One of the most hotly debated issues in the discipline of archaeology is how and why certain human societies switched from hunting and gathering to producing their own food through agriculture. Ruth Dickau, who earned her doctorate in anthropology from Temple in 2005 and currently is a post-doctoral researcher in the University of Calgary’s department of archaeology, has used a new technique called starch grain analysis to recover microscopic residues of plants directly off the stone tools that people were using in Panama 3,000 to 7,800 years ago.

“These results add to the growing evidence that the earliest beginnings of farming were not centered in arid highland regions like central Mexico and the Peruvian Andes as once believed, but in the lowland areas and humid forests of the American tropics,” Dickau said.

“What is particularly interesting is that these crops were originally domesticated outside of Panama; maize was domesticated in Mexico, and manioc and arrowroot in South America.

Panama, as a relatively narrow land-bridge between the two American continents, was an important route for the human spread of food crops, and clearly a region where agriculture was practiced very early in history.”

Dickau is the lead author of a paper titled “Starch Grain Evidence for the Preceramic Dispersals of Maize and Root Crops into Tropical Dry and Humid Forests of Panama,” which was published February 19 in the online early edition of the Proceedings of the National Academy of Sciences, an internationally respected academic publication.

Ancient tools excavated by Ranere in the 1970s and again in 1997 at sites in both central and western Panama where analyzed by Dickau as part of her doctoral dissertation. Ranere is a co-author of the study, along with Richard G. Cooke of the Smithsonian Tropical Research Institute in Panama.

Dry, arid areas favor archaeological preservation, whereas tropical regions typically don’t – especially when it comes to foodstuffs. But with starch grain analysis, researchers are able to isolate residue from microcrevices in both ground stone and flaked stone tools and identify preserved starch grains under a microscope.

“We had thought, until Ruth did this work, that those people in western Panama were hunting and gathering, while those in central Panama were farming,” said Ranere. “But she showed, through her analysis, that that wasn’t true. In both these areas, the people were farming at about the same time — minimally 7,000 years ago.”

Ranere points out that, while the crops analyzed were domesticated elsewhere and then exchanged through Panama, these various crops were moving independently of one another.

“It’s not like farmers are marching up and down the landscape with crops,” he said. “The people are already in place in Panama and they are borrowing crops like maize from the north, and they’re borrowing crops like manioc and arrowroot from the south, and putting them together with plants and crops they are already growing locally.”

Dickau’s research was supported through a National Science Foundation Dissertation Improvement Grant, a Social Sciences and Humanities Research Council Doctoral Fellowship, and a Smithsonian Tropical Research Institute Pre-doctoral Fellowship.

*****

This story was written by Greg Harris of the University of Calgary, and edited for Temple University by Preston M. Moretz.