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.