The Man-Agave symbiosis
Meal Plant, one of the earliest illustrations of agaves, as depicted by Hernandez in 1651.
The uses of agaves are as many as the arts of man have found it convenient to devise. At least two races of man have invaded Agaveland during the last ten to fifteen thousand years, where, with the help of agaves, they contrived several successive civilizations. The region of greatest use development is Mesoamerica (Fig. 1.1). Here the great genetic diversity in a genus rich in use potential came into the hands of several peoples who developed the main agricultural center of the Americas. Perhaps, as the Aztec legends suggest (Goncalves, 1956: 72), it was the animals that first showed man the edibility of agave. Evolution in use ranges all the way from the coincidental and spurious, through tool and food-drink subsistence with mystical overlay, to the practical specialties of modem industry and art. The historic period of agave will be outlined here as briefly as that complicated development will allow.
The diffusion of agave cultivation from its original nucleus in the Mesoamerican highlands occurred rapidly after the conquest. When the Spaniards began colonization of more northern regions, like Durango and Saltillo, they took Nahuatl people with them as interpreters, laborers, and farmers. The farmers took maguey with them and established the pulque culture which still persists as the northern fringe of the pulque complex. Other agaves, for ornamental and fiber uses, were apparently first carried overseas by both Spaniards and Portuguese: Agave americana to the Azores and Canary Islands; A. angustifolia, A. cantala, and others to Asia and Africa. By the eighteenth century A. americana, A. lurida, and others were established along the Mediterranean coasts. The spread of the genus to the Old World reached its height in the nineteenth century, when agaves became popular throughout Europe as ornamental succulents in both private and public gardens. In northern Europe their culture was generally limited, because of the cold winters, to pot and greenhouse culture. Agave fiber industries were developed in the nineteenth century by colonial interests in Indonesia and the Philippines, and in East Africa in the twentieth century with A. sisalana. Methods of culture, fiber harvest, and selection of varying forms have been developed in different regions, according to the regional environments and available working resources. Additional observations are given in the section dealing with fiber, pp. 16-20, and under individual species in the taxonomy part of this work.
Fig. 1.1. Region of intense agave culture with some of the principal Indian nations. Olmecs were extinct before the Spaniards appeared.
Overseas, as in America, the man-agave relationship has required mutual adaptation of both organisms for cosurvival. In the modem, competing, complex, organic world, both ornamental and fiber culturists of agaves have waxed and waned individually through the centuries, according to how interest or economic motive was served. Today in the Old World agaves are carried on, or, in localities favorable to them, they persist by themselves spontaneously. If we consider the genes as causal factors, then which of the two organisms is carrying the other? Perhaps mutualism is just a fortuitous alliance of two dissimilar gene pools, which operate better than either would do alone. Agave hosted man in the New World; man transported and hosted agave in the Old World.
The aesthetic nature of man has conserved agave as ornamentals, while his intellectual character in devising uses has fostered its evolution, but his hunger and greed have also destroyed agaves. Since both the aesthetic and intellectual character of man are dependent upon the satisfaction of his hunger, the man-agave relationship may continue for as long as mankind is not too hungry or too crowded for space. In North America, agave perhaps had as much to do in fostering the beginnings of agriculture as any other genus of plants. In Agaveland anyone can plant and grow agaves. All that is needed is to dig up or pull up a young offset and bury its base in moist or dry soil, with or without roots, wherever it is wanted. If it does not strike root and grow the first season, the chances are good that it will the next. Sauer (1965) has made a strong case that such transplants were the primary agricultural subjects of the Amerindians. Compared with seeds, the shift of useful plants from the open wild site to camp or village was more obvious and direct with transplants, and their care, protection, and culture were simpler.
The hunting and gathering tribes had good reason to regard agaves with special attention, because agaves supplied them with food, fiber, drink, shelter, and miscellaneous natural products. Protection may have been one use, for when planted around a cottage, the larger species make armed fences, a common practice in modern Mexico. While much about the first beginnings of agriculture will always remain obscure, there is a great deal now known about the history of man-agave relationship. A review of this history, especially in archaeological, historical, and ethnological literature, is perhaps the most interesting way to show the development of this indigenous American complex. The many uses of agave will become more meaningful if the man-agave mutualism is stressed rather than the uses simply enumerated. Castetter, Bell, and Grove (1938) have provided an excellent review of agave use among the Indians in the southwestern United States. This account will focus on Mesoamerica, the center of agricultural origin of the genus, and will thus provide conceptual background to agave taxonomy.
In Mesoamerica man has chewed agave for at least 9,000 years. Callen (1965) published irrefutable evidence for this statement, after having examined several hundred coprolites (mummified human feces) furnished him by McNeish, leader of the Peabody Foundation archaeological expeditions to Mexico during the 1950s and early 60s. Callen summarized the principal items in the diet from 7000 B.C. to A.D. 1500. With Agave these were Setaria, Ceiba, Cactus, Cucurbita, bean, Capsicum, Amaranthus, Diospyros, bone, meat, and Zeafrom about 5000 B.c. Agave was found throughout the time scale in 25-60 percent of the coprolites. Two of Callen's summary charts are reproduced here (Figs. 1.2, 1.3).
Callen explains that fragments of consumed plant materials pass through the alimentary tract sufficiently intact for microscopic identification: "Agave epidermis with cells arranged in a diamond shape around the stoma, and the characteristic type of crystals in its tissues." The time scale was established by carbon-14 datings. Because the coprolites represent cave sites on rocky mountain terrain, the materials do not reflect fairly the cultivated agricultural plant products, which were developing from 5000 B.C. onward, with the establishment of villages and later the Mexican city states. "It should be clearly understood right away, however, that this is a cave diet, and not a city diet." Use of the caves in village and city times was attributed to seasonal visits by hunting or gathering parties. However, the presence of cooked portions of agave in modern Mexican markets testifies to the use of agave as food through the late twentieth century.
