Archive for the ‘Trade’ Category

"Pithouse Life" Sign at Mesa Verde

“Pithouse Life” Sign at Mesa Verde

Chapter 10 of Crucible of Pueblos, by Richard Wilshusen and Elizabeth Perry, looks at the position and roles of women in early Pueblo society, with a particular focus on how those roles seem to have changed with the economic and demographic changes of the late Basketmaker III and early Pueblo I periods that recent research is bringing into focus. It’s a thought-provoking chapter but in some ways rather odd, with many of its most intriguing proposals resting on what seems like fairly thin evidence.

The chapter looks at three main topics: food production, human reproduction, and gender relations in social power. Its overall thesis is that in the northern Southwest between AD 650 and 850 interrelated changes in food production systems and human reproductive rates led to major changes in gender roles, particularly regarding the division of labor between men and women, that may have led to settlement aggregation into villages and to changes in social power related to trade and ritual. The resulting social structure, in place by the end of the Pueblo I period in at least some areas, was the earliest form of the “Pueblo” society as known from modern ethnography, with its strict division of labor by gender and extension of this gendered ideology to many other domains of life.

Of the three main topics, the authors devote the most attention to the first, and it’s here that their arguments are strongest and most clearly supported by the archaeological evidence. The key change in food production during the period in question is the intensification (not introduction) of maize agriculture as the primary subsistence activity, supplemented by the growing of other crops like beans and squash, by the raising of domesticated turkeys, and by hunting and gathering of wild foods. Recent research has clarified the sequence and extent of this change, although a lot of questions still remain.

As the authors note, one of the most puzzling results of research on early agriculture in the northern Southwest is that maize is now clearly established as having been introduced as early as 2000 BC in several widely spaced parts of the Colorado Plateau (including Chaco Canyon), but for hundreds of years it appears to have remained a minor part of the diet of the groups that used it. It was only in the Basketmaker II period, between 300 BC and AD 300, that maize use became widespread, and even then, according to Wilshusen and Perry, local groups varied widely in the contribution of maize to their diets. There may have been a distinction between immigrant groups from the south that had a heavily agricultural subsistence base and local hunter-gatherers who were gradually incorporating some farming into their lifestyles.

This slow and incomplete adoption of agriculture is in contrast to the situation in other parts of the world where agriculture, once introduced, spread rapidly and quickly replaced hunting and gathering. It’s still not clear why, although Wilshusen and Perry note that as a tropical plant originating in Mexico, maize would have been poorly suited for the harsher climate of more northern latitudes, and that it would have taken some time for people to breed hardier varieties. It is also apparent that the variety of maize initially introduced was small and not as obviously superior to local wild plant foods as later varieties, and that it was initially introduced without an accompanying “package” of other domesticated foods, as was the case with agricultural spreads in other areas. Domesticated squash seems to have been introduced not long after maize, but separately, and domesticated turkeys appear to have been introduced from a different direction altogether, although the timing and details of their domestication remain very murky.

Be that as it may, the main point Wilshusen and Perry make in regard to this slow adoption of maize is that it is likely that women, who based on cross-cultural studies of hunter-gatherers tend to be responsible for gathering of plant foods, were involved in the initial use of maize in the northern Southwest. However, this small-scale introduction of a new food, even one associated with a new type of food production, probably wouldn’t have had a major impact on existing gender roles or division of labor. That would come later.

The full “Neolithic package” appears to have arrived in the northern Southwest between AD 300 and 600, with components including a larger, more productive variety of maize known as Harinosa de Ocho; beans, newly introduced from the south; greater use of turkeys for both meat and feathers; and greater investment in facilities for food storage and processing. The greater productivity enabled by these innovations led to rapid population growth and the spread of agricultural groups over the landscape, in striking contrast to the lack of such growth with the initial introduction of maize much earlier. Wilshusen and Perry associate these developments with the transition from Basketmaker II to Basketmaker III, as well as with the major changes in the roles of women that they document.

Additional support for these changes in food production come from complementary changes in storage facilities and grinding tools. As documented in the well-studied Dolores area, the importance of storage seems to have risen over the course of the late Basketmaker III and Pueblo I periods from AD 650 to 875. Storage facilities changed from small pit rooms isolated from the main dwellings to more secure and more solidly built storage rooms directly attached to living rooms and only accessible from them. These typically consisted of two storage rooms at the back of each living room, the beginning of the “suite” layout that would continue to be a key architectural feature into Chacoan times. It is possible that at least initially these paired rooms were used to store two years’ harvests, one in each room, so as to provide a subsistence buffer against drought and other unexpected problems.

There was also a shift over this period in grinding implements from basin metates with one-handed manos to much more efficient trough metates with two-handed manos. Beyond this shift, a greater variety of grinding tools became common over time. Together with the storage data, this indicates an increased importance of grinding as a component of food preparation. In the modern Pueblos grinding is a female-associated activity, part of an overall suite of food-preparation tasks accomplished by women that also includes shucking, shelling, drying, and storing corn. Of these tasks, however, grinding is considered particularly important to the female role, and it is an important part of female puberty ceremonies (of which the Navajo Kinaaldá, of clear Pueblo origin, is probably the best known). Men, on the other hand, are responsible for planting and harvesting the corn, as well as protecting the fields. This seems to be a change from the presumed hunter-gatherer system in which women were generally responsible for gathering plant foods as well as processing them, and Wilshusen and Perry suggest that it may have arisen in early Pueblo times as fields at greater distances from residence locations in villages became increasingly vulnerable to attack by enemies, prompting men’s role as warriors to encompass guarding fields and, in time, tending them as well.

