New Insights into Ancient Grain

Maize, commonly called corn in the United States and Canada, is perhaps the most enigmatic of the major food staples. Although scientists have been able to narrate the domestication and diffusion of wheat, anthropologists, archaeologists, biologists, geneticists, and linguists continue to grapple with gaps in the history of maize. In fact, it was only in the twenty-first century that geneticists were able to definitively prove the contested notion that teosinte, a wild grass native to Mesoamerica, is the singular ancestor for maize in all its varieties. Still unresolved is the reason indigenous peoples were attracted to wild teosinte thousands of years ago. Many historical questions remain, and while scientists work on these, others in the biological and social sciences focus on the contemporary market-based and cultural concerns related to maize. Maize is both an ancient crop and modernly ubiquitous. Today, in the United States, some 99 million acres are planted in maize, nearly twice the amount that was planted in 1969. Maize is a staple food for humans, animals, and farm-raised fish; a source for biofuels; and a key ingredient in industrial food processing, with highfructose corn syrup attracting attention for its link to diabetes and obesity. The widespread use of maize has helped fuel interest in its genetics. In 2009, the genome of one variety of maize was made public for the first time, and in 2012, two National Science Foundation (NSF)–supported USDA-ARS and based in Cold Spring Harbor Laboratory in New York, led the NSF study commonly referred to as HapMap2, and she adds, “It is really amazing when you look at two corn specimens that look so much alike that they can be so different at the genome level.” Buckler underscores that maize genetic diversity, which includes the regions between genes that regulate genetic activity, is perhaps the central conveyance of recent studies. “We know that in the genome, only about half the DNA is in the same place between two varieties of maize. The genome is incredibly diverse,” Buckler says. “So maize is at the high end of genomic studies shed light on the diversity, domestication, and improvement of maize varieties. These and other ongoing studies underscore the plant’s vast genetic diversity, setting it apart from other agricultural staples. “Something we have understood for a while is that, at the DNA level, for any two varieties of maize, they are far [more] different from each other than humans are from chimpanzees,” says US Department of Agriculture’s Agricultural Research Service (USDA-ARS) geneticist Edward Buckler, who also teaches at Cornell University and was a leader and coauthor on both of the NSF-supported studies. Geneticist Doreen Ware, also with