I’ve already questioned the idea that the decline of Chaco Canyon as a regional center in the twelfth century constitutes an example of societal “collapse,” but there’s another major event in Southwestern prehistory that could conceivably qualify.  This is the large-scale and apparently complete depopulation of the entire Northern San Juan region between AD 1280 and 1300.  This cultural region, which covers large parts of southwestern Colorado and southeastern Utah, is often called the “Mesa Verde” region, after the well-known cluster of sites on and around Mesa Verde now part of major national park, but it also includes many other areas, including the recently designated Canyons of the Ancients National Monument and the Cedar Mesa/Grand Gulch area in Utah.  All of this vast area, as well as the parts of the San Juan Basin to the south that were still occupied after the decline of Chaco, seems to have been abandoned astonishingly rapidly.  The western parts in Utah were apparently abandoned first, starting around the 1260s, and all construction and other apparent activity came to a very abrupt halt throughout the region by 1280.  In some areas, such as Mesa Verde proper, construction was quite active throughout the 1270s, making the total lack of evidence for construction in the 1280s particularly remarkable.

So what happened here?  There are two main types of explanations, environmental and social, and their relative popularity has varied over the years.  The environmental explanation depends largely on the striking coincidence of the abandonment of Mesa Verde with the so-called “Great Drought” of AD 1276 to 1299, one of the earliest major climatic events to be identified in the tree-ring record.  The near-perfect alignment of the drought with the final abandonment of the area is indeed remarkable, and this explanation has been pretty popular and remains so today, but there is considerable evidence that there was more going on.  For one thing, while all of the Southwest is in some sense marginal for agriculture, within that context the northern San Juan is one of the most productive and reliable agricultural areas.  Indeed, much of southwestern Colorado is used today for commercial farming, largely using dry-farming methods not all that different from those used in antiquity.  The Mesa Verde area gets plenty of rainfall, and while a short growing season can be an issue at the higher elevations, throughout most of the region it is not generally problematic.  Models of agricultural potential based on tree-ring data have generally shown that the carrying capacity of the Northern San Juan greatly exceeded any plausible estimate of its overall population throughout prehistory, although that doesn’t necessarily mean that individual communities would always be able to support themselves on the land they happened to have.

Social factors, then, are probably involved along with the drought.  There is definite evidence for a considerable amount of violence during the thirteenth century in this area, and settlement patterns become increasingly defensive over time.  There is also an increasing diversity in public architecture among the various communities, suggesting that traditional religious or ideological structures may have been breaking down and being replaced by new ones.  A strong tendency toward settlement aggregation, perhaps due to defensive considerations, may have played a role in these religious trends.  Furthermore, all of this may have been influenced or set in motion by deteriorating environmental conditions; environmental and social factors were not necessarily separate things.

So where did the people go?  The general assumption is that they mostly went to the northern Rio Grande Valley, which sees a remarkable increase in its population right around AD 1300, just as Mesa Verde is emptying out.  This is a bit problematic, however, since there is relatively little evidence for people with obvious Mesa Verde cultural traits showing up in the Rio Grande at this time.  This may be because people were emigrating away from Mesa Verde in small groups and assimilating into existing Rio Grande communities, or it may have been because people were changing their cultures as they moved, perhaps abandoning the old social institutions that had been ineffective in preventing the abandonment and adopting new ones that seemed to work better.  It’s hard to say, really, and this is a topic of ongoing research.  One interesting effort recently has been the Village Ecodynamics Project by Washington State University and Crow Canyon Archaeological Center, which has used agent-based modeling and other innovative techniques to try to understand the culture history of the Northern San Juan.

Okay, so that’s more or less what happened.  Does it count as a “collapse”?  Let’s look back at Jared Diamond’s criteria for collapse:

1. Collapse involves a major loss of population.
2. Collapse involves a loss of complexity.
3. Collapse occurs over a large geographic area.
4. The changes brought about by collapse persist for a long time.

In this case 1, 3, and 4 are pretty obvious.  The Mesa Verde region was totally depopulated, which is about as major a loss of population as you can get.  It’s also very large, and the changes that resulted from the abandonment of the region and the influx of population to the Rio Grande have persisted to the present day; many aspects of Mesa Verde culture notable in the archaeological record were not brought to the Rio Grande, and are not present in the modern Pueblos there.  Since Diamond apparently considers only one of the first two criteria to be necessary, he probably would consider this a collapse, but most other collapse theorists, including Joseph Tainter, consider loss of complexity to be a more important consideration than loss of population, so let’s look at complexity in the Mesa Verde case.

