For hundreds of thousands of years, neanderthals roamed the planet, eventually (almost 50,000 years ago) giving way to homo sapiens, which quickly became the dominant primate species, with the neanderthals disappearing but for faint traces of DNA in their successors. That rapid disappearance, however, has remained somewhat of a mystery, with anthropologists struggling to determine whether the rapidly changing climate or the arrival of better-equipped competitors was primarily to blame for the descent of the neanderthal. Now, researchers from the Center for Climate Physics at the Institute for Basic Science (IBS) in Daejeon, Korea, have applied supercomputer modeling to uncover the truth.

The IBS climate scientists did the unprecedented: they built the first realistic computer simulation of the extinction of the neanderthals across Eurasia, incorporating the migration of both neanderthals and homo sapiens, their interaction, their competition for food resources, their occasional crossbreeding and the changing climate across the glacial landscapes. The relevant parameters were themselves obtained from other simulations, as well as genetic and demographic data.

“This is the first time we can quantify the drivers of Neanderthal extinction,” said Axel Timmermann, director of the IBS Center for Climate Physics, in an interview with IBS. “In the computer model, I can turn on and off different processes, such as abrupt climate change, interbreeding or competition.”

The model was run on Aleph, IBS’ in-house supercomputer. Aleph, which is a Cray XC50 system with 468 Skylake nodes (each with 192 GB of memory), four data analysis nodes (each with 768 GB of memory) and around 51 petabytes of storage. Aleph was purchased in 2018, delivers 971 Linpack teraflops and ranks as South Korea’s second-fastest academic supercomputer. 

Using the model, the researchers came to the conclusion that the extinction of neanderthals was likely only possible if homo sapiens had major food resource advantages (which could stem from factors such as disease resistance, hunting techniques or reproductive rate). In short: we’re to blame.

“Neanderthals lived in Eurasia for the last 300,000 years and experienced and adapted to abrupt climate shifts that were even more dramatic than those that occurred during the time of neanderthal disappearance. It is not a coincidence that neanderthals vanished just at the time when homo sapiens started to spread into Europe,” Timmermann said. “The new computer model simulations show clearly that this event was the first major extinction caused by our own species.”

The researchers are now going back to the model and improving its representation of animals and the changing climate. “This is a new field of research in which climate scientists can interact with mathematicians, geneticists, archaeologists and anthropologists,” Timmermann said.