Enamel carbon and oxygen isotope values provide evidence of 22,000 years of shifting precipitation seasonality in Malawi

The Zambezian Biome, located between equatorial and southern Africa, is an important region for the study of biogeography and human evolution. Reconstructing Quaternary environmental conditions in the region has been challenging because the basin’s paleoenvironmental record is not clearly in-phase with either the eastern or southern African records. Here we use sequential intra-tooth sampling of enamel to provide the first high-resolution terrestrial records of precipitation seasonality in Malawi over the last 22,000 years, using 333 measurements of δ 13 C and δ 18 O in 62 teeth, and 20 measurements of triple oxygen isotopes (paired δ 18 O-δ 17 O) in 10 teeth from the Kasitu Valley, Mzimba District. We show that seasonality in northern Malawi has shifted over the last 22,000 years and propose that the end of the Last Glacial Maximum was drier and more seasonal than today. These results provide a framework for testable palaeoecological and archaeological expectations, including the predictable aggregation of herbivores near water sources and increased importance of riparian habitats for human foragers during arid periods.