Archive for the ‘Pueblo Bonito’ Category

Stone Tools at Chaco Visitor Center Museum

When it comes to stone tools, archaeologists make a basic distinction between “chipped-stone” and “ground-stone” tools.  Chipped-stone tools are generally those that need to be sharp, such as projectile points, knives, scrapers, and drills, and are typically made of hard stone that keeps an edge.  Some ground-stone tools, such as axes, are also sharp, but for the most part ground-stone tools rely on other qualities of stone for purposes like hammering and grinding.  In the Southwest, ground-stone tools are usually made of sandstone, basalt, or other types of stone that are plentiful in the area immediately around a site.  These tools are heavy, and it generally wouldn’t have made any sense to import special types of stone to make them when, as is the case throughout the Southwest, there were plenty of rocks around.  The types of stone used for ground-stone tools are also generally those used for masonry in areas where masonry construction was typical, including at Chaco, where sandstone was the usual material.

Chipped-stone tools are a different story.  They are usually small and highly portable, and the best materials to make them are often scattered and not convenient for every habitation site.  Thus, widespread trade in chipping stone has very early origins.  Hunter-gatherers need very good stone for their projectile points, and also tend to be very mobile, so their chipped-stone tools tend to be very well-made and to be made of high-quality material from a wide variety of sources.  Settled agriculturalists such as the Chacoans don’t rely so heavily on chipped-stone tools for their subsistence needs (ground-stone tools like metates are much more important), and they typically put much less effort into both procuring stone for chipped-stone tools and making the tools themselves.

Flake of Narbona Pass Chert at Pueblo Alto

When it comes to Chaco specifically, chipped-stone shows a much more muted form of the pattern of massive imports of other goods such as pottery, wood, turquoise, and even foodCathy Cameron summarizes the patterns revealed by the chipped-stone assemblages from Chaco Project excavations in the 1970s in an article from 2001.  The basic pattern is that most chipped stone was from local sources throughout the occupation of Chaco, although “local” really refers to a wider area here than the canyon itself.  Good chipping stone is not plentiful in the canyon itself, but abundant sources of good chert and petrified wood occur a few miles to the north and would have been easily accessible to canyon residents in the course of their daily lives (i.e., special trips to gather stone would probably not have been necessary).  These local sources always dominate assemblages from Chaco.  Imported stone types do increase during the Chaco era from AD 1030 to 1130, especially at great houses such as Pueblo Alto.  The most abundant import at this time is Narbona Pass chert, a distinctive pinkish type of stone that comes from a very restricted area in the Chuska Mountains to the west.  The Chuskas are also the source of many other imports to Chaco, including huge amounts of pottery and wood, but the relative proportions of Narbona Pass chert in the overall chipped-stone assemblages are much more modest.  It comprises 21.1% of the total Chaco Project sample for AD 1020 to 1120 and 18.9% of the sample for AD 1120 to 1220.  This is much higher than any other type of imported stone ever reaches, and even higher than any single type of local stone for these periods (though much lower than the total proportion of local stone).

Other imported materials found in notable numbers include Brushy Basin chert from the Four Corners area, a type of yellow-brown spotted chert and a special type of petrified wood, both from the Zuni area, and obsidian.  Brushy Basin chert (along with other materials from the same formation) and Zuni petrified wood reach relatively high proportions of the overall assemblage at the same time that Narbona Pass chert does, and Zuni chert does too but at a much lower level.  The pattern of obsidian is different, and hard to understand.  It’s the most common exotic type of stone before AD 920, rising to as high as 7.6% of the assemblage in the seventh century.  Sourcing studies seem to show that most of the obsidian coming it at this point came from the area around Grants, New Mexico, near Mount Taylor, during this period.  Once the Chaco system really gets going, though, the proportion of obsidian plummets to less than 1%.  From 1120 on, however, it rises again, comprising 7.3% from 1120 to 1220 and 2% after 1220, still less than Narbona Pass chert but respectable.  This obsidian seems to come mostly or entirely from sources in the Jemez Mountains to the east of Chaco.

Log of Petrified Wood at Chaco

So what were the Chacoans doing with this imported stone?  Not much, as it turns out.  One of the oddest things about the amount of Narbona Pass chert, particularly, is that it doesn’t appear to have been used for anything special.  Like all other types of stone, both local and imported, it was used primarily for expedient, informal tools.  The Chaco Project found 2,991 pieces of Narbona Pass chert, and only 18 of these were formal tools.  This pattern is typical for most material types, though obsidian seems to have been more often used for formal tools, many of which were probably imported as finished tools rather than made in the canyon.  Of the formal tools the Chaco Project did find, of all materials, about half were projectile points, and the rest were various types of knives, scrapers, and drills.

So what’s going on here?  Hard to say.  Cameron evaluates the chipped-stone data in the context of the models for the organization of production proposed by other participants in the conference from which this paper originated, and she decides that Colin Renfrew’s pilgrimage model fits best, with some adjustments.  This conclusion is driven largely by the fact that so much of the Narbona Pass chert came from the Pueblo Alto trash mound and the idea that this indicates that it was deposited there as part of communal rituals.  I find claims like this dubious, and I think it’s more likely that people in Chaco were just importing this type of stone either because it is so visually striking or because of their strong social connections to Chuskan communities (or both).

Chuska Mountains from Tsin Kletzin

The thing I find most puzzling is the obsidian.  Obsidian was hugely important in Mesoamerica, and in view of the appropriation and importation of many aspects of Mesoamerican culture by the Chacoans, most recently dramatized with evidence for chocolate consumption, it seems very odd that the rise of the Chacoan system would coincide with a steep decline in the amount of obsidian imported.  This is particularly odd since the Grants area was very much a part of the Chaco world, and there were numerous outlying great houses and communities near Mt. Taylor.  If the Chacoans had wanted obsidian, they could easily have gotten it.  And yet, it seems they didn’t.

Or did they?  Keep in mind that this data is based mostly on Chaco Project excavations, although Cameron does incorporate some insights from a study of formal chipped-stone tools done by Steve Lekson that incorporated other data as well.  Lekson’s study noted that Pueblo Bonito in particular had an astonishing number of projectile points relative to most other sites, and I can’t help but wonder if part of the lack of obsidian at other sites was a result of more of it flowing to Bonito.  The excavations at Bonito were done a long time ago without the careful techniques of the Chaco Project, so the data isn’t totally comparable, but I’m going to look at the artifact records from Bonito (conveniently made available at the Chaco Archive) to see how common obsidian was there.

Arrowheads at Chaco Visitor Center Museum

Speaking of projectile points, another thing Cameron mentions is that many of them seem to have been imported to Chaco, some of them apparently embedded in meat.  Others were particularly finely made and left in burials and caches, suggesting that they may have been specially made for votive purposes.  That’s probably the case for many of the points Lekson identified as being particularly numerous at Bonito, but what I want to know is why arrowheads were such common grave goods and offerings there.  Was there a particular association between Chaco and hunting?  The great house residents do seem to have eaten a lot more meat than other people in the canyon and elsewhere.

On the other hand, arrows weren’t only used for hunting.  Cameron notes that one projectile point found by Neil Judd at Pueblo Bonito was embedded in a human vertebra, and the Chaco Project also found a woman at the small site 29SJ1360 near Fajada Butte who had two points inside her.  We often talk about how peaceful Chaco was and how little evidence there is for warfare during the Chacoan era, but I’m starting to wonder about that.  It’s certainly true that Chaco itself and most other sites occupied during its florescence show less obvious evidence for violence than sites afterward do, but there are still some signs that things may not have been totally peaceful throughout the Southwest in Chacoan times.  Arrowheads in vertebrae don’t get there on their own, after all.  Who shot those arrows?
Cameron, C. (2001). Pink Chert, Projectile Points, and the Chacoan Regional System American Antiquity, 66 (1) DOI: 10.2307/2694319

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Fajada Butte from Pueblo Alto

Happy solstice, everyone.  To mark the occasion I figured I’d say a bit about archaeoastronomy, which is an important topic at Chaco that I don’t discuss very often.  The various alignments identified at the great houses in the canyon have become quite famous through the work of the Solstice Project to document them, and while I don’t think all of their proposed alignments are necessarily real, there is enough evidence by now to suggest that at least some of them are.  Cardinal direction alignments are the most obvious, and the least likely to be coincidental (in my view), and these are found at a few of the sites at Chaco, particularly Pueblo Bonito, Pueblo Alto, and Tsin Kletzin.  Interestingly, these three are all in the center of the canyon (“Downtown Chaco”), and the line running due north-south from Pueblo Alto to Tsin Kletzin runs between Pueblo Bonito and Chetro Ketl through the “Chaco Amphitheater.”  This all suggests some pretty extensive planning, but it’s interesting that the other parts of the canyon don’t seem to have been part of it.  I find the Solstice Project’s proposed alignments at many of the other sites in the canyon a lot more dubious, especially since so many of them are allegedly to the minor lunar standstill.  It seems more plausible that there would be solstice alignments in the canyon, and there do indeed seem to be some “viewing points” from which solstice sunrises are marked by prominent features on the horizon, but the only solstice-aligned building proposed by the Solstice Project is Aztec West, which isn’t even at Chaco, although it’s clearly Chacoan in style.

