1491_ New Revelations of the Americas Before Columbus - Charles C. Mann [113]
In 1997 Mary W. Eubanks, a Duke University biologist, resuscitated the hybridization theory in a new variant. Maize, she suggested, might have been created by repeatedly crossing Zea diploperennis, a rare maize relative, and another cousin species, Eastern gamagrass. When species from different genera hybridize, the result can be what the biologist Barbara McClintock called “genomic shock,” a wholesale reordering of DNA in which “new species can arise quite suddenly.” In Eubanks’s theory, Indians came upon a chance combination of Zea diploperennis and gamagrass and realized that by mixing these two species they could shape an entirely new biological entity. As proof, she announced the creation of a Zea diploperennis–gamagrass hybrid in the laboratory that displayed the attributes of ancient maize.
The teosinte faction remained skeptical. A consortium of twelve maize scientists harshly attacked Eubanks’s work in 2001 for, in their view, failing to demonstrate that her hybrid was actually a Zea diploperennis–gamagrass mix and not an accidental blend of Zea diploperennis and modern maize. (Such errors are a constant threat; in a busy lab, it is all too easy for biologists to use the wrong pollen, mislabel a tray, or mistake one analysis for another.) Meanwhile other geneticists pinpointed teosinte mutations that could have led to modern maize, including sugary 1, a variant gene that alters maize starch in a way that gives tortillas the light, flaky texture celebrated at Itanoní.
Because maize is many steps removed from teosinte, these scientists argued that the modern species had to have been consciously developed by a small group of breeders who hunted through teosinte stands for plants with desired traits. Geneticists from Rutgers University, in New Brunswick, New Jersey, estimated in 1998 that determined, aggressive, knowledgeable plant breeders—which Indians certainly were—might have been able to breed maize in as little as a decade by seeking the right teosinte mutations.
From the historian’s point of view, the difference between the two models is unimportant. In both, Indians took the first steps toward modern maize in southern Mexico, probably in the highlands, more than six thousand years ago. Both argue that modern maize was the outcome of a bold act of conscious biological manipulation—“arguably man’s first, and perhaps his greatest, feat of genetic engineering,” Nina V. Federoff, a geneticist at Pennsylvania State University, wrote in 2003. Federoff’s description, which appeared in Science, intrigued me. It makes twenty-first-century scientists sound like pikers, I said when I contacted her. “That’s right,” she said. “To get corn out of teosinte is so—you couldn’t get a grant to do that now, because it would sound so crazy.” She added, “Somebody who did that today would get a Nobel Prize! If their lab didn’t get shut down by Greenpeace, I mean.”
To people accustomed to thinking of maize in terms of dark or light yellow kernels of corn on the cob, the variety in Mexican maize is startling. Red, blue, yellow, orange, black, pink, purple, creamy white, multicolored—the jumble of colors in Mesoamerican maize reflects the region’s jumble of cultures and ecological zones. One place may have maize with cobs the size of a baby’s hand and little red kernels no bigger than grains of rice that turn into tiny puffs when popped; in another valley will be maize with two-foot-long cobs with great puffy kernels that Mexicans float in soup like croutons. “Every variety has its own special use,” Ramírez Leyva explained to me. “This one is for holidays, this one makes tortillas, this one for niquatole [a kind of maize gelatin], this one for tejate,” a cold drink in which maize flour, mamey pits, fermented white cacao beans, and other ingredients are marinated in water overnight and then sweetened and whipped to a froth. As