Artificially modified ancient human crania discovered in 11,000 year-old historical site of Göbekli Tepe in Turkey's southeastern Şanlıurfa province has shed light on a Neolithic skull cult, according to new research published on Science Advances.

The research suggests that Göbekli Tepe, which is home to one of the oldest temples in history, hosted "a previously undocumented variation of skull cult in the Early Neolithic of Anatolia and the Levant." The skulls could be the first examples of modified skulls in the world.

Skulls excavated at the temple in the ancient site show evidence of carving after the heads were scalped and defleshed.

In one of the skulls, researchers also discovered a drilled perforation, which give insight into the treatment of the dead by the ancient people.

Researchers also suggested that modifications on the skulls were most likely performed shortly after death, based on analysis of the cut marks:

Cut marks are characterized by sharp edges, meaning that the bone was cut when still elastic, that is, at an early state of decay" the research said.

Researchers have noted that the ancient people visiting Göbekli Tepe could either be venerating their ancestors by displaying the skulls, or the skulls could also belong to their enemies. These people may have believed that the power of the dead could be transferred to the living.

Göbekli Tepe is considered to be the oldest temple complex in the world. Excavations at the site are carried out jointly by Turkey's Ministry of Culture and Tourism and Germany Archeology Institute.

The site was declared a first-degree protection area in 2015 and is also on UNESCO's tentative list of World Heritage Sites.The ancient site recently made it to a list by the Business Insider called "30 architectural masterpieces everyone should see in their lifetime."