Birthplace of the domesticated chili pepper identified in Mexico, say Sacramento and Davis scientists at the University of California - Davis. Central-east Mexico gave birth to the domesticated chili pepper — now the world's most widely grown spice crop — reports an international team of researchers, led by a plant scientist at the University of California, Davis.
Results from the four-pronged investigation — based on linguistic and ecological evidence as well as the more traditional archaeological and genetic data — suggest a regional, rather than a geographically specific, birthplace for the domesticated chili pepper. That region, extending from southern Puebla and northern Oaxaca to southeastern Veracruz, is further south than was previously thought, the researchers found.
The region also is different from areas of origin that have been suggested for common bean and corn, which were presumably domesticated in Western Mexico
The study findings are published online April 21, 2014 in the Proceedings of the National Academy of Sciences, as part of a series of research papers on plant and animal domestication. Crop domestication, the process of selectively breeding a wild plant or animal species, is of increasing interest to scientists.
"Identifying the origin of the chili pepper is not just an academic exercise," said UC Davis plant scientist Paul Gepts, the study's senior author, according to the April 21, 2014 news release, Birthplace of the domesticated chili pepper identified in Mexico. "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," he said.
"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," Gepts added, according to the news release.
Study co-author Gary P. Nabhan, an ethnobiologist and agroecologist at the University of Arizona's Southwest Center noted: "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," Nabhan said in the news release.
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. For this chili pepper study, the researchers used these two traditional 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.
Other researchers on the study were Kraig H. Kraft and Robert J. Hijmans, both of UC Davis; Cecil H. Brown of Northern Illinois University in DeKalb, Ill.; Eike Luedeling of the World Agroforestry Centre in Nairobi, Kenya; José de Jesús Luna Ruiz of the Universidad Autónoma de Aguascalientes in Aguascalientes, Mex.; and Geo Coppens d'Eeckenbrugge of the Centre National de la Recherche Scientifique in Montpellier, France. The Fulbright Program, the University of California Institute for Mexico and the United States, and the UC Davis Department of Plant Sciences provided funding for the study.
Chickens to chili peppers
Chickens to chili peppers: Scientists from the Smithsonian Tropical Research Institute search for the first genetic engineers. Suddenly there was a word for chili peppers. Information about archaeological remains of ancient chili peppers in Mexico along with a study of the appearance of words for chili peppers in ancient dialects helped researchers to understand where jalapeños were domesticated and highlight the value of multi-proxy data analysis, according to the news release, "Chickens to chili peppers."
Their results are from one (Kraig Kraft et al.) of nine papers presented in a special feature issue of the Proceedings of the National Academy of Sciences on plant and animal domestication edited by Dolores Piperno, staff scientist emerita at the Smithsonian Tropical Research Institute and Curator of South American Archaeology at the National Museum of Natural History and Greger Larson of Durham University in England.
Humans evolved about 200,000 years ago. We spent 95 percent of human history as hunter-gatherers. Why did agriculture begin to emerge in human cultures about 12,000 years ago? Was it the result of a prime mover: divine inspiration, environmental change or population growth?
What cultural and natural processes led to the domesticated species that supply most of the world's foods today?
The complexity of these questions requires multidisciplinary research. Bringing together scientists from a wide range of disciplines involved in domestication studies, Larson and Piperno organized a meeting funded and hosted by the National Evolutionary Synthesis Centre in 2011. The PNAS special feature is a result of the meeting.
"Having archaeologists and geneticists talking to and collaborating with each other and a suite of new techniques to play with is radically changing the way we think about domestication," said Piperno.
The overview paper (Larson and Piperno et al.) that introduces the special issue emphasizes the need to use both archaeological and genetic evidence to sort out the unique processes of domestication that occurred at about the same time around the world from "predomestication cultivation"—plants cultivated over many generations that still have features of wild plants—and the presence of animals in association with humans to truly domesticated organisms that exhibit very specific traits like large seeds, bigger flowers, reduction in physical and chemical defenses in plants and altered coat color, floppy ears and baby faces (facial neotony) in animals.
Papers in the special feature cover both older and more recent issues in the study of domestication. New genetic screening techniques and the ability to sequence DNA from ancient specimens led Greger Larson and his group at Durham University (Linus Flink et al.) to caution that using modern genetic data alone to guess which genes may have been involved in domestication origins may be misleading.
They compared DNA from 80 chickens excavated from 12 different archaeological sites in Europe dated from 280 BC to the 18th Century to modern chicken DNA. Sequencing revealed that yellow-skinned chickens were probably not common early in the domestication process. Their work suggests that yellow skin became the norm only about 500 years ago, probably as a result of global commerce.
Addressing a long-debated question—why hunters and gatherers became farmers—Gremillion, Barton, and Piperno review theories and explanations for agricultural origins, making the case that evolutionary approaches are essential because they offer coherent, empirically testable reconstructions of human behavior.
The authors of the overview paper (Larson and Piperno et al.) expect more exciting results as researchers from around the world and from many disciplines work together to nail down the environmental and ecological contexts of domestication and the shift from hunting and gathering to cultivation and herding. As they say in the paper abstract: "It is difficult to overstate the cultural and biological impacts that the domestication of plants and animals has had on our species. The next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not."
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. You also may wish to check out the STRI website.