Maize: Origin, Domestication, and its Role in the Development of Culture

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Maize: Origin, Domestication, and Its Role in the Development of Culture
The essential differences between teosinte and maize are as follows:
1. The ear of teosinte is fragile and breaks up at the rachis’s joints. All wild
cereals are fragile, and under domestication all developed non-shattering
races.
2. Teosinte ears have two rows, whereas maize has four or more rows.
3. In teosinte, only one of the two female spikelets is fertile, whereas the other
one is reduced. Both members of the pair are fertile in maize.
4. In teosinte the outer glumes are very hard, whereas in maize they are soft
and external.
5. In teosinte the glumes cover the seeds, whereas in maize the kernels are
(usually) exposed.
6. In teosinte the kernels are embedded into the deep cupules in the rachis,
whereas in maize the kernels are held in place by cupules that are not too
deep. This is a variable characteristic even in maize, and the cob conforms
to row number and seed size as an integrated unit.
7. In teosinte the kernels are fragile, but they are not so in maize.
8. Teosinte seeds are small ones; those of maize may be small but are usually
twice the size of the wild races. Increase in the size of the seed usually takes
place under domestication.
9. In teosinte the primary lateral inflorescence is usually male, whereas in
maize the primary lateral inflorescence is usually female.
10. In teosinte the primary lateral branches are long ones, but in maize they are
short ones.
Other traits, such as the number of ears per plant or the amount of cupules per
ear, are presumably secondary effects of domestication, as opposed to primary
morphogenetic changes related with the transformation of teosinte into maize
(Doebley et al., 1990: 9889; Harlan, 1995: 183–184).
Mangelsdorf analyzed and summarized the evidence for the flow of genes
between maize and teosinte. He reached four conclusions. First, F 1 hybrids of
maize and teosinte are usually vigorous, highly fertile, and easily backcrossed to
either parent to produce a fertile progeny. Second, the chromosomes of both
species are morphologically similar, and the synapse is more or less normal in
hybrids. Third, the arrangement of the gene loci, although not identical, is similar
in the two species. Finally, in both maize and teosinte, the crossing over
between linked loci follows the same order as in maize, with few exceptions.
Mangelsdorf therefore pointed out that a more realistic classification would
have maize and teosinte represent a single dimorphic species in which one component
is preserved by man, and another one by nature (Mangelsdorf, 1974:
123–124).
Clearly one of the major differences between maize and teosinte is the structure
of the cupule, as has already been noted. For Galinat (1970), the cupule
provides the connecting link between the maize cob and the origin of the