Archeology And Genetics Team Up To Put A Much Earlier Date On South American Agriculture

Working with colleagues from Ithaca College and the Smithsonian's National Museum of Natural History, Sandweiss discovered evidence of cultivated corn in the Cotahuasi Valley of southern Peru that dates back to nearly 4,000 years before the present, suggesting that corn was an important crop in that region more than 1,000 years earlier than previously thought.

"Smithsonian researcher Linda Perry's analysis of starch grains extracted from sediment samples and stone tools discovered at the site revealed two kinds of corn that had been ground into flour. No one has found a record of either from anywhere near this time for this part of Peru," said Sandweiss. "At this early time period, agricultural hadn't been demonstrated in the highlands of Peru, Bolivia or Chile."

The tools and sediments were discovered when a small test pit revealed the outline of a 3,600- to 4,000-year old circular house near Cerro Aycano, a 14,600-foot mountain that was an important source of obsidian for people of the region. Obsidian is a black volcanic glass that was used for making tools and other items.

Evidence of potato starch was also found at the site.

In addition to changing some long-held beliefs about South American agriculture, the discovery also points to the potential of microfossil analysis as an important new tool for archeologists. The technique is used to identify tiny plant particles found on tools, container fragments and other artifacts removed from dig sites.

The latest in a number of important discoveries Sandweiss has made in Peru, the microfossil remains are an excellent example of Sandweiss's multidisciplinary approach to archeology.

"By bringing in as many different kinds of people as possible who can bring their expertise to bear in what we are doing, we are able to find unexpected but significant results that might otherwise have been missed," said Sandweiss. "It is truly a process of unexpected discovery, and what you get out of it depends on how well you keep open to new ideas."

The research was published in the journal Nature on March 2.