Millions of years ago, our early ancestors roamed an area of Africa known as the Cradle of Mankind, scouring the landscape in search of perfectly round rocks. According to a new study, these long-extinct human species valued the lithic spheres for their uniqueness and may have experimented with different uses for them, although exactly what they did with the stone balls remains a mystery.
As it happens, rounded rocks have been found at sites occupied by ancient hominids across the world, although until now researchers had only shown an interest in those that were clearly sculpted by these prehistoric humans. For instance, at Qesem Cave in Israel, there’s evidence that some primitive species created rounded tools for crushing animals bones in order to access the bone marrow.
Similar finds have been made at Melka Kunture, an archaeological site in the Awash Valley in Ethiopia where ancient hominids lived for millions of years prior to our migration out of Africa. However, rather than focusing on spheres created by these prehistoric hominids, study author Margherita Mussi describes a number of naturally spherical stones that appear to have been deliberately collected by the site’s ancient inhabitants.
The stones appear at a number of spots that were occupied between 1.7 million and 600,000 years ago – a timeframe that suggests the spheres were probably collected by the ancient human species Homo erectus, as well as the later Homo heidelbergensis. Generally of volcanic origin, the spheres typically occur as accretionary lapilli, which are ash aggregates that form during explosive volcanic eruptions – of which there were many in this part of Africa during the Pleistocene.
Unlike those described in previous studies, “the volcanic spheres of Melka Kunture are not manufactured tools but the Pleistocene hominins undeniably noticed those well-rounded, strikingly geometric shapes,” writes Mussi. The fact that such specimens were probably rare in the surrounding landscape, meanwhile, “points to recurrent attentive collection for a purpose,” she continues.
Exactly what function the balls of rock served is unclear, although the author explains that “throughout the Early and Middle Pleistocene the hominins were interested in experimenting with the appropriate use(s) of the odd stone balls.” Evidence for this exploration can be found in the fact that the vast majority of the stones display “battered marks” and “abraded planes”, indicating that they were used for “percussive” purposes.
Adding to our understanding of the cognitive and behavioral attributes of Homo erectus and other early human species, these findings suggest that Pleistocene hominids paid “constant attention to the environment and to any new resource,” and were driven by their curiosity and creativity to find practical uses for these rare finds.
The study is published in the journal Quaternary International.
