Understanding and ameliorating human impacts on the natural world is an urgent challenge today, with archaeological and fossil archives providing important insight into the history of human impacts on ancient ecosystems. It has long been suggested that our hominin ancestors, in particular Homo erectus, drove extinctions and shaped the evolutionary history of Africa’s exceptionally diverse large mammal communities, extending the temporal depth of anthropogenic impacts on biodiversity back hundreds of thousands if not millions of years. Building on recent work in Science, this presentation evaluates the “ancient impacts” hypothesis through analysis of eastern African herbivore communities spanning the past seven million years. The diversity of megaherbivores (animals >1,000 kg) has steadily declined over the last ~4.6 million years, beginning long before the appearance of hominin species capable of hunting large-bodied prey. Rather than invoking ancient hominin impacts, the demise of eastern Africa’s megaherbivores can be accounted for by the expansion of grassland environments, which was likely driven by declining atmospheric CO2 concentrations.
 
About the Speaker:

Tyler Faith is Curator of Archaeology at the Natural History Museum of Utah and Assistant Professor of Anthropology at the University of Utah. His research addresses the relationships between Quaternary mammals, environmental change, and human evolution, with an emphasis on sub-Saharan Africa. Faith is the author of Paleozoology and Paleoenvironments: Fundamentals, Assumptions, Techniques (with co-author Lee Lyman; Cambridge University Press), which outlines the reconstruction of ancient climates, floras, and habitats on the basis of vertebrate fossil remains. He is currently Associate Editor for Quaternary Research and Journal of Human Evolution. 
                   
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