Long before the rise of human civilization, our ancestors walked the valleys of East Africa over a million years ago—and some of them, it seems, were on the hunt for perfectly round stones.

In the highlands of Melka Kunture, Ethiopia, archaeologists have found dozens of remarkably round stones—dark, dense balls of volcanic rock. These are not sculpted artifacts; no hands chipped them into shape. They were born of fire and geology, not craftsmanship. And yet, a new study suggests, early hominins may have used them with purpose.

Not Made, But Chosen

The spheres, made from volcanic basalt and lapilli, were discovered across eight archaeological sites in Melka Kunture, dated between 1.7 million and 600,000 years ago. That range spans three different human ancestors: Homo erectus, Homo heidelbergensis, and early Homo sapiens.

“This is possibly the first evidence of the use of natural shapes for varied activities,” said Dr. Margherita Mussi, lead author of the study, published in Quaternary International. “And this happened repeatedly over more than 1 million years of human evolution at Melka Kunture.”

For decades, archaeologists have been intrigued by round stone tools—objects found across Europe, Asia, and Africa. Most were clearly shaped by human hands: chipped, ground, or sculpted into symmetry. But the spheres in Melka Kunture are different.

“These volcanic spheres of Melka Kunture are not manufactured tools,” Mussi wrote. “But the Pleistocene hominins undeniably noticed those well-rounded, strikingly geometric shapes.”

The research team studied more than 30 of these spheres housed at Ethiopia’s National Museum in Addis Ababa. They came from sites with tens of thousands of other tools—flakes, scrapers, and core stones used for hunting and survival.

Many of the spherical rocks showed wear marks, chipped edges, and smoothed faces, as if they’d been hammered, rubbed, or pounded into service.

“I am convinced that the hard volcanic ones were used to knap or retouch lithic tools,” Mussi explained. “While the rather soft lapilli ones were used for rubbing vegetables, hides, or other stuff.”

What this says about early human ancestors

If early hominins deliberately sought out natural spheres, carried them to specific sites, and used them over thousands of years, it points to a type of pattern recognition, perhaps even aesthetic preference.

At Gombore IB, the oldest site, dated to 1.7 million years ago, archaeologists found three spheres alongside nearly 5,000 other tools and a partial arm bone belonging to Homo cf. ergaster. Younger sites, such as Garba IIIE and Gombore II-1, contained skull fragments from Homo heidelbergensis and Homo sapiens, alongside even more spheres.

Importantly, the spheres were often found in environments where they shouldn’t naturally occur.

“The metric characteristics, shape, and orientation of pebbles transported by water have been researched and are well understood,” said Mussi. “Some of the sites are fine-grained deposits where the relatively heavy rock spheres are at odds with the surrounding environment, and also… the rather soft lapilli ones would have been easily crushed during water transport.”

In other words, these rocks didn’t roll in by accident. Someone brought them. That someone, it now seems, was our ancestors. Possibly Homo erectus, one of the first species to walk upright, to wield fire, and to migrate across continents.

We may never know exactly what our ancestors did with these spheres. They may have served as hammerstones, grinding tools, or even primitive game pieces. But the behavior behind them—the attention to shape, the act of selection, the testing of function—offers an important clue into our ancetors’ evolution.

It tells us that long before the first painting on a cave wall or the first arrow loosed from a bow, early humans were watching the world closely. They were noticing. They were experimenting.

And maybe, just maybe, they saw beauty in a sphere.