The last section describes how maize was domesticated from an indigenous grass called teosinte in southern Mexico before 3500 B.C.E. and was in common use a millennium later. Maize originated in Mexico and was widely grown by 2500 B.C.E. The new staple did not, however, spread northward across the Rio Grande into the North American Southwest until some centuries later.
Human occupation of the Southwest dates back to before 9000 B.C.E. For Thousands of years¸ the descendants of these early southwesterners gathered many plant foods¸ including yucca seeds¸ cacti¸ and sunflower seeds¸ adapting skillfully to the harsh realities of desert living. They developed a remarkable expertise with all kinds of plant foods¸ which pre–adapted them from maize agriculture. Maize¸ beans¸ and squash agriculture came to the Southwest from northern Mexico¸ after generations of sporadic contacts between desert forages and settled farmers. Knowledge of domesticated plants¸ even gifts of seeds seedlings¸ passed from south to north.
Climate data from tree rings tells us that between about 2500 and 100 B.C.E. the southwestern climate was relatively stable¸ perhaps somewhat wetter than today. However¸ it was a semi–arid environment where hunting and gathering were high–risk occupations¸ mainly because rainfall was always unpredictable.
Domesticated plants like maize and beans might have low yields in these dry environments, but they had one major advantage ¦ they were predictable food sources.
Cultivators of the new crops could their locations and their availability at different seasons by storing them carefully. The people living in the southern deserts of the Southwest may have adopted maize and beans as supplementary foods, not because they wanted farmers, but so they could become more effective foragers, and maximize the potential of their environment.
Maize first entered the Southwest during a period of higher rainfall between 2000 and 1500 B.C.E. The new crop spread rapidly through the region¸ especially when combined with beans after 500 B.C.E. Beans helped return vital nitrogen to the soil¸ maintaining fertility for longer periods of time. Maize farming in the dry Southwest was never easy¸ for the farmers were working close to the limits of corn´s range. They selected moisture retaining soils very carefully, used north– and east–facing slopes that received little direct sun¸ planted near canyon mouths and diverted water from streams and springs. They did everything they could to minimize risk, dispersing their gardens to reduce the danger of local drought or flood. The earlier corns were not very productive¸ but more bountiful local forms soon because a vital staple to many southwestern groups who were now living in permanent hamlets and much smaller territories. They also led to more complex southwestern societies that adjusted to changing conditions with remarkable flexibility.
Hohokam¸ Mogollon¸ and Anasazi
By 300 B.C.E¸ many centuries of experimentation had produced much more productive domestic crops and a greater dependence on farming. The cultural changes of these centuries culminated in the great southwestern ancestral cultural traditions. Hohhokam¸ Mogollon¸ and Anasazi.
Hohokam people occupied much of what is now lower Arizona. They were desert farmers, who grew not only maize and beans, but cotton¸ which flourished in hot environments. Where they could, they practiced irrigation from flowing streams; otherwise they cultivated floodplains and caught runoff from local storms with dams, terraces, and other devices. For centuries, much Hohokaam life trading activity centered around Snaketown, a large settlement and ceremonial center near the Gila River. The inhabitants maintained trading relationships not only with other parts of the Southwest and the Pacific coast to the west, but also with Mexico. The Hohokam obtained tropical bird feathers¸ copper artifacts¸ and other exotic objects from the South¸ but scholars are sharply divided on the amount of Mexican influence on Hohokam culture and religious beliefs. The Hohokam vanished after 1500 C.E.¸ vanished its cultural heirs the O´odham peopel of today.
Mogollon was a more highland cultural tradition, which flourished mainly in what is now New Mexico from about 300 B.C.E. to between 850 to 1150 C.E. Mogollon farmers relied on direct rainfall and used little irrigation¸ living in small villages of pit dwellings with timber frames and mat or brush roofs. In only a few areas did more elaborate settlements develop¸ but by this time Mogollon was becoming part of the western pueblo Anaszai (ancestral pueblo) tradition.
