Mysterious Million-Year-Old Stone Spheres

The Mysterious Spheroids. Courtesy, Muller et al.

Although archaeologists remain uncertain of the purpose of these million-year-old stone spheres, they have solved one of big mystery—how they were made. Publishing their results in the journal Royal Society Open Science, an international team examined a large collection of these stone orbs, found at the site of ‘Ubeidiya near the Sea of Galilee and dating to 1.4 million years ago. The researchers found the spheres must have been intentionally created, showing the planning and technical abilities of early hominins.

Understanding the Strange Orbs

Found at archaeological sites dating from the Oldowan (c. 2.5 million years ago) to the Middle Paleolithic Age (c. 30,000 years ago), these lithic artifacts are quite common and appear wherever evidence of early hominins is found, although the purpose of the tools remains a mystery. Indeed, until now it was not even certain whether these spheres were intentionally made or simply a byproduct of another activity.

Using cutting-edge 3D analysis, including spherical harmonics and surface curvature, the researchers examined 150 limestone spheres at various stages of shaping uncovered at the site of ‘Ubeidiya, which represents the earliest attestation of the Acheulean culture outside of Africa. The team determined that the limestone objects became consistently more spherical over time, being chipped away in a predetermined and predictable manner. As such, they must have been intentionally crafted, with the final product in mind, and could not have been naturally shaped forms or a type of byproduct. Given the precision required to create such tools, the new findings challenge long-held assumptions about the technical abilities of early hominins.

“We had noted that almost all of the spheroids from ‘Ubeidiya, even the almost perfectly spherical ones, still preserved a flat area somewhere on their surface,” Antoine Muller, lead author of the study and a Ph.D. candidate at the Hebrew University, told The Times of Israel. “The spherical harmonics analysis helped us identify these surfaces and confirm that this was a repeated pattern, not just something in our imaginations. These flat surfaces likely helped them shape the spheroids by serving as a surface that could be struck to remove other parts of the artifact.”