Climate effects on archaic human habitats and species successions

It has long been believed that climate shifts during the last 2 million years had a pivotal role in the evolution of our genus Homo(1-3). However, given the limited number of representative palaeo-climate datasets from regions of anthropological interest, it has remained challenging to quantify this linkage. Here, we use an unprecedented transient Pleistocene coupled general circulation model simulation in combination with an extensive compilation of fossil and archaeological records to study the spatiotemporal habitat suitability for five hominin species over the past 2 million years. We show that astronomically forced changes in temperature, rainfall and terrestrial net primary production had a major impact on the observed distributions of these species. During the Early Pleistocene, hominins settled primarily in environments with weak orbital-scale climate variability. This behaviour changed substantially after the mid-Pleistocene transition, when archaic humans became global wanderers who adapted to a wide range of spatial climatic gradients. Analysis of the simulated hominin habitat overlap from approximately 300-400 thousand years ago further suggests that antiphased climate disruptions in southern Africa and Eurasia contributed to the evolutionary transformation of Homo heidelbergensis populations into Homo sapiens and Neanderthals, respectively. Our robust numerical simulations of climate-induced habitat changes provide a framework totest hypotheses on our human origin.

Automated summary

The study demonstrates that climate changes over the past 2 million years have had a significant impact on the distribution of hominin species. Early hominins settled in environments with weak climate variability, while after the mid-Pleistocene transition, humans became global wanderers adapting to a wide range of climatic gradients. Phased climate disruptions in southern Africa and Eurasia further contributed to the evolutionary transformation of Homo heidelbergensis populations into Homo sapiens and Neanderthals.