From 7000 B.C. onward the use of agave is documented also by archaeological specimens of quids (chewed fiber rejects), by artifacts made of agave fiber, and the tools used in their manufacture. The records of such uses are widely scattered in numerous reports of travelers and archaeologists (Byers et al., 1967). In Mesoamerica the many evolving varieties and forms of Agave species were selected by man, moved from place to place with him, and inadvertently crossed. As man lived with these varietal eventualities through the centuries, he was provided with new genetic combinations that he could check empirically for yield and quality of fiber, food, beverage, and other special products. As he specialized with civilization, he specialized agave, selecting characteristics according to his wants. Even though he had no concept of genetics, he quite innocently fostered an explosive evolution in agave diversification.
The main source of food in agave is the soft starchy white meristem. in the short stem and the bases of leaves, excluding the green portion. As the plant matures the starch and sugar content of these organs increases, as does their palatability. Some species and varieties are more palatable than others; those with high sapogenin content and other toxic compounds were generally known and avoided. The young, turgid, tender flowering shoot of most species is edible, as are the flowers of many. The early agriculturist doubtless selected only the sweet sorts for cultivation. The sapogenous species were not domesticated. Since merely supplying heat converts the starches to sugars, the Indian cooked the softer parts by direct fire or with hot water. In earliest times the cooking of agave was crude. "Cooking appears to have been largely of the roasting type, with the outside frequently charred, and the interior still raw. This is true of such plants as Ceiba, Agave, and Opuntia, though they appear to have been eaten raw almost as frequently" (Callen, 1965). Charring of agave flowering shoots by laying them in the fire or in hot coals and ashes overnight was still observed among the backcountry Mexicans in the 1970s, especially to appease hunger on longer journeys. From the time the Mexicans had pots, these flowering shoots were probably boiled, a practice extended to modern times in Mexico. A more sophisticated or communal method for cooking agave was pit baking, which became universal, at least north of Mesoamerica, and which has been mapped and fully discussed by Castetter et al. (1938).
Agave pit baking was a family or group effort, generally with men and boys collecting the wild mescal heads ("cabezas"), the women and girls gathering firewood and cooking. A pit large enough to hold many heads was dug and lined on sides and bottom with stones. A large fire was burned in the pit to heat the rocks and form coals. When the fire burned down, the Agave heads were pitched in the pit on the hot stones, or sometimes on a layer of green grass, palm leaves, or other green leaves. The heads were covered over with leaves or grass and sufficient earth on top to prevent steam from escaping. The mass was allowed to steam-cook for one or two days. The time necessary for cooking depended on the amount to be cooked, size of the heads, tribal customs and ceremonies. The cooked heads were cut up into chunks, after separation from the leaf butts and both could be eaten at once or could be stored indefinitely for future use. They were also pressed into flat cakes that could be easily carried and were bartered in trade between tribes. The expressed juice from the cooked chunks was rendered into syrup. Candies were also prepared with this syrup. There is considerable fiber in these chunks of agave, which when chewed are rejected and, if left in the litter of dry camp sites and caves, become the quids of archaeology.
This description barely outlines the practices of agave pit baking as we know them from northern Mexico and Southwestern United States. I have seen mescal pits as far south as northern Sinaloa and Durango and have seen baked agave in the markets of central Mexico. However I have seen no account of the practice in Mesoamerica. Miguel del Barco wrote an excellent account of the practice in Baja California (see Gentry, 1978: 5).
Among other food uses of agave is the boiling of the flowers of some species or, more commonly, scrambling them with eggs, as reported about Tehuacán. Among the Mixe Indians in the mountains of Oaxaca, the cuticle of Agave atrovirens and other species is put to a singular culinary use. The cuticle is peeled from the leaf and employed as a wrapper for tortilla sandwiches and other foods carried as lunch to the field. It forms a translucent sheet looking like an archaic forerunner of modern polyethylene plastic. This practice was drawn to my attention by the conspicuous rectangles appearing on the broad leaves of agaves, growing about the Mixe fields and houses, as a result of skinning off sections of the cuticular wrapper. In Saltillo, Coahuila, bread is still made with pulque, which gives the bread the distinctive flavor of pulque. Vinegar is easily made from aguamiel and alcohol has been distilled from pulque.
In northeastern Mexico, agave leaves are fed to livestock. In San Luis Potosi in 1963 I observed Agave salmiana being carted daily to the diary herds supplying milk to that city. The fresh green leaves amounted to several thousand tons annually. Along with Opuntia pads, this agave constitutes an important animal food resource in that desert country. Extensive young plantings of agave on hillsides 8 to 12 miles east of the city of San Luis Potosí appeared to be destined for animal forage. In Baja California the flowering panicles of Agave shawii and A. s. goldmaniana are cut and trucked to range cattle. On open cattle ranges the flowering shoots of all species of the smaller agaves are commonly cropped by the animals. However, the sharp terminal spines on the leaves of the larger species are apparently effective in foiling cattle away from the flowering shoots.
Agave as cattle forage is a recent development reflecting the pressure of human population on the available plant resources. Local ingenuity is extending milk production in a desert region with desert plants, far removed from the region of origin of animal industry. I have seen no definitive account of agave as cattle forage, but a studied comparison of this resource with conventional forage crops would be most interesting. What would be the production of meat and milk from one hectare of agaves? Is Agave salmiana the most suitable species for cattle feed? Have others been tried? Are there other peoples in other desert regions of the world that would benefit by the introduction of forage agaves to their countries? These are some of the obvious questions that appear to recommend a serious evaluation of agave as a forage resource. For a recent work on food values in agave, see Marroquin (1979).
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