Morgan Meis in The New Yorker:
Gazing with recognition at this pig, Burhan also noticed the painted silhouettes of two human hands toward its rear. The over-all look of the art work suggested to Burhan that it was very old—but how old?
Thus began a long process of trying to give the cave art a proper date. Experts were brought in from Griffith. Maxime Aubert, an archeologist and geochemist, decided to use a method called uranium-series dating. He removed some of the calcite on the surface of the painting, which archeologists sometimes call “cave popcorn,” and then analyzed it. Anything under the calcite layer had to be at least as old as what was on the surface. A number of problems arose with the machine that actually did the dating—the Nu Plasma Multi Collector Inductively Coupled Plasma Mass Spectrometer. Like “a Formula One race car,” Aubert said, it requires a team of highly trained engineers just to keep it going. Still, months later, a date was handed down: the painting of the warty pig was at least 45,500 years old. This makes it the oldest known example of figurative cave art in the world.