Ruth Blasco, Taphonomy researcher at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has participated in a study published in the journal PLOS ONE on one of the possible uses of the shaped stone balls found at the Lower Paleolithic site of Qesem Cave, in Israel, through a multidisciplinary approach which involves both technological, use-wear and residue analyses, as well as a series of bone fracturing experiments.

The type of wear and the abundant residues of bone and fat found on ten spheroids from the site suggest direct evidence that these tools were used to crush fresh bones using percussion. The experimental results of the study also show that the morphology and characteristics of replicas of the spheroids are appropriate for extracting bone marrow, offering a comfortable grip and useful active areas for repeated use.

Many of the artifacts analyzed have a visible patina indicating that their use in bone crushing at the Qesem site was subsequent to their shaping. The recycling of lithic pieces is a frequent activity at the site, and in this case in particular, this could suggest collection of artifacts at other points in the territory, very probably at older sites within the Lower Paleolithic Acheulean complex of the Levant, as has been documented previously in earlier studies.

“The results of this work, therefore, refer only to the final phases of the life of these spherical items, and not to their original function, related to their shaping”, says Blasco

The mystery of the shaped stone balls

The presence of shaped stone balls has been documented from around 2 million years ago at many Lower Paleolithic sites in Africa, Asia and Europe. Their presence has both attracted and disconcerted many researchers, since, while many studies have centered on analyzing them, even today, debate on questions to do with their typological definition, their shape and possible functionality is ongoing.

“The presence of shaped stone balls at Qesem Cave, dating back between 200,000 and 400,000 years, is the final appearance of this kind of item in the Middle East Lower Paleolithic and marks the end of a long tradition lasting more than two million years when they were produced and used”, explains Blasco.

At the moment, there basically exist two opposing lines of interpretation. The first contends that these stone balls are the final products of a preconceived shaping process for their use in capturing animals or as food-pounding tools. The second line interprets these elements not as predetermined tools but as byproducts of previous specific technological or functional trajectories: exhausted cores, hammerstones, etc.

“Nevertheless, and despite the intensity of the work centering on the shaped stoe balls, a consensus about their purpose has still not been reached, and their function remains ambiguous”, affirms Blasco.

The participants in this paper, apart from the CENIEH, were researchers from Tel-Aviv University (Israel), Sapienza University of Rome (Italy), Newcastle University (United Kingdom), the Universidad Autónoma de Madrid and the Universitat Rovira i Virg