The mound that contains the megalithic ruins of Göbekli Tepe, near the Syria-Turkey border, has been undergoing excavation since 1995. Since then, almost every new discovery has only added to the questions surrounding this extraordinary place.

It’s among the oldest known evidence of civilisation itself.

But archaeologists don’t even know what it was.

It looks like a place of worship. But did the stone-age hunter-gatherers of the Neolithic era who hewed its distinctive pillars out of the rock more than 11,000 years ago have the same idea of gods as we do?

We don’t know.

It wasn’t a settlement. There is little or no sign of people conducting their daily lives there.

So it was most likely something else that drew people to this place. Something significant.

Building Göbekli Tepe was itself an extraordinary achievement.

The T-shaped pillars are the world’s oldest known monumental architecture. Its scale is enormous. The quality of its artwork outstanding.

Yet these were made at a time when humanity didn’t have metal tools. Even pottery hadn’t yet been invented.

But ongoing excavations are providing some tantalising hints as to Göbekli Tepe prehistoric purpose.

Several fragments of skull have recently been unearthed, according to archaeologists at the German Archaeological Institute in Berlin. And the way they have been gouged and carved is something not seen elsewhere for millennia to come.

Only three such carved fragments have been found so far. But their 11,000 year preservation offers a new window to the past.

Their discovery is strong evidence that the dead played a central role among the circular arrays of megalithic pillars at Göbekli Tepe.

SKULL CULT

“Throughout history, people have valued skulls for different reasons, from ancestor worship to the belief that human skulls transmit protective properties,” the researchers write in a study published this week in the Science Advances journal.

The prevalence of this culturally significant practice has been well documented by modern anthropology.

Different skull cults have been identified around the world, from the medieval Aztecs of Central America to the mesolithic steppes of Eurasia. Their characteristic practices — such as how they modified the bones — have been carefully catalogued.

The Göbekli Tepe skull fragments match none of them.

Researcher Julia Gresky and colleagues examined the Göbekli Tepe partial skulls closely.

Were the marks caused by animals? Were they the result of natural scrapes and erosion over the eons?

A variety of microscopic tools were brought into play.

The results removed any doubt.

“Each skull had intentional deep incisions along its sagittal axes and one of those skulls also displayed a drilled hole in the left parietal bone, as well as red ochre remnants,” the authors say.

Close inspection of each gouge also revealed them to be consistent with cut marks from stone tools.

This also eliminated the possibility all of the markings were the product of ‘scalping’. Most were simply too deep.

But the presence of other minor cut-marks on the bone suggested a process of defleshing — the removal of the skin and hair to expose clean bone as a ‘clean slate’ for their deliberate designs.

“(Most) likely, the skulls were carved to venerate ancestors not long after their death”, the study authors write, “…or, to put recently “dispatched” enemies on display.”

GETTING INSIDE ANCIENT HEADS

Göbekli Tepe is odd. There is no natural water supply nearby. There don’t seem to be any habitable buildings, and almost no domestic tools or products.

Yet, the Neolithic people invested huge amounts of time and energy building the place.

Then, suddenly, in the 10th millennium BC — about the time agriculture began to explode across the Fertile Crescent of the Middle East — it was all deliberately buried.

This was an enormous undertaking in itself. It also appears to have been culturally significant, as artefacts and sculptures were carefully placed alongside the often richly carved T-shaped pillars as they were covered over.

Most appear to have been heads intentionally broken off from sculptures or idols — unlike similar objects depicting animals.

“Human heads seem to have had a special role in the beliefs connected with the enclosures,” the Göbekli Tepe project’s blog ‘The Tepe Telegrams’ reads. “During backfilling of the enclosures, a selection of fragments, mostly heads, was placed inside the filling, most often near the central pillars.“

Detached heads also feature in Göbekli Tepe’s extensive array of stone relief carvings.

One central pillar shows a head among animals including a vulture and hyena. Other sculptures show birds and animals carrying or sitting on human heads.

On anoother pillar, a headless human body (with an erection) is placed among birds, snakes and a scorpion.

“This practise is highly evocative of elements of neolithic death cults that also reflects in Göbekli Tepe´s iconography,” the researchers say.

WHAT IS GOBEKLI TEPE?

“At Göbekli Tepe we do not know very much about the actual use of the buildings,” the Tepe Telegrams blog states. “We have however the enclosures themselves, their layout, and the richly decorated pillars as starting points. And we know a lot of the things people did with these enclosures at the end of their uselife.”

The large, circular-arrayed central T-shaped pillars — some as high as 5.5m — are often depicted as abstract, clothed human bodies as seen from the side. Smaller, similar pillars surrounding them are more often richly decorated with animals.

“(These) are always ‘looking’ towards the central pillars, and the benches between them further amplify the impression of a gathering of some sort,” the researchers write.

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They speculate the deliberately abstract human design places the central pillars ‘in another sphere’ to that of other, more naturalistic, nearby carvings.

Are these ‘pillar-beings’ significant?

“Whether we are dealing with depictions of ancestors of different importance, or even of gods, would be a topic for itself and an answer is hard to find at the moment,” the researchers write.

But the concept of culturally significant, communal mausoleums is not uncommon in prehistory. And there is plenty of evidence of human head cults in the stone age.

It would not be unreasonable to speculate that Göbekli Tepe could have been the ritual centre of an enormous hunter-gatherer death-cult, where the skulls of the recently deceased were ritually passed from this world to an idealised, ancestor-based afterlife.

The oldest known evidence of religion.