Climate as a driver for Hominin Evolution

Abstract:

The history of our species Homo sapiens overlaps with some of the most dramatic climate transitions in earth’s history, such as ice ages and Dansgaard-Oeschger events. To elucidate what role past climate and environmental conditions played in the dispersal of Homo sapiens and in the extinction of other hominin groups and megafauna, I will present and discuss a series of simulations conducted with an integrated climate/human migration computer model.

The model simulates ice-ages, abrupt climate change, the "peopling" of our planet and captures the arrival time of Homo sapiens in the Levant, Arabian Peninsula, Southern China and Australia in close agreement with paleo climate reconstructions, fossil and archaeological evidence. The human dispersal model simulates multiple prominent orbitally-paced migration waves of Homo sapiens across the Arabian Peninsula and the Levant region. Such shifts opened up green corridors between Africa, the Sinai and the Arabian Peninsula, enabling our ancestors to migrate into Asia, Europe, Australia and eventually into the Americas.

The human dispersal model also simulates the extinction of Neanderthals around 38 thousand years ago. By running different scenarios with and without abrupt climate change, interbreeding or competition between Homo sapiens and Neanderthals, we can isolate the dominant mechanism for Neanderthal extinction. According to the model simulations a realistic extinction is only possible, if Homo sapiens had significant advantages over Neanderthals in terms of exploiting existing food resources. Abrupt climate change, associated with Dansgaard-Oeschger events, only played a minor role.

Over the past 200,000 years our species has shaped the environment dramatically by interacting with major ecosystems. I will present some new simulations with an extended version of the Hominin Dispersal model, which includes megafauna as well as parameterizations of culture and cognitive ability. By running a multi-parameter ensemble, the model reveals complex dynamics, chaotic predator-prey cycles, cross-diffusion and cyclic competition, which may have further impacted the evolution of our species.