There basically isn’t any evidence for significantly complexity in Mesa Verde before its abandonment or in the Rio Grande afterwards.  Unlike the Chaco case, the villages in the thirteenth-century Northern San Juan seem to have had relatively egalitarian social structures, at least economically and probably politically as well.  This is not to say that there were definitely no disparities in political power, but that they were likely masked and subverted by an egalitarian ideology that prevented massive accumulation of wealth and power.  This is the case in the modern Pueblos, where despite some possible inequalities in power and political influence among different clans or societies the overall ideology has enforced a general economic equality.  This seems to have been the case in the thirteenth-century Northern San Juan as well, and it could have been in part a reaction to the perceived excesses of the Chacoan era, although it’s noteworthy that a certain amount of Chacoan influence seems to have persisted, especially in the Totah area around Aztec, albeit without much evidence for the economic inequality that marked the Chacoan era itself.

Mesa Verde doesn’t get mentioned in the collapse literature as much as Chaco, although sometimes the two are kind of muddled together incoherently, and for good reason.  What we seem to be seeing at Mesa Verde is a period of societal difficulty that resulted in depopulation and migration, a common pattern in Southwestern prehistory.  While there were some changes in society during the abandonment and migration that make it difficult to tell exactly where the people ended up, these changes don’t seem to have been related to any change in the overall complexity of the society, which remained about as complex as it had been before.

I said I would talk about the “collapse” concept while I’m here, so here’s a start.  This topic has gotten a lot of play in the public discourse in the past few years, as the prospect of severe impacts from climate change has led to an increase in apocalyptic doomsaying among certain environmentalists and others as well as a renewed interest in studying past episodes of societal collapse to understand their dynamics and whatever lessons they may hold for us today.  Jared Diamond’s 2005 book Collapse is probably the best-known and most prominent examples of this type of thinking.  I haven’t read it, so I can’t comment on the specifics of it, but it’s gotten quite a bit of criticism from various quarters that I think is important to acknowledge regardless of the merits of Diamond’s argument overall.

First, though, we need to understand what exactly we mean by “collapse.”  What does it mean for a society to collapse?  Intuitively it seems obvious, but there are actually a variety of processes that have been interpreted as “collapses” in both the scholarly and popular literature, and the term is often left undefined.  One place to start is with a 2006 review article by Joseph Tainter, an archaeologist now at Utah State University who, unlike many people who have been talking loudly about collapse in the past few years, is an actual expert on the subject who has been studying it for decades.  In the article Tainter discusses Diamond’s book at length, along with a variety of other primarily scholarly studies explaining various events in the archaeological record in terms of societal collapse.  More specifically, the works Tainter talks about here deal with one type of collapse, that attributed to “overshoot,” i.e., the overexploitation of natural resources through either population growth or increased per capita consumption.  This is the type of collapse that gets the most attention in a modern context, since the idea behind most predictions of doom for our own society is that we are on an unsustainable trajectory due to expanding population or overconsumption.  The overpopulation argument goes back to Thomas Malthus, of course, and its current form owes a lot to Paul Ehrlich’s 1968 book The Population Bomb.  More recently this concept of overpopulation has been variously supplemented or replaced by the idea that it is per capita consumption, especially in wealthy nations like the US, that is on an unsustainable course that will lead to exhaustion of natural resources and, perhaps, societal collapse.  There are other ways societies can collapse, but this is the one people tend to be worried about today, and finding examples of it in the archaeological record has been a high priority for many people.

Tainter’s article goes through a variety of collapses that have been linked to overshoot, and finds most of them severely wanting in evidence.  He is particularly scathing about Diamond’s work, calling his discussion of the Anasazi “a confused muddle” and rejecting many of the case studies in the book as not even really being examples of collapse at all, but rather unsuccessful attempts to colonize areas unsuitable for the subsistence practices of the colonizers, who eventually died or left.  Tainter’s criteria for collapse rely heavily on a loss of complexity, with a “simpler” society succeeding a more “complex” one, and this notion is echoed in Diamond’s stated criteria for collapse as well, although Tainter argues that Diamond doesn’t actually apply these criteria rigorously and consistently.  Instead,

Diamond’s approach was seemingly to find cases where (a) bad things happened, and (b) he could construct a plausible environmental reason. The outcomes, however diverse their nature, are lumped into the category “collapse.”