Another important female task in modern Pueblos is making pottery, and this too seems to have become increasingly important with the expansion of agriculture in early Pueblo times. With more use of crops and additional cultigens such as beans, pots would have become more important for food preparation, and with the number of vessels needed and their short use-lives of 1 to 6 years women would have had to be constantly making new ones. (This is of course assuming that most pots for domestic use were made by the family unit itself, which may well be true for this early period but was not necessarily later on.) Based on detailed study of an isolated Pueblo I hamlet in the Central Mesa Verde area, Wilshusen and Perry estimate the following assortment of vessels for a typical household at any given time:

  • 2 to 7 small cooking jars
  • 1 to 4 medium cooking jars
  • 0 to 2 large cooking jars
  • 1 bowl
  • 0 to 3 ollas for water
  • 2 to 3 other vessels
  • 10 to 20 sherds from broken pots used as containers or tools

Keeping a household supplied with all these pots would have been a major part of a woman’s domestic labor, in addition to the food processing tasks mentioned above, along with other major responsibilities such as caring for children.

And speaking of children, Wilshusen and Perry go on to discuss human reproduction and the apparent changes in it associated with the other changes they identify. The two main changes they note are shifts in the use of cradleboards and an apparent increase in the societal fertility rate. This part is somewhat less thorough than the food production part of the paper, but it does still identify some intriguing evidence for change.

First, cradleboards. The authors note that study of these items, in which infants were bundled while they were very young,  has been surprisingly limited, despite their relevance to an important event that has long been recognized: the beginning of evidence for “cranial deformation,” or the reshaping of skulls as a result of prolonged contact with certain kinds of cradleboards in infancy. The shift from “undeformed” to “deformed” (the terminology is very problematic, as there is no evidence of health problems from the practice) crania is traditionally associated with the transition from Basketmaker III to Pueblo I, and early in the history of Southwestern archaeology the change in head shape was even taken as evidence for a population replacement. (That was in the early twentieth century when anthropologists put much more emphasis on skull shapes in defining populations than they do now.) It is now generally thought that the distinction is actually due to the use of soft versus hard cradleboards, but recent research that Wilshusen and Perry discuss suggests that both types of cradleboards were present in both Basketmaker and Pueblo times. Thus, the shift in cranial shape is actual due not to a change in the type of cradleboard but in how it was used. The main changes that actually seem to have occurred in the Pueblo I period are:

  • Foot rests on cradleboards disappear.
  • Hoods become more common.
  • Construction is more expedient.

According to Wilshusen and Perry, these changes together indicate that women had less need to move while carrying children in cradleboards, but that they needed more cradleboards overall, possibly indicating that they had more children. This part of the paper does not go into much detail about where these conclusions come from, but the overall conclusions is that this is further evidence that women were more tied to the domestic sphere in Pueblo I, and possibly that they had more children.

On that note, demographic data appear to indicate that the population increases seen in at least some part of the Pueblo world during Pueblo I were due largely to natural increase after initial immigration into new areas. The best data come from the Central Mesa Verde and Eastern Mesa Verde areas, both of which seem to show this pattern. Prehistoric demographics are notoriously hard to reconstruct, but based on the large recent data sets from major excavation projects Wilshusen and Perry propose that a Neolithic Demographic Transition (a major increase in fertility associated with the beginning of intensive agriculture) began in the northern Southwest around AD 300, with major consequences over time for women in particular, given their gender-defined economic roles. This is comparable to evidence seen in other parts of the world with the beginning of agriculture. The key point here for the role of women is that with increasing rates of both childbirth and survival of children beyond infancy, families would have become larger, increasing the amount of domestic labor required of women to maintain their households given the gendered division of labor presumed to have developed. This would be one explanation for the increased importance of food processing mentioned above.

Finally, Wilshusen and Perry talk about exchange and social power. The discussion here is very abbreviated, and relies heavily on references to the next chapter in the book (which is a little odd), but the basic idea is that rock art evidence shows a shift in social power to male leadership of ritual in late Basketmaker III, continuing into Pueblo I. Female economic roles expressed in matrilocal residence may have driven men to make external trade alliances, which over time developed into new ritual systems focused on important lineages within villages rather than large public rituals at central places not necessarily associated with a specific lineage or community. Matrilineal lineages were still important, and the focus of key rituals, but changing gender roles may have involved an increased role for the men of the lineage in certain types of rituals. Burial evidence from Ridges Basin may support some of these ideas, with striking differences in male and female burials, particularly in the types of exotic goods included. Both women and men were buried with exotic items occasionally, but the specific types of items varied, suggesting gendered access to different trade systems. There are also geographic differences within the basin suggesting different community connections and ideological systems. This section is intriguing but very sketchy, even compared to the rest of the paper. More detailed discussion of some of these ideas will have to wait for the next chapter.

Overall, the conclusion of this chapter is that over the course of the early Pueblo period gender roles shifted in a way that evolved into the system(s) that are well known from the modern Pueblos. This may have been a response, in part to the demographic shift resulting from the development of intensive agriculture, with its resulting higher birthrates and changes to the roles of women. Women’s labor was key to this transition, but it’s not clear that it was actually good for women as a class on net. There has been some discussion of the idea of “parallel status hierarchies,” in which men and women had different tasks but both allowed meaningful status through high achievement. However, later evidence from Pueblo sites shows that women were often excluded from access to high-value resources such as meat, and that their graves were generally less elaborate than men’s (a contrast to the Pueblo I situation in at least some areas). It doesn’t appear that many strictly comparable studies of these issues have been done of the Pueblo I period itself, so it’s hard to say how these changes felt for the women who were living through them. The authors of this paper seem to lean toward thinking the changes were not actually beneficial for those women, but the evidence is thin enough that it’s not clear.

Above I have summarized the arguments of this chapter as best I could, but it’s worth noting that the argumentation of the chapter itself is highly abbreviated, and summarizing it has required a lot of assumptions and interpretive leaps. It kind of reads like this paper is an abbreviated version of a longer argument, with some important parts left out. Nevertheless, it raises a lot of interesting questions that have rarely been addressed in Southwestern archaeology, especially regarding the early Pueblo period, and for that alone it is valuable.