Anasazi developed out of indigenous forager roots and was centered on the four Corners area where Utah¸ Colorado¸ Arizona¸ and New Mexico meet. Anasazi people made heavy use of wild plant food, even after they took up serious maize farming after 400 C.E. Most of their farming depended on seasonal rainfall, although they used irrigation where practicable.
At first the Anaaszi lived in small pthouse villages, but after 900 C.E. much of the population congreated in above-ground settlements of adjoining rooms. These became the famous pueblos, often clustered in small arcs to make them equidistant from the sub-terranean ceremonial rooms, the kivas, in the middle of the settlement. The largest and most spectaular pueblos were located in densely populated areas like Chaco Canyon in New Mexico and Mesa Verde in Arizona. It was in areas like these that Pueblo society sometimes achived a higher degree of complexity, with larger densely population denselt populated towns that controlled large exchange networks.
Chaco Canyon with its dramatic cliffs was the center of a remarkable flowering of Anasazi culture that lasted for two centuries after 900 C.E. During this time¸ the Chaco phenomenon, as it is called, expanded from its canyon homeland to encompass an area of 25¸000 square miles of the San Juan Basin and adjacent uplands. The people constructed large¸ well–planned towns¸ extensive road and water control systems¸ and outlying sites linked to the canyon by ceremonial roadways and visual communication systems. The “great houses¸” large pueblos of Chaco Canyon such as Pueblo Bonito¸ contained many luxury items¸ including turquoise from near Santa Fe¸ seashells¸ copper bells¸ even the skeletons of macaws¸ colorful birds from the lowlands rainforests of Meso–america much prized for their bright feathers.
When Chaco was in its heyday between 1075 and 1115 C.E.¸ the canyon was not only a focus for turquoise ornament manufacture, but an important ceremonial center for dozens of outlying settlements. Chaco flourished during a period of uncertain rainfall¸ and the local farming land could never have supported more than about 2000 people. The population estimates for the pueblos rise as high as 5600. Thus¸ archaeologists argue Chaco may have had a relatively small permanent population and been a place where much food was stored. It is also where large crowds of Anasazi congregated for major ceremonial observances.
What then was Chaco? Was it a highly centralized chieftainship¸ controlled by a small but powerful elite of chiefs and nobles¸ who had a monopoly over trade and important spiritual powers? It could have been as archaeologist Gwinn Vivian calls it an egalitarian enterprise¸ a cooperative mechanism developed by dozens of communities living in a harsh and unpredictable environment? The Anasazi lived in a society where kin ties were all important¸ where everyone had complex obligations to fulfill both to his own community and to the clan. Without such obligations¸ it would have been impossible to carry large quantities of food to Chaco´s storerooms¸ or to transport the more than 200¸000 wooden beams needed to build its large pueblos and kivas. Perhaps the phenomenon was an adaptive mechanism whereby local kin leaders regulated and maintained long–distance exchange networks and ceremonial life as a means of supporting far more people than the environment would normally carry. They used economic¸ social¸ and ritual ties among a scattered rural population to encourage cooperation between isolated communities in times of need.
The Chaco phenomenon reached its peak between 100 C.E. and 1130 C.E.¸ when a prolonged drought and environment degradation caused the system to collapse. The Anasazi moved away into more dispersed settlements maintained alliances with one another or flourished in scattered independent pueblos. Perhaps the most famous Anasazi cultural developments is that centered on the Mesa Verde canyon system in the northern San Juan Basin. By 1100 C.E.¸ as many as 30¸000 people lived in the nearby Montezuma valley. They were mainly concentrated in villages of 2000 people or more. Only about 2500 of them lived in Mesa Verde. Then between 1200 C.E. and 1300 C.E.¸ people moved from open locations into crowed pueblos. Cliff Place¸ which was the largest settlement¸ had 220 rooms and 23 kivas.
Both in Mesa Verde itself and in the surrounding countryside¸ large villages¸ almost towns¸ were homes for between 1000 and 2500 people¸ living in room clusters associated with kivas and other ceremonial buildings. Everywhere in Mesa Verde the emphasis was on individual communities. Judging from the numerous kivas there was considerable cooperative and ritual activity¸ and there were numerous occasions when inhabitants of different communities organized large labor parties to carry out sophisticated water control works and other communal projects. Then Anaszi tradition was quite similar to Chaco Canyon¸ with its intricate mechanisms for integrating dispersed communities, or the chiefdoms of the South and Southeast with their large centers and satellite villages.
