A couple of recent papers of the UC Davis crops sciences group, continue the research tradition of Paul Gepts in providing further refinements in out undrerstanding of Phaeseolus vulgaris domestications, especially in terms of locating these two domestications and identifying closed related wild popualations.
Kwak and Gepts published in Theoretical & Applied Genetics 118 [March 2009] an open access paper on a phylogenetic and population structure analysis on wild and domesticated beans, reinforcing earlier inferences of separate Mesoamerica and SOuth American origins.
Further details on the Mesomaerican wild populations, their relationships and distributions, can be found in another paper by Kwak, Kami and Gepts (2009) The Putative Mesoamerican Domestication Center of Phaseolus vulgaris Is Located in the Lerma-Santiago Basin of Mexico, Crop Science 49: 554-563. This study concludes that Mexican beans did not originate in the Rio Balsas valley favoured for maize origins--and supported by recent archaeobotany work, but elsewhere in Southwest Mexico. This was on the News feeds of the Crop Society of America last week.