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Rio Grande from Coronado State Monument, Bernalillo, New Mexico

Rio Grande from Coronado State Monument, Bernalillo, New Mexico

Chapter seven of Crucible of Pueblos brings us to the final geographical region covered by the volume: the Rio Grande Valley, at the eastern edge of Pueblo settlement for the period in question. As it happens, I’m currently visiting my mom in Albuquerque, so I’m actually in this region as I write this. (Today also happens to be my birthday; I’m 31.) The chapter is by Steven Lakatos and C. Dean Wilson, and in a lot of ways it echoes an earlier paper by Lakatos about the Rio Grande Developmental Period that I have discussed before. This chapter, however, discusses only the Early Developmental Period, defined as AD 600 to 900, and primarily focuses on the part of the region that the authors called the Middle Rio Grande Valley, defined as lying between the Rio Puerco of the East on the west, the Sandia and Manzano Mountains on the east, the Isleta area on the south, and the La Bajada escarpment on the north. This is because agricultural populations only occupied this restricted area of the region during the Early Developmental, expanding north of La Bajada only after AD 900 when there was a huge increase in regional population at the beginning of the Late Developmental Period.

The key point Lakatos and Wilson make about the Rio Grande is that the Early Developmental period was a time of low population density and gradual growth, with little change in material culture over hundreds of years. This is in striking contrast to the “boom-and-bust” pattern now richly documented for the Mesa Verde region during the contemporaneous Pueblo I period there. The picture of continuity is reminiscent of that proposed by the authors of the previous chapter for the Little Colorado region, but it’s worth noting that the major data gaps that plague the study of that region are less of an issue for the Rio Grande, which has a long history of intensive archaeological research continuing to the present day. Furthermore, Lakatos and Wilson present several lines of evidence supporting their conclusions, which seem pretty solid to me. Based on this evidence, it really does seem like the Early Developmental was a time of low population, slow growth, and cultural continuity.

As Lakatos and Wilson note, this is actually a rather surprising conclusion in the context of many theories about early agricultural societies. Most strikingly, there is no evidence here for a “Neolithic Demographic Transition,” in which the increased productivity of agricultural societies compared to hunter-gatherers leads to massive growth among early agriculturalists, with all sorts of ecological and social consequences. Some have argued that the Mesa Verde boom-and-bust cycle is a result of this process. In the Rio Grande, however, the adoption of agriculture does not seem to have resulted in this sort of population growth. This is definitely not for lack of arable land, as the Rio Grande Valley is one of the richest agricultural areas in the northern Southwest, and it was intensively farmed later in prehistory and into historic times. Rather, Lakatos and Wilson argue that the richness of the Rio Grande environment allowed for a mixed farming-foraging economic pattern with high residential mobility, in contrast to the more agriculture-dependent societies further west. The greater importance of foraging versus farming is supported by evidence from faunal assemblages and wear patterns on human remains, and the mobility by the fact that residential pit structures were rarely remodeled.

In keeping with low density and high mobility, the settlement pattern consisted of scattered hamlets, with only occasional evidence for “communities” of hamlets loosely grouped together with possible communal architecture such as “protokivas” or oversized pit structures. Sites were mainly located along the major rivers of the region: the Rio Grande itself, the Rio Puerco of the East, the Jemez. Architecture consisted of residential pit structures and surrounding activity areas, generally oriented toward the east or southeast (perhaps oriented to the winter solstice).

Rio Grande people also appear to have been in closer contact with remaining hunter-gatherers than populations further west. It’s not clear if Early Developmental populations resulted from the adoption of agriculture by existing hunter-gatherers in the Middle Rio Grande Valley or if there was some migration of already agricultural populations involved, but in any case the areas north of La Bajada and east of the Sandias/Manzanos were definitely still occupied by hunter-gatherers during this period, and it’s clear that there was a lot of contact between the two groups. This may have contributed to the greater importance of foraging to Early Developmental people and their differences from other Pueblo populations.

Sandia Mountains from Tent Rocks National Monument

Sandia Mountains from Tent Rocks National Monument

All that said, the Early Developmental people definitely were part of the Pueblo cultural tradition, and their material culture shows a lot of connections to populations to both the west and south. This is particularly true of pottery, which was dominated by plain gray ware similar to that of late Basketmaker groups on the Colorado Plateau, but with small amounts of a decorated white ware, San Marcial Black-on-white, which shows stylistic influence from Mogollon populations to the south but with technological characteristics more like those of early white wares to the west. Lakatos and Wilson mention one model of Southwestern prehistory under which early “strong patterns” of material culture originated in the San Juan Basin (ancestral to the Chaco system) and in the river valleys of the Mogollon region, with the Middle Rio Grande forming a “weak pattern” with influences from both but in varying combinations.

The clear picture that emerges from this is of a small population of forager-farmers moving around within the Middle Rio Grande area but maintaining their basic cultural features with little to no change for about 300 years, from AD 600 to 900. Then, in a development that is likely very important but poorly understood, there was a massive increase in population at the same time that agricultural groups for the first time began to occupy the higher areas about La Bajada. Lakatos and Wilson note that the timing of this change, while not as precise as might be ideal, seems to correspond closely to the collapse of the late Pueblo I villages in the Mesa Verde region and the major population movements involved with the depopulation of that area, including the apparent influx of people into the Chaco Basin that likely laid the groundwork for the Chaco Phenomenon.

It seems very plausible that the increase in population in the Rio Grande was linked to these developments, though exactly how is unclear. Material culture actually remained fairly stable and consistent with Early Developmental patterns across this transition, although architecture did become more standardized and San Marcial Black-on-white was replaced by Red Mesa Black-on-white as the main decorated ceramic type. The latter change, especially, suggests influence from the west, as Red Mesa is the main decorated type in the Chaco area and other parts of the southern Colorado Plateau during this same period. It’s possible, as Lakatos and Wilson suggest, that the increased population in the Chaco Basin directly spurred Middle Rio Grande populations to move northward, although it’s not clear how exactly this would have worked. Other possibilities are that populations from the intermediate areas, such as the Puerco of the East, began to move eastward in the Rio Grande Valley as a result of the population movements immediately to the west of them, perhaps pushing existing Rio Grande populations north, or that western populations were moving directly to the Northern Rio Grande area above La Bajada, “leap-frogging” existing populations in the Middle Rio Grande.

