It's "the first-ever fireplace," said Tel Aviv University archaeologist Ran Barkai in an email, and the earliest-known evidence of domestication of fire. Bringing home and roasting meat are "two very human phenomena that for us seem natural, but really are not. [The hearth] belongs to a crucial time in human biological and cultural evolution."

The hearth lies inside Qesem Cave, which is located in a geographical area known as the Levant—southern Turkey, Syria, Jordan, Lebanon, and Israel.

The identity of the hearth users is a mystery, though. "We call it for now a new hominin lineage," Barkai says.

"It is clearly different than [Homo] erectus and has affinities of both [Homo] sapiens and Neanderthals," he explains. "Since Neanderthals appear very late in the Levant and are of European origin, and since the Qesem [hominin] teeth bear more resemblance to early Homo sapiensin the Levant, we believe they are closer to Homo sapiens."

Qesem Cave was originally uncovered in October 2000 by a construction crew building a road. But it has taken years of excavation and analysis for Barkai, one of the co-leaders of the project, and his colleagues to build what they say is an unequivocal case for how the site was used.

Scientists found a thick bed of ash in the center of the cave. Using infrared spectroscopy, they were able to determine that the tiny bits of bone fragment mingled among the ash had been heated to high temperatures. That suggests this fire pit was used for cooking.

The ashes were not the product of a single blazing bonfire one night at a long-ago barbecue, though. Microscopic analysis of a cross section of the ash bed revealed a vast number of microstrata—layer upon layer of ancient ash, the residue of many, many fires built there over a long period of time.

Charred remnants of animal bones and flint tools used in butchering meat offered additional evidence for the activities that took place there.