The Chaco system is distinctive in a number of ways, some of which distinguish it from other contemporaneous societies elsewhere in the southwest and others of which distinguish it from later societies in the same area. Among the most striking examples of the latter is the low-density settlement pattern typical of Chacoan sites, though by no means limited to them. In contrast to the highly aggregated cliff-dwellings and massive pueblos of later periods, Chacoan communities were composed of loosely clustered small-house sites, generally in open locations. These communities are generally marked as “Chacoan” by the presence of one or more great houses and other examples of Chacoan-influenced “public” architecture, such as roads, encircling berms, and Chaco-style great kivas. This settlement pattern has been proposed as a marker of the extent of the Chacoan system, and it is perhaps the way of defining the system that gives it the largest geographical extent.
It is important to note, however, that while the low-density settlement pattern certainly distinguishes Chacoan communities from the high-density aggregated pueblos that succeeded them within that same geographical area, during Chacoan times that same community pattern minus the great houses and other specifically “Chacoan” features was quite widespread throughout the Pueblo world, including in areas that show no sign of direct Chacoan influence. That is, the “Chacoan settlement pattern” is a temporal rather than a spatial marker of Chaco-ness.
The shift in Pueblo community layout from the widespread pattern of low-density clusters of small houses during the Pueblo II period to the equally widespread pattern of high-density aggregated roomblocks during the Pueblo III period has long been a matter of considerable interest in southwestern archaeology. Many theories have explained this using vague references to increased pooling of labor resulting in increased economic efficiency or some such. Another idea, which I find more persuasive, is that increasing climatic volatility led to resource shortages, which led to competition and warfare, which led to aggregation for defensive purposes.
This theory has been expressed in the most detail by Steven LeBlanc, who makes the point that, far from being a generally optimal strategy for maximizing economic efficiency, aggregation is actually a very problematic strategy that leads to over-exploitation of nearby resources and under-exploitation of resources further away, with the resulting depletion of accessible resources leading to a lower standard of living. In addition, aggregated living is pretty unsanitary, and the combination of a lack of sanitation with a less diverse diet, on top of the general tendency toward malnutrition typical of small-scale agriculturalists, led to shockingly high levels of disease. And, indeed, studies of human remains from aggregated pueblos have shown a population that is much less healthy than that of the dispersed communities of Chacoan times. The obvious implication of this is that people lived spread out across the landscape, a settlement pattern which LeBlanc characterizes as maximally efficient for resource exploitation, whenever regional political conditions were peaceful enough to make that a viable strategy, and they only aggregated (or went with other more defensive but less efficient strategies) when forced to by increasing warfare.
Even if a dispersed pattern of settlement is more efficient than an aggregated one, though, it’s by no means inevitable that such a pattern will arise. A variety of social factors come into play that end up having at least as much effect on settlement patterns as the location of resources and the most efficient ways of exploiting them. The lack of warfare is one obvious prerequisite for a dispersed pattern, which necessarily involves a certain amount of vulnerability to attack and therefore is only likely to arise when the threat of attack is minimal. Since the Chaco era is a famously peaceful time in the southwest, for reasons that remain somewhat obscure, it’s hardly surprising that this condition was met.
There’s more to it than that, though. Not all peaceful societies involve people spreading themselves evenly across the landscape. Historical contingency and traditional patterns of land ownership and usage rights play a role as well. In the prehistoric southwest this issue has been most intensively studied in southern Colorado, particularly by scholars associated with the Crow Canyon Archaeological Center. They have found that, while this area remained quite productive agriculturally throughout the prehistoric period, environmental variability could have devastating effects on particular communities given the restrictions on land use resulting from traditional rights to particular pieces of land. In other words, the maximally efficient usage of land could not be realized because of cultural and historical factors that kept people from having complete freedom of movement in the event of environmental perturbations impacting their ability to cultivate their own lands productively. This eventually resulted in regional abandonment around AD 1300.
Even this, though, may not go far enough. The idea of traditional land-use rights and restrictions is plausible enough, but what, exactly, were they? What sort of units held the rights to cultivate (or otherwise exploit) particular pieces of land, and why?
One possible answer is suggested in a study by James Kendrick and Jim Judge published in an edited volume on Chacoan outlier communities. This study looked at long-term changes in land-use and settlement patterns at the community surrounding Lowry Pueblo north of Cortez, Colorado. Lowry is one of the best-known Chacoan outliers in southern Colorado, and one of the northernmost outliers in the Chacoan system. While this study does talk a bit about the great house, however, particularly noting that there is little evidence that it ever served anything other than a residential purpose (not an uncommon conclusion for the studies in this volume), the main focus is on the small-house sites surrounding the great house where most of the population lived.
The conclusion Kendrick and Judge come to after looking at where these small houses are located in each period of occupation is that during the Pueblo II period individual households were largely autonomous economically, and the basic unit of economic production and land-use rights was the individual family group occupying a single small house. These small houses were, therefore, distributed fairly uniformly across the landscape throughout the community. Later, in the Pueblo III period, the community began to aggregate, and Kendrick and Judge argue that part of this process involved the transfer of land-use rights to the community as a whole. They posit this as an explanation for why, when the Mesa Verde region as a whole was abandoned around 1300, entire communities seem to have moved as units, making the abandonment throughout the region remarkably complete.
This all seems reasonable enough, and it would explain a number of puzzling elements of the late prehistory of southern Colorado, although some other research suggests that land-use rights were still held at the household level after the migration of at least some of the population further south into the Pajarito Plateau area. When it comes to taking this idea out of isolation and wondering about its implications for the present (which is what I’m all about), however, there’s something troubling about it.
The recent trend in policy discussions about community planning is to extoll the virtues of density and bemoan the evils of sprawl, which is held to be horribly inefficient as well as aesthetically appalling. In the current context, of course, this makes perfect sense, and the data backing it up is compelling. When it comes to looking at the lessons of the past, however, a problem arises: in prehistoric communities like Lowry, sprawl (in the form of low-density patterns of settlement) is presented as maximally efficient, and aggregation (i.e., increased density) is presented as uncomfortable, unsanitary, and a last resort of a desperate people under siege from both a declining environment and hostile neighbors. This seems totally plausible as well, in its context. So how can these both be true.
The answer, I think, lies in the way that prehistoric societies, and preindustrial societies more generally, were really quite different in their economies from our own (post-)industrial society. Basically, a dispersed settlement pattern is maximally efficient in a society based on subsistence farming. If everyone or almost everyone is farming for their own sustenance, and possibly for export if they happen to produce a surplus, it makes sense to put as much land under cultivation as possible, and the most efficient way to do that is to spread the population out so as to have fields everywhere and people living as close as possible to them.
In an industrial society, however, most people don’t farm. Those who do have to do so on a vast scale to feed the huge numbers of unproductive non-farmers. As a result, supply chains are necessary to bring food from the farms to the towns and other locations where most of the population lives. The more spread-out the people in those towns are, the longer and more elaborate (and more fragile) those lines have to become. If people are packed in densely, it takes less effort to supply them with both food and other necessary resources, which in an industrial society generally come from far away and need to be brought in just as food does.
So while for a place like Lowry low density farming was efficient, for us it makes a lot more sense to live more densely. Modern medicine and other technological advances have made it a lot more comfortable to live this way than it was for the people at Lowry, so we can count ourselves lucky in that respect. This is a good example of how important it is to look carefully at the lessons of the past and not just blindly apply prehistoric solutions to modern problems.