How a Homo goes extinct. Climatic change and the demise of our ancestors

Abstract

At least six different Homo species populated the World during the latest Pliocene to the Pleistocene. The extinction of all but one of them is currently shrouded in mystery, and no consistent explanation has yet been advanced, despite the enormous importance of the matter. We used a high-resolution past climate emulator and an extensive fossil database spanning 2752 archaeological records to model climatic niche evolution in Homo. We found strong, statistically robust evidence that the three Homo species representing terminating, independent lineages, H.erectus, H. heidelbergensis, and H. neanderthalensis lost a significant portion of their climatic niche space and became particularly vulnerable to climatic change just before their extinction. The increased extinction risk was probably exacerbated by competition with H. sapiens in the case of Neanderthals. This study demonstrates that climate change was a pervasive factor in the extinction of Homo species, despite their great ecological plasticity and cognitive abilities.