Steve Lekson has proposed that one possible reason for the variety of alignments in Chacoan great houses is conflict between factions within Chacoan society.  The way he sees it, solstice alignments were the regional tradition, and cardinal alignments were a new idea at Chaco, perhaps threatening to the old order in the way that many new developments at Chaco were.  Indeed, alignment to the southeast was a common architectural practice in pre-Chaco communities, and this may well have had something to do with the solstices, although as far as I know none of these buildings have been demonstrated to have precise solstitial alignments.  I’m not so sure that cardinal direction alignments were not present in the region before Chaco, however, and I’m also unsure of whether differences in building orientation really represent ideology the way Lekson proposes.  I’m more inclined to wonder if they may instead reflect different ethnic or regional origins for different groups.  In either case, though, the factionalism idea is interesting, and quite compatible with what we know of later Pueblo societies.  In Lekson’s version, the solstice alignment of Aztec reflects the founding of that center by the solstitial faction at Chaco, while the cardinal faction went elsewhere, maybe to Paquimé, which has a strong cardinal alignment.  I’m not sure how much of that I buy, but it’s worth thinking about.

Pueblo Alto and New Alto from Tsin Kletzin

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Train Station, Dolores, Colorado

Southwestern archaeology, especially in the Chaco area, is structured chronologically primarily by the Pecos Classification.  This system was initially worked out at the first Pecos Conference in 1927, and it was originally interpreted as a series of stages in cultural development, with the assumption that sites with similar characteristics and material culture were roughly contemporaneous.  Once tree-ring dating became available, however, it became clear that this wasn’t quite true, and furthermore that different sub-regions of the Southwest went through the stages at different times.  There have been a variety of approaches developed in the decades since to either redefine the Pecos system or abandon it.  In the Four Corners, the main approach has been to just recast the Pecos stages as chronological markers without any inherent cultural content.  The exact dates used for each stage vary by specific area and specific researcher, but here’s a rough outline of how they are often defined:

  • Basketmaker II: 500 BC to AD 500
  • Basketmaker III: AD 500 to 750
  • Pueblo I: AD 750 to 950
  • Pueblo II: AD 950 to 1150
  • Pueblo III: AD 1150 to 1300
  • Pueblo IV: AD 1300 to 1540

There’s no Basketmaker I.  The Pecos Conference attendees were unsure what, if anything, came before Basketmaker II, and they provisionally included an earlier stage in case there did turn out to be earlier sites.  As it turned out, there were, but they were sufficiently different from Basketmaker sites that they ended up being considered part of the Archaic period of hunter-gatherer societies predating the introduction of agriculture.  (Recent discoveries have begun to muddle this picture, at least for certain areas, but while not everyone still uses the term “Archaic” for the period just before Basketmaker II no one has yet begun to call it “Basketmaker I.”)

Camping at McPhee Campground for 2009 Pecos Conference

Although the stages are generally interpreted as chronological rather than developmental these days, there is still a general sense of what sorts of sites are “typical” or expected for each stage, and this has driven a lot of the variation in specific date ranges.  Basketmaker II sites are generally associated with corn and squash agriculture, a scattered settlement pattern, lots of basketry but no pottery, and the use of the atlatl.  In Basketmaker III this pattern was adjusted by the introduction of the bow and arrow, pottery, and beans, and people began to cluster in some cases into pithouse villages, although there were still many isolated hamlets in some areas.  Pueblo I was something of a transition between Basketmaker III and Pueblo II, with the first construction of significant above-ground architecture in addition to pithouses.  Pueblo II was associated with masonry roomblocks and kivas, generally organized as “unit pueblos” of a few rooms with a kiva and trash mound in front and loosely grouped into “communities.”  The height of Chaco dates to this period, and within the area of Chacoan influence these communities typically had great houses in addition to the unit pueblos but separate from them.  In Pueblo III people began to aggregate into larger, denser communities more like the “pueblos” of historic times.  The cliff dwellings at Mesa Verde and elsewhere date to this period and are the best known of these aggregated sites, but there were many others in a variety of locations.  At the end of the Pueblo III period almost all of the Four Corners area was abandoned and people aggregated further into even larger pueblos in the Rio Grande Valley and the Zuni and Hopi areas to the west, in addition to a few other areas.  The Pueblo IV period is marked by the increasing concentration of population into ever-larger sites and the clustering of these sites in particular areas separated from other clusters by uninhabited “buffer zones.”  This period also saw the apparent introduction of the kachina cult and various other novel social phenomena, and it continued until the Spanish showed up and smashed everything.

That’s the picture in a nutshell, but some periods are better-known than others.  Pueblo II and III have been particularly well-researched in the Chaco and Mesa Verde areas, although there is still plenty that remains unknown about them.  In contrast, Pueblo I was very poorly understood until the Dolores Project in the 1980s totally revolutionized our knowledge of it.  This project was a massive cultural resource management (CRM) salvage project in advance of the damming of the Dolores River and the creation of McPhee Reservoir.  At the time it was the largest CRM project ever, and it might still have that distinction.  Numerous sites in the Dolores River Valley were excavated carefully and thoroughly documented.

McPhee Reservoir from McPhee Campground, Site of 2009 Pecos Conference

It’s impossible to overstate how much our current knowledge of the Pueblo I period is based on the discoveries made at Dolores.  What the project found was that the Dolores Valley, although sparsely occupied both before and after Pueblo I, during Pueblo I contained numerous large, dense villages, most of which only existed for a very short period of time during the AD 800s.  As research continued throughout southwestern Colorado, it became more apparent that these villages were just part of the story of the incredibly dynamic Pueblo I period.  People were moving all over the place, very rapidly, and forming and dissolving villages within the space of one or two generations.  Abundant evidence for drought and conflict at certain key points during the period provided some explanation for why, but the really important thing that came out of the Dolores Project specifically was the detailed study of some of the specific villages that allowed reconstruction of their short histories with remarkable precision.

On a larger scale, it appears that the Pueblo I period involved the movement of people into higher elevations than they had occupied during Basketmaker III, followed by movement back down after 900 and into Pueblo II.  While areas with Pueblo I villages typically didn’t have substantial earlier or later occupations, many other areas (including Chaco) had major Basketmaker III and Pueblo II occupations but little evidence of use during Pueblo I.  This probably had to do with climatic changes, but there were clearly also a lot of social processes going on as well.  Since the rise of Chaco as a regional center began right after all of this, Chacoan specialists have been realizing recently that the evidence from Dolores is very important as background for understanding Chaco.

McPhee Reservoir, Dolores, Colorado

Particularly influential in shaping understandings of Chaco has been one of the Dolores villages in particular, known as McPhee Village.  Like the other Dolores villages, McPhee was founded around 840 as people began to move out of earlier villages further south around Mesa Verde and Durango.  Not everyone from these earlier villages went to Dolores (an important point), but many did, and the Dolores villages grew rapidly, only to decline just as rapidly as people moved out starting in the 870s and continuing until around 900, at which point there was only a very small remnant population in some of the villages.

The remarkable thing about McPhee Village was the presence of some roomblocks there that bore an uncanny resemblance to the early “great houses” that would arise in the San Juan Basin to the south, including at Chaco, shortly afterward.  Not all of the roomblocks were like this; most were small, linear unit pueblos typical of those in most other villages.  Two roomblocks in particular, however, known as McPhee Pueblo and Pueblo de las Golondrinas, looked astonishingly like the early form of Pueblo Bonito.  They were arc-shaped rather than linear, with two arcs making up McPhee Pueblo and Pueblo de las Golondrinas consisting of one larger arc.  (Note that “McPhee Pueblo” refers to a specific roomblock within “McPhee Village.”  The terminology is confusing.)  Furthermore, these roomblocks were made up of room suites consisting of three rooms, with one large room facing the “plaza” within the arc backed by two smaller “storage” rooms.  The “plaza” area within each arc contained pit structures presumably associated with these suites.  Again, this is much like the layout of Pueblo Bonito and other early Chaco great houses.  These roomblocks were also made largely of masonry rather than adobe, in contrast to most earlier sites as well as many other Dolores villages, which again linked them to the later Chaco sites.

