Evolution and Environmental Change in Early Human Prehistory^1,*

Understanding the interaction between past environmental and evolutionary change informs scientific and public awareness about natural environmental dynamics. Evidence of dramatic climate variability, cooling, and aridity over the past six million years has stimulated research about whether environmental change has been a major causal factor in the development of our species' defining characteristics. Examples pertaining to the evolution of bipedality, earliest known toolmaking, dispersal of Homo erectus, extinction of Neanderthals, and the global spread H. sapiens all point to the emergence of adaptability in response to environmental uncertainty as a recurrent theme in human evolution. A synthesis of African paleoclimate data suggests that significant events in human origins tended to occur during lengthy eras of strong climate fluctuation. Human adaptability will continue to be tested as societies face the challenges of adjusting to unprecedented change in Earth's environmental dynamics.