In the Peru's Andean foothills, a group of archaeologists say they have found remnants of the oldest known irrigation canals in South America, which they hope will provide clues to the origin of the region's agriculturally based societies.
"There are four sites in the area that have canals that date minimally 5,300 years ago, maybe a little earlier," team leader Tom D. Dillehay, an archaeologist at Vanderbilt University in Nashville, Tenn., told The Associated Press.
Dillehay started his research nearly 30 years ago in the Zana Valley, 37 miles (60 kilometers) inland from the Pacific Ocean and about 385 miles northwest of Lima.
The conclusions, reported in the Nov. 22 issue of the Proceedings of the National Academy of Sciences, offer evidence, long suspected by archaeologists, that irrigation technology was critical to the development of Peru's early civilization, Dillehay said.
"The Zana Valley canals are the earliest known in South America," wrote the authors of the journal article, Dillehay, Herbert H. Eling Jr. of the National Institute of Anthropology and History in Mexico and Jack Rossen of Ithaca College.
Dr. Daniel Morales, director of the school of archaeology at Peru's San Marcos University, said he had not seen the article, but was familiar with Dillehay's work. He said the "discovery of the Zana canals is very important because it could be linked to the first form of irrigated agriculture" in Peru.
Discovered a decade ago
Dillehay, in a telephone interview from Chile, said the team first discovered some of the canals and agricultural features in 1985 and dated them for the first time in 1989.
But he said his team waited until now to publish its findings to better understand the hydraulic engineering of the hunters and gatherers who made a historic break from their ancestors to tend "early gardens."
Carbon dating of the four silt-filled canals, buried under sediments, showed that they were used to irrigate cultivated fields about 5,400 years ago, in one case possibly as early as 6,700 years ago, the article said. The team found evidence of domesticated cotton, beans and squash and stone hoe-like tools near the site.
Peruvian civilization
Peru was one of the only places in the world where a complex society flourished, largely independent of outside influence, at the same time the pyramids of Egypt were being built.
In recent years, Peruvian archaeologist Ruth Shady discovered the ruins of Caral, the earliest known city in the Americas, about 300 miles (480 kilometers) southeast of Zana. Jonathan Haas and Winifred Creamer, a Chicago-area husband-and-wife team, later documented more than 20 other major residential centers nearby with platform mounds and pyramids along the Peruvian coast, known collectively as the Norte Chico.
"Those settlements come at least 800 to 1,000 years later," Dillehay said, explaining that what his team documented are earlier pieces of the puzzle: small communities with the beginnings of "social mobility, social complexity" that over centuries "percolated" into the complex societies that followed.
"These huts and residential camp sites we have found that are above the canal, they had to share the water, first of all," he said.
"They had to keep the canals clean, so we're talking about some sense of communal labor and sharing and coordination and planning over a distance of at least two kilometers. So it's not just scattered individual households, but some initial social aggregation with communal responsibility."