The fact that material culture continued to show local Rio Grande features throughout the region, however, suggests that some level of assimilation or cultural accommodation between the locals and immigrants was involved, rather than a more directly confrontational situation. It’s noteworthy that Lakatos and Wilson don’t discuss evidence for warfare or defensive features at all, which of course doesn’t mean those things didn’t exist but does suggest that they may have been less prevalent than in some other regions.

Turquoise-Encrusted Cow Skull, Santa Fe, New Mexico

Turquoise-Encrusted Cow Skull, Santa Fe, New Mexico

Another thing Lakatos and Wilson don’t discuss, but which seems particularly important to understanding these relationships, is turquoise, specifically that from the well-known mines in the Cerrillos Hills east of the Sandias. Turquoise is of course strongly associated with Chaco, and while not all of the turquoise there has turned out to be from Cerrillos, a substantial portion of it definitely was. Evidence for increased connections between the San Juan Basin and the Rio Grande area at the same time as the rise of Chaco as a regional center is very intriguing in this light. Could increasing demand for turquoise at Chaco have led to the Cerrillos mines being a “pull” factor leading western groups into the Rio Grande Valley? Could the mines have even led local Rio Grande groups, or mixed groups of locals and immigrants, to move further east, across the mountains and even up over La Bajada into the Santa Fe area, which may have become more attractive as increased immigration reduced the supply of land in the Middle Rio Grande? And what about those remnant hunter-gatherer groups east of the Sandias and north of La Bajada? What happened to them? Were they attacked and defeated by the encroaching farmers? Pushed out into areas further north and east? Assimilated into agricultural society, which even in the Late Developmental period had a strong foraging component? There are a lot of questions about this period in this area, and very little evidence on which to base any answers. Lakatos and Wilson recognize this and suggest some research directions that would be helpful in answering the remaining questions, although they don’t point out as many as I have here.

Overall, this is a very informative chapter that brings into the discussion of Pueblo I societies an area that is often left out of these discussions. It’s an area of crucial importance for understanding regional dynamics throughout the northern Southwest, however, so I’m glad it was included in this volume. This chapter concludes the geographical summaries in the book; the remaining chapters cover various thematic topics of interest in understanding the Early Pueblo period as a whole.

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Utah Welcome Sign

Utah Welcome Sign

The initial discovery of chemical markers for chocolate on potsherds from Chaco Canyon in 2009 was a hugely significant development in understanding Chaco. The evidence for the presence of chocolate, a Mesoamerican product that couldn’t possibly have been locally grown and is very unlikely to have been gradually traded northward through a series of intermediaries, gave a huge boost to the “Mexicanist” school of thought about Chaco, which holds that many of the unusual aspects of the Chaco system are due to influence from Mesoamerica.

The initial study only involved a few sherds, though, and understanding the exact role of chocolate at Chaco and its implications for Mexican contact needs a much deeper understanding of where and when cacao was present in the ancient Southwest. Thus, soon after the initial discovery further research by a different set of researchers (using somewhat different methods) began to test other pots from Chaco and elsewhere. They did find further evidence that at least some of the famous cylinder jars from Chaco were used in the consumption of chocolate, but they also found traces of cacao in vessels of similar form from the later Classic Hohokam period in southern Arizona, and, most surprisingly, also in vessels from the “small-house sites” at Chaco and elsewhere that are thought to have housed the lower classes of Chacoan society. The previous evidence for chocolate came from distinctive vessels at the “great houses” that are the hallmark of the Chaco system and seem to have been used by elites (though exactly what they used them for remains unclear and controversial). This is exactly the kind of setting where it would be unsurprising to find unusual, exotic things, and indeed the great houses clearly contained many such things in addition to the chocolate. Finding this sort of exotic foodstuff in more mundane pots at the small houses implies that it may have been more widely accessible than previously thought, which has important implications for understanding the nature of the Chaco system.

Well, now things have become even more complicated. The same researchers who did that follow-up study have done another, this time looking at a much earlier period and a different part of the Southwest. They used their same techniques to test for the presence of chocolate in pottery at Alkali Ridge Site 13 in southeastern Utah, a very important early village site dating to the eighth century AD. Site 13 was one of the earliest large villages established in the northern Southwest during the Pueblo I period, and its architecture shows some striking parallels to later Pueblo I villages such as McPhee Village in the Dolores, Colorado area, as well as to some of the early great houses at Chaco and elsewhere that developed even later. The early Pueblo I period in southern Utah is also associated with the introduction of a new type of pottery, San Juan Red Ware, which was widely traded from an apparently rather restricted production area and probably used for ceremonial purposes of some sort. In addition to being a different color from the more common gray and white pottery of the area, San Juan Red Ware also featured a distinctive design system in its decoration, one without obvious local antecedents. Combined with the distinctive architecture, this has led some archaeologists to posit that there was a migration into southern Utah during early Pueblo I from somewhere to the south, bringing these distinctive traits.

In that context, looking for cacao makes sense, as that would be a clear sign of ties to the south and cultural distinctiveness. Dorothy Washburn, who was the lead author on both this and the previous study,  has actually written mainly on design style in ceramics and other handicrafts, focusing on symmetry patterns. Based on the changes she has found in these patterns, she has argued for a very strong Mexicanist interpretation of Chaco, involving actual migration of people from far to the south bringing a distinctive pottery decoration style. She seems to have a similar view about Alkali Ridge, for similar reasons.

