A peculiar fossil skull discovered in a Greek cave over six decades ago may finally reveal some of its mysteries. Recent analysis indicates that at least 300,000 years ago, the early Homo sapiens coexisted with the first Neanderthals in Africa and Europe.

Unearthed in northern Greece in 1960, the Petrarona skull has long puzzled paleontologists, who are challenged to place it within the human lineage.

The fossil includes traits from Neanderthals and Homo erectus, yet it was found completely isolated, lacking artifacts or animal bones that could provide context for dating.

“The moment I examined and measured it, I realized it wasn’t a Neanderthal or Homo erectus,” stated Professor Chris Stringer, a paleontologist and co-researcher at the Museum of Natural History in London, in an interview with BBC Science Focus. “It was something unique.”

Stringer has long believed that the specimen belonged to our relative, Homo heidelbergensis, a robust human species that existed hundreds of thousands of years ago across Africa, Europe, and possibly Asia.

However, without a reliable date for the skull, understanding its place in the human narrative remained difficult.

A recent study utilized uranium series dating on the fossil’s calcite coating.

Calcite, one of the most common mineral forms of calcium carbonate, forms as water seeps into the pores and cavities, resulting in new mineral structures. This uranium series dating method estimates fossil ages by analyzing the calcite and measuring the decay level of uranium within it.

The findings suggest an age of approximately 286,000 years. Nevertheless, the methodology raises questions about the skull’s actual age.

“If fossil calcite forms swiftly after deposition in the cave, an age of around 288,000 to 290,000 years is plausible for the fossil,” Stringer noted.

“However, if the fossil was in the cave before the calcite developed, that age is a minimum estimate.”

Despite this caution, the timeline for Petrarona now closely aligns with another well-known Homo heidelbergensis skull from Kabwe, Zambia, which dates back about 300,000 years.

“Morphologically, they are similar and seem to be converging in their dating,” Stringer remarked.

This discovery underscores the idea that Homo heidelbergensis had a broad geographic presence and an extensive time span, overlapping rather than directly giving rise to other human species.

In simpler terms, contrary to earlier beliefs, they are not the common ancestors of modern humans and Neanderthals; Homo heidelbergensis was likely our contemporary for at least some time.

Stringer emphasized that this enriches our understanding of human evolution.

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