An Edible History of Humanity Read Free

nutrient supply and can potentially grow much larger. Once again,
     human selection guided this process. As proto-farmers gathered ears of protomaize, they would have given preference to plants
     with larger ears; and kernels from those ears would then have been used as seeds. In this way, mutations that resulted in
     larger ears with more kernels were propagated, so that the ears grew larger from one generation to the next and became corn
     cobs. This can clearly be seen in the archaeological record: At one cave in Mexico, a sequence of cobs has been found, increasing
     in length from a half inch to eight inches long. Again, the very trait that made maize attractive to humans made it less viable
     in the wild. A plant with a large ear cannot propagate itself from one year to the next, because when the ear falls to the
     ground and the kernels sprout, the close proximity of so many kernels competing for the nutrients in the soil prevents any
     of them from growing. For the plant to grow, the kernels must be manually separated from the cob and planted a sufficient
     distance apart—something only humans can do. As maize ears grew larger, in short, the plant ended up being entirely dependent
     on humans for its continued existence.
    What started off as an unwitting process of selection eventually became deliberate, as early farmers began to propagate desirable
     traits on purpose. By transferring pollen from the tassel of one plant to the silks of another, it was possible to create
     new varieties that combined the attributes of their parents. These new varieties had to be kept away from other varieties
     to prevent the loss of desirable traits. Genetic analysis suggests that one particular type of teosinte, called Balsas teosinte,
     is most likely to have been the progenitor of maize. Further analysis of regional varieties of Balsas teosinte suggests that
     maize was originally domesticated in central Mexico, where the modern-day states of Guerrero, México, and Michoacán meet.
     From here, maize spread and became a staple food for peoples throughout the Americas: the Aztecs and Maya of Mexico, the Incas
     of Peru, and many other tribes and cultures throughout North, South, and Central America.
    But maize could only become a dietary mainstay with the help of a further technological twist, since it is deficient in the
     amino acids lysine and tryptophan, and the vitamin niacin, which are essential elements of a healthy human diet. When maize
     was merely one foodstuff among many these deficiencies did not matter, since other foods, such as beans and squash, made up
     for them. But a maize-heavy diet results in pellagra, a nutritional disease characterized by nausea, rough skin, sensitivity
     to light, and dementia. (Light sensitivity due to pellagra is thought to account for the origin of European vampire myths,
     following the introduction of maize into European diets in the eighteenth century.) Fortunately, maize can be rendered safe
     by treating it with calcium hydroxide, in the form of ash from burnt wood or crushed shells, which is either added directly
     to the cooking pot, or mixed with water to create an alkaline solution in which the maize is left to soak overnight. This
     has the effect of softening the kernels and making them easier to prepare, which probably explains the origin of the practice.
     More importantly but less visibly, it also liberates amino acids and niacin, which exist in maize in an inaccessible or “bound”
     form called niacytin. The resulting processed kernels were called nixtamal by the Aztecs, so that the process is known today as nixtamalization. This practice seems to have been developed as early
     as 1500 B.C.; without it, the great maize-based cultures of the Americas could never have been established.
    All of this demonstrates that maize is not a naturally occurring food at all. Its development has been described by one modern
     scientist as the most impressive feat of domestication and