The mysterious origin of maize

Domesticated maize emerged from human selection, exploitation, and cultivation of natural recombinants between two wild grasses that had novel characteristics desired by humans for food. Crossing experiments reconstructing prototypes of ancient archaeological specimens demonstrate how the simple flowering spike of the wild relatives of maize was transformed into the prolific grain-bearing ear within a few generations of intergenomic recombination between teosinte and Tripsacum. The high degree of morphological similarities of segregating intercross progeny to archarological specimens front Tehuacan, Oaxaca, and Tamaulipas provides strong support for this evolutionary scenario. Comparative genomic analysis of maize, teosinte, and Tripsacum confirms that maize has inherited unique polymorphisms from a Tripsacum ancestor and other unique polymorphisms front a teosinte progenitor. This supports the hypothesis that Tripsacum introgression provided the mutagenic action for the transformation of the teosinte spike into the maize ear. This model for the origin of maize explains its sudden appearance, rapid evolutionary trajectory, and genesis of its spectacular biodiversity.