The Anasazi from A.D. 400 to A.D. 700

Environmental reconstructions suggest that climatic conditions on the Colorado Plateau were once again favorable for agriculture beginning around A.D. 400. Although a short period of falling water tables and floodplain degradation once again emerged between A.D. 500 and 600, fairly stable pattern of precipitation continued throughout the time period from A.D. 400 to approximately A.D. 750. This stability appears to have affected Anasazi culture, which during this period is referred to as "Basketmaker III."

In this context, small, widely dispersed groups of Basketmaker III Anasazi occupied the higher piñon-juniper woodlands of the Colorado Plateau. The degree of sedentism during this period is controversial, but occasional seasonal movements within a well-defined territory seem likely. Settlements consisted of a few shallow round or square pithouses with associated storage features both inside and outside the structures that contained surpluses of both wild foods and agricultural products. Although many pit houses were placed singly or in small clusters, some larger clusters are interpreted as small villages. Large "oversized" pit structures containing ritual features are found in some of the pithouse villages in the northern San Juan Basin, and these are generally believed to represent public structures whose suspected function includes the accommodation of communal ritual events. In a study of nearby Mogollon pithouse villages, Lightfoot and Feinman (1982) argue for the presence of authority-based community leaders by A.D. 600, which, if true, probably also characterized neighboring Anasazi groups during Basketmaker III.

Basketmaker III diet and economy increasingly relied on domesticated plants, which in turn stimulated the production of crude grayware ceramics for storing and processing these foods. Although maize continued in importance, other cultigens were also added to the agricultural repertoire. Sometime after A.D. 500, the Lower Sonoran Agricultural Complex made its appearance on the Colorado Plateau, but adoption of these cultigens was slow. For example, cotton and tepary beans were the first plants from this complex to enter the area, with some scholars arguing that tepary beans may have been domesticated locally since wild forms exist in the Southwest. Other members of this new agricultural complex such as jack beans and cushaw squash appear no earlier than A.D. 700, and it would not be until the A.D. 1100s that sieva beans and warty squash were planted on the Plateau. The Lower Sonoran Agricultural Complex never enjoyed much prominence in the Anasazi area, a situation that can most be likely attributed to the higher amounts of water that these crops required.

During the minor environmental downturn of the A.D. 500s, many pithouse settlements decreased in overall size and fewer storage pits were constructed. There is some evidence to suggest that these groups began to move to the wider lowland valleys, which would have been least affected by falling water tables and floodplain degradation. However, in general, Anasazi groups were not negatively affected by this minor climatic change. Seasonal mobility was still employed and populations were still relatively low, conditions that allowed the Anasazi to more readily change their subsistence strategies to cope with minor environmental fluctuations.

The appearance of a highly productive variety of maize sometime during the A.D. 600s coincided with increasing sedentism and agricultural dependence in the Anasazi area. This maize, called Maiz de Ocho, consists of fewer kernel rows, larger kernels, and earlier flowering. In marked contrast to the earlier Chapalote popcorn, Maiz de Ocho is highly productive and contains four, flint, and dent endosperm. For a long time, archaeologists believed that Maiz de Ocho developed in Mesoamerica and diffused into the Southwest. However, a "proto" Maiz de Ocho was recently identified in rock shelter deposits in the southern Mogollon Lowlands that date before the appearance of Maiz de Ocho in Mesoamerica. These deposits show a gradual indigenous evolution from the earlier Chapalote to the Maiz de Ocho. This suggests that over a long period of time, Southwestern groups consciously selected plants that would produce larger kernels and flower earlier. It's not too hard to figure out why they would do this. Larger kernels are much easier to grind, especially for people who do not use the lime-water technique for removing the pericarp. Experimental data indicate that the selection of larger kernels would have led to a correlated decrease in kernel row number and earlier flowering. And in turn, this earlier flowering would allow people living at higher, moister altitudes with correspondingly shorter growing seasons to successfully grow maize.

The appearance of Maiz de Ocho is generally correlated with the appearance of other varieties of maize. Archaeologists have traditionally believed that these varieties were the result of hybridization between Chapalote and the new Maiz de Ocho. However, if Maiz de Ocho was indeed developed in the Southwest, the accompanying varieties may have been created during the evolution of the Maiz de Ocho, perhaps in response to localized conditions in other areas of the Southwest. For example, the Pima-Papago variety is an extremely drought-resistant maize adapted to the extreme desert areas of southern Arizona. It can be planted much deeper than other types of maize, where it can take advantage of ground moisture retained from winter precipitation. This plant also possesses a single long root for tapping ground water located far below the surface. For other varieties of Southwestern maize, different morphological characteristics were selected. For example, Reventador is a flint corn with hard-shelled kernels with soft interiors, while Maiz Blando is a flour maize. Most of these varieties differ from Maize de Ocho through the mutation of a single gene. Clearly, Southwestern groups were becoming quite adept at manipulating maize to serve their needs.

The appearance of these highly productive, drought-resistant, and early flowering maize varieties between A.D. 600 and 750 corresponded with increasing intensification of agricultural pursuits in most areas of the Southwest. Perhaps equally as important, above-ground masonry architecture appeared in the Southwest during this period of favorable climatic conditions and new domesticates. This architectural shift seems to be related to an increasing need for storage space. Patricia Gilman (1987) has collected information on societies around the world that use above-ground masonry architecture, which she labels "pueblos." She found that the shift from pithouse to pueblo structures in most societies is highly correlated with agricultural intensification, almost complete sedentism, and the production of surpluses requiring storage. In contrast to subsurface storage pits, foods stored in masonry rooms are less susceptible to moisture and vermin, and can therefore be stored for longer periods of time. These are necessary requirements for a society dependent on agriculture, for as their reliance on agriculture grows, their ability to pursue more flexible forms of subsistence such as gathering wild foods decreases. The result is the need to produce enough agricultural surpluses to cope with any sudden environmental crises.

The capacity for increased storage would have been an important benefit for Anasazi groups after the period of minor climatic instability that took place between A.D. 500 and 600. Populations were rapidly increasing, and any further climatic degradations could not have been dealt with by increasing the duration and range of mobile gathering forays; a period of high seasonal variability beginning in A.D. 700 probably also encouraged the Anasazi to increase their storage facilities. Furthermore, the introduction of highly productive cultigens and the mesic conditions during the period from A.D. 600 to 750 most likely resulted in increasing yields and greater surpluses that needed to be stored. This scenario is supported by the nature of the shift to pueblo architecture; most Anasazi groups during this period continued to live in pithouses, but behind these were situated above-ground masonry rooms for storage and specialized food processing activities.

The events of the late Basketmaker III period illustrate how the different components of Anasazi culture were closely interrelated. Prior to this period, the Anasazi had pursued a flexible lifestyle incorporating seasonal mobility and a mixed economy based on domesticated and wild foods. During Basketmaker III, the combination of both favorable and unfavorable minor environmental changes, the development of new cultigens, and perhaps population growth contributed to the need for storage and a decrease in seasonal mobility. The need for storage in turn led to the development of above-ground storage facilities, which in turn further inhibited mobility (you can't just leave your storage facilities), which then would have encouraged a reliance on agriculture, which probably led to more experimentation with cultigens, and on and on. Understanding the end of Basketmaker III is clearly critical, for these changes lay the foundation for the rapid developments during subsequent periods of Anasazi prehistory.