Plio-Pleistocene environmental variability in Africa and its implications for mammalian evolution

Andrew S. Cohen, Andrew Du, John Rowan, Chad L. Yost, Anne L. Billingsley, Christopher J. Campisano, Erik T. Brown, Alan L. Deino, Craig S. Feibel, Katharine Grant, John D. Kingston, Rachel L. Lupien, Veronica Muiruri, R. Bernhart Owen, Kaye E. Reed, James Russell, Mona Stockhecke

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Understanding the climatic drivers of environmental variability (EV) during the Plio-Pleistocene and EV’s influence on mammalian macroevolution are two outstanding foci of research in African paleoclimatology and evolutionary biology. The potential effects of EV are especially relevant for testing the variability selection hypothesis, which predicts a positive relationship between EV and speciation and extinction rates in fossil mammals. Addressing these questions is stymied, however, by 1) a lack of multiple comparable EV records of sufficient temporal resolution and duration, and 2) the incompleteness of the mammalian fossil record. Here, we first compile a composite history of Pan-African EV spanning the Plio-Pleistocene, which allows us to explore which climatic variables influenced EV. We find that EV exhibits 1) a long-term trend of increasing variability since ∼3.7 Ma, coincident with rising variability in global ice volume and sea surface temperatures around Africa, and 2) a 400-ky frequency correlated with seasonal insolation variability. We then estimate speciation and extinction rates for fossil mammals from eastern Africa using a method that accounts for sampling variation. We find no statistically significant relationship between EV and estimated speciation or extinction rates across multiple spatial scales. These findings are inconsistent with the variability selection hypothesis as applied to macroevolutionary processes.

Original languageEnglish (US)
Article number2107393119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Apr 19 2022

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  • Africa
  • mammalian evolution
  • paleoclimate
  • Plio-Pleistocene
  • variability selection

Continental Scientific Drilling Facility tags

  • GLAD7

PubMed: MeSH publication types

  • Journal Article


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