Findings may rewrite history of horticulture in Americas

Domestication of food and fiber plants in the New World — as well as the emergence of communities built around farming — appears to have occurred earlier than previously believed.

Researchers from four institutions, including the Agriculture Department, reported in the journal Science that they have determined certain cultivated plant material from northern Peru to be 9,240 years old.

The researchers, led by Vanderbilt University anthropologist Tom Dillehay, dated both newly found and previously excavated material from the Nanchoc Valley, which is about 1,500 feet above sea level on the Pacific slope of the Andes. They studied a few squash seeds, part of a peanut shell and a virtually intact cotton boll from the floors and hearths of ancient dwellings.

Radiocarbon dating put the squash seeds at more than 9,200 years old, the peanut hull at 8,000 and the cotton at 5,500. All bore evidence of being cultivars — plant varieties intentionally selected and maintained through cultivation — rather than wild plants. None was closely related to nearby species, suggesting they had been domesticated elsewhere.

The archaeological context in which these vegetable remnants were found strongly suggests that horticulture was already well established by at least 6,000 to 7,000 years ago. The communities included canals for water management; mounds associated with the production of lime, which was used in preparing coca extracts; and personal garden plots.