An ancient pig on a wall
In a remote valley on the Indonesian island of Sulawesi, a limestone cave called Leang Tedongnge holds the world's oldest known figurative artwork. Discovered in 2017 by archaeologist Basran Burhan, the painting is a life-sized depiction of a Sulawesi warty pig (Sus celebensis), a wild pig species still found on the island today. The remarkably preserved painting measures 136 cm by 54 cm (53 by 21 inches) and was created using a dark red ochre pigment.
The pig is part of a larger composition. Although time has damaged other figures on the same panel, at least two other partially preserved pigs seem to be in a confrontation, while the main, complete figure appears to be watching them. The artist detailed features of an adult male pig, including a short crest of upright hair and horn-like facial warts in front of the eyes. Above the pig's rear flank are two stencils of human hands, a common feature in Pleistocene rock art that may have been a signature.
Dating with cave popcorn
The artists of the Pleistocene era did not leave records of when they created their works. To find the age of the Leang Tedongnge pig, scientists had to date the rock itself. The red ochre pigment used for the painting cannot be reliably dated. Instead, researchers analyzed a small calcite deposit, sometimes called "cave popcorn" (a type of coralloid speleothem), that had formed over one of the pig's hind legs. This deposit was created by water seeping through the limestone and leaving behind minerals.
Scientists used a technique called Uranium-series (U-series) dating on the calcite. This method measures the radioactive decay of uranium isotopes, which are present in the seeping water, into thorium. By calculating the ratio of uranium to thorium in the calcite sample, researchers determined the mineral deposit began to form at least 45,500 years ago. Because the painting had to exist before the calcite could grow on top of it, the artwork is older than this date. This establishes it as the oldest known representational painting of an animal in the world. Prior to this, a depiction of human-animal hybrids from a nearby cave, dated to 43,900 years, was the oldest known figurative art.