In any case, the study found that there was in fact evidence for cacao on several of the vessels found at Site 13, including some (but not all) of the redware ones. The conclusions, understandably, focus on the association between the new ceramic design system and the use of chocolate, but in fact the redware vessels don’t seem to be much more likely to have evidence of chocolate use than the other ones that were tested. It’s quite possible that San Juan Red Ware was associated with consumption of chocolate specifically, but it seems that other types of pottery were also used for chocolate-related purposes.

This is all very interesting, but it’s also confusing and hard to interpret, in a way that the authors of this paper don’t really address. Back when it seemed like chocolate was limited to cylinder vessels at Chaco great houses, that was easy to interpret: chocolate, like many other exotic goods found at these sites, was part of an extensive trading systems for elite goods, probably used for ritual purposes, which the elites of Chaco participated in (and perhaps dominated and directed). Finding it in the Hohokam vessels implied a similar system operating among elites at Classic Hohokam sites, which is consistent with some interpretations of Classic Hohokam society, plus the Hohokam in general show lots of evidence of contact with Mesoamerica in general so the presence of chocolate is much less surprising there than it was at Chaco. Finding it in the small houses at Chaco complicated the story somewhat and implied that the chocolate imported to Chaco wasn’t as restricted as had been thought, but since it was already known to be present at the great houses it’s not too surprising that the contemporaneous small houses had it too.

Alkali Ridge, though, is much earlier and much further north than any of these other sites. Getting chocolate there in significant quantities would have required a pretty elaborate and robust supply chain over a very long distance, much of which was inhabited by societies that are not generally considered to have been capable of this kind of long-distance coordination. Checking some of those intermediate areas (especially the Hohokam region) to see if they too had chocolate this early is necessary to understand the logistics of this.

There’s also the question of time. We now have evidence of chocolate from Utah in the eighth century, New Mexico (and to a lesser extent Colorado and Arizona) in the eleventh, and Arizona in the fourteenth. There are some big gaps there that need to be filled in to determine if these are three snapshots of a long-term and continuous tradition of chocolate consumption in the Southwest (which would have important implications about trade networks and relations with Mexico) or three separate episodes of chocolate being introduced from the south, possibly through population movement (which would have important implications for regional culture history in general). I think the most important place to look for evidence of continuity between Alkali Ridge and Chaco is in the large late Pueblo I villages in southwestern Colorado, especially the Dolores-area ones like McPhee Village. These sites have apparent connections to both earlier villages like Site 13 and later developments at Chaco. If they also reveal evidence for chocolate use, that would be a strong indication of continuity. The most important places to check for continuity between Chaco and the Classic Hohokam would probably be the Pueblo III communities in east-central Arizona, which again show connections in both directions. Both of these sets of sites are among the best-studied in the Southwest and there should be plenty of pots available for these analyses.

Finally, there is a methodological issue here. It’s possible that these tests aren’t actually detecting chocolate at all, but something else. The authors of the recent paper noted this possibility and looked into whether there are any plants native to the Southwest that might have chemical profiles similar to cacao that would throw off the analysis. They didn’t find any, but they note that many plants have not been analyzed in this way and it’s possible there is a different plant that is showing up in these analyses instead. Another possibility is that there is something about their method itself that is leading to false positives. It’s noteworthy that they have been finding much more extensive evidence of chocolate than the team, led by Patricia Crown and Jeffrey Hurst, that did the initial Chaco study found. That team hasn’t published any more about chocolate at Chaco since then, but I hear Crown was able to do some re-excavation in Room 28 at Pueblo Bonito this summer so there may be more from her on this in the future. Ideally I’d like to see a test of both methods on the same vessels to see how they match up.

The ultimate message here is that even important discoveries, like chocolate at Chaco, require many further studies and refinements to interpret properly. We’re nowhere near a full understanding of the true role of chocolate at Chaco or any other site in the prehistoric Southwest, but every study gets us closer.
Washburn DK, Washburn WN, & Shipkova PA (2013). Cacao consumption during the 8th century at Alkali Ridge, southeastern Utah Journal of Archaeological Science, 40, 2007-2013 DOI: 10.1016/j.jas.2012.12.017

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Mt. Taylor from Chaco

As I’ve discussed before, the patterns of use and importation of chipped stone at Chaco are somewhat puzzling. Unlike many other commodities, such as wood, corn, and pottery, which were imported from specific distant locations within the Chacoan sphere of influence in astonishing quantities during the height of Chaco’s regional power, chipped stone seems to have been largely a mundane, utilitarian concern. Throughout all periods of Chaco’s occupation most chipped stone was local. At Chaco’s peak of power and influence between AD 1020 and 1130 there was a slight uptick in imports of stone, particularly a distinctive pink chert from the Narbona Pass area to the west.

As I noted in the earlier post, however, obsidian follows a different pattern from the other imported stones. It is most common not at the height of Chaco’s regional power in the eleventh century but much earlier, in the Basketmaker III period between AD 500 and 750, when it is the most common nonlocal type of chipped stone. This was a time when Chaco may have seen an earlier period of regional importance, although figuring out what was going on at this time is very difficult for several reasons. By the Pueblo I period the amount of obsidian seems to drop precipitously, and it doesn’t start to recover until the very end of Chaco’s period of Pueblo occupation after AD 1120. This pattern puts obsidian decidedly out of phase with most other material culture imports to the canyon, which tend to correlate with the well-known evidence for social complexity and monumental architecture that we associate with the Chaco Phenomenon.

A recent paper by Andrew Duff, Jeremy Moss, Tom Windes, John Kantner, and Steven Shackley tries to put the obsidian evidence on a firmer footing by using geochemical sourcing to identify the source outcrops for a broad sample of obsidian found at Chaco and at various Chacoan outlier communities in the San Juan Basin. As they note, this is the latest chapter in a complicated story. Way back in the 1980s, the Chaco Project did an extensive sourcing study of obsidian found in its excavations in the canyon using X-ray fluorescence (XRF), a non-destructive sourcing technique that was then relatively new in archaeology. Their results, reported by Cathy Cameron in a number of publications, were surprising. They seemed to show that the closest source of obsidian, Mt. Taylor, provided very little of the obsidian found at Chaco (about 4%), while a distant source, Red Hill in Catron County, New Mexico, provided a very high proportion, especially in the assemblages from earlier sites. Also well-represented was obsidian from the Jemez Mountains, the second-closest source, with the proportion of Jemez obsidian increasing over time, a common pattern in the northern Southwest.

