Limestone spheroid 3D models for: The limestone spheroids of 'Ubeidiya: Intentional imposition of symmetric geometry by early hominins?

Spheroids are one of the least understood lithic items yet are one of the most enduring, spanning from the Oldowan to the Middle Palaeolithic. Why and how they were made remains highly debated. We seek to address whether spheroids represent unintentional by-products of percussive tasks or if they were intentionally knapped tools with specific manufacturing goals. We apply novel 3D analysis methods, including spherical harmonics and surface curvature, to 150 limestone spheroids from 'Ubeidiya (c.1.4Ma), presently the earliest Acheulean occurrence outside of Africa, to bring a new perspective to these enigmatic artefacts. We reconstruct the spheroid reduction sequence based on trends in their scar facets and geometry, finding that the spheroid makers at 'Ubeidiya followed a premeditated reduction strategy. During their manufacture, the spheroids do not become smoother, but they become markedly more spherical. They approach an ideal sphere, a feat that likely required a mental template and skilful knapping. Acheulean bifaces are currently thought to represent the earliest evidence of hominins imposing a premeditated, symmetrical shape on stone. With evidence of spheroids occurring before the Acheulean, the intentional production of a sphere-like object now represents the oldest evidence of hominins desiring and achieving intentional geometry and symmetry in stone.Funding provided by: Gerda Henkel FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001653Award Number: AZ 32/V/19Funding provided by: Ministerio de Ciencia e InnovaciónCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004837Award Number: CEX2019-000945-MFunding provided by: Generalitat de CatalunyaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100002809Award Number: SGR: 2021 SGR 01238 (AGAUR