A new study led by Logan Kistler, curator of archaeobotany and
archaeogenomics at the Smithsonian National Museum of Natural History
reveals that while maize originated from Mexico with the domestication of
the ancient grass teosinte, the trajectory of teosinte's evolution may be
more complex than previously thought.

The study analyzed the genomes of more than 100 varieties of modern maize
and 11 ancient plants. The researchers discovered several distinct lineages,
each with their own unique relationship to teosinte. The results also
revealed that although maize domestication began with a single large gene
pool in Mexico, the grain was carried elsewhere before the domestication
process was complete.

According to the study, there was a major wave of "proto-corn" movement from
Mexico to South America, where the domesticated maize landed in the
southwest Amazon, a hotspot for the domestication of other plants, including
rice, squash, and cassava. Kistler said that it is possible, though not
certain, that maize in this new location evolved more quickly than maize in
the center of domestication. After incubating in southwest Amazon for
several thousand years, maize moved to the eastern Amazon. The researchers
also discovered that modern maize from the Andes and southwestern Amazon is
closely related to maize grown in eastern Brazil, pointing to another
eastward movement.

Jeffrey Ross-Ibarra, a plant scientist at the University of California,
Davis said that the team's work shows how maize continued to evolve after it
arrived in South America. "While not a second domestication per se, it does
highlight that South American maize has undergone a considerable amount of
adaptation somewhat independently of maize in Mexico," he adds.

[www.smithsonianmag.com]
971038/