Mysterious cave paintings in Patagonia are thought to be the oldest examples of rock art in South America, a new study in Science Advances finds. Radiocarbon dating suggests pigments on the cave walls are in fact over 8,200 years old and not only a few thousand as first assumed.

“We got the results and we were very surprised,” recalled Guadalupe Romero Villanueva, an author of the study and an archaeologist with the Argentine National Scientific and Technical Research Council (CONICET). “It was a shock, and we had to rethink some things.”

The unusual comb-like patterns cover the walls of Cueva Huenul 1, a remote archaeological site located in the desert of northwest Patagonia. Scientists were able to calculate the age of the patterns by radiocarbon dating organic components in the charred black wood paint, possibly derived from cactuses or shrubs.

It indicated that the paintings were significantly older than the 900 others in the cave, which depict humans, animal figures, and abstract designs in mostly red paint. They also discovered that the prehistoric people had drawn the comb-like designs on top of the previous generation’s similar paintings for several thousand years.

“As interesting as the ages are, for us it’s more significant that they span, more or less, 3,000 years of painting basically the same motif during all this time,” said Ramiro Barberena, an author of the study and an archaeologist also at CONICET, as well as the Temuco Catholic University in Chile. “We think it was part of a human strategy to build social networks across dispersed groups, which contributed to making these societies more resilient against a very challenging ecology,” added Barberena.

Patagonia was one of the last places on Earth settled by humans, only 12,000 years ago during the Late Pleistocene. Then around 10,000 years ago, climate shifts forced the population to migrate away from the area as it became more arid and hostile. The revised date of the cave paintings points to a far earlier communication system used by the small, dispersed groups that remained in the area. The cave became a central spot in which to preserve memories and oral traditions across generations in the heat-ravaged environment.

“You cannot help but think about these people,” said Villanueva. “They were at the same place, admiring the same landscape; the people living here, maybe families, were gathering here for social aspects. It’s really emotional for us.”

Although the purpose of the comb motif has been lost to the annals of time, its persistent presence in the cave has sparked new conversations about how humans preserve cultural knowledge in periods of climactic change.