Did Chaco Collapse?

Posted by: teofilo  :  Category: Anasazi, Archaeology, Native Americans, chaco canyon, collapse, southwest

Chaco Canyon is often discussed in the “collapse” literature as a prime example of societal collapse, often tied to climatic change and sometimes to ecological overshoot (although that part’s pretty dubious).  Both Jared Diamond and Joseph Tainter use it as an example of societal collapse in their respective books on the subject.  It’s easy to see why; Chaco is remarkable for its impressive remains in a very harsh and unpromising setting, but it’s clear that those impressive remains date to a remarkably short period of time, and that something happened afterward that changed things considerably and led to a near-total cessation of further activity in the canyon.

The human occupation of Chaco Canyon goes back a very long way, but the key developments that made it an important regional center seem to have begun in the AD 800s with the initial building of a few “great houses,” which in that period were large masonry structures similar in layout and construction techniques to the “small houses” in which most Southwestern people lived at the time but much on a much larger scale.  These early great houses, including Pueblo Bonito and Una Vida, show considerable signs of residential use in their earliest parts, and it seems that they were at least initially residential structures.  It’s not at all clear what inspired their construction, but there were similar structures being built in other parts of the region at the time, so Chaco may not have been particularly special at first.  Over the course of the next hundred years, however, something seems to have happened to make Chaco a major regional center, and starting around AD 1030 a building boom in the canyon in which the existing great houses were expanded using much more elaborate techniques and an even larger scale of construction coincided with the construction of entirely new great houses both in the canyon and throughout the San Juan Basin of northwestern New Mexico and beyond into Colorado, Utah, and Arizona.  These “outlying” great houses were mostly placed in existing small house communities, which continued to be occupied, and were connected to the canyon via an elaborate road system.

Over the next hundred years, construction both inside and outside the canyon continued almost without pause, and at the same time a vast amount of material of all kinds was brought into Chaco from a vast surrounding region: turquoise, shell, copper bells, macaws, and other exotic materials, as well as more quotidian items such as pottery, construction timbers, and corn.  Then, around AD 1130, everything seems to have come to an abrupt halt.  Construction of great houses, after a shift around AD 1100 toward a different type of architecture, seems to stop entirely by around 1125, and activity in the canyon slowed to a crawl at that point.  There was probably at least a small population remaining until the depopulation of the whole region in the late 1200s, but it was nowhere near as large as the apparent population at the system’s height.  It is this decline in activity that collapse theorists seek to explain when they look at Chaco as a case study.

So what happened?  There are various theories out there.  Many point to a prolonged period of drought from around 1130 to 1180, which coincides suspiciously closely with the end of major activity at Chaco, as having somehow led to the collapse, although this explanation is somewhat problematic given that earlier droughts, especially a short but severe one in the 1090s, didn’t have nearly the same effects on the system.  Others argue that political, social, or economic instability within the Chaco system itself, whatever its nature, was the main cause of the collapse, with drought perhaps playing a subsidiary role.  Most people agree, however, that Chaco is indeed an example of societal collapse.

But is it?  Let’s look at some of the criteria for defining collapse, using Diamond’s list:

  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.

Measuring the population of Chaco at any time is surprisingly difficult, but given the much lower level of activity after 1130 I think it’s safe to say that there was a major decline of some sort.  The extent to which Chaco was a complex society at all is disputed, but I find the arguments for complexity more convincing than the arguments against it, so let’s take relative complexity as a starting point and see if there’s evidence for a loss of it.  Recall Ben Nelson’s definition of complexity:

Social systems are considered complex if they are comparatively large demographically and spatially, encompass multiple settlements in an integrated political structure, and exhibit horizontal and vertical social differentiation. Other properties associated with complexity are hereditary ranking, production of surplus and its appropriation by an elite, craft specialization, and long-distance exchange.

Large demographic scale is basically the same as population, so that one’s covered.  We’ll get back to spatial scale and settlement pattern later.  There isn’t much evidence for horizontal social differentiation at any point in the Chacoan archaeological record, but the vertical differentiation implies by the elaborate burials in Pueblo Bonito does seem to end around 1130.  Ranking goes along with vertical differentiation, and surplus and its appropriation are controversial and hard to find in the archaeological record, as is craft specialization.  That leaves us with long-distance exchange, which does continue to go on at Chaco, but at a much lower level than before.  So yes, I think it’s fair to say that Chaco became less complex according to most of the criteria that can be used to assess complexity there.

