The Our Way Model for Human Dispersal in Changing Paleoclimate

Abstract

<p>DNA studies on present-day humans and Anatomically Modern Humans (AMHs) point to our genetic origin in Africa around 300 ka BP. The debate on our ancestry is continuing, which hinges upon the history of human population networks and dispersal. We know in general that AMHs started to migrate out of Africa around 200 ka, arriving in the Middle East 90-65 ka, Asia 80-50 ka, Europe 60-40 ka and the Americas after 14 ka BP. But we also know that human dispersal is, rather than unidirectional, a highly complex process of advancement, retreat, abandonment and resettlement on different time scales. On a historical dimension, it implies that there are special windows of best or even one-time opportunities for human dispersal, provided by the constellation of climate conditions and human activities. Despite the achievements in reconstructing the AMH dispersal history, large knowledge gaps exist in understanding the underlying dynamics and many questions remain unanswered. One of the most essential is how climate influenced population dynamics which in turn affected human evolution, and what are the constellations for the historic momentum. </p><p>Human dispersal is a manifestation of the human system. Like the Earth system, the human system is a complex system characterized by (1) a large degree of freedom, (2) a range of non-linearly processes competing and interacting on different scales, and (3) external forcing which are unsteady or stochastic. So far, the quantitative study on human dispersal has been bottlenecked by the critical lacks of knowledge of human-system dynamic processes, capacity for quantifying the climate-human relations, comprehensive Human System Models (HSMs), and the integration of HSMs and ESMs. The progress in Global Climate Models (GCMs) and ESMs and their applications to paleoclimate simulations signal that quantitative human-system and Earth-system coupled research is becoming feasible.</p><p>Here, we present the Our Way Model (OWM) for human dispersal, a preliminary framework for HSM and ESM coupled modelling. In OWM, we attempt to account for the  biological, cultural, and climate dimensions of the human system, and to integrate human- and Earth-science concepts, model and data, and the macroscopic and microscopic views of human dispersal. The OWM provides a platform for knowledge integration, hypothesis testing and conceptual development. We also present the results of two OWM simulations. The first is a 25-kyr numerical reconstruction of the Aurignacian dispersion on the pan European scale, and the second is a simulation of the impact of climate change on the population dynamics on the Iberian Peninsula.</p>