Neanderthal Skeleton Discovery Changes What We Know About Human Evolution

A "truly extraordinary" Neanderthal skeleton covered in "cave popcorn" is shedding new light on some of the mysteries of human evolution. Known as the "Altamura Man," it is one of the best-preserved Neanderthal specimens yet discovered and probably the most complete.

Giorgio Manzi, a researcher with Sapienza University of Rome, told Newsweek the Altamura skeleton "is a truly extraordinary discovery, of enormous interest for our knowledge of Neanderthals, ourselves as a species and human evolution in general."

The skeleton is trapped deep in a cave system near the town of Altamura, southern Italy. It was found in 1993, but has never been moved for fear of damage.

"Being able to study this Neanderthal—especially if it were eventually extracted from the limestone, with all the necessary precautions—would mean having the possibility of clarifying aspects of human evolution which, otherwise, simply would not be knowable," Manzi added.

"Unfortunately, that extraordinary scientific heritage is still there, as if it were a prisoner of the calcareous concretions that have enveloped it over the course of tens of thousands of years."

Now Manzi and his fellow researchers have discovered that the skeleton's cranium has a combination of features never before seen in the species. Their study, published in the Nature journal Communications Biology, suggests one of the major theories of Neanderthal evolution needs to be reassessed.

Neanderthals—Homo neanderthalensis—are one of our closest ancient relatives and lived in Eurasia until disappearing around 40,000 years ago. Evidence indicates that they emerged in the Middle Pleistocene, which ran from around 780,000 to 126,000 years ago. The earliest Neanderthal-like fossils are about 430,000 years old, but major parts of the Neanderthal origin story remain unclear.

Altamura Man's skull might change that. Manzi said his team had to conduct a "virtual excavation" so they could digitally reconstruct the cranium. This revealed a "very peculiar combination" of physical traits, Manzi said. "I would say unique."

Some of the cranium's features are typical of Neanderthals. Others appear more ancient, comparable to specimens hundreds of thousands of years older. Some even resemble those in an earlier and potentially distinct human species, Homo heidelbergensis.

Altamura Man lived between around 130,000 and 170,000 years ago, according to scientists. This period is marked by the transition between Homo heidelbergensis and the Neanderthals, but the Italian specimen does not appear to fall neatly into either category.

"One could almost say that, on the basis of the characteristics observed on the cranium, the Italian specimen is more likely to be the last representative of the species Homo heidelbergensis rather than being among the earliest Homo neanderthalensis," Manzi said.

The unexpectedly archaic features led the researchers to hypothesize that the southernmost regions of the Italian peninsula may have provided a "refuge" for ancient humans during the coldest phases of the Middle Pleistocene and the Upper Pleistocene (around 126,000 to 12,000 years ago).

The archaic traits may have resulted from the geographic isolation of early Neanderthal populations in southern Italy. In this region, the archaic traits persisted for longer than in other parts of Europe, the authors said.

As a result, Manzi said there might have to be a rethink of aspects of the "accretion model," one of the main hypotheses of Neanderthal evolution. It states that Neanderthals evolved in partial or complete genetic isolation from the rest of humanity, through the gradual accumulation of distinctive physical traits in European populations.

The latest study shows that the accretion model can only be accepted if the varied environmental conditions of different European regions are taken into account. In some areas, local conditions may have accelerated the process. In others—such as southern Italy—local conditions may have slowed down this process.

Why Is Altamura Man Still in the Cave? And What Is Cave Popcorn?

Studying the Altamura specimen is not easy. It is located deep in the Lamalunga cave system, which can only be reached using special equipment.

To make it more difficult, the skeleton is suspended within a sheet of mineral deposits, so only parts of it are visible. It straddles two distinct chambers in the cave, which are separated by the mineral "curtain." It is also covered in coralloids—or "cave popcorn"—small, bulbous mineral structures that form on surfaces in caves.

The arrangement of the bones indicate that Altamura Man might have collapsed and died in the spot where his skeleton remains. One possibility is that he fell down a shaft in the cave complex and was unable to escape.

Scientists have long hoped to bring Altamura Man back to the surface, so the skeleton can be examined thoroughly in a lab. But until they have a plan to excavate the specimen without causing irreparable damage, the Italian authorities will not issue a permit.

For now, working in the cave is the only option. Although the skeleton was found in 1993, it took another 22 years before a team of researchers—including Manzi—confirmed it was a Neanderthal.

In their latest study, Manzi and his colleagues wanted to examine the skeleton's cranium, but not all the skull can be seen in the cave. One side of the cranium faces into the back chamber, which is inaccessible. Only a few gaps in the mineral curtain allow researchers to peek into the chamber.

Probes were used for a "virtual excavation" of the skull and the information gathered helped the team create a digital reconstruction of the complete cranium. This allowed the scientists to examine the shape of the cranium as a whole, in detail, for the first time.