That brings us back to spatial scale, and here’s where things get tricky.  It turns out that the evidence for reduced activity at Chaco Canyon after 1130 doesn’t correspond to a similar reduction in activity in most other parts of the Chaco system at the same time.  Indeed, some areas, such as Aztec Ruins on the Animas River to the north, see a marked increase in activity after 1130, and both Aztec and the Mesa Verde area further north see continued activity on a large scale, indicative of a large population, until the depopulation of the whole area in the late 1200s.  The area to the west doesn’t see such dramatic growth, but it does seem to keep on going without much change after 1130.  Similarly, while the area immediately south of Chaco seems to have been largely depopulated even earlier than the canyon itself, the area further south continued to see activity long after, indeed up to the present day at Zuni Pueblo.  And in many of these areas, especially at Aztec and at the northern and southern extremes of the original Chaco system, the outlying Chacoan great houses seem to have continued to be used, though perhaps not the same way as they were originally intended to be used, long after the cessation of great house construction in Chaco itself.

So it seems that the Chaco “collapse” really only applies to a single location, Chaco Canyon itself, and not to the society as a whole.  Indeed, some archaeologists have interpreted these data as showing not so much the collapse of the system centered on Chaco but a series of changes in it, possibly including a shift in emphasis away from Chaco itself toward Aztec, which replaced it as the center of the system.  Whether or not some form of the system that developed at Chaco continued at Aztec, it’s clear that there were a lot of changes going on in the region during the 1100s, including an apparent movement of population away from Chaco, probably at least in part to Aztec and Mesa Verde.  The lack of continued construction on the scale seen from 1030 to 1130 and the reduced level of trade do seem to suggest that the Chacoan system declined in power and influence after 1130 whether or not it moved to Aztec, but there turns out to be very little evidence of a “collapse” occurring over a large spatial scale, although the changes do seem to persist for a long time.

So what are the implications of this for studies of collapse in general?  It’s hard to say, but I think one lesson is that it’s important to look at these things on the societal level rather than on individual sites or localities, no matter how important or central they seem.  Some Southwestern archaeologists now prefer the term “reorganization” to “collapse” for situations like the changes at Chaco after 1130 and the contemporaneous events in the Mimbres Valley of southwestern New Mexico.  It’s certainly quit different from the massive depopulation of the whole Four Corners region in the late 1200s, which however doesn’t fit well into “collapse” models either because there’s little evidence of a system on any level larger than the individual community during this period, with the possible exception of a rump Chacoan system operating on a small scale out of Aztec.  That event, which corresponds to another prolonged drought, is of interest in its own right, but this post is long enough already.

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22 Responses to “Did Chaco Collapse?”

  1. Keith Kloor Says:

    Basically, what you’re saying is that Chaco moved, or the people who ran Chaco relocated to Aztez-what Steve Lekson calls Pax Chaco in his latest book (chapter six, page 160), in which he writes:
    “Aztec started strong but faded fast. The bustle and excitement of building a new city maintained, convincingly, the aura of Chaco-monumental construction was that canyon’s constant. By accident or hard work, the Pax Chaco was prolonged through the twelfth century.”
    Lekson goes on to say that fifty year drought (1130-1180) then finished off that experiment.
    Fifty year drought. Can you imagine that today in the Southwest?
     

  2. teofilo Says:

    Yeah, that’s basically what I’m saying, and it’s influenced considerably by Lekson’s work.  I haven’t read  his latest book or the Meridian one; I’ll get around to them at some point.
    One interesting thing about the whole drought explanation is that you’d be hard pressed to find anywhere in the Southwest less vulnerable to drought than Aztec.

  3. BobN Says:

    Interesting viewpoint, Teofilo.  Is there any evidence for some time of disease event at Chaco that would have affected a sizeable part of the population.  If there was, those that survived might have moved away to the other areas rather than return to a potentially “haunted” city.    The continuing and/or increased activities at the other great houses certainly makes one question the drought theory.

  4. Keith Kloor Says:

    Okay, but here’s the thing about those mega-droughts in the 10th and 11th centuries: they whack them upside the head pretty good in successive nature. How many hits to the system can a culture take?
    The argument that they weren’t done in by drought because they had withstood previous droughts doesn’t wash with me. You can rebound from one disaster but sometimes another one shortly after can get you..not to mention the social factors that come into play.

  5. teofilo Says:

    Bob: No evidence of epidemic disease that I know of, but not all diseases would necessarily leave traces in the archaeological record.  And there were still changes in use patterns at the other great houses that suggest that something was changing throughout the region, whether or not it was due to drought.
    Keith: Oh, I’m sure drought played a role.  I don’t think it’s coincidental that Chaco, one of the most marginal areas for agriculture in the Southwest, lost its central role at the time of a major drought while the peripheral great houses in better agricultural areas were unaffected or gained importance.  The increasing evidence for transport of food to Chaco from outlying communities both before and after the drought does muddle the picture a bit, however.