Dolores Medical Center, Dolores, Colorado

A variety of studies have been done of these sites, particularly focused on what differentiated them from other roomblocks at McPhee Village.  James Potter did a study of animal remains at McPhee Pueblo and Pueblo de las Golondrinas, looking for evidence that the residents of these sites might have hosted community-wide feasts and/or conducted special rituals, either of which could have been ways for them to gain social power within the community.  Both sites contain, in addition to the standard residential pitstructures common at all sites in the village, special “oversized” pitstructures with more formal, elaborate features that could have served as special locations for feasts or rituals.  He found that McPhee Pueblo did indeed have a much higher number of different types of animal remains present, including many “non-economic” species such as carnivores and certain birds that may have had important ritual uses.  Furthermore, it had a higher proportion of rabbits than most other roomblocks, which is significant because among the modern Pueblos rabbits are often hunted communally and eaten in ritual feasts.  Interestingly, Pueblo de las Golondrinas, despite its size and the presence of an oversized pitstructure, did not have these characteristics, suggesting that its inhabitants may not have been as successful as those at McPhee Pueblo at hosting communal rituals and increasing their power.

Another take on this question comes from an analysis of ritual architecture by Gregson Schachner.  Starting from the assumption that times of significant environmental and social change, such as those that surely accompanied the rapid founding and dissolution of the Dolores villages, offer opportunities for ambitious individuals or groups to gain power and influence by taking control of ritual practices or introducing new ones, he noted that unlike some other Dolores villages McPhee Village doesn’t have a great kiva, the standard community ritual structure both before and after the Pueblo I period.  Instead, roomblocks like McPhee Pueblo and Pueblo de las Golondrinas have the oversized pitstructures that might have been used for special ritual practices that the inhabitants of those sites may have tried to introduce to their communities. Schachner assumes that these pitstructures were primarily ritual rather than residential, which I think is dubious, but otherwise his arguments make sense.  He basically sees the process as having involved certain individuals or groups having tried to introduce new rituals that gave them increased status and power in the context of the convulsions of the Pueblo I period.  Those rituals might have been adopted because they offered a new way forward during the drought that coincided with the founding of the Dolores villages in the 840s, but they might have lost their appeal as a new drought in the 880s led people in the village to reject the innovations of these would-be leaders.  As the village dissolved, construction seems to have begun on a new great kiva over the oversized pitstructure at Pueblo de las Golondrinas.  This great kiva was not completed, however, and the whole village was soon abandoned.  Great kivas continued to be a key part of the new villages further to the south that appear to have absorbed many of the people leaving Dolores after 880, but the oversized pitstructure does not seem to have continued as a recognizable architectural form.

Mac's Plumbing, Dolores, Colorado

The great house form, however, which began to proliferate in the San Juan basin starting in the tenth century, seems to have some connection to the arc-shaped roomblocks at Dolores.  Recently, a model for the rise of Chaco incorporating the insights of the Dolores Project has begun to gain increasing acceptance.  Under this model, the frustrated would-be elites from the Dolores villages moved south into Chaco and other communities and began to build similar structures to those they had lived in at Dolores.  This time, however, circumstances were better, and they were able to gain more control over their communities.  These communities were spread throughout the basin, but those in Chaco Canyon specifically eventually gained ascendancy over the others, and the Chaco Phenomenon was born.

There is a certain logic to this, and parts of it are likely true, but it’s important to note that the timing isn’t quite right for frustrated elites from Dolores to have founded the first great houses at Chaco.  The earliest parts of Pueblo Bonito are now thought to have been built by 860 and perhaps considerably earlier, while the Dolores villages didn’t start to dissolve until the 870s.  It’s quite possible that later additions to the site in the 890s and early 900s involved immigration from Dolores, and indeed it is these room suites that are particularly similar to those at McPhee Pueblo.  It’s worth considering, however, the possibility that the early history of Chaco involved people moving in from the south as well as the north, and we don’t know nearly as much about the Pueblo I period in that area.  Were there large, unstable villages with ambitious families or individuals there too, or was something totally different going on that led people to head north at the same time people were heading south from Dolores?  We can only guess at this point, but it’s important not to let our greater knowledge of developments at Dolores lead us to focus too much on it to the exclusion of other important areas.  Dolores was very important, no question, but it wasn’t the only important place at the time.
Potter, J. (1997). Communal Ritual and Faunal Remains: An Example from the Dolores Anasazi Journal of Field Archaeology, 24 (3) DOI: 10.2307/530690

Schachner, G (2001). Ritual Control and Transformation in Middle-Range Societies:
An Example from the American Southwest Journal of Anthropological Archaeology, 20, 168-194 DOI: 10.1006/jaar.2001.0379

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Room 38, Pueblo Bonito

Pueblo Bonito is the best-known and most-studied site at Chaco, but there’s still a lot we don’t know about it.  Because it was excavated early in the history of Southwestern archaeology, provenience information for the vast numbers of artifacts found at Bonito is not nearly as precise as would be expected today.  We do generally have information about what was in each excavated room, and often where in the room specific artifacts were, but the careful stratigraphic approaches used today were either totally unknown or in their infancy during the excavation of various parts of Bonito, so interpreting the field notes and site reports can be a challenge.  Partly for this reason, a lot of recent interpretations of Chaco have been based mainly on the more recent and better-documented excavations by the Chaco Project in the 1970s.  This makes Pueblo Alto in particular, the only great house extensively excavated by the Chaco Project, enormously influential in recent interpretations, not always in beneficial ways.  The Pueblo Bonito data has been incorporated into most theories to varying extents, but this often just takes the form of vague gesturing at the elaborate burials and huge quantities of high-value artifacts found there, and sometimes it basically amounts to discounting the importance of Bonito because it is so unlike the other sites.

Still, Bonito is important!  The problematic nature of the documentation notwithstanding, there’s still a ton of data available, and the Chaco Archive has been doing excellent work lately in making it more widely accessible.  Their cool interactive map of the site even allows you to click on a room and see a list of all the features, artifacts, tree-ring dates, and pictures associated with that room.  I’ve been playing around with it a lot lately, and there’s really a ton of interesting stuff in many of the rooms that we don’t hear so much about.

Room 309, Pueblo Bonito

Building on what I was saying earlier about a badger burial at a small site excavated by Earl Morris near Aztec, I decided to look for unusual animal burials or remains that might suggest some patterns in ritual practices or group identities at Bonito.  Many modern Pueblo clans are named after specific animals, and it seems reasonable that some Chacoan social groups (which may or may not be equivalent or ancestral to the modern clans) might have had similar identities that would lead them to leave animal remains in certain contexts that could indicate connections through time between different rooms or sites.  The Chaco Archive database allows you to search for specific types of artifacts, and it even has a special option for non-human burials.  The database doesn’t have all the sites included yet, but it does have all of Bonito, and it’s a powerful tool for finding information about the sites that are included.

Starting with the non-human burials, the ones at Bonito seem to all be of macaws and parrots.  The close connection between Bonito and macaws has long been noted, and Room 38 is particularly known for its large numbers of them, but one thing I hadn’t realized is that, like so much else at Bonito, the distribution of macaws is highly concentrated, not just in a few rooms, but specifically in a few rooms on the east side of the site.  The macaw burials, in addition to the two in Room 38, are in Rooms 71, 78, and 306, all of which are in the eastern part of Old Bonito.  Not all of these are actually formal burials, but they are all complete skeletons.  Extending the search to individual bones adds Rooms 249, 251, 309, and 312, as well as Kiva J and the east mound in front of the site.  Again, these are all on the east side of Bonito, although not just in Old Bonito this time.  Rooms 309 and 312 aren’t technically in Old Bonito, but they are among the rooms added right in front of it, and are very close to Rooms 306, 71, and 78, which also had macaws.  Rooms 249 and 251 are in the block of rooms added onto the southeast part of the site over an earlier extension that apparently built over part of the eastern end of Old Bonito (this part of the site is very complicated and its construction sequence is poorly understood).  Kiva J is one of the six blocked-in kivas between this block and the plaza.  And, of course, the east mound is the easternmost of the two mounds.

Kiva J, Pueblo Bonito

What does all this mean?  Many have suggested that the number of macaws at Bonito indicates the possible presence of a macaw clan like the one known today at Zuni.  If this is indeed the explanation for all the macaws, and it seems plausible given the restricted distribution of them to just a few sites at this time and the contexts in which they are found, it seems that this clan probably lived in or had claims on the eastern part of Pueblo Bonito, and that this association held not just in the earliest stages of the site but even after it was expanded.  Perhaps members of this clan were the initial residents of the eastern suites in Old Bonito, then when those rooms were converted to other uses as the site was expanded they moved into the new southeast wing.

One question that might be raised at this point is whether this distribution is actually specific to macaws.  Maybe all exotic birds and animals are concentrated in this part of the site, which would suggest that there might be something special about the eastern half of the site but not necessarily anything tied to a specific clan.  Some research into the layout of the rooms has shown that the southeast corner is unusual in not being divided into obvious room suites, whereas the southwest corner seems to be.  Maybe instead of the macaw clan living in the eastern half, everyone lived in the western half and they used the eastern half for macaw-related (and other) ritual.

