Extinct megafauna dominated human subsistence in southern South America before 11,600 years ago

One of the most widely cited objections to hypotheses that defend a central role for humans in late Pleistocene megafaunal extinctions in South America has been the assumption that extinct megafauna was a marginal resource in early human economies. On the basis of accurate chronological frames and faunal quantitative data, we demonstrate that extinct megafauna were the principal prey item of early foragers from ~13,000 to 11,600 calibrated years before the present, and this fact had likely been obscured by lumping together pre- and postextinction archaeological faunal assemblages within a single chronological window. We also show that the most exploited extinct taxa were at the apex of the ranking of the prey choice model. After the diversity and abundance of megafauna had already declined severely (~12,500 B.P.), and especially after they had virtually disappeared (~11,600 B.P.), the human diet was broadened. This strongly reinforces the idea that humans must be central to the debate on Quaternary extinctions in South America.