In a surprising discovery, cave paintings found in Indonesia have been determined to be as old as their counterparts in Europe.

The estimated 40,000 year old stencils of hands and other art depicting animals were found in limestone caves on the island of Sulawesi. They’re about the same age as cave art discovered in Spain and southern France says the study published Wednesday in the journal Nature.

Lead author of the study, Adam Brumm points out that now we have 40,000 year old cave art in both Spain and Sulawesi. Brumm is a research fellow at Griffith University in Queensland, Australia. He also expects other cave art to be discovered and to be of similar age ranges, perhaps even earlier. It was in the 1950s that Dutch archaeologists first reported the cave art but the art had remained undated until recently. Previous researchers had assumed the art was produced during the pre-Neolithic period that took place around 10,000 years ago.

There were no preconceived ideas regarding the true age of the cave art when the researchers first started their project around three years go but using today’s dating technology they have been able to determine a more accurate age. They used a technological technique called U-series dating.

In order to determine the age of the paintings they searched the art that was covered by small cauliflower-like growths on them. When they found suitable samples of the “cave popcorn” as their called, they used the small traces of uranium in them which decays to a substance called thorium. This decay has a known rate of decay. Using this data they look at the ratio between the elements as it behaves as sort of a geological clock that dates the formation of the calcium carbonate deposits.

Using a diamond drill they bored into the cave popcorn and took small samples that also included pigment from the cave art. This layer of pigment should be as old as the first layer of mineral deposit that lay on top of it.

This allowed the researchers to determine the age of the cave art as around 40,000 years old.

The combination of cave art data give scientists an idea of when art arose amongst humans. Did humans discover art independently at different locations? Had humans developed art from even earlier cultures?

These and other questions are before the scientists now that they have the comparative data.