Room 330, Pueblo Bonito

One way to test this would be to look at other unusual animals.  Finding animals of ritual importance beyond obvious exotics like macaws is tricky, because many animals were certainly used for mundane purposes and their remains are therefore all over.  Dogs and turkeys were kept domestically, so their remains probably wouldn’t indicate anything special about social groupings, and game animals such as rabbits and deer might have interesting implications for access to different kinds of meat but, again, not necessarily specific symbolic implications.  That basically leaves animals that don’t serve a clear subsistence or other utilitarian purpose but are nevertheless found in sufficient numbers to suggest something more than mere chance is behind their presence.  The best example I’ve found: bears.

You basically never hear about bears in discussions of Chaco.  They are not present in the area now and probably weren’t in antiquity either, and their remains are certainly rare at Chaco but not entirely absent.  At Pueblo Bonito, bear remains are mostly concentrated on the west side of the site, in stark contrast to the macaw remains on the east side.  There are some artifacts made of bear bone, including two apparent gaming pieces, one each from Rooms 267 and 290 (both on the east side), but there are also unworked bear bones, especially jaws and feet, particularly concentrated in Rooms 92, 102, and 109, which are part of the same suite of rooms in the west wing of Old Bonito.  Room 92 also had a bear hide and mass of hair that is probably also from a bear.  Another room in this part of the site, Room 330, had a grizzly bear jaw.  Another bear jaw was in Room 66 and a claw was in Room 10; both these rooms are on the east side of the site.  So not as clear-cut as the macaw evidence, but still a strong suggestion that people with some sort of connection to bears lived in the western part of the site.  The “bear-paw” motif is well-known in rock art, and George Pepper, who excavated these rooms, reported that Room 97 (the room under Room 92) had similar “bear paws” drawn on the smoke-blackened plaster.  Finally, Kiva Q, the great kiva in the west plaza, contained a (dedicatory?) cache of objects that included bear paws.  This is all very suggestive, though of course not totally dispositive.

Kiva Q and West Plaza, Pueblo Bonito

There may be other examples of these sorts of patterns that could give us a better sense of who exactly was living at Pueblo Bonito and what other people at which other sites they had particularly close ties to.  Despite the fact that this information has been available for a long time, it’s only now that it’s starting to become widely available in a useful form.  New analytical techniques are revolutionizing our understanding of Chaco in all sorts of ways, but one of the most important contributions technology can make is just to make existing information available so it can be assembled, analyzed, and compared to information from elsewhere.

Bear Paw at Three Rivers Petroglyph Site

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Metate Incorporated into Wall Capping, Pueblo Bonito

I’ve written a bit about the recent research, spearheaded by Larry Benson of the USGS, into the sources of the corn found at Chaco.  These studies continue to refine the techniques used to identify source areas, but so far they have shown that corn was almost certainly being imported to Chaco both during and after the florescence of the Chaco system between AD 1030 and 1130.  As they begin to test more potential field areas, of course, the number of matches for the strontium isotope ratios in the corn at Chaco has increased.  While early studies indicated that much of it likely came from the Chuska Valley, it now looks much more likely that it instead came from the area along the Chaco River between there and the canyon.  This is an area with numerous outlying great houses, and it was probably the main route for the many commodities from the Chuska area that were brought to the canyon, and it’s also generally a better area for agriculture than the canyon itself, so this all makes sense.  There has also been some evidence that at least some corn was also coming from the Totah area to the north, again a more productive agricultural area with many Chacoan outliers.

Based on the proveniences of the corncobs from Pueblo Bonito that were tested early on, one tentative suggestion emerging from this research was that the main sources of imported corn changed over time.  The cobs that came from the lower Chaco River were from Rooms 3 and 92 in the northern part of Old Bonito, one of the earliest parts of the building to be built, while the one cob of possible Totah origin came instead from Room 170, in the southeast corner, one of the newest parts of the site.  Since there does seem on other grounds to have been a shift in the emphasis of the Chaco system from south to west to north over time, it would make sense that the early rooms contained early cobs from the west while a later room contained a later cob from the north.

Talus Unit with Snow

A paper published in 2008 by a group of big names in Chacoan studies sought to look at this directly by radiocarbon dating the cobs.  This is an interesting paper which goes beyond that narrow topic to also look at the characteristics of the corn found at the various great houses and other sites.  One of the co-authors is Mollie Toll, a specialist in archaeobotany who has done a lot of research on Chacoan corn.  As part of that research, she had long noted that the corn at Pueblo Bonito generally had bigger ears with more rows of kernels than most other corn known from the prehistoric Southwest.    It was bigger than earlier and later corn, for one thing, but it was also bigger than most other corn from the same period.  Corn from the Chacoan occupation of Salmon Ruin was also unusually large, as was corn from the Talus Unit behind Chetro Ketl, but corn from Pueblo Alto and Pueblo del Arroyo, other contemporary great houses at Chaco, was smaller and more in line with that from earlier and later sites.

Toll came up with three possible explanations for the difference.  Pueblo Bonito corn could be a different variety or “landrace” from the others, which is plausible but not directly testable with current technology.  It could also have been grown outside of the canyon where conditions were better for agriculture, while the corn from other great houses was grown in the canyon where conditions were poorer.  Finally, and problematically, the corn at Bonito might not have been Chacoan at all!  Since modern corn is generally bigger than ancient corn, Toll (when she was first looking at this in the 1980s) couldn’t exclude the possibility that the corn found at Pueblo Bonito had actually been put there by Navajos in the nineteenth century.  Much of it was from George Pepper‘s excavations in the 1890s, so it couldn’t be newer than that, but there was no way for Toll to tell how much older it was.

Room 3a/92/97, Pueblo Bonito

We still can’t tell different ancient landraces apart (although the recent sequencing of the maize genome may make this more feasible in the future), but the strontium isotope testing is giving us a sense of where the corn was grown, and accelerator mass spectrometry now makes directly dating the corn relatively easy.  Seven cobs from Pueblo Bonito that had been used in the strontium studies were dated for this paper.  One was the cob from Room 170 that possibly came from the Totah, one was from Room 92, and the rest were from Room 3.

The results were illuminating, but also challenging.  All the cobs clearly dated to ancient times, so the possibility that the size of Pueblo Bonito’s corncobs represents recent deposition is effectively quashed.  Three of the Room 3 cobs had closely clustered dates with intercepts around AD 1000, which offered some partial support for the idea that the corn in the early rooms was relatively early, but the other two were widely spaced, one at 870 and at 1170.  This is problematic for the idea that the date of corn in a room can be predicted from the date of that room’s construction, but it makes sense that the deposits in a room may date to well after its construction.  Since Room 3 dates very early, probably to the 900s, it’s likely that the deposits there resulted from much later trash dumping once it was no longer used for its original purpose.  Room 3 has a firepit, so it was probably originally a residential room, and it is likely one of those “big square rooms” that I have argued began to take the place of kivas in Chacoan room suites of the tenth century.  Room 92 is part of the maze of confusing rooms next to Room 3.  It had a well-preserved floor with corn and bean bushes on it (it’s not clear from Pepper’s description if this was the second or third floor), which suggests that it was used as a storeroom at the end of the period of occupation in this part of the building.  The cob from this room had the latest date of any in the study, with an intercept of AD 1220, which is consistent with the idea that this room was in use as a storeroom at the end of occupation.

Room 170, Pueblo Bonito

The biggest surprise, however, was the cob from Room 170, which dated to AD 1010.  This is particularly odd, since Room 170 was probably built around 1080 or even later.  Looking at the probability curve for this date, there is some chance that the actual date was around 1100, but the curve as a whole has a much more prominent peak around the intercept at 1010 than any of the other reported dates, which suggests that the probability is quite high that the intercept does in fact represent the true date or close to it.  The authors give various possibilities for why the cob might have been placed in this room long after it was grown, including the idea that it was put there as some sort of ritual offering of continuity with the occupation of earlier parts of the building.  I prefer another explanation they also suggest, which is that it was part of an earlier trash deposit that was redeposited in Room 170 for some reason.  There is very little information on what the deposits in this room were actually like, but many of the rooms in this part of the building were full of trash when excavated, and I think it’s most likely that this one was too.  The trash could have been put there for any number of reasons; if it was redeposited from somewhere else, it may have served as structural fill to support an upper story.  In any case, this puts a damper on the idea that the overall sources of corn changed over time.  Indeed, the sources seem to have been pretty constant through time for cobs left in different areas of the site, which suggests that the real story is much more complicated.

