Examining the relationship between an increasingly carnivorous Homo erectus and Pleistocene mammal extinctions.

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Modern humans have an unparalleled capacity to modify their ecosystems. When and how humans obtained this ability is uncertain. This project seeks to clarify the timing and nature of human ecosystem modification over the course of human evolutionary history. Specifically, this project examines the potential impacts of a new emphasis on meat-eating by Pleistocene Homo erectus on mammal communities using a quantitative, food-web approach, informed by studies of the anatomy and isotopic composition of fossil predators with which human ancestors competed for access to meat. The project broadens participation in paleoanthropology by creating new opportunities for student research, enhances international, multidisciplinary research collaborations, and disseminates results broadly, including public-facing outreach events. The Ancient Hominin Impacts Hypothesis (AHIH) states that meat-eating by Homo erectus caused profound impacts on Pleistocene mammal communities, driving both large herbivore prey species, and competing predators to extinction. However, at the time Homo erectus first appeared, the region in which they appeared was experiencing climate-driven grassland expansions, which may also have contributed to extinctions in predators and prey. It is currently unknown whether environmental change, human impacts, or a combination of both best explains the observed Pleistocene mammal extinctions. This project tests the AHIH using a paleo food webs approach at the site where Homo erectus first appears in the fossil record. Anatomical and isotopic studies of local carnivores reveal which herbivore species extinct carnivore consumed, informing a quantitative paleo food-web model of the local community. The outputs of numerical food-web modeling experiments will be compared to the predictions the AHIH to reveal what impact, if any, human ancestors had on Pleistocene mammal communities. The project expands an understanding of the evolutionary significance of meat eating to ecosystem modification.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.