Finely incised ostrich eggshell fragments from sites including Diepkloof, Klipdrift, and Apollo 11 in southern Africa and Namibia preserve geometric motifs such as grids, parallel lines, right angles, rhombuses, and complex cross-hatching. Researchers analyzing 112 engraved fragments found that more than 80% display coherent spatial organization and consistent regularities, indicating intentionality rather than random doodling. The findings have been interpreted as one of the earliest known instances of geometric thinking and suggesting the beginnings of abstract thought.

Archaeologist Silvia Ferrara described the organization of lines by recurring principles—parallelisms, grids, rotations, and systematic repetitions—as an embryonic visual grammar, according to Scienze Notizie. “These signs reveal a surprisingly structured and geometric way of thinking,” she said.

Valentina Decembrini, a PhD student and first author of the study, noted that Homo sapiens 60,000 years ago already possessed a remarkable ability to organize visual space according to abstract principles, and that the results illuminate the evolution of the human mind.

The engraved ostrich eggshells were first described in 2010 and have since been recognized for their well-defined geometric patterns—notably grids and rhombuses—that place them among the world’s oldest examples of geometric reasoning. The precision of the lines is consistent with a stepwise procedure: setting a baseline or axis, reproducing parallel marks at measured intervals, and joining elements at deliberate right angles. Over time, the repetition of these methods appears to have produced families of motifs with shared rules.