One nice thing about this paper is that the authors do a very good job of properly reporting their radiocarbon dates, particularly in giving point estimates as intercepts, which are meaningful, rather than midpoints, which are not.  Many papers make this mistake, including some of Benson’s reporting these and other dates on corn.  This paper also shows the probability curves for the dates, which give even more information.  This seems to be pretty common these days among Mesoamerican archaeologists, but it’s still quite rare in the Southwest, where radiocarbon dating has only recently become a major focus.  The availability of tree-ring dates, which are much more precise, has generally led Southwestern archaeologists to neglect radiocarbon, but it’s becoming increasingly obvious from studies like this one that the ability to date things other than trees is very useful in interpreting sites.

Obviously this paper just reports a handful of dates, and the authors take pains to point out the tentative nature of any conclusions they draw, but it’s an important contribution to the issue of where the Chaco system, whatever its nature, was getting its means of support.  As is often the case with new avenues of research, at this point papers like this pose more questions than they answer, but there are plenty of corncobs out there to date and analyze in other ways, just as there are plenty of potsherds to test for theobromine.  Once we get a bigger database of dates and strontium (and other) ratios, we’ll start to get a clearer picture of the behavior behind these remains.

Metate Fragment at Pueblo Alto

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Display Case at Chaco Museum Showing Cylinder Jar and Canteens

I mentioned earlier that there was a new paper out on chocolate at Chaco that I needed to read.  I read it today, and it’s quite interesting.  One of the most interesting things about it is that it’s by a different group of researchers than the first one and uses somewhat different methods.  As far as I can tell, all the study of chocolate residue in archaeological pottery until this paper has been done by Jeffrey Hurst at Hershey, in collaboration with a variety of archaeologists.  Except for the Chaco paper he did with Patricia Crown, all of Hurst’s work in this area has been on Mesoamerican pottery and in collaboration with Mesoamerican archaeologists.  This makes sense, since Mesoamerica is where chocolate is grown and was used most extensively in antiquity.  Hurst’s methods involve scraping residue from the interior of pots or grinding up potsherds to test them for the presence of theobromine, a chemical compound that serves as a biomarker for chocolate.  They aren’t hugely destructive methods, as analytical methods applied to artifacts go, but there is a certain amount of damage inherent in the scraping (and more in the grinding, of course).

This new paper pioneers a different method, which uses a wash of deionized water on whole vessel interiors (this could presumably be done with sherds too, but these authors used whole vessels) and subsequent analysis of the water with a very sensitive mass spectrometer.  The researchers are not affiliated with Hershey, but instead with Bristol-Myers Squibb, except for the lead author, Dorothy Washburn.  Washburn has for many years now been studying symmetry patterns on pottery and other artifacts and she has come up with a variety of interpretations of social structure and change from the patterns she sees.  The work she has done on Chaco has led her to posit that the “special” vessel forms associated with the Chaco Phenomenon, particularly cylinder jars but also pitchers and shallow bowls, show a very different type of symmetry from that prevailing on Pueblo pottery before and after Chaco.  In publications such as her chapter in the Salmon Ruins synthesis volume, she further contends that this sudden difference indicates an influx of people from elsewhere with a very different social structure, and she points to Mexico as the most likely source given the presence of both similar symmetries and similar vessel forms there.  This puts her in what I’ve called the “hard Mexicanist” camp, not a popular position among Chacoan scholars these days (although this chocolate stuff may start to change that).  I don’t really buy her arguments for physical migration of Mesoamericans to Chaco, and I think she generally goes a bit too far in inferring specific social structures from the abstract symmetries she studies, but her evidence for a big difference between Chacoan and other designs is solid and well-taken.

Cylinder Jar at Chaco Museum from Above

Given Washburn’s theories, it makes sense that she would jump at the chance to look for chocolate residue in Chacoan vessels.  The Crown and Hurst paper that started all this really came out of nowhere; no one in the Southwest was expecting it at all, and it’s likely to end up being one of the major turning points in interpretations of Chaco.  The paper itself, though, was short, and the research behind it was modest in scale.  Crown and Hurst only tested five sherds from the mounds in front of Pueblo Bonito, three of which seemed from their curvature to be from cylinder jars while one of the others was from a pitcher and the final one could have been from either a cylinder jar or a pitcher.  Testing revealed that the three definite cylinder jar sherds showed evidence of chocolate, while the other two didn’t.  This was remarkable, groundbreaking stuff, to be sure, but it was still only five sherds.  The really important thing about that paper was that it opened up the possibility of running tests like this on all sorts of sherds and vessels to determine the extent of chocolate use in the prehistoric Southwest, and it seems Washburn was inspired to take it a step further.

Room 28 at Pueblo Bonito

She and her coauthors, William Washburn, who I presume is her husband, and Petia Shipkova, both of whom work for Bristol-Myers Squibb’s Pharmaceutical Research Institute in Princeton, NJ, apparently developed this new technique for doing the theobromine testing and they applied it not to sherds but to whole vessels.  Not just any whole vessels, either; they went straight for the important ones: the cylinder jars from Room 28 at Pueblo Bonito, along with cylinder jars, pitchers, and shallow bowls from burial rooms elsewhere in Bonito (including Room 33).  They also tested three cylinder jars from Pueblo del Arroyo, at least two of which are of plain redware rather than the whiteware that characterizes all other known cylinder jars (there is some confusion over whether the other jar is red or white, in that the paper says all three are red but the National Museum of Natural History catalog seems to say that one is white).  In addition, they tested a variety of similar forms from the Hohokam site of Los Muertos.  This is interesting, because the Hohokam in southern Arizona showed a wide variety of Mesoamerican influences to a much greater degree than Chaco ever did, and one of the first things I wondered when I read the Crown and Hurst paper was whether a similar study of Hohokam vessels would also show chocolate use.  They picked Los Muertos specifically because it’s a Classic-period platform-mound complex with what appear to be elite burials.  The platform mounds of the Hohokam Classic are the only other phenomenon except for Chaco in the prehistoric Southwest that show clear evidence of social hierarchy, and the authors of this paper clearly chose this set of vessels to see if chocolate use corresponded to increased hierarchy.  In all they tested 57 vessels from Chaco great houses and 10 from Los Muertos, and as a control they also tested eight vessels from small sites at Chaco, on the Little Colorado River in Arizona, and in southwestern Colorado.

Pitchers at Chaco Museum

What they found was that most of the great-house and Hohokam vessels did indeed test positive for theobromine.  Specifically, 80% of the Los Muertos vessels tested positive, as did 65% of the Chaco cylinder jars, 41% of the Chaco pitchers, and 83% of the shallow bowls from Chaco.  The lower percentage for the pitchers may indicate that they were used for a variety of things, not just chocolate, which might in turn explain why Crown and Hurst’s pitcher sherd tested negative.  The very high number of positives for the shallow bowls is very interesting, and suggests that this class of vessels, largely overlooked because they resemble local forms more than the cylinder jars, may be more important than people have thought.  On the other hand, only 12 bowls were tested (versus 23 cylinder jars and 22 pitchers), so this could just be a fluke of sampling size.  These results seem to confirm the Crown and Hurst results and reinforce the idea that the presence of chocolate, a clear sign of ongoing trade and contact with Mesoamerica as well as acceptance of Mesoamerican ideas and practices, may correlate strongly with the evidence for social hierarchy at both Chaco and the Classic Hohokam platform mounds.

But wait, what about the small-house sites?  Here’s where things get really interesting, in an unexpected way.  All eight vessels from the small houses tested positive for theobromine.  This was totally unexpected, and the authors devote quite a bit of discussion to this result.  Apparently concerned that there might be a problem with the whole theobromine-testing enterprise, they went looking for native plants in the Southwest that might contain theobromine.  If there were any, of course, that would call all of these results into question.  They couldn’t find any, so it does seem (unless there’s something amiss with their experimental protocols) that the results for the small houses really do indicate that chocolate was not just confined to the great houses at Chaco and the platform mounds in Phoenix.  They suggest that commoners might have been paid in chocolate for their work for the great-house elites, a very interesting idea.  In Mesoamerica cacao beans were often used as currency, and if something similar was going on at Chaco that would be cause for some serious rethinking of how the Chacoan economy worked.

Bc 51

One issue that the authors don’t really address is that the small houses they picked are all within areas that could plausibly have been part of the Chaco system, so there isn’t really an independent check here on how widespread chocolate was in the region as a whole.  They preferentially selected vessels from early excavations because early excavators usually didn’t wash the vessels they found, which makes sense for this type of project but also means that provenience information for the small sites is not ideal.  Nevertheless, one of the small houses that produced these vessels was Bc 51 at Chaco, which is right across the canyon from Pueblo Bonito and would obviously have been closely incorporated into the Chaco system.  The others included a cluster of sites in the Montezuma Valley of southwestern Colorado, which is an area with several nearby Chacoan outliers, and a site on the Little Colorado River in eastern Arizona that is not located very precisely but could have been relatively close to the far western edge of the Chacoan system.  There are several major outliers along the Rio Puerco of the West, a major tributary of the Little Colorado, and some evidence for at least a small amount of Chacoan influence as far west as Winslow.

