Coupled climate-human drivers of Late Quaternary megafaunal decline

Global megafaunal populations experienced widespread decline and extinctions during the Late Quaternary period. Adverse climatic conditions during the Last Glacial Maximum (LGM), and the emergence and global spread of modern humans are widely considered as the primary drivers of megafaunal loss and the associated decline in global biodiversity. However, the relative contributions of climate change and human influence on the unprecedented Late Quaternary megafaunal extinctions remain unresolved, largely due to the scarcity of palaeoecological evidence. Here, we employ a new spatially explicit dynamical model (ICCP Global Mammal Model, IGMM) to simulate climate-driven changes in the distribution of about 2000 terrestrial mammal species (including humans), incorporating biotic interactions through predation and competition, across space and through time on a global scale. While adverse climatic conditions during the LGM, marked by dramatic changes in habitat suitability, created a favorable background for the megafaunal decline, our model reveals that the global spread of culturally advanced modern humans played a crucial role in exacerbating the population loss of iconic species including mammoths, mastodons, stegodons, and giant sloths, ultimately leading to their extinction during the Late Quaternary period.