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

We have developed an Africa-wide synthesis of paleoenvironmental variability over the Plio-Pleistocene. We show that there is strong evidence for orbital forcing of variability during this time that is superimposed on a longer trend of increasing environmental variability, supporting a combination of both low- and high-latitude drivers of variability. We combine these results with robust estimates of mammalian speciation and extinction rates and find that variability is not significantly correlated with these rates. These findings do not currently support a link between environmental variability and turnover and thus fail to corroborate predictions derived from the variability selection hypothesis.