Further testing of vessels and sherds from a wide variety of sites and time periods should help to clarify this picture.  The great thing about this chocolate stuff is that it’s all about analyzing pottery, which is by far the most common type of artifact found at sites in the Southwest.  There are vast numbers of vessels in museums throughout the country that could easily be tested using these techniques, and even vaster numbers of sherds collected from sites throughout the region that could potentially produce an unbelievably huge and detailed database of information on the distribution of chocolate in the prehistoric Southwest.  There are a lot of questions still outstanding at this point, but there is also a huge opportunity to try to answer them.  Hopefully this question will keep a lot of archaeology grad students set for thesis and dissertation topics for years to come, and the rest of us will benefit from the information they find and the patterns they discover.
Washburn, D., Washburn, W., & Shipkova, P. (2011). The prehistoric drug trade: widespread consumption of cacao in Ancestral Pueblo and Hohokam communities in the American Southwest Journal of Archaeological Science, 38 (7), 1634-1640 DOI: 10.1016/j.jas.2011.02.029

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Pueblo Alto Trash Mound

Kristina Killgrove has an interesting post on the numerous broken Cycladic figurines on the Greek island of Keros that have been documented over the past few years by the prominent British archaeologist Colin Renfrew.  Renfrew’s interpretation seems to be that these figurines were deliberately broken in various Cycladic communities, then deliberately brought to Keros to be deposited.  This is based partly on the fact that the various pieces can’t be fit together, suggesting that they were not broken on Keros and that the remaining portions were disposed of in some other manner (perhaps dumped in the ocean).  Furthermore, as a Cambridge press release on the project explains, there is other evidence suggesting that Keros served as a ritual destination rather than a normal residential community:

Meanwhile, across the short stretch of water to Dhaskalio, a very different picture was emerging. From the outset, the islet showed evidence of having been a major Bronze Age stronghold with structures built on carefully prepared terraces circling a summit, on which a large hall was erected. The settlement dates from around the time of the Special Deposits, and then continued to operate before being abandoned around 2200 BC.

Examination of its geology showed that the beautifully regular walling of the settlement was imported marble rather than the flaky local limestone found on Keros. Remarkably, in the same era the pyramids were being built and Stonehenge erected, Cycladic islanders were shipping large quantities of building materials, probably by raft, over considerable distances to build Dhaskalio.

Here, too, there were puzzling finds: a stash of about 500 egg-shaped pebbles at the summit and stone discs found everywhere across the settlement. And, although there was evidence that the olive and vine were well-known to the inhabitants of Dhaskalio, the terrain there and on Keros could never have supported the large population the scale of the site implies, suggesting that food also was imported.

Readers who are familiar with Chaco will probably have realized by now why I’m talking about this, as it’s eerily similar to a lot of recent interpretations of Chaco Canyon as a destination for pilgrims who brought in vast amounts of pottery, wood, and other materials as part of some sort of ritual system focused on the canyon but also including the whole area throughout the San Juan Basin and beyond in which Chacoan “outliers” are found.  There is even evidence that food was being imported to Chaco.  The Chaco Project‘s excavations at Pueblo Alto uncovered evidence in the trash mound of repeated events in which huge numbers of pots were broken, which some have interpreted as evidence for ritual breakage of pottery (though not everyone agrees with this).  This sort of pilgrimage model is one way to explain the rather inexplicable findings of huge amounts of material being imported to Chaco but basically nothing coming out.  It also potentially offers a way to explain the apparently low permanent populations of both the canyon as a whole and the individual great houses, and one version (espoused by Wolky Toll) even posits that there may have been virtually no permanent population at all, with the small houses that comprise the bulk of the residential space in the canyon having only been occupied seasonally or for special gatherings by people who spent most of their time in the outlier communities.

Corrugated Potsherd at Pueblo Alto

What’s particularly interesting about this comparison is that Renfrew himself, in an article stemming from one of the Chaco Project capstone conferences, proposed a model like this for understanding Chaco as a “Location of High Devotional Expression” or “LHDE.”  The article is quite reasonable and measured in pointing out the characteristics of such a center and how Chaco seems to fit pretty well, although Renfrew really seems to go overboard with the use of the passive voice to a greater extent even than most other archaeologists.  He acknowledges that some known LHDEs are part of hierarchical societies or states and are often associated with political or economic authority, but he emphasizes that this is not necessarily the case and that many well-known examples such as Stonehenge seem to have clearly been built by egalitarian societies.  The implication is that Chaco may have been egalitarian as well, an idea near and dear to the heart of a certain type of Southwestern archaeologist and still quite deeply entrenched in both Southwestern archaeology and popular perception.  He does note that the rich burials in Room 33 at Pueblo Bonito are problematic for this interpretation, but like most people proposing egalitarian models for Chaco he doesn’t really pursue the implications of that.

At one point, Renfrew discusses where he’s coming from with all this:

My approach to Chaco is colored by my experience of several early societies that are by no means urban but which can nonetheless boast impressive monumental constructions and other presumably symbolic features. Prominent among these are the so-called “temples” of prehistoric Malta, the ahu of Easter Island, and in particular the henges and other prehistoric monuments of Orkney.

It would seem his approach to the Cyclades is similarly colored.  Thus the title of this post, although it is admittedly unfair, as Renfrew has a done a lot more in his long career than this LHDE stuff.  Still, I think it’s interesting to see the way archaeologists’ backgrounds can influence how they perceive novel sites and societies.  In many cases this can lead to important insights that people who have been myopically focused on that society for decades may have missed, and there is some interesting and useful stuff in Renfrew’s article along these lines, but his clearly (and admittedly) superficial knowledge of Chaco leads him to not seem to realize that many of his arguments for an egalitarian Chaco are basically old wine in new bottles.  As alternatives to his LHDE model he evaluates two other models, which basically correspond to the “Mexicanist” idea of Chaco as a trading center providing turquoise to Mesoamerica and the “indigenous complexity” model of Chaco as an “elite power base.”  These are indeed two of the models that have been frequently put forth to explain Chaco, but there are others, including some egalitarian ones quite similar to his own.  He acknowledges this to some degree, but he again doesn’t really go into the details.

Hachured Potsherd at Pueblo Alto

I don’t mean to criticize Renfrew too harshly here.  He’s clearly a very smart guy, and Chaco is well outside his areas of expertise, so he can be forgiven for not being totally aware of all the nuances of Chacoan research.  His article is probably the best summary out there of the evidence for Chaco as a pilgrimage center and what that might mean.  As I said above, this is a popular idea these days among a lot of archaeologists who otherwise disagree about the exact nature of Chaco.  I have expressed some fondness for it myself in the past, but I’m now starting to reconsider.  It’s an attractive way to explain a lot of things about Chaco, but it has the distinct disadvantage of not having any direct evidence supporting it.  Any pilgrimage model is therefore sort of inherently speculative about who these pilgrims were, where they were coming from, and why.  This isn’t to say that I think Chaco was definitely not a pilgrimage center, but I’m not really convinced that there’s any particular reason to believe it was, based on the evidence we have.  The strength of models involving pilgrimage will just have to depend on the strength of the evidence supporting the other aspects of the models, I think.
Renfrew, C. (2001). Production and Consumption in a Sacred Economy: The Material Correlates of High Devotional Expression at Chaco Canyon American Antiquity, 66 (1) DOI: 10.2307/2694314

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Western Burial Rooms in Old Bonito

There’s a persistent archaeological meme about there being a “lack of burials” at Chaco Canyon.  The idea is that not nearly enough burials have been found there to account for the size and magnificence of the architecture, so something odd is going on.  This has been interpreted in various ways and used as support for a variety of theories seeking to explain the Chaco Phenomenon.  As Nancy Akins pointed out 25 years ago, however, the idea of a “lack of burials” is not very well founded.  It’s true that the extensive excavations at Pueblo Bonito produced relatively few burials for such a large site, but excavations at small houses have found plenty of burials, and there are historical sources indicating that many more were looted, especially from small-house trash mounds, in the late nineteenth century.  Add to this the fact that preservation conditions at Chaco are often fairly poor for human bone, and the mystery becomes a lot less pronounced.

And, to reiterate, there were in fact quite a few burials at Pueblo Bonito.  Over a hundred individuals were found, almost all of them clustered in two small sets of rooms in the oldest part of the site.  One of these clusters, in the north-central part of the site, contained the richest collections of burial goods known from the prehistoric Southwest, especially in Room 33.  The other cluster, in the western part of the site, had less lavish burial assemblages but contained more individuals.  Both clusters contained many disturbed burials, which the excavators found hard to understand given the good preservation of the remains and the numerous grave goods.  Akins suggested that secondary burial might account for the disturbance, and this seems like a reasonable theory.  Secondary burial is not known to have been practiced by any Pueblos in historic times, but there’s a lot about Chaco that hasn’t been maintained by the modern Pueblos (perhaps deliberately).

