Mesoamerica

Beginnings of Agriculture-

Mesoamerica is a cultural super-region extending from northern Mexico to Central America, whose diverse environmental zones (arid; mountainous; tropical lowlands) each became ancestral areas for major crops ranging from squash, corn, and beans to cotton and chocolate.

In Mesoamerica, only one domesticated plant, maize (Zea mays subsp. mays; Gramineae) ever became the object of large-scale, intensive agriculture. Often readily detectable, as well, are related modifications to the landscape from clearance, ground levelling via terracing or other means, and irrigation or other water management schemes (ie., diversion, drainage, and containment).

Maize and its origins:

maize, or corn possesses certain attributes that justifies the enormous efforts expended in land tillage, planting, tending and harvesting. Above all, the yield of usable produce per plant must be quite high.

This criterion is met by maize by virtue of its remarkable ear and is the reason maize became the most important crop by far throughout Mesoamerica.

The question is, how and when did the fruitful maize cob develop?

-All specimens of primitive maize known from archaeological sites are domesticated forms. Maize is not included in the taxa considered above under "wild-food production," nor does it appear on the list of the earliest cultigens. This is because it simply wasn't there.

-it is estimated (Bruce Smith) that maize was fully domesticated in SW Mexico by 3600BC

-three leading hypotheses are: the Wild Maize Hypothesis, the Orthodox Teosinte Theory, and the Catastrophic Sexual Transmutation Theory

-The Wild Maize Hypothesis claims that there must have once been a wild race of maize, now extinct, from which the cultivated form evolved. This theory explains the development of the cob by asserting that the hypothetical ancestor was a naturally occurring pod-corn with vertical rows of kernels (polystichy). The problem with this theory is that no fossilized examples of the putative ancestral maize has ever been found. Prior to domestication this wild maize must have been exploited to some extent by prehistoric people and, therefore, should have found its way into the archaeological record.

-The Orthodox Teosinte Theory says that maize was derived from the wild grass teosinte (Zea mays mexicana). In some classifications annual teosinte is treated as a separate species (Zea mexicana). The basis of this argument is that teosinte is the closest known relative of maize. Some reject teosinte as the direct ancestor because the very minute female inflorescences ("ears") of teosinte seem unlikely to have been transformed into the huge polystichous maize ears by means of human selection. A variant of the Teosinte Theory, which serves to reconcile it with the Wild Maize Hypothesis, is that maize is a hybrid of teosinte and a wild maize ancestor. In other versions teosinte and another related grass are the hybridizing pair

-considerable support for teosinte as the direct ancestor of maize has accumulated as a result of DNA and isozyme (genetically variant enzyme) studies that provide measures of genetic distance much more reliable than judgments based on morphological characters. These investigations have revealed such a high degree of similarity between teosinte and maize with respect to the presence and frequency of specific molecules that a close phylogenetic relationship must be a matter of fact

-the molecular evidence has identified a particular race of teosinte (Z. mays subsp. parviglumis), a perennial grass, more similar to maize than any other race of teosinte. This finding supplies a probable geographic origin for maize domestication, as well as an immediate ancestor. The wild Z. mays subsp. parviglumis race that best matches the isozyme profile of maize has a limited distribution today in the central portion of the Balsas River drainage in northern Guerrero, eastern Michoacan and western Mexico states. Archaeologists in general are impressed by the statistical soundness of the perennial teosinte's claim as the progenitor of maize and the view is widely (though not unanimously) accepted in the discipline. The Orthodox Teosinte Theory, however, does not resolve the questions about the development of the maize cob. Botanists are harder to convince and continue proposing other evolutionary reconstructions.

-The Catastrophic Sexual Transmutation Theory, first advanced by Hugh Iltis, offers an explanation for the development of the maize ear while completely accommodating the Teosinte Theory.

