The key traits that separate the ears of teosinte and maize are: (1) solitary in teosinte vs. paired female spikelets in maize; (2) two-ranked in teosinte vs. many-ranked central spike (ear) in maize; (3) shattering in teosinte vs. nonshattering rachis (cob) in maize.

It is significant that all of these key traits make the maize ear more adapted as a food source for man and at the same time less adapted for survival in the wild. This is not a change in reproductive strategy expected from evolution under natural selection but under domestication.

The close cytological homology of teosinte and maize indicates a parent to progeny relationship, and evolutionary trends leading to formation of the cupulate fruit case indicate that teosinte is the parent. The simple genetic changes under domestication would be: (1) a reactivation of the pedicellate female spikelet; (2) a proliferation to many ranks of spikelets; and (3) a reduction of abscission layers between rachis segments.

Walton C. Galinat

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