Computer simulated paths of Neanderthal dispersals demonstrate they could have reached the Altai Mountains in Siberia within 2,000 years during warm climatic conditions in one of two ancient time periods—MIS 5e (approximately 125,000 years ago) or MIS 3 (approximately 60,000 years ago)—as demonstrated by the three different possible paths shown here. These paths follow a northern route through the Ural Mountains and southern Siberia, often intersecting with known archaeological sites from the same time periods.
Image: Emily Coco and Radu Iovita.
One of the ancestral species of all non-African Homo sapiens, the Neanderthals, migrated across Eurasia from Central Europe to Central Asia between 120,000 and 60,000 years ago. In the Altai Mountains of Siberia, they encountered the Denisovans and interbred with them—just as they would later interbreed with Homo sapiens migrating northwards out of Africa some 20,000 years later.
This is the fascinating history of our cousin species, now being brought to light by researchers at New York University’s Centre for the Study of Human Origins.
It almost goes without saying that this, along with the very existence of Neanderthals and their interbreeding with Eurasian Homo sapiens, is entirely incompatible with basic creationist beliefs and a literal reading of the Bible. Like all scientific discoveries, however, it fits seamlessly with what we already know and further enriches our understanding of both Neanderthal life and our own evolutionary history.
The discovery also addresses one of the long-standing mysteries surrounding Neanderthal dispersal during the Ice Age—namely, how they migrated from their central European ‘homelands’ to the Altai Mountains in Central Asia, where they interbred with Denisovans in what was likely the northern limit of the Denisovans’ range. Until now, their migration route had remained unclear due to a lack of archaeological evidence.
The breakthrough comes from computer simulations, which reveal a network of habitable valleys that connected Central Europe to Central Asia during a warmer period lasting some 2,000 years—long enough for Neanderthals to have reached within 600 kilometres of the Altai Mountains. The New York anthropologists have recently published their findings in the journal PLOS One.
Neanderthal Distribution and Their Presence in the Altai Mountains. Neanderthals (Homo neanderthalensis) were a widespread and resilient hominin species that inhabited much of western and central Eurasia. Their range extended from the Atlantic coasts of Europe to as far east as the Altai Mountains in southern Siberia, a span of over 5,000 kilometres. For much of their history—spanning roughly 400,000 to 40,000 years ago—Neanderthals were concentrated in Europe and western Asia, adapting to a variety of challenging Ice Age environments.They have also explained their work in a news release from New York University.
Until relatively recently, the easternmost boundary of Neanderthal occupation was poorly understood due to a lack of archaeological and fossil evidence. However, the discovery of Neanderthal remains and DNA at the Denisova Cave in the Altai Mountains has confirmed that they were present in this region around 100,000 to 60,000 years ago, contemporaneously with another archaic hominin population—the Denisovans.
This overlap strongly suggests that Neanderthals and Denisovans not only coexisted but also interbred in this remote part of Asia. Genetic evidence from both ancient remains and modern humans supports this conclusion, with traces of both Neanderthal and Denisovan DNA found in many non-African populations today.
The Altai region is thus a crucial location for understanding hominin interactions and migrations during the Late Pleistocene, serving as a genetic and geographic crossroads for our ancient relatives.
The evidence for interbreeding among Homo sapiens, Neanderthals, and Denisovans was largely uncovered by the team led by Svante Pääbo, a pioneering figure in the field of paleogenetics. His work at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has been foundational in sequencing ancient hominin genomes and revealing their complex relationships.
Key milestones from Pääbo’s team include:
- 2010:: The first draft of the Neanderthal genome was published. Comparison with modern human genomes revealed that non-African populations inherited about 1–4% of their DNA from Neanderthals, providing the first strong evidence of H. sapiens–Neanderthal interbreeding.
- 2010–2012: Discovery and sequencing of DNA from a finger bone in Denisova Cave (Altai Mountains), revealing an entirely new archaic human group: the Denisovans.
- Subsequent studies: Demonstrated that Denisovans interbred with H. sapiens (notably contributing DNA to modern Melanesians and some Southeast Asians) and also with Neanderthals.
- 2018: Pääbo’s team identified a first-generation hybrid individual nicknamed “Denny,” the offspring of a Neanderthal mother and a Denisovan father—direct evidence of Neanderthal–Denisovan interbreeding.
In recognition of his groundbreaking work, Svante Pääbo was awarded the 2022 Nobel Prize in Physiology or Medicine for his discoveries concerning the genomes of extinct hominins and human evolution.
