African Climate of the Last 400,000 Years

Given East Africa’s role in the origin of Homo sapiens, this region’s climate history deserves attention, although pertinent models are lacking. Analysis of earth’s orbital dynamics yields a new model that shows the alternation of high and low climate variability for tropical East Africa over time, with potentially important implications for Pleistocene human evolution. This high/low variability model reconciles evidence that typically supports either aridity or strong moisture as factors in human evolution. Based on current evidence, key events such as the appearance of Middle Stone Age behaviors and Homo sapiens in tropical East Africa coincided with prolonged eras of climate instability. The complexity of climate dynamics, and associated resource uncertainty, likely influenced the evolution of adaptive versatility in our species, expressed by the expansion of mobile technologies, symbolism, social networks, and behavioral diversity.