WASHINGTON, April 21 (Xinhua) -- U.S. researchers said Monday that they have identified central-east Mexico as the likely birthplace of the domesticated chili pepper, the world's most widely grown spice crop.
The region extends from southern Puebla and northern Oaxaca to southeastern Veracruz, the researcher reported in the U.S. journal Proceedings of the National Academy of Sciences.
"Identifying the origin of the chili pepper is not just an academic exercise," said senior author Paul Gepts, a plant scientist at the University of California, Davis, in a statement. "By tracing back the ancestry of any domesticated plant, we can better understand the genetic evolution of that species and the origin of agriculture -- a major step in human evolution in different regions of the world."
To determine crop origins, scientists have traditionally studied the plants' genetic makeup in geographic areas where they have observed high diversity among the crop's wild ancestors. More recently, they have also examined archaeological remains of plants, including pollen, starch grains and even mineralized plant secretions.
In the new study, the researchers used these two approaches but also considered historical languages, looking for the earliest linguistic evidence that a cultivated chili pepper existed. They also developed a model for the distribution of related plant species, to predict the areas most environmentally suitable for the chili pepper and its wild ancestors.
The genetic evidence seemed to point more to northeastern Mexico as the chili pepper's area of domestication, however there was collectively more evidence from all four lines of study supporting the central-east region as the area of origin, the researchers said.
"This is the first research ever to integrate multiple lines of evidence in attempts to pinpoint where, when, under what ecological conditions, and by whom a major global spice plant was domesticated," said co-author Gary Nabhan, an ethnobiologist and agroecologist at the University of Arizona's Southwest Center. "In fact, this may be the only crop-origins research to have ever predicted the probable first cultivators of one of the world's most important food crops."