The Anasazi from 1,000 B.C. to A.D. 400

The period beginning around 1,000 B.C. is known as the Terminal Archaic. When it ends is a subject of considerable debate, mainly because the end of the Archaic is supposed to be correlated with the beginning of agriculture, an event that has proven difficult to pinpoint. The adoption of domesticated plants throughout the Southwest appears to have been a gradual process, and therefore assigning a fixed date to mark the beginning of agriculture is artificial. However, for the purposes of this discussion, the Terminal Archaic will be considered as having lasted until around A.D. 400.

Environmental conditions during the Terminal Archaic were relatively moist and stable compared with preceding and subsequent periods, but there was considerable instability. After a brief period of lower moisture around 500 B.C., fluctuating conditions prevailed in which episodes of floodplain degradation, higher temperatures, and marked seasonal variability alternated with periods of moderate rainfall and temperature, soil aggregation, and less extreme seasonality. The generally mesic conditions did encourage forest and grassland expansion and overall productivity, but resources became more localized both across the landscape and through the seasons. For the Anasazi's predecessors, this meant that they could target succulents and wild game in the lowlands during the winter and spring, and then move to the highlands in summer and fall to harvest nut-bearing trees and seed- and berry-bearing plants.

On the Colorado Plateau, the appropriately named En Medio Phase of the Oshara Tradition emerges around 800 B.C. Some archaeologists believe that a general hunting-and-gathering Archaic lifeway persisted for some time and they push the En Medio Phase all the way to A.D. 400. Other scholars believe that this lifeway ended around A.D. 1 as subsistence turned to agriculture. They use the term "Basketmaker II" to identify the period from roughly A.D. 1 to A.D. 400. (The archaeologists who coined the term "Basketmaker" saved "Basketmaker I," believing that an older non-Archaic phase would eventually be identified; it hasn't.) In theory, this marks the beginning of the "Anasazi" as a separate cultural trajectory, although clearly there is continuity from the Archaic into the Basketmaker period.

Introduction of Domesticated Plants

Whatever you call it, this is a period of gradual but persistent change. The most significant changes appear to be related to the increasing use of domesticated plants. The first domesticated plants to enter the Southwest are collectively referred to as the Upper Sonoran Agricultural Complex, which consists of maize, beans, squash, and the bottle gourd. The timing of the appearance of these cultigens in the Southwest have been the subject of great debate, especially since some of the earliest radiocarbon dates were recently found to be inaccurate. The oldest, best-dated samples of maize anywhere in the Southwest date to 1200 B.C., and these were recovered from Tornillo Rockshelter in the Sonoran Desert. In the Mogollon Highlands, maize remains dated to around 1100 B.C. were recovered from the oldest deposits of Bat Cave. The earliest cultigens found in northern parts of the Southwest consist of squash rinds recovered in Chaco Canyon that were dated to 1000 B.C. The evidence available so far suggests that maize first appeared in the Sonoran Desert and spread rapidly to other regions of the Southwest. Maize, squash, and the bottle gourd were apparently introduced together in most areas of the Southwest, although the bottle gourd was never adopted by groups in northern areas due to its sensitivity to short growing seasons. Soon after the appearance of these three plants, the common bean entered the area, perhaps before 300 B.C.

The introduction of domesticated plants to the Southwest has been described as "a monumental nonevent with little immediate impact on native human populations" (Minnis 1985:310). The first maize to enter the Southwest was from the Chapalote series of 12- to 14-rowed popcorns with brown kernels and thick rachis. It was not very productive, and did not contain the nutritious flour, flint, or dent endosperms found in later varieties. Furthermore, within a few centuries, the Chapalote maize had introgressed with teosinte in the Upper Sonoran Desert, which resulted in an extremely unpredictable hybrid. There is therefore no reason to assume that Archaic groups would have willingly become dependent upon this unpredictable and unproductive resource, especially since the period in which cultigens were adopted was characterized by a generally moist climate that would have stimulated the productivity of the wild resources that Archaic groups traditionally ate.

