African Climate Change and Human Evolution

Analytical advances, new sediment archives, and heroic international collaborations have advanced our understanding of the role that climate change may have played in shaping major junctures in early human evolution. Gone is the dated view of our ancestors emerging from some ancient dark forest to assert dominion over the grassy plains. In its place is new evidence from ocean and terrestrial sediment archives and faunal remains that document large orbital-scale climate cycles that shifted, stepwise after 2.8 and then again after 1.8 million years ago to establish the African savannah we know today. These observations show the dual influences of orbital-scale hydroclimate variability as well has longer-term secular shifts toward increasingly open landscapes. These climate transitions are coincident with clusters of hominin speciation, extinction, and behavioral innovation milestones that came to define us as human. Much remains to be known but evidence is mounting for the significant role climate change played in shaping the physical and behavioral attributes that define us as human.