The one case that Tainter does give some credence to is Easter Island, although even here he notes substantial criticism of the overshoot model of deforestation leading to the collapse of the complex society that developed there.  The cases he finds most convincing as examples of overshoot leading to collapse are the Third Dynasty of Ur and the Abbasid Caliphate, both in southern Mesopotamia though separated by thousands of years.  Even here, though, Tainter sees the collapse as being less a result of “pure” environmental degradation and more a matter of inadequate decision-making by elites in response to problems caused by overexploitation of natural resources, in these cases salinization caused by intensive irrigation agriculture.  In most of the other cases of collapse, the major problem seems to have been climatic or other uncontrollable changes that disrupted systems that had worked fine otherwise, in many cases probably combined with the same problems of poor decision-making.

Now, climate change and poor decision-making are obviously factors that are very relevant to modern-day problems, so in a sense Tainter’s dismissal of overshoot-based collapse theories in archaeology doesn’t matter too much for the relevance of case studies like Diamond’s to the present day.  Indeed, it seems like the overall negative tone of the review article is a function largely of its narrow focus on overshoot specifically rather than collapse in general.  Still, Tainter’s conclusion, surprising even to him, that there are very few documented cases of environmental degradation due to human exploitation leading to societal collapse is an important cautionary note in showing how important it is to carefully analyze the archaeological record before trying to apply its lessons to contemporary problems.

Which will win: peak oil or global warming?

If you follow both narratives in the blogosphere, which is where the debate is most kinetic, you already know that peak oil and global warming are flip sides of the same coin.

I come at this mainly as a journalist, but also as someone who is interested in archaeology and the collapse literature of recent decades. I’ll leave the modern-day parallels to Jared Diamond, though I tend to think he oversimplifies his case studies.

What fascinates me about the respective peak oil and global warming narratives is that both revolve around the same meme: that civilization is on the fast track to collapse, unless we make systemic changes to the way we live. The peak oil camp take the argument to its logical extension and talk earnestly about such things as overshoot, or carrying capacity. The gobal warming camp dabbles in this debate, but because they have a big tent (which must accomodate politicians), their overriding goal is to replace the world’s carbon economy with one that doesn’t spew greenhouse gas emissions. And hey, that is plenty formidable.

Still, in the global warming camp, there is no real engagment with underlying, socio/economic forces. There really can’t be when much of the rest of the world (understably) aspires to live like average Americans. Copenhagen is proof of that. Ironically, Andy Revkin, one of the few persons who has used his prominent platform to expand the intellectual sphere of the climate change debate, is often pilloried by hardcore climate advocates. Some of them hold to the notion that Revkin, despite a stellar body of work on the energy & climate change beat, has aided and abetted the guys in “black hats.” Go figure.

This recurring complaint against Revkin is part of a deeper animus that the the global warming camp has towards the media at large. The peak oil folks, for their part, are fighting just to be relevant. It’s mind-boggling to them that nobody but them seems to get the dire trajectory the world is on.

But some pretty famous climate scientists feel that way too about global warming.  Thus, as far as representatives from these two camps are concerned, the race to doomsday is on. Which will get their first? Will it be when the global demand for oil exceeds the supply, or will it be when the carbon load in the atmosphere tips a baking planet into ecological and social mayhem? Go ahead, flip a coin.

The Oil Drum is the only site I know of that makes you think seriously about the end of the world. But even Nate Hagens, my favorite commentator there,  feels compelled to offer a disclaimer of sorts for this guest post by George Mobus.  Hagens writes:

As an editor here, I continually struggle to find a balance of discourse that presents scientific reality in ways that don’t come across as apocalyptic or frightening. In my opinion, the larger the lens with which we view our situation, the more informed choices will be made towards more sustainable trajectories.

Well, Nate, this Oil Drum review of William Catton’s new book, Bottleneck: Humanity’s Impending Impasse, is enough to  make even Richard Dawkins embrace the Rapture.