  6. Artifex Says:

    Keith says - You can rebound from one disaster but sometimes another one shortly after can get you..not to mention the social factors that come into play.

    I think in many cases Diamond and some of the others do not give social factors their just due. If the society has significant internal flaws and stresses, I could easily imagine environmental problems being magnified in scope. You might not even need multiple disasters if the society is particularly unstable for some reason.

    Consider a society that we know more about due to more available records. When the Roman empire suffered several periods of contraction, I would think modern historians would attribute that more to social pressures than environmental ones. That being said, one can definitely show issues with food supply and source contributed a wide variety of problems for the Roman society some of which grew from very subtle beginnings. I could easily imagine similar issues with the Chaco Canyon culture. I suspect without the existence of an ancient Chaco Herodotus, we may just be out of luck in getting a better feel for those sorts of issues.
     

  7. teofilo Says:

    Indeed, Tainter’s book (which I haven’t read) discusses both Chaco and Rome as case studies, and I believe he comes to similar conclusions about social and economic pressures being key to understanding the events in both cases.

  8. Keith Kloor Says:

    Artifax (6):
    I have taken up the collapse meme in numerous posts on this blog and specifially to your point, you might want to check out this post.

  9. Pascvaks Says:

    Rome and Chaco.. the past is prolog.. disasters happen.. cities, states, and even civilizations collapse.. dark ages happen.. ice ages happen.. hot ages happen.. life’s a beach.. teach you kids how to swim.. be careful!
     

  10. Jim Allison Says:

    One piece of the puzzle missing here is that a number of archaeologists think that population movements out of southwestern Colorado in the late A.D. 800s (as part of another localized “collapse” on a relatively samll geographic scale) contributed significantly to the emergence of Chaco. And I think there were earlier movements from south to north into southeastern Utah in the 700s (although I’m still working on building the argument for that). So movement out of Chaco north to Aztec and beyond would be part of a larger, cyclical pattern of relatively large population movements that endured for several centuries. I think it’s part of the pattern in the northern Southwest for population centers to shift around, and not a collapse.

  11. teofilo Says:

    That’s a good point.  I tend to buy the argument that movement away from the Dolores villages went to the Chaco area, and in general I’m inclined to see movement of communities on a generational scale as a useful response to changing circumstances in the unpredictable environment of the Southwest.  I didn’t mention this earlier part in the post because it was long enough already, but I do think it is an important part of the story.
    Where do you see the south-to-north migrants in the eighth century coming from?  The Basketmaker III villages in the San Juan Basin, or somewhere else?

  12. Tom Fuller Says:

    Maybe they just piled everything in the pickup and went to Californy, or whatever the equivalent was.  Do we have analogues for relocation that maintained societal structures? Hunter gatherers have no problem with doing that. Even pastoralists get away with it. How about developed agricultural societies?

  13. Keith Kloor Says:

    Maybe they just piled everything in the pickup and went to Californy…

    A couple of years ago, when I was working on a story about the Fremont, Kevin Jones, Utah’s state archaeologist, said some interesting things about the larger question we’re discussing here (but he was referring to the fate of the Fremont):

    “If it seems that archaeolgists equivocate on it, its because its that complicated. We desire a simple answer, but its not, ‘yeah, they all died out’ or they become the ute’ or they packed up and moved to nebraska’. There is no simple answer…”

  14. Jarmo Says:

    Lawrence Keeley has written about primitive warfare and its devastating effects in pre-Columbian America in his book War Before Civilization. Here is an example what went on:

    “Contrary to Brian Ferguson’s claim that such [inter-tribal] slaughters were a consequence of contact with modern European or other civilizations, archaeology yields evidence of prehistoric massacres more severe than any recounted in ethnography. For example, at Crow Creek in South Dakota, archaeologists found a mass grave containing the remains of more than 500 men, women, and children who had been slaughtered, scalped, and mutilated during an attack on their village a century and a half before Columbus’s arrival (ca. A.D. 1325).”

    Southwest was probably not a peaceful enclave in otherwise warlike continent.
     

  15. Pascvaks Says:

    Ref - Jarmo Says:
    August 27th, 2010 at 1:43 am
    A mass grave?  Hummmm.. sounds like their side won.  Guess they left their enemy on the field to be eaten by the ravens, wolves, and coyotes.  Digging is hard work.  You don’t waste time and energy digging to bury your enemy.  Just imagine what happened when the Mongol Horde came East, bet the ravens had a feast.  Yhep!  The winners buried their own.

  16. teofilo Says:

    Southwest was probably not a peaceful enclave in otherwise warlike continent.
    Indeed, Steven LeBlanc wrote an entire book on that exact subject.