Many archaeologists believe that the new domesticates were planted simply to increase the variety of plants and animals available to these prehistoric foragers. The cultigens of the Upper Sonoran Agricultural Complex required neither supplemental water or attention if planted in moist habitats above 2000 m in elevation. Archaic groups could have planted the cultigens in the spring before descending to the lowlands to forage, then harvest them upon their return in the fall--as long as rainfall had been sufficient and other animals had not consumed the cultigens first. This pattern is in fact suggested by the archaeological record, in which most of the earliest occurrences of domesticated plants in the Southwest are in highland sites that were occupied during the winter or early spring. Most importantly, the addition of cultigens would not have interfered with the procurement of wild resources. Acorns, most grains and seeds, yucca, and cacti are available before maize is ready to be harvested, while piñon seeds and juniper berries cannot be harvested until after maize matures. The only conflict of resource scheduling would be with a few seed-producing plants, and if these were particularly abundant, the Archaic groups could forgo the maize harvest. Southwestern groups could have easily added the planting and harvesting of cultigens in their annual resource schedule.

Ethnographic examples from the Southwest show that resource scheduling based on both wild and domesticated plants can be incorporated in a pattern of biseasonal mobility. For example, the Western Apache of east-central Arizona exploited habitats ranging from 1500 to 3300 m in elevation. Their diet was variable, but generally 35-40% of their diet was from hunting, 35-40% was from wild plants resources, and 20-25% was from agricultural products. In the spring, the Apache moved to the highlands and planted crops while hunting and collecting various resources. Fields were small and located on floodplains or near springs. After preparing the soil and planting the seeds, fields were usually left to fend for themselves. In the fall, the Apache harvested the crops and returned to the lowlands during the winter. This pattern produced a reliable source of storable food that was an inexpensive buffer against the failure of the important wild. A similar subsistence pattern appears to have existed for late Archaic groups in the Southwest.

Cultural Changes On The Colorado Plateau

On the Colorado Plateau, the best evidence for the use of the new domesticated plants is found by examining human remains. Analyses of human coprolites (preserved fecal matter) provide the most intriguing insight into Terminal Archaic/Basketmaker II diet. For example, analyses of coprolites from sites in southeastern Utah dating to approximately A.D. 1 have revealed a variable diet composed of a wide variety of wild resources, including large quantities of piñon, chenepods, beeweed, and Indian ricegrass. In one study, 17 of 28 coprolites consisted of from 50 to 100% maize. Another study of 20 coprolites from several pithouse sites also contained numerous wild and domesticated plant foods. An average of 55% of these samples were maize, but this varied from 0.12% to 98% of any given sample, illustrating the variability of the early Anasazi diet. Carbon isotope analyses of skeletons dating to this period suggest that the pithouse occupants obtained 84% of their protein from C4 plants, although these proteins could have been from either maize or any of the numerous wild C4 plants available in the area.

Other evidence from material culture reflects the growing importance of domesticated plants. For example, pottery appeared in the Hohokam region of Arizona by A.D. 1 and spread to other parts of the Southwest by A.D. 200. Ceramic vessels would have made the use of cultigens more efficient, for maize could have been presoaked prior to the hard task of grinding, and the flour could have been more easily stored. Grinding implements were also continually improving. Earlier groundstone was characterized by small grinding surfaces used in a circular motion for crushing small seeds. However, after the introduction of domesticates, large two-hand manos and basin metates used in a back-and-forth motion were developed, presumably for grinding the larger maize kernels. As stored maize increased in dietary importance, larger trough metates were created for grinding quantities of hardened, dried maize kernels.

