The archaeological site of Caral, located in central Peru's Supe Valley, may represent the oldest complex society in the Americas, according to a study published today in the journal Science. Carbon dating indicates that large-scale stone structures at the site are as much as 1,000 years older than other comparable remains. "What we're learning from Caral is going to rewrite the way we think about the development of early Andean civilization," asserts co-author Jonathan Haas of the Field Museum in Chicago.

Caral's elaborate stony remains include an array of architectural forms: two sunken circular plazas, numerous residential buildings, and platform mounds, the largest of which measures 160 meters long and 18 meters high. Monumental stone structures like those found at Caral are usually associated with civilizations dated to after 1500 B.C., but the new dates place the Caral remains somewhere between 2627 and 1977 B.C. "The size of a structure is really an indication of power," Haas remarks. "It means that leaders of the society were able to get their followers to do lots of work. People don't just say 'Hey, let's build a great big monument,' they do it because they're told to and because the consequences of not doing so are significant."

The finding calls two established archaeological theories into question. One of these holds that complex civilization didn't arise until the so-called ceramic period, around 1500 B.C. The other posits that civilization first evolved in coastal areas, not inland, where Caral is located. Another puzzle is how a civilization such as Caral could have evolved without some kind of cultivatable grain. In most other complex societies, grain, which can be stored in large amounts, was given in exchange for labor. "There wasn't a product like corn in the Supe Valley," team member Winifred Creamer of Northern Illinois University observes, "but they still managed to develop in this complex way." She suspects that the people of Caral, within traveling distance of the ocean, may have resorted to another currency: dried fish.