As if that isn't tantalizing enough, new research published in Science Advances suggests Göbekli Tepe was once home to a "skull cult." In addition to being popular fodder for band names , skull cults are communities that attach particular significance to cranial remains, often displaying them or modifying them into functional items, like mugs or drums. This behavior has many permutations in human history, but this study marks the first osteological (bone-based) evidence of how Göbekli Tepe's bygone denizens treated dead bodies and their skulls.

Göbekli Tepe, a monumental structure in southern Turkey established over 11,000 years ago, has enraptured archeologists and laypeople alike since site excavations began in the 1990s. Decorated with imaginative artwork depicting animals, people, and animalistic people, this ancient temple contains the oldest known megaliths in the world.

"Those deep incisions are really exceptional," explained Julia Gresky, a paleopathologist based at the German Archaeological Institute and the study's lead author, in a Skype interview with Motherboard. "Maybe there will be other findings at other sites, but so far, it's really new."

Seven cranial fragments found at the site are believed to have been sourced from three individuals ranging in age from 20 to 50, one of which appears "more female than male," the authors said, though it's difficult to tell from fragmentary evidence. The pieces have been marked with features like deep carvings, ochre coloring, and even a drilled hole in one case.

The modified skulls were recovered from trenches around the monolithic site that were mysteriously backfilled several millennia after the complex was constructed. Gresky tells me this may have been a natural process, in which animal and human remains scattered due to heavy rain or other environmental causes, or the structure could have been intentionally buried by ancient peoples. Either way, there's a bunch of broken stuff lying around at Göbekli Tepe for researchers to sift through, including these cranial remains etched with rudimentary grooves.

Microscopic analysis of the bone revealed that the markings were created by stone tools, probably a short time after the skulls' owners died. Gresky and her colleagues suggest two possible explanations for the modifications: Ancestor veneration, or "branding" of perceived enemies for display. The grooves may have acted as "a track for a cord" to mount the skull, she said, and the drilled hole on the top of the cranium may have been used to suspend the skull like a mobile.