Despite the appearance of maize in the of Terminal Archaic/Basketmaker II diet, the distribution of sites across the landscape indicates that people still pursued a fairly mobile lifestyle, leaving behind numerous small sites as they targeted locally and seasonally abundant resources. During the fall, however, people did tend to move into more permanent canyon-head sites that were used year after year. For example, at Sheep Camp Shelter in Chaco Canyon, a study of open-air and rockshelter sites containing early cultigens concluded that groups foraged across the open grasslands during most of the year but returned to sheltered canyon areas during the winter.

To archaeologists, these fall/winter sites appear much more permanent, for the occupants built subsurface pithouses and storage pits, and they left behind significant accumulations of trash that built up over the years. Some archaeologists have debated whether these early aggregations of pithouses represent the first permanent villages on the Colorado Plateau. For many years, archaeologists believed that the first pithouse villages marked the beginning of sedentary patterns and the intensification of horticultural pursuits. However, researchers now realize that these conclusions were based on the assumption that the presence of structures organized in settlements automatically meant that their occupants were permanent residents. These assumptions are beginning to be eroded by the recovery of evidence suggesting that the pithouse builders were both residentially mobile and subsisting on a large proportion of wild foods. For example, absolute dates from some of the pithouse settlements in the Southwest show that they were being built a lot earlier than originally thought, probably even before domesticated plants were introduced to the region. Furthermore, when archaeologists look at a cross-section of the trash middens found alongside these early pithouses, they see numerous thin layers of trash, suggesting that these pithouses were reoccupied again and again, but for no longer than a few months each year.

Several interesting approaches have been developed to determine the patterns of occupation in pithouse villages. Patricia Gilman (1987) compiled data from pithouse dwellers around the world and concluded that the clear majority of societies residing in pithouses are seasonally mobile and based primarily on a "broad-spectrum" resource base. She also examined pithouse settlements on Black Mesa in northeastern Arizona and found that the majority of storage pits were located outside the structures, where they could have been easily hidden during seasons when the pithouse villages were abandoned. Gilman contrasted this pattern with the absence of exterior pits in later settlements that were clearly fully sedentary. She concluded that pithouse habitations were most likely winter structures associated with a relatively low dependence on agriculture. A similar study was conducted at Shabik'eschee Village in Chaco Canyon. This pithouse community contained 18 structures, some that were superimposed on others and others that had been partially dismantled in order to obtain material for the construction of new pithouses. The village also contained over 40 storage features located outside of the habitations. Researchers concluded that these features were used for caching food supplies when the village was seasonally abandoned; these subsurface pits could have been easily hidden so that they would not be disturbed until the occupants returned.

Another study by Shirley Powell (1983) examined ethnographic and archaeological records of Navajo seasonal camps to determine the assemblages characteristic of seasonally mobile groups with residential winter base camps. Variables such as interior structure space, total site space, hearth distributions, and artifact compositions were recorded, and then a model for identifying site use created. This was then compared with similar data obtained from sites on Black Mesa. A high degree of correlation was found to exist between small Anasazi sites and Navajo summer camps. Although a weaker correlation was identified for the large pithouse sites and Navajo winter habitations, Powell felt that the correlations were strong enough to conclude that most Anasazi pithouses were not permanent habitations but instead were occupied seasonally.

The Definitive End Of The Archaic

Between A.D. 200 and 375, climatic conditions throughout the Southwest became extremely unfavorable for agricultural pursuits. Effective moisture decreased, floodplains began to degrade, and seasonal variability increased drastically. However, surprisingly, the archaeological record suggests that this change had little effect on Southwestern groups. Populations during this period apparently relied upon the flexibility of the subsistence patterns to absorb environmental deterioration. Population sizes were generally low and many parts of the Colorado Plateau were not yet occupied, so an increase in both the duration and range of mobile foraging was possible. This hypothesis is supported by the fact that the colonization of many new areas began around A.D. 200. Agricultural activities during this drought therefore probably continued to supplement a strategy of seasonal mobility based upon wild resource availability.