Room 326, Pueblo Bonito

One of the disturbed burials from the western burial group is the subject of an interesting recent paper by Don Ortner and Kerriann Marden.  The individual in question is a woman who was between 35 and 45 years old at death and was buried in Room 326, which happens to be one of the more visible rooms at Pueblo Bonito today.  It’s probably best known among visitors and staff for its particularly well-preserved plaster on the south wall.  Room 326 contained at least 10 adults, but the burials were quite disturbed and the collections of bones cataloged in the National Museum of Natural History from the excavations don’t correspond to separate individuals.  This woman’s bones ended up being catalogued under four separate numbers, some of which also contained bones from other individuals.  One contribution Marden and Ortner make in this article is to show that this skeleton is actually mostly complete, once the matching bones from the various cataloged specimens are reassembled.  This jumbling of individuals is a common feature of burials excavated from Chaco, so seeing that distinguishable skeletons can be defined at least in some cases is a significant development.

Perhaps more significant, however, is that, when reassembled, the woman’s bones showed clear evidence that she had suffered from infection by the treponema bacteria.  This type of infection is known generically as “treponematosis,” a cover term for a variety of diseases caused by specific treponema species.  These diseases include pinta, yaws, bejel, and syphilis.  Pinta is a skin disease that doesn’t affect the skeleton, but the other three all leave similar lesions on certain bones that can make them visible in archaeological populations.  These include most importantly a certain type of depression on the exterior of the skull which is associated with peculiar “stellate grooves” and lesions on the tibia and, much less often, on other long bones on both sides of the body.

South Wall of Room 326, Pueblo Bonito

The skull of this woman from Pueblo Bonito has lesions that have been tentatively suggested by previous analysts as possible evidence for treponematosis, but this remained speculative as long as the skull was thought to be isolated without other associated bones.  It turned out that those bones were just classified under other catalog numbers, however, and Marden and Ortner show clearly that they all go together and that lesions on one tibia and a few other bones confirm the diagnosis of treponematosis.  Some of the lesions seem to have been active at the time of death, which is important in assessing the type of treponematosis involved.  Marden and Ortner carefully assess other possible explanations but conclude that none is as plausible as treponematosis in explaining the observed lesions.

But what type of treponematosis is this?  Surely not pinta, which wouldn’t leave any sign in the skeleton.  The other three leave similar lesions, and Marden and Ortner reject claims by some other physical anthropologists that it’s possible to distinguish them based on the physical evidence, so they instead look at environmental and demographic factors.

Chuska Mountains from Peñasco Blanco

Yaws is only found in hot, humid regions and is typically found in children, so it is very unlikely that it would afflict a grown woman in an arid location like Chaco.  Bejel is found in arid regions, but is again primarily a childhood disease, so it is unlikely that this woman had it.  It’s not impossible, however; while the active state of the lesions suggests that she did not contract this disease in childhood, she could possibly have contracted it in adulthood through travel to a place where it was endemic or contact with someone who came to Chaco from such a place.  Given the far-flung trading networks in which Chaco was involved, this is certainly possible, although not particularly likely.  Like pinta and yaws, bejel is not sexually transmitted.  It generally spreads through mouth-to-mouth contact or by sharing domestic utensils.  Marden and Ortner also suggest that it’s possible that the nature of bejel has changed over time and that it was once more common among adults than it is now or that the skeletal lesions developed after a longer incubation period, but in the absence of any other evidence for this (and they don’t cite any) I don’t see any reason to find this probable.  While bejel is a more plausible source for the observed lesions than pinta or yaws, it’s still not very likely given the circumstances.

That leaves syphilis.  Unlike the other types of treponematosis, syphilis infection would make sense in an adult woman, given its sexually transmitted nature.  Oddly, Marden and Ortner seem to downplay this conclusion.  Although they do argue that syphilis is the most likely explanation, they bend over backwards to accommodate other possible explanations, mostly focusing on ways this woman could have been infected with bejel as an adult.  It’s not really clear why they do this (perhaps a response to comments during the peer review process?), since a diagnosis of syphilis is plausible given the known epidemiology of that disease and the known characteristics of the other types of treponematosis.  It’s almost as if they are trying to sidestep the implications for this woman’s sexual history of a syphilis diagnosis, but that seems rather silly to me.  The woman’s been dead for a thousand years.  Who cares how slutty she was?

Pueblo del Arroyo from the Southwest Corner of Pueblo Bonito

Because I clearly can’t leave a pithy-enough quip alone, I hasten to add that “how slutty she was” is of course not at all the best way to think about this.  While a diagnosis of syphilis does imply sexual transmission, and thus that this woman was not a life-long virgin, it doesn’t even necessarily imply that she had more than one partner.  Even saying that, however, probably brings too much of our own modern, Western sexual mores into the matter.  Chacoan sexual mores were probably different, perhaps to a significant degree.  The Christian heritage of European societies has tended to leave them a legacy of attitudes toward sexuality that are quite unlike those of many other societies, and while we can never know exactly how the Chacoans felt about sex, there’s no reason to assume that they felt the same way we do.  There are few hints in the archaeological record of what Chacoan sexual attitudes actually were, and the ethnographic record of the modern Pueblos doesn’t contain a whole lot of detail on the matter either, probably due to a combination of Pueblo reticence and Victorian modesty.  One interesting clue, however, is the very detailed and accurate rendering of the female genitalia on an effigy vessel from Pueblo Bonito, especially in contrast to the equally obvious but much less detailed penises on other effigy vessels.  The implications of this for Chacoan social mores and sexual practices are unclear, but the contrast to, say, ancient Greek sculpture is interesting.

The Marden and Ortner paper is very interesting along numerous dimensions, and it’s an example of the kinds of information that can be obtained by careful study of human remains.  I’m still a bit dubious about the ethics of all this, but there’s no denying that important information can come out of it.
Marden, K., & Ortner, D. (2011). A case of treponematosis from pre-Columbian Chaco Canyon, New Mexico International Journal of Osteoarchaeology, 21 (1), 19-31 DOI: 10.1002/oa.1103

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Peñasco Blanco

Returning to my theory that the large square rooms with hearths and other residential features found at some great houses in Chaco and elsewhere were in some sense replacements for earlier kivas, I think the best evidence for this at Chaco itself (as opposed to at outlying great houses like Salmon) comes not from Pueblo Bonito, which is just too complicated a palimpsest to make something like this easy to see, but from the other early great houses: Una Vida and Peñasco Blanco.  These at least seem to have simpler layouts than Bonito, though the extent to which this is just an effect of their being (mostly) unexcavated is unclear.  Nevertheless, at least some parts of these two great houses do seem to show basically the pattern that I’m proposing for the development of residential room suites at great houses.

To recap the idea: The very earliest great houses, those built in the AD 800s, seem to show a pattern of suites similar to that seen at small houses or unit pueblos, with each suite consisting of one rectangular room backed by two smaller rooms.  In front of each roomblock there are subterranean kivas, usually with slightly fewer than would be expected if each suite had its own kiva.  This suggests to me that the suites housed individual nuclear families, but that they were grouped into larger units, perhaps extended families, which shared kivas.  Whatever rituals these residential units would have conducted would probably have been in the kivas, but for the most part these were still residential structures, similar to the pithouses occupied in earlier centuries but with some of their functions transferred to the rectangular front rooms of the roomblocks.  The smaller rooms in the back would have been used for storage.  A typical great house would contain a few of these suites, with a kiva for every two or three.  It’s unclear what the relationships among different kiva-units within a great house would have been, but they could have either been separate extended families within the same real or fictitious “clan” or “lineage,” or they could have been separate lineages that were politically or ceremonially allied.  Importantly, all of these buildings are still residential at this point, although the residents may well host rituals or feasts open to the whole community either to solidify their political authority or because generosity is expected of them in exchange for community acceptance of their greater wealth or political/religious authority.  The main difference between great houses and small houses is just that great houses are bigger, with multiple stories in some instances and generally bigger rooms, as well as more extensive use of masonry rather than adobe or jacal construction.