This seemed to indicate that there were substantial early ties between Chaco and the Red Hill area, far to the south but still just barely adjacent to some known Chacoan outliers. This result was mentioned in many publications on Chaco over the years, although many people didn’t really seem to know what to think of it. However, it soon began to be questioned. After this initial sourcing study had been done, Tom Windes submitted some samples of obsidian from Pueblo Alto and the Spadefoot Toad site for obsidian hydration dating, which involved a sourcing analysis as an intermediate step in the dating process. These analyses were inconclusive when it came to dating the artifacts (not uncommon in the Southwest, where obsidian hydration has a poor record as a dating technique), but the sourcing portion suggested strongly that the samples that had previously been sourced to Red Hill instead came from Mt. Taylor. Windes mentioned this anomaly in his site reports, as did Cameron in her subsequent publications on the subject, but a full published account didn’t appear until this new study.

The new study also used XRF to do the sourcing analysis, but both analytical techniques and source characterizations have improved considerably since the 1980s, so the results were quite different from the first effort. For some reason this study was unable to do a complete reanalysis of the earlier samples (although it implies that this may be possible in the future), so there was only limited overlap and the focus was mostly on recent samples collected by Windes at Basketmaker III and Pueblo I site in and around Chaco, as well as outlier sites studied by Kantner in the Red Mesa Valley near Mt. Taylor and by Duff at the southern edge of the Colorado Plateau near Red Hill.

The results were not really surprising, in that they have been known in broad outline since Windes submitted his samples for dating and reported on the sourcing anomalies, but it’s nice to see them formalized in a peer-reviewed paper. Basically, this study found that no samples from Chaco came from Red Hill, although a few came from other sources in the same general area, and that the most common source found at Chaco was Mt. Taylor. Over time there was a trend in the Chaco data showing a shift from Mt. Taylor to Jemez sources, accompanied by the well-known trend toward less obsidian in assemblages overall. The sample from the Blue J site near Mt. Taylor, in contrast, showed high proportions of Mt. Taylor obsidian increasing over time, in marked contrast to the Chaco pattern. The southern sites showed assemblages of obsidian almost entirely composed of Red Hill and other nearby sources.

Basically, the overall pattern was a classic distance-decay distribution, where the prevalence of a given source at a given site was mostly predictable by the distance between the source and the site. This is in sharp contrast to the pattern for many other imported goods at Chaco, which are present in high quantities in the source areas and at Chaco but not in between. This suggests strongly that obsidian was not part of any general Chacoan exchange system(s) but was procured by individual communities in accordance with their own needs, mostly using the closest sources. This is in keeping with the general tendency for chipped stone to be a relatively low-priority commodity in these societies.

The paper mentions the decline in overall abundance of obsidian after the Basketmaker III period at Chaco, but doesn’t spend much time discussing it beyond saying this:

The overall decrease in obsidian use noted at Chaco sites may reflect a shift in technological focus away from hunting and a subsequent focus on grinding technology as agriculture becomes the dominant subsistence strategy.

As I’ve noted before, this is almost certainly wrong; the decrease in question occurs at the end of the Basketmaker III period, at which time there is considerable evidence that Southwestern populations were already heavily dependent on agriculture. The decrease in obsidian is still odd, though. One thought I’ve had to explain it is that maybe the obsidian from after this period isn’t actually missing at all, but is at Pueblo Bonito, which had lots of obsidian but was excavated a long time ago using techniques that aren’t really comparable to the modern techniques used by the Chaco Project and later efforts that resulted in the collections being analyzed here. I would suggest that an XRF sourcing analysis of the Bonito obsidian would be interesting. As it is, there’s a huge shift in the proportions of the different sources at Chaco between Basketmaker III and Pueblo I. The earlier samples (dominated by the huge samples from the major villages of Shabik’eschee and 29SJ423) show a predominance of Mt. Taylor obsidian, while the later ones show mostly Jemez sources. The sample size is so much smaller for the later period, however, that I’m skeptical about taking this flip at face value. Including the Bonito assemblage might help to bridge this gap, or at least explain it.

Finally, it’s again noteworthy how unimportant obsidian appears to have been to the Chaco system. Even if the Pueblo Bonito evidence ends up indicating a more important role at Chaco itself, the various outlier communities appear to have used local sources and to have followed their own priorities in acquiring this commodity rather than getting it through any Chaco-controlled or -oriented system. This is one of the ways that Chaco appears to diverge from Mesoamerican societies, despite recent evidence that it may have had more contact with them than was previously believed. Obsidian was hugely important symbolically in Mexico, and control of major sources was a major source of power and wealth for various Mesoamerican polities. In the Southwest, however, nobody seems to have cared that much about controlling major obsidian sources, and obsidian seems to have been distributed as a fairly ordinary commodity without any particular symbolic importance. I think this is one of the strongest pieces of evidence suggesting that whatever influence Mesoamerican societies may have had on Chaco was indirect and mediated by Chacoan elites rather than imposed directly from Mexico, as some have argued.

