Tracking the Ancestry of Corn Back 9,000 Years - NYTimes.com
This is a delightful article by Sean B. Carroll tracing the history of maize as it developed out of a single domestication of teosinte in ca. 7000 B.C. in the Balsas Valley of southern Mexico.
For the scientific article at the root of the story, see A single domestication for maize shown by multilocus microsatellite genotyping by Yoshihiro Matsuoka, Yves Vigouroux, Major M. Goodman, Jesus Sanchez G., Edward Buckler, and John Doebley, where the Abstract reads:
"There exists extraordinary morphological and genetic diversity among the maize landraces that have been developed by pre-Columbian cultivators. To explain this high level of diversity in maize, several authors have proposed that maize landraces were the products of multiple independent domestications from their wild relative (teosinte). We present phylogenetic analyses based on 264 individual plants, each genotyped at 99 microsatellites, that challenge the multiple-origins hypothesis. Instead, our results indicate that all maize arose from a single domestication in southern Mexico about 9,000 years ago. Our analyses also indicate that the oldest surviving maize types are those of the Mexican highlands with maize spreading from this region over the Americas along two major paths. Our phylogenetic work is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. We also found only modest evidence for postdomestication gene flow from teosinte into maize. "See also Rio Balsas most likely region for maize domestication by Christine A. Hastorf who writes, inter alia:
"It is curious that with so much interest in the topic of plant domestication in archaeology, geography, and botany, it took until 2005 to include this region of Mexico in our search for the roots of domestication. This investigatory blind spot is most probably because visible early plant evidence was uncovered in dry conditions. Following the data, scholars pursued domestication where they could easily find the evidence, ignoring the regions where the interactions were more likely to occur."In other words, without the genetic evidence, mainstream archaeology would still be looking for evidence of domestication in the WRONG places because that is where "drilling" for the truth was the easiest.