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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.

Research in ecology and biogeography often assumes that ecological communities are shaped primarily by recent drivers, such as current climate and human activity. Here we analyze a comprehensive dataset of 515 large mammal communities across the Earth’s tropics and subtropics and show that present-day diversity patterns are codetermined by both past and present factors. Although current climate is important, paleoclimatic influences are strong. Likewise, while post-Industrial Revolution human impacts have affected mammal diversity patterns, imprints of prehistoric human-driven extinctions over the last ∼100,000 y are also evident. The influence of past versus present climate and human impacts varies markedly around the world, highlighting the importance of regionally unique evolutionary and ecological histories in shaping global patterns of biodiversity.