Archaeologists discover 1.4 million year old limestone balls carved by humans

Archaeologists have long been intrigued by stone spheroids, peculiar artifacts scattered across archaeological sites worldwide.

Dating as far back as 2.5 million years, these roughly spherical limestone objects have been discovered in areas ranging from East Africa to Europe, the Middle East, and Asia. Despite their widespread presence and enduring significance in early human toolkits, their purpose has remained enigmatic.

One of the most significant discoveries involving these artifacts comes from the Early Acheulean site of ‘Ubeidiya, located in the Dead Sea Rift Valley in the southern Levant. This site, dated to approximately 1.4 million years ago, represents the earliest known evidence of the Acheulean outside of Africa.

Researchers have unearthed 150 limestone spheroids at ‘Ubeidiya, providing a rare opportunity to analyze these artifacts and their potential role in early human technology and behavior.

The Acheulean period, part of the broader Paleolithic era, spans from about 1.7 million to 200,000 years ago. It marks a time when early humans mastered the art of stone tool creation, producing hand axes, cleavers, and other tools. The ‘Ubeidiya spheroids, meticulously carved using deliberate techniques, exemplify the sophistication of Acheulean craftsmanship.

For the first time, researchers employed advanced 3D mapping and analysis to investigate the ‘Ubeidiya spheroids. Led by Antoine Muller, a PhD candidate at Hebrew University of Jerusalem, the team used spherical harmonics and other geometric metrics to characterize the artifacts’ shapes and surface features.

This novel approach allowed researchers to quantify the complexity of the spheroids’ geometry and uncover patterns in their manufacture.

“Almost all of the spheroids from ‘Ubeidiya, even the nearly perfectly spherical ones, had a flat area on their surface,” explained Muller. “The spherical harmonics analysis helped us identify these surfaces and confirm that this was a repeated pattern, not just in our imagination. These flat surfaces likely served as striking platforms to help shape the spheroids.”

The study, published in Royal Society Open Science, suggests that early humans employed a premeditated reduction strategy, known as knapping, to create these spherical objects. Knapping involves shaping stone by striking it with another object to remove flakes systematically.

The researchers hypothesize that the spheroids represent a continuum of reduction, evolving from initial nodules to polyhedrons, sub-spheroids, and finally to spheroids.

The significance of these findings extends beyond ‘Ubeidiya. While spheroids have been documented sporadically at other Lower Paleolithic sites in the Levant, such as Hummal, Latamne, and Qesem Cave, the large sample size and advanced analysis methods at ‘Ubeidiya provide unparalleled insights into their creation.

Researchers have made their dataset available online, enabling further study and comparison with spheroids from other regions.

If intentional shaping can be demonstrated on even older spheroids from the Oldowan period—the earliest part of the Stone Age, beginning about 2.5 million years ago—it would represent the earliest evidence of hominins imposing symmetrical geometry on tools. Such a discovery would reshape our understanding of early human cognitive and technological evolution.

Despite these advances, the function of the spheroids remains uncertain. Were they tools for pounding, hammering, or grinding? Could they have served as weapons or symbolic objects? Muller acknowledges that much work remains to determine their precise role. “Unfortunately, it is still unclear what the spheroids may have been used for,” he said. “Narrowing down their functionality will require a lot more work.”

The ‘Ubeidiya site’s importance lies not only in its contributions to understanding spheroids but also in its broader implications for the migration of early humans. Situated at a geographic crossroads, the site provides evidence of the first hominin forays out of Africa into the Levant. It offers a window into the technological and cultural practices of these pioneering populations.

The use of 3D mapping technology marks a turning point in archaeological research, enabling unprecedented precision in analyzing ancient artifacts. By quantifying variables such as surface curvature, sphericalness, and edge angles, researchers can reconstruct the manufacturing process and gain insights into the cognitive abilities of early humans.

“The data from ‘Ubeidiya has the potential to change how archaeologists view these artifacts globally,” said Muller. “It demonstrates that early humans were capable of advanced planning and intentionality in toolmaking.”

The study underscores the importance of interdisciplinary collaboration in archaeology. Researchers from Hebrew University, Tel Hai College, and Rovira i Virgili University combined their expertise to tackle questions that have puzzled scholars for decades. Their findings highlight the value of applying cutting-edge technology to ancient questions, paving the way for future discoveries.

While the mystery of the spheroids’ function endures, the ‘Ubeidiya findings represent a significant step forward. They offer a glimpse into the ingenuity and adaptability of early humans, shedding light on a pivotal chapter in the story of human evolution.

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