Linguistic, ecological, archaeological and genetic evidence show that the domesticated chili pepper, Capsicum annuum, originated in central-east Mexico more than 6,500 years ago.
Capsicum annuum from Köhler’s Medizinal Pflanzen, 1887. Image credit: Missouri Botanical Garden.
“Identifying the origin of the chili pepper is not just an academic exercise. 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,” Dr Paul Gepts from the University of California, Davis, who is the senior author of the paper published in the Proceedings of the National Academy of Sciences.
“This information, in turn, better equips us to develop sound genetic conservation programs and increases the efficiency of breeding programs, which will be critically important as we work to deal with climate change and provide food for a rapidly increasing global population.”
To determine crop origins, scientists have estimated the genetic distance between 139 wild and 49 cultivated types of chili pepper.
They have also examined archaeological remains of plants from two locations in Mexico for which there is evidence of the earliest use of chili – the Romero’s Cave near Ocampo, Tamaulipas, and the Coxcatlán Cave, Tehuacán Valley, Puebla.
For their study, Dr Gepts with colleagues also considered 30 protolanguages of Mesoamerica, 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, evidence from all four lines of study supports the central-east region as the area of origin, extending from southern Puebla and northern Oaxaca to southeastern Veracruz.
“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. 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,” said study co-author Dr Gary Nabhan from the University of Arizona.
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Kraig H. Kraft et al. Multiple lines of evidence for the origin of domesticated chili pepper, Capsicum annuum, in Mexico. PNAS, published online April 21, 2014; doi: 10.1073/pnas.1308933111
