Reconstructing contact and a potential interbreeding geographical zone between Neanderthals and anatomically modern humans.

While the interbreeding of Homo neanderthalensis (hereafter Neanderthal) and Anatomically modern human (AMH) has been proven, owing to the shortage of fossils and absence of appropriate DNA, the timing and geography of their interbreeding are not clearly known. In this study, we applied ecological niche modelling (maximum entropy approach) and GIS to reconstruct the palaeodistribution of Neanderthals and AMHs in Southwest Asia and Southeast Europe and identify their contact and potential interbreeding zone during marine isotope stage 5 (MIS 5), when the second wave of interbreeding occurred. We used climatic variables characterizing the environmental conditions of MIS 5 ca. 120 to 80 kyr (averaged value) along with the topography and coordinates of Neanderthal and modern human archaeological sites to characterize the palaeodistribution of each species. Overlapping the models revealed that the Zagros Mountains were a contact and potential interbreeding zone for the two human species. We believe that the Zagros Mountains acted as a corridor connecting the Palearctic/Afrotropical realms, facilitating northwards dispersal of AMHs and southwards dispersal of Neanderthals during MIS 5. Our analyses are comparable with archaeological and genetic evidence collected during recent decades.

Correction: Modelling Neanderthals' dispersal routes from Caucasus towards east.

[This corrects the article DOI: 10.1371/journal.pone.0281978.].

Modelling Neanderthals' dispersal routes from Caucasus towards east.

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.

The discovery of an in situ Neanderthal remain in the Bawa Yawan Rockshelter, West-Central Zagros Mountains, Kermanshah.

Neanderthal extinction has been a matter of debate for many years. New discoveries, better chronologies and genomic evidence have done much to clarify some of the issues. This evidence suggests that Neanderthals became extinct around 40,000-37,000 years before present (BP), after a period of coexistence with Homo sapiens of several millennia, involving biological and cultural interactions between the two groups. However, the bulk of this evidence relates to Western Eurasia, and recent work in Central Asia and Siberia has shown that there is considerable local variation. Southwestern Asia, despite having a number of significant Neanderthal remains, has not played a major part in the debate over extinction. Here we report a Neanderthal deciduous canine from the site of Bawa Yawan in the West-Central Zagros Mountains of Iran. The tooth is associated with Zagros Mousterian lithics, and its context is preliminary dated to between ~43,600 and ~41,500 years ago.

Species distribution models advance our knowledge of the Neanderthals' paleoecology on the Iranian Plateau.

Neanderthals (Homo neanderthalensis) were distributed across a vast region from Europe to western and Central Asia. The Neanderthals' paleoecology and distribution has been extensively studied in Europe where the species originated. However, very little is known about their paleoecology in south-western Asia. Here, we employed species distribution modelling and 45 Middle Palaeolithic (c. 200,000-40,000 years BCE) sites location associated with fossil and/or lithic artefacts made by the Neanderthals to examine the expansion of the Neanderthals on the Iranian Plateau in south-western Asia. We estimated the niche overlap between Neanderthals and wild goat, wild sheep and Persian gazelle by modelling their past distribution using 200, 143 and 110 occurrence records respectively. The results show that Neanderthals had highest niche overlap with wild goat in the study area. This analysis revealed that the most suitable Neanderthals' habitats in south-western Asia were located in the Zagros Mountains stretches from north-western and western and some isolated patches in the central parts of the Iranian Plateau. The annual precipitation and maximum temperature of the warmest month were the most important predictor of the species' distribution. This finding shows that the southern edge of the Neanderthals distribution was limited by warm summer. Our results provide important information for future field investigations and excavations in the area.

Upper Paleolithic cultural diversity in the Iranian Zagros Mountains and the expansion of modern humans into Eurasia.

This paper aims to understand the cultural diversity among the first modern human populations in the Iranian Zagros and the implications of this diversity for evolutionary and ecological models of human dispersal through Eurasia. We use quantitative data and technotypological attributes combined with physiogeographic information to assess if the Zagros Upper Paleolithic (UP) developed locally from the Middle Paleolithic (MP), as well as to contextualize the variation in lithics from four UP sites of Warwasi, Yafteh, Pasangar, and Ghar-e Boof. Our results demonstrate (1) that the Zagros UP industries are intrusive to the region, and (2) that there is significant cultural diversity in the early UP across different Zagros habitat areas, and that this diversity clusters in at least three groups. We interpret this variation as parallel developments after the initial occupation of the region shaped by the relative geotopographical isolation of different areas of the Zagros, which would have favored different ecological adaptations. The greater similarity of lithic traditions and modes of production observed in the later phases of the UP across all sites indicates a marked increase in inter-group contact throughout the West-Central Zagros mountain chain. Based on the chronological and geographical patterns of Zagros UP variability, we propose a model of an initial colonization phase leading to the emergence of distinct local traditions, followed by a long phase of limited contact among these first UP groups. This has important implications for the origins of biological and cultural diversity in the early phases of modern human colonization of Eurasia. We suggest that the mountainous arc that extends from Anatolia to the Southern Zagros preserves the archaeological record of different population trajectories. Among them, by 40 ka, some would have been transient, whereas others would have left no living descendants. However, some would have led to longer term local traditions, including groups who share ancestry with modern Europeans and modern East/Southeast Asians.