Early human ancestors deliberately fashioned rocks into spheres 1.4 million years ago, a study published Wednesday said, but what prehistoric humans used the spheres for remains a mystery. Archaeologists have long debated exactly how the tennis ball-sized “spherical shapes” were created.

Did early hominids deliberately carve them to form a perfect sphere, or were they an accidental byproduct of repeatedly smashing stones like ancient hammers?

A new study by the Hebrew University of Jerusalem suggests that our ancestors knew what they were doing. A team of scientists studied 150 1.4-million-year-old limestone spheroids found at the Ubeidiya archaeological site in northern modern Israel.

Using 3D analysis to reconstruct the stones’ geometry, the researchers determined that the sphericity of the stones was “likely created on purpose.” According to them, the first hominins, whose exact human lineage is unknown, tried to reach the Platonic ideal of the sphere.

As spheroids were built, the stones did not become smoother, but became “significantly more spherical,” according to the study published in the journal Royal Society Open Science.

This is important because although nature makes pebbles like rivers or streams smoother, the study says they “almost never approach a truly spherical shape.”

This means the hominins had a “preconceived mental” idea of ​​what they were doing, archaeologist Julia Cabanas of France’s Natural History Museum, who was not involved in the research, told AFP.

This shows that our ancient relatives had the cognitive abilities to plan and carry out such tasks.

The same technique could be used on other spheroids, Cabanas said. For example, it could shed light on the oldest known spheroids, which are two million years old and were found in the Olduvai Gorge in modern-day Tanzania.

But why exactly our ancestors were engaged in the creation of spheres remains a mystery. Possible theories include that hominins tried to create a tool that could extract marrow from bones or grind plants. Some scientists have suggested that the spheroids may have been used as projectiles or had a symbolic or artistic purpose.

“All hypotheses are possible,” Cabanes said. “We will probably never know the answer.” Source