Prehistoric people may have used firelight to create the illusion of movement in their art.
An analysis of 50 engraved stones excavated in France suggests that when the stones were placed near a fire, the flickering light made the engraved animals seem to move, researchers report April 20 in PLOS ONE.
These stones, or “plaquettes,” were found in the 1860s in a rock-shelter called Montastruc, and are engraved with animals such as horses, ibex and deer. The site was used by Magdalenian people, hunter-gatherers who inhabited the area between 23,000 and 14,000 years ago.