Scientists believe that the 1.4-million-year-old stone spheroids were deliberately made

In the 1960s, when scientists carried out excavations at a 1.4-million-year-old site in northern Israel, they encountered a baffling discovery – they unearthed nearly 600 stone “balls” among other traditional stone tools. Now, scientists have analyzed 150 of these baseball-sized stones and concluded that our ancestors intentionally made these spheroids! They speculate that early human ancestors may have been motivated by a desire to create symmetry and enjoy craftsmanship, although the exact function remains unclear.

The results of this study were published today in the latest issue of the journal Royal Society for Open Science , possesses the ability to provide valuable insights into the cognitive processes of ancient artisans. This is according to Julia Cabanes, a scientist at the National Museum of Natural History in Paris, who was not part of the research team but spoke to Sciences.

Spheroids and software used

These spherical-shaped stone artifacts, or “spheroids”, have been discovered at various prehistoric sites around the world, dating roughly from the end of the Oldowan period (1.7 million years ago) to the Middle Paleolithic ( 250 thousand years ago). Their existence has long been a mystery to archaeologists – was it deliberately chipped with the aim of making a ball, or was it an accidental by-product of repeated smashing of stones, such as ancient hammers or stone hand-axes to some extent?

Map of selected sites where stone spheres (including spheroids) have been documented. Right: Map of the sites of the stone spheres in the southern Levant, including the site of Al-Ubaidiya. Mueller, A, and others. Royal Society for Open Science )

“It appears that hominins 1.4 million years ago had the ability to visualize a sphere in their minds and shape their stones to match,” says lead author Antoine Müller of the Hebrew University of Jerusalem, who conducted the study. “This requires great planning and forethought, as well as a great deal of manual dexterity and skill.”

The HUJI team used a new method using cutting-edge 3D analysis software developed by a group of scientists at the university’s Computational Archeology Laboratory. With this, they were able to measure the surface angles on the spheroids, calculate the levels of surface curvature, and determine the center of mass of these objects, according to a press release.

Using this technology, they conducted a comprehensive analysis of 150 limestone spheres recovered from the archaeological site in northern Israel known as Ubeidiya. It is believed that this site was inhabited standing man an ancient humanoid species known for its tool-making abilities.

It was quoted by Professor Lior Grossman, co-author of the study Interesting geometry explaining that ” ‘Ubaidiya is currently recognized as the oldest known Acheulean event outside of Africa, making it a crucial site for studying the evolution of early hominin technology.

The 3D scans showed precisely the angles of the marks on the spheroids, allowing the scientists to reconstruct the process involved in making the spheroids, to the best of their abilities.

Subsequently, analysis of the scar aspects and geometry of the stones allowed for a successful reconstruction of the spheroid reduction sequence. During this process, they identified a distinctive pattern in the spheroids of the Ubaidiya, suggesting a deliberate strategy of craftsmanship.

Cabanes advocates applying this 3D analysis method to other artifacts, even ancient ones, which would increase the scope and scope of this technology. Spheroids dating back up to 2 million years have been excavated from other sites in Africa, and if they are also deliberately shaped to the scope of the current study, that would open a Pandora’s box of possibilities for what our ancestors were capable of.

Study methods for measuring the angles of edges, center of mass, and surface curvature of each stone in an effort to understand how spherical bodies are made and whether they are intentional. (Mueller, A, et al. Royal Society for Open Science )

Discussing “intentionalism”: smooth toolmaking vs. rough toolmaking

“Our results indicate that Obeidian spheroids are a complex formal technique that is a manifestation of the complex cognitive and skill capabilities of early Asholin hominins,” the authors write in the study. It is worth noting that each sphere has a prominent ‘prime surface’ surrounded by smaller planes, which means a manufacturing process that involves the removal of a large stone chip followed by the fine cutting of the edges of the flat area.

Obviously, these balls are very unlikely to have been the product of any natural processes, as they do not have the soft quality that would indicate wear over time. If this were the case, it would be similar to the stones found in riverbeds that have been extensively smoothed by water erosion. Natural stones rarely take a completely spherical shape.

In contrast, the stones unearthed at the Ubaidiya site exhibit rough surfaces, consistent with craftsmanship, and some approach near-perfect spherical shapes—a feat that could only be achieved through the deliberate efforts of skilled toolmakers.

Adding to the hypothesis about intentionality, the scientists compared these spheroids with other artifacts from this historical period, such as finely crafted stone hand-axes. Viewed side by side, these spheroids appear to have possessed a love of symmetry, proportion and aesthetics for our early ancestors, though their purpose remains “a mystery” – it is possible that they had a function as projectiles or had some other artistic symbolism that cannot be only explored in future studies.

“If similar intentional shaping can be demonstrated on Oldduan spheroids, this would likely represent the first evidence of hominins imposing a desirable symmetrical geometry on their tools,” the researchers wrote in the article.

Top image: Obeidi spheroids. source: Mueller, A. et al. / Royal Society for Open Science

Written by Sahir Pandey