60,000-year-old ostrich eggshell engravings reveal a surprisingly sophisticated human mind

Archaeologists working at several sites in southern Africa have uncovered hundreds of unusual pieces of engraved ostrich eggshell. More than 60,000 years old, these fragments were created by groups of Homo sapiens living in the region.

A new study led by researchers at the University of Bologna suggests that the markings were far more organized than simple scratches or improvised decorations. Published in PLOS One, the research finds that the engravings followed recurring geometric principles involving parallel lines, right-angle relationships, and repeated regular patterns.

"These signs reveal a surprisingly structured, geometric way of thinking," says Silvia Ferrara, Professor at the University of Bologna's Department of Classical Philology and Italian Studies, who coordinated the study. "We are talking about people who did not simply draw lines, but organized them according to recurring principles -- parallelisms, grids, rotations and systematic repetitions: a visual grammar in embryo."

Ancient Eggshells Reveal Geometric Order

The ostrich eggshells were probably used as containers for carrying or storing water. To examine the engravings in detail, the researchers conducted a systematic quantitative analysis of 112 fragments recovered from two archaeological sites in South Africa (Diepkloof and Klipdrift) and one in Namibia (Apollo 11).

Using geometric and statistical techniques that had not previously been applied to these artifacts, the team reconstructed the directions, angles, and paths of the engraved lines.

Their results showed that more than 80% of the configurations contained consistent spatial patterns. Angles close to 90° appeared repeatedly, as did sets of parallel lines. More elaborate designs, including hatched bands, grids, and diamond-shaped motifs, also showed evidence of rotation, translation, repetition, and "embedding," i.e., the ability to build hierarchical levels of signs within the same surface.

"These engravings are organized and consistent, and show mastery of geometric relationships," Ferrara explains. "There is not only a process of repeating signs: there is real visuo-spatial planning, as if the authors already had an overall image of the figure in mind before engraving it."

A Window Into Early Abstract Thought

The researchers emphasize that the importance of the engravings goes beyond whatever meaning the individual markings may once have carried. Their broader significance lies in the mental abilities required to create visual designs according to consistent rules.

The capacity to arrange shapes and lines in organized configurations may represent an important sign of emerging abstract thought, a major development in the evolution of human cognition.

"Our analysis shows that Homo sapiens 60,000 years ago already possessed a remarkable ability to organize visual space according to abstract principles," notes Valentina Decembrini, PhD student at the University of Bologna's Department of Classical Philology and Italian Studies and first author of the study. "Transforming simple forms into complex systems by following defined rules is a deeply human trait that has characterized our history over millennia, from the creation of decorations to the development of symbolic systems and, ultimately, writing."

Studying Humanity's Earliest Geometries

The study was published in PLOS One under the title "Earliest Geometries. A Cognitive Investigation of Howiesons Poort Engraved Ostrich Eggshells." The authors are Valentina Decembrini, Ludovica Ottaviano, Mattia Cartolano, Enza Elena Spinapolice and Silvia Ferrara.

The research was conducted as part of the FIS Advanced project SAPIENCE -- Symbols, Preliteracy and Code Evolution, directed by Professor Silvia Ferrara, in collaboration with Professor Enza Spinapolice of Sapienza University of Rome.

Reporting from ScienceDaily contributed to this story.