These images, discovered in limestone caves on the island of Sulawesi just east of Borneo, are about the same age as the earliest known art found in the caves of northern Spain and southern France, suggesting that Europe can no longer claim to be the sole birthplace of art.
“We now have 40,000-year-old rock art in Spain and Sulawesi,” said Adam Brumm, a research fellow at Griffith University in Queensland, Australia, and one of the lead authors of the study. “We anticipate future rock art dating will join these two widely separated dots with similarly aged, if not earlier art.”
The ancient Indonesian art was first reported by Dutch archaeologists in the 1950s, but had never been dated until now. For decades researchers thought that the cave art was made during the pre-Neolithic period, about 10,000 years ago.
“I can say that it was a great — and very nice — surprise to read their findings,” said Wil Roebroeks, an archaeologist at Leiden University in the Netherlands, who was not involved in the study. “‘Wow!’ was my initial reaction to the paper.”
The researchers said they had no preconceived ideas of how old the rock art was when they started on this project about three years ago. They just wanted to know the date for sure.
To do that, the team relied on a relatively new technique called U-series dating, which was also used to establish minimum dates of rock art in Western Europe.
First they scoured the caves for images that had small cauliflower-like growths covering them — eventually finding 14 suitable works, including 12 hand stencils and two figurative drawings.
The small white growths they were looking for are known as cave popcorn, and they are made of mineral deposits that get left in the wake of thin streams of calcium-carbonate-saturated water that run down the walls of a cave. These deposits also have small traces of uranium in them, which decays over time to a daughter product called thorium at a known rate.
“The ratio between the two elements acts as a kind of geological clock to date the formation of the calcium carbonate deposits,” explained Maxime Aubert of the University of Wollongong in Australia’s New South Wales state, the team’s dating expert.
Using a rotary tool with a diamond blade, Aubert cut into the cave popcorn and extracted small samples that included some of the pigment of the art. The pigment layer of the sample would be at least as old as the first layer of mineral deposit that grew on top of it.
Using this method, the researchers determined that one of the hand stencils they sampled was made at least 39,900 years ago and that a painting of an animal known as a pig deer was at least 35,400 years old.
In Europe, the oldest known cave painting was of a red disk found in a cave in El Castillo, Spain, that has a minimum age of 40,800 years. The earliest figurative painting, of a rhinoceros, was found in the Chauvet Cave in France; it goes back 38,827 years.
The unexpected age of the Indonesian paintings suggests two potential narratives of how humans came to be making art at roughly the same time in these disparate parts of the world, the authors write.
It is possible that the urge to make art arose simultaneously but independently among the people who colonized these two regions. Perhaps more intriguing, however, is the possibility that art was already part of an even earlier prehistoric human culture that these two groups brought with them as they migrated to new lands.