS ONE Modelling Neanderthals’ dispersal routes from Caucasus towards east on the Neanderthal remains documents that this species appeared in Europe at least 400 ka [2–4] and ca. 150 ka in western Asia [5]. In their long-lasting period of occupation until ca. 30 ka, they colonized a vast territory that covered the entire European continent, the Levant and parts of Central Asia and Siberia [6–9]. Recent studies observed genetic variability among the Neanderthal groups and could potentially show high range of migration between them [10]. Mitochondrial DNA from Neanderthals found in Teshik-Tash in Uzbekistan and in the Altai region of southern Siberia shows that this species was of European origin [6]. Therefore, it can safely be concluded that they followed a long expansion route (at least 2000 km) eastward. The archaeological evidence and genetic sequence from Chagyrskaya and Denisova caves in the Siberian Altai confirm that Neanderthals migrated eastwards into Siberia. This process is understood not as a single dispersal event, but rather occurred repeatedly during the warm and temperate phases of the long time-span of MIS 5–3 (~130 to 28 ka) [8, 11–13]. In the Greater Caucasus, at Mezmaiskaya Cave, Middle Palaeolithic (MP) industry is known by foliate and Micoquian artefacts [14–16]. This industry resembles the one recorded from Chagyrskaya Cave. This cultural group, recovered from both Mezmaiskaya and Chagyrskaya caves and Central Trans-Urals sites [17], is considered to be sourced in Eastern Europe [8]. Moving to the lower latitudes (ca. N 35–30˚) (Fig 1), in the Lesser Caucasus, there is no sign of Micoquian. This issue gives rise to the hypothesis that Neanderthals split into different cultural groups in the Caucasus [14]. The Mousterian industry is well known in the Lesser Caucasus [18–20]. Research on the Azokh 1 Cave, in Lesser Caucasus, yielded Neanderthal remains associated with lithic artefacts ranging in age from Middle Pleistocene (MIS 9–8) to Late Pleistocene [20–24]. The Neanderthal physical remains and the associated MP lithic artefacts from this cave revealed a relatively contemporaneous age to the Zagros Mousterian from the Northern (i.e. Shanidar Cave: [25, 26]) and West-Central Zagros (i.e. Bawa Yawan Rockshelter: [27]) but older than the eastern-most Neanderthals’ territory in Central Asia [6]. At about 35 ka, a small and isolated group of Neanderthals appeared in Teshik-Tash Cave, in Uzbekistan; Central Asia. It is believed that this group of migrants was possibly assimilated, and their arrival did not result in long-lasting changes in the material culture of the local, possibly, Denisovan population [28]. The cave was excavated in 1930s and yielded Neanderthal remains named ‘Mousterian Child’ [29]. Brief analysis of the lithics at the time of excavation assigned them to the Mousterian cultural group [30]. The recent detailed lithic techno-typological analysis shows a hierarchical Levallois core reduction system, production of side scrapers and heavy-duty tools [31]. The current data prov (...truncated)