The twelfth and thirteenth centuries saw the culmination of four centuries of rapid social and political development in the Mesa Verde region. About 1300 C.E.¸ however¸ the entire San Juan drainage including Mesas Verde was abandoned by Pueblan peoples. They moved in scattered groups south and southeastward into lands of the historic Hopi¸ Zuni¸ and Rio Grande pueblos¸ where their ultimate descendants live to this day. Following the abandonment of large areas of the Southwest in the thirteenth and early fourteenth centuries¸ large settlements formed in previously sparsely inhabited areas. Some of these pueblos are recognized as those of direct ancestors of modern communities.
Southwestern pueblo society never achieved the cultural complexity found in eastern North America or among the Hawaiians or Tahitians¸ but it achieved the limits of regional integration possible for a region where rainfall was irregular and the climate harsh. Perhaps the best way to describe much southwestern organization is as a theocracy. That is a government that regulated religious and secular affairs through both individuals¸ like chiefs¸ and kin groups or associations (societies) that cut across kin lines. The basic social and economic unit was the extended family. However¸ for hundreds of years southwestern peoples fostered a sense of community and undertook communal labors like irrigation works using wider social institutions that worked for the common good.
Science
Dendrochronolgy (Tree–Ring Dating)
Everyone is familiar with tree rings— concentric circles¸ each circle representing annual growth– visible on the cross section of a felled tree's truck. These rings are formed by all trees, but especially where seasonal changes in weather are marked¸ with either a wet and dry season or a definite alternation of summer and winter temperatures. As a rule¸ trees produce growth rings each year. They are formed by the cambium¸ or growth layer¸ lying between the wood and the bark. When the growing season starts¸ large cells are added to the wood. These cells develop thicker walls and become smaller as the growing season progresses ; by the end of the growth season¸ cell production has ceased altogether. This process occurs every growing year¸ and a distinct line is formed between the wood of the previous season, with its small cells¸ and the wood of the next¸ with its new, large cells. The thickness of each ring may according to the tree´s age and annual climatic variations ; thick rings are characteristic of good growth years.
Weather variations within a circumscribed area tend to run in cycles. A decade of wet years may be followed by five dry decades. One season may break a 40–year rainfall record. These cycles of climate are reflected in patterns of thicker or thinner trees rings¸ which are repeated from tree to tree within a limited area. Dendrochronologists have invented sophisticated methods of correlating rings from different trees so they can build up long master sequences of rings from a number of trunks that may extend over many centuries.
Samples are normally collected by cutting a full cross section from an old beam no longer in a structure¸ by using a special core borer to obtain samples from beans still in a building¸ or by V-cutting exceptionally large logs. Once in the laboratory¸ the surface of the sample is leveled to a precise plane. Analyzing tree rings consists of recording individual ring series ad then comparing them against other series. Comparisons can be made be eye or by plotting the rings on a uniform scale so that one series can be compared with another. The series so plotted can then be computer–matched with the master tree–ring chronology for the region.
Extremely accurate chronologies for southwestern sites come from correlating a master tree ring sequence from felled trees and dated structures with beams from Indian pueblos. The beams in many such structures have been used again and again, and thus some are very much older than the houses in which they were most recently used for support. The earliest tree rings obtained from such settlements date back to the first century B.C.E.¸ but most timbers were in use between 1000 C.E. and recent times.
Dendrochnology was once confined to the American Southwest, but is now widely used in many other parts of the world, including Alaska¸ Canada, parts of the eastern United States¸ England¸ Ireland¸ and continental Europe¸ and also the Aegean Islands and eastern Mediterranean. The Europeans have worked with oak trees with ages of 150 years or more to develop master chronologies for recent times. Using visual and statistical comparisons¸ they have managed to link living trees to dead specimens serving as church and farmhouse beams and others found well–preserved in bogs and waterlogged peats prehistoric sites. The resulting tree ring sequence go back at least 10¸021 years in Germany and 7¸289 years in Ireland. The Aegean Dendrochnology Project has developed a tree ring sequences covering 6¸000 of the last 8¸500 years¸ which is leading to much more precise dates for the Minoan and Myceanean civilizations than an expert can date even short ring cycles to within a handful of years.