-Briefly, the theory holds that through a series of genetic mutations the staminate teosinte tassel spike (the male reproductive organ) was transformed into the unisexual distillate maize ear (the female organ). This contrasts with conventional thinking that has the maize ear developing from the teosinte ear. But Iltis claims that there is greater structural homology between the teosinte spike and the maize ear than between the two ears. Furthermore, the maize ear exhibits vestiges of its former male anatomy. The radical and rapid anatomical changes associated with transmutation provides explanations for the late development of maize as a cultigen and the failure to find "wild maize" in the fossil record. Such evolutionary adaptations may have been encouraged by volcanic activity typical of the Balsas River region in the recent past, and sexual transmutation may have occurred as late as 8000 years ago. The Catastrophic Sexual Transmutation Theory is a complex argument not uniformly embraced by maize researchers.

-Numerous examples of primitive maize obtained from archaeological excavations suggest that cultivated maize diffused quite swiftly throughout Mesoamerica, especially if we accept a single center of domestication and a date of about 8000-6000 BC. Tehuacán in the central highlands of Mexico has yielded the oldest remains of cultivated maize in Mesoamerica, dated to 5050 BC (calibrated) by accelerator mass spectrometry dating of actual specimens. Racial diversification arose as a result of adaptations to different environmental conditions and human selection for traits related to productivity, taste and cooking properties. Within a few thousand years, maize had become a staple food crop throughout Mesoamerica, and was a main subsistence base of the Maya, Aztec, and related early civilizations.

Some of the best evidence for maize domestication as well as other domesticates comes from the Tehuacan Valley

-located in highlands of southern Mexico and consists of dry caves and open sites

-MacNeish did a lot of work here

-Coxcatlan Rock shelter yielded maize that may be the hypothetical ancestor of later maize. This site dates back to 10000BC

-people in this area probably were domesticating by 4500BC

-after 2500BC people definitely grew beans, amaranth, gourds, and maize; had larger more permanent settlements. Maize was ground using metates. This maize was probably more like teosinte than later maize. Storage facilities.

Maize, however, may not have been the first domesticate in Mesoamerica:

Several species of the squash family (Cucurbitaceae; genus Cucurbita) are among the earliest known cultigens. Cucurbita pepo, the pumpkin squash, has been dated to 8000-7000 BC at Guilá Naquitz (A small cave in the Oaxaca valley of Mexico, Guila Naquitz contains evidence of the domestication of bottle gourd and squash; six occupations are known from the site, which are dated between 8000 and 6500 BC.)

-and at Ocampo Cave in Tamaulipas to about 7000-6500 BC. The specimens were identified as cultivated forms on the basis of morphological criteria and, as the Guilá Naquitz material has been dated directly, C. pepo is confirmed as the oldest known cultigen for Mesoamerica, C. pepo, along with the other domesticated cucurbits known from archaeological contexts (C. argyrosperma, C. ficifolia, C. lundelliana and C. moschata), appear to have arisen from different wild species. Although none of the wild cucurbit progenitors has been identified with certainty, it is believed that the centers of cultivated species diversity are the areas of origin. The ancestral squashes would have been cultivated principally for their nutritious edible seeds, since their scant bitter flesh would have required repeated boilings to eliminate the unpalatable cucurbitacins . Selection for larger, fleshier, non-bitter fruits could have been accomplished relatively rapidly given the growth habit of these species and their capability of self-pollination.

Another member of the Cucurbitaceae family, Lagenaria siceraria, the calabash or bottle gourd, is thought to have been brought under cultivation for its usefulness as a container, owing to its unusually thick rind, rather than for food. The bottle gourd also occurs very early in several Mesoamerican archaeological deposits (Tamaulipas ca. 7000 BC, Tehuacán ca. 5050 BC, Guilá Naquitz ca. 7000 BC). It is usually encountered as rind fragments and it is not known exactly when Lagenaria became domesticated.

The evidence for bean (Phaseolus spp.; Fabaceae) cultivation is not of such antiquity as that for squash, although ultimately beans became the high protein staple of the Mesoamerican diet.

-they have many of the same characteristics that made the squashes such willing domesticates. Wild beans had a significant presence in the older levels at Guilá Naquitz of ca. 8900-6500 BC. The kinds of remains suggest that in Preceramic times, beans had been harvested for their tender shoots or pods.