In any case, while this isn’t really the most exciting paper, it’s still an important one in straightening out a part of Chacoan archaeology that had become pretty confused. Obsidian may not have been all that important at Chaco, but it’s still worth studying in part precisely because of its mundanity.
Duff, Andrew I., Moss, Jeremy M., Windes, Thomas C., Kantner, John, & Shackley, M. Steven (2012). Patterning in procurement of obsidian in Chaco Canyon and in Chaco-era communities in New Mexico as revealed by X-ray fluorescence Journal of Archaeological Science, 39 (9), 2995-3007 DOI: 10.1016/j.jas.2012.04.032

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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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Whiteware Sherd at Una Vida

Pottery is the most important type of artifact for archaeology in the Southwest.  This is because the agricultural societies of the prehistoric Southwest made huge numbers of pots and often decorated them in distinctive ways that differed both from place to place and over time, often within quite short periods.  With the precision available from tree-ring dating, certain pottery types can be dated to remarkably short periods, in some cases consisting of less than 100 years, and those types in turn can be used to date unexcavated sites with no tree-ring dates of their own.  Differences in decoration over time are more obvious than differences among places for most periods, which is an interesting fact that probably deserves more attention than it has gotten.  Ceramic design styles changed at roughly the same times over amazingly large areas that in some cases don’t show any other evidence of substantial contact.  During the Chaco era, from about AD 1030 to 1130, the dominant design style throughout the northern Southwest used a lot of hachure, for example.  The specific types have different names, assigned to them by archaeologists working in different regions, and despite the general similarity in design these can be distinguished by distinctive aspects of their manufacture.  These include the type of clay used for the vessel (known as the “paste”), the presence and nature of an additional type of clay (the “slip”) put on top of the paste especially for painted types, the type of paint used, and the material used to temper the clay.  Tempering is the addition of some material to the paste to make it easier to work.  Almost all Southwestern pottery types are tempered, and the type of tempering material is one major way different regional wares are distinguished.

To make this more concrete, let’s look at the Cibola pottery tradition, to which Chaco’s pottery belongs.  There are two “wares” within this tradition: Cibola white ware and Cibola gray ware.  The gray ware is the “utility ware” used for cooking pots and other mundane vessels.  It is never painted, and when it has any type of decoration this typically consists of some sort of corrugation.  Types of corrugation vary over time.  During the height of the Chaco era, the dominant type was corrugation all over the vessel, whereas in earlier times only the neck would be corrugated.  Corrugated sherds are very common at Chacoan sites, because these vessels were made in large numbers, broke frequently from heavy use, and were mostly large jars that broke into many pieces.  Vessels forms are almost entirely jars rather than bowls.  Temper is typically either sand (in some cases probably from ground-up sandstone) or ground-up sherds.

Black-on-white Sherd at Pueblo Alto

Cibola white ware is more complicated.  This is the main “decorated” ware made at Chaco and in the area to the south of it.  These vessels have the same sand- or sherd-tempered gray paste as the gray wares, but the decorated surface also has a white slip that gives vessel a white appearance from the exterior.  The slips are thin and often applied in a sort of “washy” manner, and in some cases the gray paste can be seen beneath them.  Designs are painted on with mineral-based paint (usually made with iron oxide), at least until about AD 1100.  Forms are both jars and bowls.  Jars are decorated on the exterior, while bowls are usually decorated on the interior.

Similar gray and white wares are present for most other regions during the same period.  San Juan gray and white wares were made north of the San Juan River and are distinguished primarily by the use of crushed volcanic rock rather than sand or sherds as temper.  The white slips on the white ware are also thicker and often highly polished.  To the west, in the Kayenta area, white wares were generally painted with organic (carbon-based) paints, and over time this practice spread eastward, until after 1100 it was common in the Cibola and San Juan areas as well.

Chuska Mountains from Peñasco Blanco

A particularly important ceramic area for understanding the Chaco system is the Chuska Mountain area to the west, along the Arizona-New Mexico border.  In regional ceramic terms this area basically separates the Cibola and Kayenta traditions, and in some ways it was transitional between the two.  Chuskan potters adopted carbon paint earlier than those in the Cibola and San Juan areas, so imported white wares from the Chuskas to Chaco are typically carbon-painted although the designs on them are generally the same as local types.  The thing that really distinguishes Chuska pottery, though, is temper.  Chuskan ceramics are nearly universally tempered with trachyte, a rare and very obvious type of volcanic rock that outcrops only in a small area in the Chuskas.  Trachyte-tempered pottery is therefore virtually guaranteed to have been imported from the Chuskas.

Why is this?  Because potters are generally thought to have used local materials for temper (and for clay, but pinpointing clay sources is much more difficult).  Designs might be similar over a wide area, but if the temper in a vessel is a material only found in a very restricted area, it’s virtually certain that the vessel was made near there.  Unfortunately, most of the materials used for temper in the Southwest are very widespread; there’s sand everywhere, sherds would be present wherever anyone had broken pottery (so, again, everywhere), and the types of volcanic rock used in the San Juan region were quite widespread.  Luckily, however, trachyte-tempered Chuska pottery is an exception to this, which makes it very easy to identify imports from the Chuska area at Chaco and elsewhere.

Corrugated Grayware Sherd at Wijiji

There are other ways to determine the source areas for pottery.  X-ray fluorescence (XRF) and instrumental neutron activation analysis (INAA) are two widely-used methods of determining clay sources by the concentrations of trace elements in sherds, but they are very expensive and the results can be difficult to interpret.  Some studies using these techniques have been done in the Southwest, and a database of element concentrations for different source areas is beginning to develop.  At Chaco, however, analysis of pottery sources has so far depended primarily on the more traditional techniques of looking at paint, slip, and especially temper.  The biggest study was that done in connection with the Chaco Project, the results of which were presented in a 1997 publication by Wolky Toll and Peter McKenna (available on the Chaco Archive website).  Some of the data from this study was also used by Toll in his 2001 article that I have discussed before.

In brief, what Toll and McKenna found was that the Chacoans imported a lot of pottery.  The amounts of imports and their sources varied over time, however.  Imports were relatively rare before AD 800, making up 16.6% of the sample, but they came from a variety of sources, including the Chuskas, the San Juan region, and the Mogollon region to the south, which has very distinctive brownwares that are obvious imports when they appear.  Trachyte temper is only present in 3.6% of the total sample.  The period from 800 to 920 has a rather small sample from the Chaco Project excavations, but an increase in imported ceramics is apparent, with 28.1% imports and 9.7% trachyte-tempered.  The most common non-local temper, however, was chalcedonic sandstone, thought to come from the area to the south of Chaco, which comprised 13.2% of the ceramics from this period.  This is consistent with other evidence for intense contact with the area to the south at this time.