Tree ring chronologies provide records of short-term climate change in areas such as the American southwest¸ where cycles of wetter and drier weather can cause radical changes in settlements patterns. Southwestern chronologies are accurate to within a year, a level of accuracy rarely achieved with archaeological anywhere. In recent years¸ the Laboratory of Tree Ring Research at the University of Arizona has undertaken a massive dendroclimatic study that has yielded a reconstruction of relative climate variability in Southwest from 680 C.E. to 1970 C.E. This enables them to study such phenomena as the Great Drought of 1276 C.E. to 1299 C.E.¸ which caused many ancestral pueblo peoples to abandon their large pueblos. In 1276 C.E.¸ the beginnings of the drought appeared in tree rings in the northwest. During the next 10 years¸ very dry conditions expanded over the entire southwest before improved rainfall arrived after 1299 C.E.
Science
Weather variations within a circumscribed area tend to run in cycles. A decade of wet years may be followed by five dry decades. One season may break a 40–year rainfall record. These cycles of climate are reflected in patterns of thicker or thinner trees rings¸ which are repeated from tree to tree within a limited area. Dendrochronologists have invented sophisticated methods of correlating rings from different trees so they can build up long master sequences of rings from a number of trunks that may extend over many centuries.
Samples are normally collected by cutting a full cross section from an old beam no longer in a structure¸ by using a special core borer to obtain samples from beans still in a building¸ or by V-cutting exceptionally large logs. Once in the laboratory¸ the surface of the sample is leveled to a precise plane. Analyzing tree rings consists of recording individual ring series ad then comparing them against other series. Comparisons can be made be eye or by plotting the rings on a uniform scale so that one series can be compared with another. The series so plotted can then be computer–matched with the master tree–ring chronology for the region.
Extremely accurate chronologies for southwestern sites come from correlating a master tree ring sequence from felled trees and dated structures with beams from Indian pueblos. The beams in many such structures have been used again and again, and thus some are very much older than the houses in which they were most recently used for support. The earliest tree rings obtained from such settlements date back to the first century B.C.E.¸ but most timbers were in use between 1000 C.E. and recent times.
Dendrochnology was once confined to the American Southwest, but is now widely used in many other parts of the world, including Alaska¸ Canada, parts of the eastern United States¸ England¸ Ireland¸ and continental Europe¸ and also the Aegean Islands and eastern Mediterranean. The Europeans have worked with oak trees with ages of 150 years or more to develop master chronologies for recent times. Using visual and statistical comparisons¸ they have managed to link living trees to dead specimens serving as church and farmhouse beams and others found well–preserved in bogs and waterlogged peats prehistoric sites. The resulting tree ring sequence go back at least 10¸021 years in Germany and 7¸289 years in Ireland. The Aegean Dendrochnology Project has developed a tree ring sequences covering 6¸000 of the last 8¸500 years¸ which is leading to much more precise dates for the Minoan and Myceanean civilizations than an expert can date even short ring cycles to within a handful of years.
Tree ring chronologies provide records of short-term climate change in areas such as the American southwest¸ where cycles of wetter and drier weather can cause radical changes in settlements patterns. Southwestern chronologies are accurate to within a year, a level of accuracy rarely achieved with archaeological anywhere. In recent years¸ the Laboratory of Tree Ring Research at the University of Arizona has undertaken a massive dendroclimatic study that has yielded a reconstruction of relative climate variability in Southwest from 680 C.E. to 1970 C.E. This enables them to study such phenomena as the Great Drought of 1276 C.E. to 1299 C.E.¸ which caused many ancestral pueblo peoples to abandon their large pueblos. In 1276 C.E.¸ the beginnings of the drought appeared in tree rings in the northwest. During the next 10 years¸ very dry conditions expanded over the entire southwest before improved rainfall arrived after 1299 C.E.