-Cultivation and selection for certain seed characteristics probably followed the introduction of ceramic technology and attendant cooking techniques that enhanced the seeds' desirability as food.

-earliest known domesticated beans do not appear until b/t 4000 and 3000BC

Another domestic was Cotton:

-We do not know when or where prehistoric Mesoamericans first began to appreciate the utility of the cotton plant, even though something is known about the complex distribution of wild populations in the New World.  

-wild cotton seems to occur in distinctive and restricted littoral (shoreline) or related habitats.

-The seeds of the littoral wild cottons, perennials which do not propagate vegetatively, have very sparse fibers. Domesticated seeds have long fibered seeds

The oldest known archaeological samples of Mesoamerican cotton are from the Tehuacán Valley, dated 3500-2300 BC; these represent a fully domesticated form, Gossypium hirsutum.

Cotton may possibly have been introduced to Mesoamerica as an already domesticated form from the southern hemisphere where, in coastal Ecuador and Peru, cultivated cotton of another species (G. barbadense) has been documented for much earlier periods. Yet most views favor the independent domestication of G. hirsutum in Mesoamerica.

The Coxcatlán Cave data from the Tehuacán Valley show a predominance of fruits gathered from perennials (trees, agave, and cacti) in the earlier levels of ca. 7000-3500 BC. Wild grasses and annuals were certainly available but appear not to have been high priority foodstuffs. Likewise, no grasses at all were reported for the Archaic period (8900-6670 BC) occupations at Guilá Naquitz Cave in the Oaxaca Valley near the town of Mitla . Kent Flannery (1986) and colleagues, who excavated Guilá Naquitz, emphasize the selectivity of the occupants with respect to number of plants exploited compared with the great variety available.

-In the tropical lowlands, starch in the diet is more likely to have come from roots or tubers than from cereals.

-not a lot of data with regard to possible root crops.

-manioc (Manihot esculenta; Euphorbiaceae) domestication has most evidence

-Variants with large underground storage organs would survive best in areas with a marked dry season where such reserves would have been adaptive. But, few sites have yielded direct evidence for manioc consumption. Root crops are rarely found as carbonized remains and desiccated specimens are extremely hard to identify.

-manioc pollen has been identified in freshwater cores from northern Belize. On the basis of the pollen data, the researchers estimated a date of ca. 3400 BC for the introduction of manioc.

-this date roughly coincides with that for the appearance of maize as well as indications of local deforestation, they conclude that the manioc was cultivated

Manioc has been identified for Formative Period Cuello, also in Belize

These identifications are open to doubt, and the major arguments for manioc cultivation still rely on inferences based on availability, the weedy tendencies of the plant, and the technical simplicity of cultivating it.

Transplantation:

One precursor to domestication that we evidence of is the direct transplantation of desirable resources closer to a camp or settlement.

Candidates are mainly small trees or bushy plants with a perennial growth habit, whose produce (sap, fiber and wood as well as edible portions) is readily harvested and processed for consumption.

-such plants as avocado, cacao, capulín, ciruela, cotton, mesquite, papaya, ramón, zapote blanco, and zapote negro, among others. Other easily transported, edible species include cacti (ie., prickly pear), maguey, and fruit-bearing palms such as coyol.

To document early transplantation, it must be demonstrated that a species occurs in prehistoric sites outside of its natural habitat.

-Good evidence for this practice exists from some occupation strata in the dry cave sites of the Tehuacán Valley from at least 3500 BC and perhaps much earlier (with dates for wild avocado proposed for ca.7000-6500 BC). Archaeologists agree that the remains of avocado, ciruela, coyol, zapote blanco and zapote negro represent exotics introduced by humans into the Tehuacán Valley. All of these species are native to considerably more mesic (wetter) environments, and their establishment in the semiarid Tehuacán area would have required some irrigation.

The Tehuacán cave deposits are extraordinary for their preservation, richness and depth.

So by 5000-4000 BC, there is evidence for extensive forest clearance for fields. Population growth seems to have accompanied these new farming strategies.