One of the oldest known pieces of art on the planet is a figurine of a mammoth that was carved in ivory by a Stone Age artisan some 40,000 years ago. Found in what is now Germany, it is marked with crosses and dots. The meaning of these markings is a mystery—but a new analysis of the object and hundreds of others found in the same region reveal that the markings may have meant something specific to their ancient creators.

Researchers analyzed more than 3,000 markings on 260 objects, including the mammoth, that were found in caves in Germany. They determined that the markings’ patterns are as statistically complex as protocuneiform, an early form of writing that was found on tablets from ancient Mesopotamia that were dated to around 3,500 B.C.E.