The Petralona Skull Reexamined: At Least 286,000 Years Old, Researchers Say

The Petralona skull, one of the most debated fossils in human evolution, has been brought back into the spotlight by a recent geochronological study.¹

The Petralona skull, discovered in 1960 in a cave in Greece and preserved in almost complete condition, had not been definitively dated despite the passage of so many years. However, recent analyses using uranium-thorium dating methods reveal that the fossil is at least 286,000 years old.

According to researchers, the Petralona skull reinforces the idea that multiple human lineages may have coexisted in Europe during the Middle Pleistocene. Since its discovery, the skull, which has been associated with different human species such as Homo erectus, Homo neanderthalensis, and Homo sapiens, has remained at the center of debate due to the uncertainty surrounding its age.

Uranium-thorium dating was applied

As the article states, unlike previous studies, the research team chose to examine the calcite layers directly formed on the Petralona skull. This was because, although the fossil’s location within the cave was disputed, the calcite accumulation on the skull would provide a reliable lower limit for how long it had been there.

Uranium-thorium based dating is a technique that has long been used to determine the age of carbonate formations such as calcite. According to the researchers, the reason this method did not yield clear results in the Petralona sample before was that the calcite layers were heavily contaminated with clay and other foreign materials. In the new study, however, only the purest and earliest formed calcite layers were analyzed by performing micro-level sampling.

The results show that the oldest calcite layer on the skull formed 286,000 years ago. The study emphasizes that this date represents the youngest possible age of the fossil, not its true age. In other words, the Petralona skull may be older than this, but it is unlikely to be younger.

Researchers also conducted a comparative analysis with other calcite samples taken from different parts of the cave. This comparison revived the question of whether the skull was once attached to the cave wall, as had been claimed. According to the article, the calcite covering the skull and the thick stalactites and other formations on the cave walls are not from the same period. Therefore, the skull may have been moved or relocated into the cave later.

The initial dating studies conducted in the 1970s and 1980s relied on methods that were innovative at the time, such as electron spin resonance, thermoluminescence, and paleomagnetic analysis. However, the reliability of these methods in karst cave environments was already met with serious criticism in those early years.

The authors of the new study state that the main reason for the wide age ranges obtained in the past is the uncertainty of the fossil’s stratigraphic position. The inability to directly correlate the skull with animal remains and stone tools found around it made indirect dating attempts inevitable. This led to extremely wide age estimates ranging from 170,000 to 700,000 years.

The latest analyses, led by Christophe Falguères, are now supported by undeniably strong data. Nevertheless, the study uses cautious language. The authors state that the exact age of the Petralona skull is still unknown, only that it cannot be younger than 286,000 years.

Were there multiple human species in Europe?

The morphological features of the Petralona skull do not fully match either Neanderthals or modern humans. However, comparisons with the Kabwe skull, previously found in Africa, show significant similarities in facial structure and skull proportions between the two fossils. This is very important because it suggests that some Middle Pleistocene human populations in Europe and Africa may have had closer relationships than previously thought. The existence of such fossils, which do not exhibit Neanderthal characteristics but cannot be directly linked to modern humans either, shows that the evolutionary process exhibited a branching rather than a linear structure.

1. Falguères, C., Shao, Q., Perrenoud, C., Stringer, C., Tombret, O., Garbé, L., & Darlas, A. (2025). New U-series dates on the Petralona cranium, a key fossil in European human evolution. Journal of Human Evolution, 206, 103732. https://doi.org/10.1016/j.jhevol.2025.103732[↩]