A three-year project will study the effects of feedbacks between climate change and increasing human impacts as an intensifier of extinction. The rich record of fossil mammals from South America will be used to develop a refined chronology of Quaternary megafaunal extinction (QME) with respect to the timing of significant human presence and abrupt climate change in different regions of the continent. The work will involve an international team of North American and Latin American Quaternary scientists, with research specialties in Quaternary paleobiology, archaeology, paleoclimatology, and radiocarbon dating, to obtain, evaluate, and interpret the meaning of approximately 150 radiocarbon dates on some 52 genera of extinct large-bodied mammal species. Statistical approaches will be employed to assess how closely the youngest radiocarbon dates reflect the true time of extinction and to compare extinction intensity with rates and magnitudes of climate change and growing human presence on the landscape. In essence, South America will be treated as a replicate natural experiment (the others are similar, already-available chronological data from North America, Europe, and Australia) to test, through a new quantitatively-based approach, current ideas that synergy between different faunal stressors greatly enhances magnitude and rapidity of extinction. South America is the appropriate place to do this because, although the extinction chronology is less well-known than on other continents, it had the greatest number large-bodied mammal genera go extinct, has adequate paleontological, archaeological, and paleoenvironmental data, and has the earliest accepted record of Homo sapiens in the Americas.
The project is important in understanding how combinations of different causal agents can intensify extinction of species, which is a major global problem today. Results of this research will be used to inform the general public and conservation and policy communities about how best to conserve biodiversity under current conditions of unusually intense and rapid global change. It will contribute educational resources for high school and undergraduate students. Peer-reviewed results will be communicated through media that will be accessible to general audiences and policy makers. The project will develop human resources and contribute to science and engineering literacy by training Ph.D. students, building international research networks, and contributing fundamental data that will be of use in future research and biodiversity monitoring efforts.
