The Dynamics of Early Human Dispersal Across Europe: A New Population Model
The Dynamics of Early Human Dispersal Across Europe: A New Population Model
A Comprehensive Analysis of Human Migration During the Last Ice Age
Researchers have developed an innovative population model1 that sheds new light on the complex dynamics of human dispersal across Europe during the Aurignacian period, approximately 43,000 to 32,000 years ago. This interdisciplinary collaboration between climate scientists and archaeologists offers unprecedented detail in understanding how early anatomically modern humans spread across the continent, influenced by the dramatic climatic fluctuations of the Last Ice Age.
The "Our Way Model": A New Tool for Understanding Human Migration
The groundbreaking model, termed the "Our Way Model," was developed by a team from the University of Cologne's Institute of Geophysics and Meteorology and the Department of Prehistoric Archaeology. This model provides a nuanced understanding of human migration by simulating the movements and population densities of early humans over time and space. By examining these factors, the researchers have identified four distinct phases in the process of human settlement across Europe.
The first phase, as revealed by the model, involved a slow westward expansion of human settlement from the Levant to the Balkans. This was followed by a rapid second phase of expansion into western Europe. The third phase saw a decline in human population, coinciding with a period of severe climatic conditions. Finally, the fourth phase was marked by a resurgence in population density and further advances into previously uninhabited regions, including Great Britain and the Iberian Peninsula.
Climate Change as a Driver of Human Dispersal
The integration of paleoclimatic data into the model has allowed researchers to quantitatively examine the impact of climate change on human dispersal. During the late Last Glacial Period, the global climate was significantly cooler and drier than today, with frequent oscillations between colder and warmer periods. These climatic shifts played a crucial role in shaping the migration patterns of early humans, as they adapted to the changing environment.
Dr. Isabell Schmidt from the Department of Prehistoric Archaeology emphasized the importance of this interdisciplinary approach:
"Regional studies can hardly capture all factors at play when trying to reconstruct human dispersal, including how they work together at different scales and contribute to overall long-term trends. This is a major advantage of the new modeling approach."
A Complex Process of Migration and Adaptation
The model demonstrates that early human habitation in Europe was a highly complex process, characterized by cycles of advance, retreat, abandonment, and resettlement. These movements were driven not only by climatic changes but also by the adaptive capacities of early human populations.
The "Our Way Model" simulates human dispersal through two main steps. First, it combines climate and archaeological data to model the Human Existence Potential (HEP). HEP is a measure that defines the likelihood of human existence under specific climate and environmental conditions for a given culture. This crucial variable is estimated using a machine learning approach that constructs the climatic constraints for the Aurignacian culture. The trained model then estimates the spatial and temporal HEP patterns using data simulated by the Global Climate Model and oxygen isotope data from Greenland ice cores.
Key Phases of Human Dispersal in Europe
The results of the model highlight four key phases in the dispersal of early humans across Europe:
Phase 1: Slow Westward Expansion (45,000 to 43,000 years ago)
The initial phase involved a gradual westward movement of human populations from the Levant to the Balkans, laying the groundwork for future expansions.Phase 2: Rapid Expansion into Western Europe (43,250 to 41,000 years ago)
This phase was marked by a rapid spread of Homo sapiens across western Europe, despite brief setbacks. The population reached an estimated 60,000 individuals, distributed across all known archaeological sites of the period.Phase 3: Population Decline During Severe Cold (41,000 to 39,000 years ago)
A prolonged period of severe cold, known as the GS9/HE4 period, led to a significant decline in both the size and density of human populations. However, some groups survived in the "climate shadows" of large topographical features, such as the Alps.Phase 4: Recovery and Further Expansion (Starting around 38,000 years ago)
As climatic conditions improved, human populations quickly recovered, leading to regional increases in population density and further migration into previously uninhabited areas, including Great Britain and the Iberian Peninsula.
Insights from the Human Existence Potential (HEP) Maps
The HEP maps generated by the model provide valuable insights into the adaptability of early human populations. They suggest that by the end of the process, certain groups had become better adapted to cold climates, allowing them to push the boundaries of previously settled environments. This adaptability was crucial in enabling the continued expansion of human populations across Europe.
Future Directions in Human Dispersal Research
The "Our Way Model" represents a significant advancement in the study of human migration during the Aurignacian period. By integrating paleoclimatic data with archaeological evidence, the model offers a comprehensive view of the complex processes that shaped early human dispersal across Europe.
Looking ahead, the research team plans to test the underlying assumptions of the model, with a particular focus on the role of cultural evolution in the dispersal process. The ongoing Human and Earth System Coupled Research (HESCOR) project at the University of Cologne will integrate further aspects of Human-Earth system interactions into the model, providing even deeper insights into the dynamics of early human migration.
This innovative research opens new avenues for understanding the intricate relationship between climate change, human adaptation, and migration during one of the most critical periods in human history. As our knowledge of early human dispersal continues to evolve, models like "Our Way" will play a crucial role in unraveling the complex history of human migration across the globe.
Shao, Y., Wegener, C., Klein, K., Schmidt, I., & Weniger, G.-C. (2024). Reconstruction of human dispersal during Aurignacian on pan-European scale. Nature Communications, 15(1). https://doi.org/10.1038/s41467-024-51349-y