Room 330, Pueblo Bonito

Then, at some point in the 900s, a change takes place in some (all?) great houses.  Use of the kivas is discontinued, and instead the activities that had been conducted in them are transferred to square surface rooms added onto the existing roomblocks.  This definitely seems to be what happens at Una Vida and Peñasco Blanco, although the extent to which there were earlier kivas is unclear given the lack of excavation.  In great houses newly begun during this time (it’s unclear how many of these there were in Chaco itself, but Kin Nahasbas may be an example), room suites were built without any kivas but with large, square rooms in front and smaller rectangular rooms varying in number behind them for storage.  This pattern continues well into the 1000s, at least at some great houses, and it’s associated with the very formal, symmetrical, rectilinear layout seen at sites such as Hungo Pavi, Chetro Ketl, and Pueblo Alto.  Some outlying great houses, such as Kin Bineola and (especially) Salmon, show this pattern as well.  Salmon seems to show that new great houses with (almost?) exclusively square rather than round living rooms were still being built as late as 1090, and if the early construction at Aztec is in the same pattern, which seems to be a matter of some dispute, it would still be going on well into the early 1100s.  This is probably also what we see at Pueblo Bonito too, with the possible addition of square rooms like 329 and 330 to the older suites at the west end of Old Bonito and the later addition of linear suites to the south of these rooms at the southwest corner of the site.

At some point in the late 1000s, however, a different type of room suite begins to arise at some Chaco great houses.  This is still a linear suite, sort of, but it consists of a round kiva built aboveground into a first-story square room, with one or two rows of two- or three-story rectangular rooms extending back from it.  These are the “blocked-in” kivas that are probably the most famous innovation of Chacoan architecture.  I see them as still residential spaces, in combination with the rooms behind them.  Their appearance at most outlying great houses indicates residential use of those sites, perhaps by local elites.  It’s not clear what the relationship is between these plaza-facing blocked-in kiva suites and the “elevated” kivas surrounded by rectangular rooms that start to appear at the centers of the rectilinear great houses with the square living rooms around this same time.  If those rooms are still residential, they’re pretty damn fancy residences.  They’re also quite unlike the other residential rooms at these sites, which are still square.  The “Tower Kiva” at Salmon is one example, as are the corresponding kiva at Hungo Pavi and the numerous examples at Chetro Ketl.  The central placement and unusual elaboration of these structures has led many to assume that they were ceremonial rather than residential in function, but I’m not so sure.  These sites do generally have great kivas, which pretty much everyone agrees were community-scale ceremonial/integrative structures, and they look quite different from elevated kivas (although it’s not clear to what extent the unique features of great kivas are due to structural requirements following from their size).

Kivas in the Southeast Part of Pueblo Bonito

In any case, the best examples of the plaza-facing blocked-in kiva suites are at Pueblo Bonito in the southeast and southwest wings.  These appear to have been built over earlier construction, so it’s not totally clear what was going on with these multiple, quite rapid changes in site layout during this period.  Again, though, they’re also obvious at Una Vida and Peñasco Blanco, where some (but not all!) of the earlier square living rooms are replaced by blocked-in kivas.  This also appears to have happened in the west wing of Chetro Ketl, but it’s unexcavated so it’s hard to say for sure.  There definitely are two blocked-in kivas there, though, and they appear to have rooms behind them like at Pueblo Bonito.

Then, at some point toward the very end of the eleventh century or very early in the twelfth, a totally new type of room suite begins to appear at Chaco great houses.  This is the famous “McElmo unit,” with a central blocked-in kiva surrounded on three or four sides by rectangular rooms, most of them significantly higher (three or four stories), creating a sort of “patio” over the kiva.  These rarely have ground-floor exterior walls, and they are remarkably uniform and modular in form.  The most famous of these structures are the freestanding ones, including New Alto, Casa Chiquita, and Kin Kletso (which comprises two adjacent units), but clearly analogous forms can be seen within certain great houses, including the north and south wings of Pueblo del Arroyo and the Kiva B complex at Pueblo Bonito.  Similar units that are just outside of existing great houses can be seen at Chetro Ketl and Peñasco Blanco.  The masonry of most of these is very different from that used at earlier great houses, being composed of blocky yellow sandstone rather than fine, hard, dark sandstone, and this has been used to argue that they represent influence from the north.  The masonry may indeed reflect northern influence (though in a different way from what the original proposers of this idea thought), but the form predates the shift in masonry and probably developed locally in Chaco.

Kiva E, Kin Kletso

There has been a lot of debate over the function of McElmo units.  Some see them as warehouses, while others see them as ritual (or possibly astronomical) special-use sites.  I’m increasingly thinking that all this speculation is based on an overemphasis on their differences from earlier great houses, and that they were probably residential and represent the final version of the Chacoan room suite.  More on this later.

McElmo units may represent the final development of Chacoan architecture in terms of form, but the great houses continued to be occupied for quite some time after the construction of these roomblocks in the early 1100s.  What we see at this point is an increased emphasis on the blocked-in kiva concept, with new kivas, often of “non-Chacoan” form, being built into earlier square or rectangular rooms.  Some call these “intra-mural” rather than “blocked-in” kivas, to emphasize that they were built into earlier rooms rather than having square rooms built around them, and I think this is a helpful distinction.  These really proliferate at Pueblo Bonito late in the occupation period, and this also happens at Aztec and Salmon during their “post-Chacoan” (also called “secondary” or “Mesa Verdean”) occupations.  At the same time, many great houses also see the construction of new subterranean kivas in the plazas, often with accompanying small blocks of square rooms.  These aren’t usually datable directly, but they appear to be very late.   Pueblo Bonito has particularly many of these, and there are a few in the southeast corner of Chetro Ketl too.  These appear to represent the construction of typical small-house or unit-pueblo style residential units within earlier great houses, and they may or may not represent an occupational discontinuity of some sort.

So basically, what we see is a sequence of underground kiva to above-ground square room to above-ground kiva.  There are plenty of variations and complications, but that’s the general sequence.  The later use of intra-mural kivas, especially at Pueblo Bonito, has tended to obscure the middle stage here, but it really seems to represent something meaningful at least as a chronological marker in Chacoan architecture.  Does it mean anything else culturally?  That part I’m still looking into, but it may.

Fajada Butte from Una Vida

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Room 329, Pueblo Bonito

When I initially proposed that the square, plaza-facing rooms at Chacoan great houses that have features suggesting residential use represented an alternative to residence in kivas, I speculated that the difference between the two patterns might reflect some meaningful social difference within Chacoan society, perhaps different ethnic or geographic origins.  I’m still willing to entertain that idea as a hypothesis, but after looking a bit more closely at the development of the well-documented great houses I think it’s more likely that what we see  here is a difference over time, with different styles of residential architecture predominating in construction projects dating to different periods.  Basically, it looks like the earliest great houses generally have subterranean kivas associated with suites of rectangular rooms, which is the standard pattern at small houses as well.  There are typically fewer kivas than there are room suites, which suggests that kivas might have been shared by multiple households (extended families?) living in close proximity.  At some point, however, probably in the tenth century, a new style emerged in which the kiva was replaced by an above-ground but single-story square room backed by two or three two-story (or even three-story) rooms that were smaller and more rectangular.  These are the “linear suites” well-known to Chaco architecture scholars.  It’s unclear how prevalent they were, and it doesn’t seem that they were ever universal at all great houses, but a substantial amount of great-house construction in the late 900s seems to be of this type, with no new kiva construction and older kivas possibly falling into disuse.

At some sites this pattern persists well into the late 1000s, such as at Salmon, and in general it seems to be typical at many later great houses with very formal, rectilinear, symmetrical layouts.  At some point, however, it seems to have been supplemented and ultimately replaced by a new pattern of building round kivas into aboveground square rooms, which in some ways seems like a combination of the two styles.  In some cases these kivas were actually built into what appear to have been square living rooms that had been built earlier; this is what happened at Salmon in the post-Chacoan era, but it also seems to have happened in some cases at Pueblo Bonito, probably still within Chacoan times.  Other examples of these “blocked-in” kivas were clearly built as units, with the square enclosure and the circular chamber built together.  It’s not clear exactly when this change happened, but it was probably in the late 1000s or early 1100s, right at the peak of Chaco’s power and influence or shortly thereafter.  Later, and definitely after Chaco’s decline, a new pattern arose, with kivas and associated surface room blocks strongly resembling those at small houses being built into the plazas of Chacoan great houses.  This probably also involved additional building of new kivas into older Chacoan square or rectangular rooms.  It’s not clear how long this persisted, as these late units are very hard to date, but it may well have gone on into the 1200s.

Any of these changes through time may well have been associated with changes in regional influence or social dynamics, and I’ll be  looking into the possibilities for explaining them, but I think it’s pretty clear that there’s a strong temporal component to these differences in architecture.  One implication of this is that while the large numbers of visible kivas at Chacoan sites have led to an idea that Chacoan architecture is associated with lots of kivas, it may well be the case that the most “Chacoan” innovation in domestic architecture is precisely a lack of kivas, and that this is not obvious today because it didn’t take and after a period of kivaless construction people, including Chacoans, went right back to building (and living in) kivas.  I’ll be thinking about and looking into other potential implications for understanding the Chaco system and its place in the broader region.

Kivas in East Plaza, Pueblo Bonito

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