Anthropologists Map Neanderthals’ Long and Winding Roads Across Europe and Eurasia
Computer simulations of pathways point to how ancient migrations shaped human history
Recent scholarship has concluded that Neanderthals made a second major migration from Eastern Europe to Central and Eastern Eurasia between 120,000 and 60,000 years ago. But the routes they took have long been a mystery—primarily because there are few archaeological sites connecting the two regions.
In a new analysis, a team of anthropologists—using computer simulations—has offered a map of possible pathways, which concludes Neanderthals likely used river valleys as natural highways and traveled during warmer periods to move approximately 2,000 miles (3,250 km) in less than 2,000 years.
Our findings show that, despite obstacles like mountains and large rivers, Neanderthals could have crossed northern Eurasia surprisingly quickly. These findings provide important insights into the paths of ancient migrations that cannot currently be studied from the archaeological record and reveal how computer simulations can help uncover new clues about ancient migrations that shaped human history.
Dr Emily Coco, lead author
Interdisciplinary Center for Archaeology and the Evolution of Human Behavior (ICArEHB)
Universidade do Algarve, Faro, Portugal
And Center for the Study of Human Origins
Department of Anthropology
New York University, New York, New York, USA.
The research, which appears in the journal PLOS One, was conducted with Radu Iovita, an associate professor at NYU’s Center for the Study of Human Origins.
Based on detailed computer simulations, it appears (Neanderthals') migration was a near-inevitable outcome of landscape conditions during past warm climatic periods.
Assistant professor Radu Iovita, co-author.
Center for the Study of Human Origins
Department of Anthropology
New York University, New York, New York, USA And Department of Early Prehistory and Quaternary Ecology
University of Tübingen
Tübingen, Germany.
In building their simulation of Neanderthals’ two-millennia journey, Coco and Iovita considered the elevation of the terrain, reconstructed ancient rivers, glacial barriers, and temperature to model movement decisions of individuals—an approach similar to that used to model both modern human and animal movement, but not previously applied to Neanderthals.
The authors find possible migration routes in two ancient periods—Marine Isotope Stage 5e [MIS 5e] (beginning approximately 125,000 years ago) and Marine Isotope Stage 3 [MIS 3] (beginning approximately 60,000 years ago)—marked by warmer temperatures and therefore more suitable for movement.
Computer simulations, conducted on the NYU Greene Supercomputer Cluster, indicated that Neanderthals could have reached Eurasia’s Siberian Altai Mountains within 2,000 years during either MIS 5e or MIS 3 using multiple possible routes that all follow the same basic northern path through the Ural Mountains and southern Siberia, often intersecting with known archaeological sites from the same time periods.
The authors add that the study sheds light on Neanderthal interactions with other ancient human groups. Specifically, their routes would have taken them into areas already occupied by Denisovans—consistent with existing evidence of interbreeding between the two species.
Neanderthals could have migrated thousands of kilometers from the Caucasus Mountains to Siberia in just 2,000 years by following river corridors. Others have speculated on the possibility of this kind of fast, long-distance migration based on genetic data, but this has been difficult to substantiate due to limited archaeological evidence in the region. Based on detailed computer simulations, it appears this migration was a near-inevitable outcome of landscape conditions during past warm climatic periods.
Assistant professor Radu Iovita.
AbstractResearch grounded in tangible, verifiable evidence — like the work described here — reveals the true story of our ancient hominin relatives. It is a narrative far more compelling, nuanced, and awe-inspiring than the simplistic origin myths devised by Bronze Age pastoralists, later codified and treated as literal truth by those with a vested interest in maintaining fear and obedience to an imagined, vengeful deity with whom they claim exclusive communion.
Genetic and archaeological evidence imply a second major movement of Neanderthals from Western to Central and Eastern Eurasia sometime in the Late Pleistocene. The genetic data suggest a date of 120−80 ka for the dispersal and the archaeological record provides an earliest date of arrival in the Altai by ca. 60 ka. Because the number of archaeological sites linking the two regions is very small, the exact route taken and its timing have been the matter of considerable debate. In particular, climate change in this period modified landscapes considerably, changing the cost of moving in different directions. Here, we apply agent-based least-cost path simulations for the first time to Neanderthals, showing that they most likely took a northern route through the Urals and southern Siberia under all climate scenarios. Agents leaving either the southern or the northern Caucasus Mountains reach the Altai in less than 2000 years during two time windows when the climate was mild, in MIS 5e (the Last Interglacial) and in MIS 3. The latter coincides with the dated presence of Neanderthals at Chagyrskaya and Okladnikov Caves in the Altai. The results of this modeling approach demonstrate a remarkable east-west geographic connectivity of northern Eurasia via river corridors despite the presumed barriers of the Ural Mountains and major north-south flowing rivers. Our results highlight the unique strengths of agent-based simulations to reconstruct pathways for ancient migrations.
