Past tropical forest changes drove megafauna and hominin extinctions

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Past tropical forest changes drove megafauna and hominin extinctions
Artist’s reconstruction of a savannah in Middle Pleistocene Southeast Asia. In the foreground Homo erectus, stegodon, hyenas, and Asian rhinos are depicted. Water buffalo can be seen at the edge of a riparian forest in the background Credit: Peter Schouten

In a paper published today in the journal Nature, scientists from the Department of Archaeology at MPI-SHH in Germany and Griffith University’s Australian Research Centre for Human Evolution have found that the loss of southeast Asian grasslands was instrumental in the extinction of many of the region’s megafauna, and probably of ancient humans too.


“Southeast Asia is often overlooked in global discussions of megafauna extinctions,” says Associate Professor Julien Louys, who led the study, “But in fact, it once had a much richer mammal community full of giants that are now all extinct.”

By looking at stable isotope records in modern and fossil mammal teeth, the researchers were able to reconstruct whether past animals predominately ate tropical grasses or leaves, as well as the climatic conditions at the time they were alive. “These types of analyses provide us with unique and unparalleled snapshots into the diets of these species and the environments in which they roamed,” says Dr. Patrick Roberts of the MPI-SHH, the other corresponding author of this study.

The researchers compiled these isotope data for fossil sites spanning the Pleistocene, the last 2.6 million years, as well as adding over 250 new measurements of modern Southeast Asian mammals representing species that had never before been studied in this way.

They showed that rainforests dominated the area from present-day Myanmar to Indonesia during the early part of the Pleistocene but began to give way to more grassland environments. These peaked around 1 million years ago, supporting rich communities of grazing megafauna such as the elephant-like stegodon that, in