Schmidt returned a year later with five colleagues and they uncovered the first megaliths, a few buried so close to the surface they were scarred by plows. As the archaeologists dug deeper, they unearthed pillars arranged in circles. Schmidt's team, however, found none of the telltale signs of a settlement: no cooking hearths, houses or trash pits, and none of the clay fertility figurines that litter nearby sites of about the same age. The archaeologists did find evidence of tool use, including stone hammers and blades. And because those artifacts closely resemble others from nearby sites previously carbon-dated to about 9000 B.C., Schmidt and co-workers estimate that Gobekli Tepe's stone structures are the same age. Limited carbon dating undertaken by Schmidt at the site confirms this assessment.
The way Schmidt sees it, Gobekli Tepe's sloping, rocky ground is a stonecutter's dream. Even without metal chisels or hammers, prehistoric masons wielding flint tools could have chipped away at softer limestone outcrops, shaping them into pillars on the spot before carrying them a few hundred yards to the summit and lifting them upright. Then, Schmidt says, once the stone rings were finished, the ancient builders covered them over with dirt. Eventually, they placed another ring nearby or on top of the old one. Over centuries, these layers created the hilltop.
Today, Schmidt oversees a team of more than a dozen German archaeologists, 50 local laborers and a steady stream of enthusiastic students. He typically excavates at the site for two months in the spring and two in the fall. (Summer temperatures reach 115 degrees, too hot to dig; in the winter the area is deluged by rain.) In 1995, he bought a traditional Ottoman house with a courtyard in Urfa, a city of nearly a half-million people, to use as a base of operations.
On the day I visit, a bespectacled Belgian man sits at one end of a long table in front of a pile of bones. Joris Peters, an archaeozoologist from the Ludwig Maximilian University in Munich, specializes in the analysis of animal remains. Since 1998, he has examined more than 100,000 bone fragments from Gobekli Tepe. Peters has often found cut marks and splintered edges on them—signs that the animals from which they came were butchered and cooked. The bones, stored in dozens of plastic crates stacked in a storeroom at the house, are the best clue to how people who created Gobekli Tepe lived. Peters has identified tens of thousands of gazelle bones, which make up more than 60 percent of the total, plus those of other wild game such as boar, sheep and red deer. He's also found bones of a dozen different bird species, including vultures, cranes, ducks and geese. "The first year, we went through 15,000 pieces of animal bone, all of them wild. It was pretty clear we were dealing with a hunter-gatherer site," Peters says. "It's been the same every year since." The abundant remnants of wild game indicate that the people who lived here had not yet domesticated animals or farmed.
But, Peters and Schmidt say, Gobekli Tepe's builders were on the verge of a major change in how they lived, thanks to an environment that held the raw materials for farming. "They had wild sheep, wild grains that could be domesticated—and the people with the potential to do it," Schmidt says. In fact, research at other sites in the region has shown that within 1,000 years of Gobekli Tepe's construction, settlers had corralled sheep, cattle and pigs. And, at a prehistoric village just 20 miles away, geneticists found evidence of the world's oldest domesticated strains of wheat; radiocarbon dating indicates agriculture developed there around 10,500 years ago, or just five centuries after Gobekli Tepe's construction.
To Schmidt and others, these new findings suggest a novel theory of civilization. Scholars have long believed that only after people learned to farm and live in settled communities did they have the time, organization and resources to construct temples and support complicated social structures. But Schmidt argues it was the other way around: the extensive, coordinated effort to build the monoliths literally laid the groundwork for the development of complex societies.
The immensity of the undertaking at Gobekli Tepe reinforces that view. Schmidt says the monuments could not have been built by ragged bands of hunter-gatherers. To carve, erect and bury rings of seven-ton stone pillars would have required hundreds of workers, all needing to be fed and housed. Hence the eventual emergence of settled communities in the area around 10,000 years ago. "This shows sociocultural changes come first, agriculture comes later," says Stanford University archaeologist Ian Hodder, who excavated Catalhoyuk, a prehistoric settlement 300 miles from Gobekli Tepe. "You can make a good case this area is the real origin of complex Neolithic societies."
What was so important to these early people that they gathered to build (and bury) the stone rings? The gulf that separates us from Gobekli Tepe's builders is almost unimaginable. Indeed, though I stood among the looming megaliths eager to take in their meaning, they didn't speak to me. They were utterly foreign, placed there by people who saw the world in a way I will never comprehend. There are no sources to explain what the symbols might mean. Schmidt agrees. "We're 6,000 years before the invention of writing here," he says.