  17. teofilo Says:

     
    Maybe they just piled everything in the pickup and went to Californy, or whatever the equivalent was.  Do we have analogues for relocation that maintained societal structures?
    Yes, the abandonment of Mesa Verde and presumed movement to the Rio Grande Valley is one of the classic examples, and there are probably others in the Southwest that are less obvious.

  18. Jim Allison Says:

    But it’s not clear that the people who moved from the Mesa Verde region to the Rio Grande in the late 1200s maintained their social structure. There are some continuities, but most of the distinctively Mesa Verde traits didn’t survive the journey. The arrival of immigrants in the Rio Grande is visible mostly as a population increase; there are few sites that look like they were built by people from the Mesa Verde region. And there is some debate about which part of the Rio Grande the Mesa Verde people went to.
     
    This contrasts with what happens to immigrants from the Kayenta region of northeastern Arizona. People move out of that area at about the same time, and some of the people who moved out moved to southern Arizona, where they created sites that are easily recognizable as having been created by people from the Kayenta region.
     
    So, the Kayenta migrants seem to have maintained their cultural identity to a much greater degree than the Mesa Verde emigrants. Social structure is harder to see, but it seems likely that the Kayenta folks maintained that to a greater degree as well. What accounts for those differences is a very interesting question, but it seems clear that there was a great deal of turmoil and violence in the Mesa Verde region in the 1200s, and, in moving away from there, people may have been rejecting the prevailing cultural and social norms.

  19. Jim Allison Says:

    Back in comment #11, teofilo asks:
    “Where do you see the south-to-north migrants in the eighth century coming from?  The Basketmaker III villages in the San Juan Basin, or somewhere else?”
     
    I think they some are coming from the southern part of the Southwest, at least as far south as the Mogollon Rim region, and possibly as far south as northern Mexico.
     
    The predominant decorated pottery at the early Pueblo I villages that appear at about A.D. 760 in what is now southeastern Utah and the western parts of southwestern Colorado is a type we call Abajo Red-on-orange. Technologically, Abajo Red-on-orange is more similar to the red-on-brown tradition than to the black-on-white pottery that characterizes earlier sites in southeastern Utah and contemporary sites in most of southwestern Colorado. Painted designs on Abajo Red-on-orange are also very different from earlier and contemporary black-on-white designs, but similar to designs on contemporary red-on-brown ceramics from farther south.
     
    But, for now, that’s just me talking. I think the connections to the southern Southwest are obvious from just looking at the pottery, but I think most of the archaeologists who would argue immigration into the area aren’t looking at the pottery closely, and would probably suggest the San Juan Basin as a likely source (of course, people may have moved in from more than one area). I’m writing an article that includes the argument based on the ceramics for a source farther south than the San Juan Basin, but it’s not done yet.
     
    On the other hand, there is a rapid population increase at the same time (A.D. 750 or 760) in the area around Durango, Colorado. There is variation in architecture and ceramics among the early Pueblo I sites there that suggests the population included people with heterogenous origins, but there is little to indicate that people came from very far away (at least not as far away as I think some of the people moving into southeastern Utah came from). Many of those people might have come from the San Juan Basin, south of the San Juan River, maybe even including Chaco.

  20. teofilo Says:

    But it’s not clear that the people who moved from the Mesa Verde region to the Rio Grande in the late 1200s maintained their social structure. There are some continuities, but most of the distinctively Mesa Verde traits didn’t survive the journey. The arrival of immigrants in the Rio Grande is visible mostly as a population increase; there are few sites that look like they were built by people from the Mesa Verde region. And there is some debate about which part of the Rio Grande the Mesa Verde people went to.

    True, and that’s what makes the Mesa Verde migration to (presumably) the Rio Grande so difficult to see; they were changing their culture as they were moving, and apparently assimilating pretty significantly once they got there.

  21. teofilo Says:

    I think they some are coming from the southern part of the Southwest, at least as far south as the Mogollon Rim region, and possibly as far south as northern Mexico.
    Now that’s very interesting.  I didn’t know that about the pottery.  It’s interesting that despite the long history of reliance on pottery for dating and the study of trade contacts in the Southwest, it’s only recently that people are beginning to look carefully at the pottery itself technologically.  I’ll keep an eye out for that paper when it comes out.

    On the other hand, there is a rapid population increase at the same time (A.D. 750 or 760) in the area around Durango, Colorado. There is variation in architecture and ceramics among the early Pueblo I sites there that suggests the population included people with heterogenous origins, but there is little to indicate that people came from very far away (at least not as far away as I think some of the people moving into southeastern Utah came from). Many of those people might have come from the San Juan Basin, south of the San Juan River, maybe even including Chaco.
    And then the Dolores villages a little later, then back to Chaco…
    Interesting stuff.  Now that migrations are no longer verboten by processualist dogma, all sorts of connections are beginning to emerge.

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