The analysis dated fossil starch grains

Feb 16, 2007 08:03 GMT  ·  By

A complex research carried on at Smithsonian's National Museum of Natural History found that chili peppers (Capsicum species) were cultivated and traded in the Americas at least 6,000 years ago, before the emergence of pottery in some areas.

To track the age of ancient chili peppers, the investigators dated starch grains from archaeological sites.

Chili peppers were already among the most widespread cultures in the Americas when the Europeans discovered it.

But tracing the place of their origins and the chronology of their cultivation was a hard task, as the tropical habitats - where most varieties were first cultivated - decay most organic material from archaeological sites, and only the most resistant last till nowadays. The research team overcame this issue by identifying chili pepper starch microfossil grains (microfossils like starch and pollen grains are named phytoliths).

Starch grains of chili peppers (different Capsicum species) are red blood cell shaped, split on the side. "Sorting through microscopic particles and finding a type that distinguishes such an important plant group is like opening a window to the past," said lead researcher Linda Perry. "While we once based our understanding of chili peppers on rare sites with exceptionally good preservation, suddenly we are able to gain incredible insight into ancient agriculture, trade and cuisine by making these plants visible nearly everywhere they occurred."

Cultivated chili starch grains are differentiated from wild chilies as they are associated with corn, in an ancient food complex that also included canna, arrowroot, leren, yuca, manioc, squash, beans and palm fruit. The chili starch phytoliths were discovered at seven sites, located from the Bahamas to southern Peru. The oldest grains were discovered in southwestern Ecuador at two 6,100 years old sites.

But Ecuador is not regarded as the center of domestication for any of the five cultivated chili species, and future investigations could find even older phytoliths.

Chilies associated with corn and yams were cultivated 5,600 years ago in Panama and in the Peruvian Andes; 4,000 years ago, chili from the species Capsicum pubescens were cultivated together with corn and arrowroot; and currently, one variety of pubescens, the rocoto pepper, is a staple ingredient in the Peruvian diet.

Recently discovered sites in the Bahamas (1,000 years old) and in Venezuela (500-1,000 years old) revealed the existence of the corn-chili complex. "It's hard to imagine modern Latin American cuisine without chili peppers," said co-author Dolores Piperno, Smithsonian scientist at the National Museum of Natural History and at the Smithsonian Tropical Research Institute in Panama. "We demonstrate that prehistoric people from the Bahamas to Peru were using chilies in a variety of foods a long time ago. The peppers would have enhanced the flavor of early cultivars such as maize and manioc and may have contributed to their rapid spread after they were domesticated."