Improved resolution records from radiocarbon and ancient DNA studies of megafauna and human populations have allowed us to disentangle the roles of climate change and human impact in the Late Pleistocene megafaunal extinctions. We find that Holarctic megafaunal populations underwent repeated local or global extinctions in association with rapid warming events, known as interstadials, on a millennial scale. The extinction events took place both before and after the presence of modern humans on the landscape, and the metapopulation processes which appear to stabilize the ecosystem may have evolved to provide resilience to rapid and frequent climate shifts in the past.
In the Americas, we find that the rapid movement of the first Native Americans throughout both continents creates a powerful and unique model system due to the opposing climate trends in each hemisphere at the time. While megafaunal extinctions were associated with warming trends in both cases, the out of phase climate patterns caused the sequence and timing of events to be mirrored, providing an illuminating high-resolution view of the interactions of human colonization and climate change on megafaunal ecosystems.