The Formative is the last of several periods in a sequence of cultural development that traces the overall progression from stone-tool-using, hunter- gatherer societies to fully developed agricultural societies. The process that occurred is analogous to the Old World’s “Neolithic Revolution.” It is evident in Colorado and led to the rise of cultures such as those at prehistoric Mesa Verde, although its origins lay far to the south in Mexico.
What Is Formative?
A prehistoric society is said to have reached a Formative stage of development when it is fully dependent on agriculture and completely settled with people living in permanent villages. The Formative was reached at different times in different parts of the world. In general, it happened later in the New World than in the Old World because people have been in North and South America for a shorter period of time than, for example, in Asia and Africa. Also, for the most part Formative development was achieved earlier in tropical and subtropical climates than in temperate latitudes, where more native plants existed that could be domesticated into crops.
In Colorado, true Formative development only took place in the southwestern corner of the state, in the Four Corners region, where Colorado, Utah, New Mexico, and Arizona come together. However, prehistoric agriculture was widespread in Colorado even if most people never came to rely completely on food crops for their survival. Outside the Four Corners region, people remained essentially hunters and gatherers of wild plant foods, but in some areas supplemented their diets with domesticated crops. The beginning date for Formative development is 1000 BC and the ending date is AD 1450. The actual dates vary from one area to the next. Establishing a beginning date is especially difficult because in any area the transition to full dependency on agriculture was a gradual process.
Domesticated Plants in Colorado
Three crops were grown prehistorically in Colorado: corn (maize), beans, and squash. These cultivated plants were not domesticated in Colorado. All native to Mexico, they arrived in western North America in fully domesticated form. Corn is basically a domesticated form of grass, and compared to other crops developed from wild grasses it is not especially nutritious. Archaeologists in the United States often refer to corn, beans, and squash as the “triad,” indicating that the most favorable diet for prehistoric farmers featured all three crops, which complemented each other in a nutritional sense. While this is true, the three crops have different histories of dispersion despite their common Mexican origin.
Corn was the first to arrive in the American Southwest, where it has been found in archaeological sites in the Tucson, Arizona, area that date to around 2000 BC. Within a few centuries it had spread northward to the Colorado Plateau, the high-desert region that encompasses the Four Corners. Domesticated squash was the next to arrive. Its northward progress is not as well documented as that of corn, but it is known to have been present in the Southwest by sometime in the first millennium BC. Beans were the last to arrive, probably reaching the Southwest around 200 BC, but not appearing regularly in archaeological sites until the AD 300–600 interval, and possibly during the latter portion of that span. Clearly, the corn-beans-squash dietary combination is a relatively new when the overall history of agriculture in western North America is taken into consideration.
Not all areas of Colorado were suitable for agriculture. The corn that spread from the southern deserts to the Colorado Plateau had adapted to a higher, colder climate over time, but its usefulness as a food crop was still constrained by the length of the growing season as well as by water availability. Even areas where corn thrived during most years could be affected by drought, and both elevation and latitude affected the growing season. In general, valleys at lower elevations where water was most plentiful and the growing season reliably longer were the optimal locations for farming. South-facing mesa surfaces were also farmed. Such environments were present in the southwestern corner of the state. Farther north, along the western margin of Colorado, farming possibilities diminished as latitude increased, and only a few low-elevation settings have provided good archaeological evidence of prehistoric agriculture. Agriculture was also practiced to some degree in southeastern Colorado in the upper Purgatoire River Valley and adjacent Park Plateau east of the Sangre de Cristo Mountains, and in the vast network of canyons in the dry plains to the east. There is virtually no evidence of plant cultivation in the Colorado mountains or on the northeastern plains.
Shift from Hunting/Gathering to Agriculture
Why do hunter-gatherers become farmers? The shift is not inevitable, as there are many historical examples of hunter-gatherers living near farming societies without adopting agriculture themselves. Commonly, there is interaction between such groups such as trade or even intermarriage. But adoption of agriculture is not automatic, and anthropologists have long noted that hunter-gatherers on average work less hard than farmers to obtain the food products needed for survival. Proximity to agricultural technology is not by itself an adequate explanation for the shift away from a hunting-gathering way of life.
Population pressure may be a primary reason that hunter-gatherers turn to agriculture. Not long after the last Ice Age, which ended about 10,000 years ago, the world was essentially “full,” meaning that humans occupied most habitable areas, although in many places the population density was low. Human populations have a natural tendency to increase in numbers. With gradual population increases over time, and essentially no place for people to migrate to without creating conflict with other groups, it became necessary to improve food production capacity. In some places, at various times, environmental changes such as long-term drought also may have pushed people to adopt new methods of producing food. In essence, the beginnings of domestic plant cultivation in hunter-gatherer societies were about establishing greater food security rather than a newfound preference for farming.
Agriculture may spread to new areas through either outright migration of people or by diffusion of crops and farming technology from one society to another. We may never learn which mechanism was mainly in play in prehistoric Colorado, and perhaps some of both are reflected in the various societies that adopted farming in different parts of the state. It should be noted, though, that hunter-gatherer groups were well-established in all parts of Colorado prior to the introduction of agriculture, and it seems probable that the part- and full-time farmers we see in the archaeological record were mainly descended from these indigenous groups.
When hunter-gatherers first began to experiment with agriculture, there was little about the structure of their societies that changed. They remained highly mobile and lacked permanent dwellings because there was no reason to make investments of time and labor in building houses that would only see short-term use. Domesticated plants such as corn may have been planted in the spring and left to mature with little further attention as people followed traditional hunting-and-gathering routines. But domesticates generally don’t do well without human intervention, and some will not reproduce at all. Casual farming is often ineffective because crops, once planted, need to be watered, weeded, and protected against pests. Otherwise, crop yields are low and some crops will fail altogether. Over time, as the commitment to domesticated crops grew in some societies, patterns of human settlement changed. People became semisedentary as some members of the group were left behind to tend crops while others left to hunt and collect wild plant foods. The justification for building more permanent dwellings increased, while at the same time diets began to reflect a more even mix of domesticated and wild foods. Eventually some groups became reliant on agricultural products for most of their subsistence needs, a process that unfolded over the course of centuries or even a millennium or more. Permanent, year-round settlements were established near prime farming areas, with houses that could be occupied for a generation or longer.
Agriculture in Colorado, 1000 BC–AD 1450
Five prehistoric culture groups in Colorado are known to have practiced agriculture. However, only the Ancestral Pueblo people of the Four Corners region, with a culture sequence dating from 1000 BC to AD 1300, became completely dependent on agriculture and lived in permanent villages. The remaining four cultures combined hunting and gathering of wild foods with agriculture to varying degrees. The Fremont tradition (AD 400–1300) extended into northwestern Colorado from Utah and is best known from the Dinosaur National Monument area. The Gateway tradition (400 BC–AD 1250) was located along the Colorado-Utah border midway between the Ancestral Pueblo and Fremont areas. In southeastern Colorado, people of the Sopris phase (AD 1050–1200) occupied the upper Purgatoire River Valley and Park Plateau in the Trinidad vicinity, while the Apishapa phase (AD 1050–1450) is associated with the extensive network of canyons of the lower Purgatoire River and other Arkansas River tributaries. In southeastern Colorado there is archaeological evidence of small-scale experimentation with agriculture that predates the Sopris and Apishapa phases by a thousand years or more.