Introduction
The advances during the last few decades of research have revealed that Neanderthals colonized a vast territory that stretched from Spain to Siberia [1–3]. The earliest Neanderthals likely arrived in Asia shortly before marine isotope stage (MIS) 6 (190−130 ka) [4,5]. Following MIS 6, we see a new, and genetically distinct, connection between European and Siberian Neanderthals dated between 120−80 ka during MIS 5; first documented in the genetic similarities between the Mezmaiskaya and Chagyrskaya fossils [2], this genetic evidence of a second movement of Neanderthals east now is confirmed by ancient DNA from sediments at several caves in Europe and Siberia [3]. Archaeologically, this genetic connection is accompanied by a number of sites in the Russian Plain, the Caucasus, and Siberia that share morphological characteristics in their stone tool assemblages belonging to the Middle Palaeolithic [6].
Ancient human populations in Eurasia have consistently been structured by geographic changes. During the penultimate (MIS 12) and antepenultimate (MIS 6) glacial periods, continental ice sheets reached down to the Dnieper basin, almost completely separating Europe from Asia [7]. The earlier of the two may have contributed to the separation of Neanderthals (in the west) and their closely related Denisovan cousins, in eastern Asia [8]. The MIS 6 glacial expansion likely separated Siberian Neanderthals from European Neanderthals until glaciers retreated, reopening the connection between the Russian and West Siberian plains. It is unclear if the two populations came into contact during the succeeding warm interglacial (MIS 5e) or not, because there are too few sites (see Fig 1) [for example, as demonstrated by the ROCEEH Out of Africa Database, 9]. The next connection between the European and Siberian Neanderthals is documented solely through genetic evidence that suggests a dispersal of Neanderthals east at the end of MIS 5e and during the next cooling phase (MIS 5d-a, 110−70 ka) [3,10]. The colder phase that follows, MIS 4, is believed to have transformed the open Eurasian landscapes into a cold desert, with populations retreating into mountain refugia, where they persisted until the next warm phase, MIS 3. Broadly, the archaeological record of MIS 3 is characterized by an increased diversification and regionalization of stone tool assemblages [11], as well as by sparse, fragmented populations [12] occupying smaller and smaller territories [13].Despite the genetic evidence for multiple long-distance dispersals by Neanderthals across Eurasia, we still have limited knowledge about the possible routes they would have taken to get to Siberia and the behavioral adaptations required for that journey. Archaeologists often use least-cost paths (LCP) to model past movement [15,16]. However, traditional LCP analyses make the assumption that the entire landscape is perfectly known in advance and that travelers will always choose the easiest and shortest route between two points [15]. This is not realistic for modeling movement in unknown environments. Here, we use an agent-based least cost path (AB-LCP) approach to more realistically model mobility decisions when a traveler can only use information about their local surroundings [17] and, importantly, when they do not have a specific destination they must reach. This methodology is similar to step selection models used to model animal movement and to investigate the peopling of Australia [18], but has yet to be applied to Neanderthals. Our model improves on traditional LCP analyses and simplifies the step selection methodology to reconstruct ancient migrations with as few assumptions as possible.
Fig 1. Current state of archaeological record for MIS 6 to MIS 3 in Eastern Eurasia between the Caucasus Mountains and the Altai Mountains.
Labels provided for some sites with Neanderthal remains to orient the viewer. Base map is derived from a digital elevation model (SRTM15 + V2.5.5) provided by Open Topography [14] with hydrological features from Natural Earth.
Here, we created a paleogeographically realistic agent-based least cost path model to simulate dispersal of Neanderthal populations between MIS 6 and MIS 3. Using cost surfaces derived from elevation, climate, hydrological, and glacier data, we explore possible paths that Neanderthals may have taken across Eurasia when dispersing out of the Caucasus Mountains.
The human story — as illuminated by archaeology, palaeogenetics, and evolutionary science — is one of deep time, migration, adaptation, and interconnection. It includes not only Homo sapiens, but also our evolutionary cousins, the Neanderthals and Denisovans. Far from diminishing our place in the world, this knowledge enriches our understanding of what it means to be human.
It is unfortunate that some still find meaning only by imagining themselves as the special creations of a supernatural being — fashioned not by the slow, majestic processes of evolution, but by the will of a deity whose temperament resembles that of a tribal autocrat. In truth, we are the remarkable outcome of nearly four billion years of natural history — refined by selection, shaped by chance, and connected to all life by the thread of shared ancestry.
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