Contrasting the Structure of Teosinte with That of Corn - Essay Example

The possibility that teosinte may have been the progenitor of corn somehow lies in the mere hypothetical existence of a primitive “wise lady” who was believed to possess “the gift of creative imagination” and an understanding of the “particulate nature of inheritance, about dominant and recessive traits, about the recombination of traits” and many other technical aspects of genetics (Galinat 571). Furthermore, the fact that there is only one kernel per cupule in teosinte and the presence of hard casings on its kernels make them difficult to eat.

The movement of corn as a crop throughout the Americas was very slow. What accounts for this?
One of the probable reasons why it took a relatively long time for corn to move throughout America during its early stages of cultivation was that corn required “special cultivation techniques,” and that it took several thousands of years for the size and length of the cob of early maize to develop before it was cultivated as an agricultural crop (Prindle). Moreover, it took a long time for the hunters and gatherers of North America to transform into sedentary agricultural groups that cultivated maize (Prindle).

What archaeological data was used to provide information on the domestication of corn? What did each type of information reveal?

The domestication of corn was proven by archeological data. Some of these include 6000-year-old “cobs or cob fragments without kernels in place or direct association with cobs” or “cob macrofossils” found in southern Mexico (Eubanks 492, 494). These account for around 90% of evidence of the domestication of maize. However, more reliable than this would be the “ceramic models of maize” from Mexico and Peru for these provide some insight into how maize evolved (492-493). Another piece of archeological evidence is the “ancestral figures bearing attributes of different deities” found in the Zapotec pantheon in Mexico (493). These urns and jars contain engraved images of the maize god with a headdress of maize ears. Another type of evidence includes 129 vessels with maize replicas found in Mexico, Peru, the United States, and Europe (493). All this archeological evidence proves the domestication of corn in prehistoric times.

How did the domestication of corn differ from that of wheat? Could Galinat’s scenario for corn be applied to the domestication of wheat? Explain your answer.
According to Galinat, the domestication of corn involved the addition of the number of spikelets in teosinte (572). Teosinte and Tripsacum both had only two spikelets or two rows of seeds and due to cultivation practices that the wise lady devised, some mutants of four spikelets were produced, although the best mutation that she hypothetically discovered was one with “eight male rows,” which she called “the breakthrough advance to create humanity’s maize” (572). This eventually led to the evolution of modern maize. The hunters then began domesticating this maize as society transformed into a more sedentary, agricultural one.

Although the domestication of wheat occurred at particularly the same time, the difference lies in the fact that while corn domestication involved the production of more rows, the domestication of wheat involved “an increase in grain size and the development of nonshattering seed” (Eckardt). This means that ancient wheat had “a relatively small grain with a long, thin shape” and the challenge was to produce “a short, wide shape” (Eckardt). Galinat’s scenario may not entirely be applied to the domestication of wheat because the production of larger grains might have involved cultivation methods that were different from those used for the production of more spikelets in corn.

Explain why corn seed is most commonly purchased every year rather than saved from a previous year’s crop (3).
The reason that corn is commonly purchased every year and not saved from a previous year’s crop is that it is “relatively short-lived even under ideal storage conditions” (Lerner & Dana 1). If one saves corn seed from last year’s crop, the “seed…shows considerable variability and usually produces inferior plants and ears” (1). Therefore, due to the perishable nature of corn seed, one should purchase it every year.

What are the main differences between the Tripartite and the Teosinte theories? What type of information would provide evidence that would put to rest the controversy?
One difference between the Tripartite and Teosinte theories is that while the former proposes that maize came from the hybridization between wild maize and a species of Tripsacum, the latter contends that teosinte is the progenitor of maize. According to the teosinte theory, a hypothetical “wise lady,” or a female native who possessed “creative imagination” and an “extraordinary intellectual genius” put forth a series of agricultural experiments involving teosinte that eventually gave rise to maize (Galinat 570, 573).

The evidence lies in the genes of both plants: “…at the DNA level, the two are surprisingly alike [with] the same number of chromosomes and a remarkably similar arrangement of genes” (“The Evolution of Corn”). On the other hand, according to the tripartite hypothesis, “domesticated maize is a composite of the genomes of teosinte and Tripsacum” (Eubanks 509). This is based on the idea that Tripsacum chromosomes resemble those of maize and teosintes in terms of size and structure as well as other morphological features (497). Read More