Pots from Early Periods at Chaco Museum

From 920 to 1040, overall imports drop slightly to 25.1%.  Chalcedonic sandstone drops to 7.9%, while trachyte rises to 12.3%, the highest percentage for any specific type of import.  This trend continues in the following period, from 1040 to 1100, which corresponds to the height of the Chaco system and the construction of most of the great houses in the canyon.  The overall percentage of imports rises to 39.8%, with almost all of that (30.7%) being trachyte-tempered.  It’s well-known that many other goods were being imported from the Chuskas at this time, especially wood, so it’s not surprising that Chuskan pottery would also have been popular.  There were a lot of Chacoan great houses and communities in the Chuska area, which seems to have been closely integrated into the overall Chacoan system, perhaps to a greater degree than other “outlying” areas.  The shift from south to west in the focus of the system seen in the pottery data is echoed in other types of evidence from this period.

The trend toward higher imports reaches a peak in the 1100 to 1200 period, which includes the end of Chaco’s regional dominance (but perhaps also its peak).  Imports constitute an astonishing 50.4% of all the ceramics from this period, and trachyte-tempered pots comprised 31.3%, a gain in overall percentage from the previous period but a loss relative to other imported types.  Chalcedonic sandstone continued to decline, while Kayenta wares increased to 4.8% after never having exceeded 1% before.  It’s important to note, however, that the sample from this period is much smaller than that for the previous period and it may not be totally representative.  The last period, from 1200 on, has a very small sample but continues to show a high percentage of overall imports (45.7%).  Trachyte drops to 21.6%, and San Juan wares skyrocket to 16.4% after never having exceeded 5% before.  This shift to the north for ceramic sources surely has to do with the relative decline of Chaco in this period and the rise of centers to the north, especially Aztec, which probably succeeded Chaco as the center of whatever Chaco had been the center of.  This is also the period during which Mesa Verde became a major population center, but despite the fact that the main decorated white ware type is known as “Mesa Verde Black-on-white” it’s unlikely that many of the San Juan wares found at Chaco came from Mesa Verde itself.  It’s much more likely that they came from Aztec or elsewhere in the Totah area, which had much closer ties to Chaco than Mesa Verde proper ever had.

Pots from Later Periods at Chaco Museum

So basically, the pattern that emerges from the ceramic data is of a shift in imports from the south to the west as the Chaco system really got going, followed by a shift to the north as it faltered or changed.  This is paralleled in other types of artifacts, as well as in settlement patterns.  The outlying communities to the south in the Red Mesa Valley were being abandoned in the late eleventh century even as new outliers like Salmon were being built to the north.  There are enough lines of evidence pointing in this direction to suggest that it corresponds to something real, but it’s hard to say what exactly was going on and why.

It’s also important to note the weaknesses in this analysis.  Remember, this is Chaco Project data.  It doesn’t include any of the pottery excavated from Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo, or any other sites excavated prior to the 1970s.  It also has a heavy bias toward data from Pueblo Alto, which as I’ve mentioned before can be problematic in overall interpretations of Chaco.  However, at least the heavy importation of Chuska wares does seem to be supported by data from Pueblo Bonito.  Anna Shepard, the ceramic analyst who pioneered many of the techniques that are now standard in the Southwest, analyzed the sherds from Neil Judd’s excavations at Bonito in the 1920s and concluded that many of them were imported from the Chuskas based on the presence of trachyte temper.  Judd, who was heavily devoted to the currently prevailing notion that Pueblos were self-sufficient for utilitarian goods like pottery, was so skeptical of this finding that he actually wrote a rebuttal to Shepard’s analysis and published both in his report.  As it turns out, however, Shepard was right, and ahead of her time, in seeing substantial importation of pottery to Chaco.

Corrugated Grayware Sherds at Kin Ya'a

Of course, this leaves open the question of why the Chacoans would have imported so much pottery.  Was it due to a shortage of materials?  Surely there was no shortage of clay or sand; Chaco may be lacking in most resources, but it has virtually inexhaustible supplies of clay and sand.  Wolky Toll is inclined to think that a shortage of fuel for firing may have been a factor, and that the heavily forested Chuskas may have been a better place to find fuel and thus to make pots.  Certainly local wood resources in the sparsely wooded area around Chaco would have run out quite quickly what with all the monumental construction, but I don’t really buy this.  Wood isn’t the only type of fuel you can use to make fires.  There is plenty of evidence that the Chacoans burned corncobs and other material in their domestic hearths, and Toll and McKenna refer in their report to an apparent pottery production location in the Chuskas, dating to Basketmaker III times, that was not near wood sources but did have “complex hearths with substantial fuel waste build up (primarily corn stalks).”

So if not for lack of fuel, why all the imports?  One clue may come from the types of vessels imported.  The Chuska imports were primarily gray ware utility vessels, which were used for cooking.  It has been proposed that trachyte provides better resilience to thermal shock from repeated heating and cooling than other tempers, and Chuska vessels may thus have been higher-quality cooking pots than other local or imported vessels.  (Similar arguments have been made for the superiority of corrugated pots as compared to plainwares.)  This is certainly possible, but in light of the numerous other Chuskan imports it’s not really clear to me that functional considerations were primary determinants of Chacoan trade patterns.  Maybe the Chacoans just had particularly close social and political ties to Chuskan communities, and that led to closer economic ties.  A lot of this depends on the nature of the Chaco system, which of course we don’t know much about.

In any case, the large-scale importation of pottery is one of the most striking examples of how Chaco was very much at the center of a regional system.  We may not know what that system was, exactly, or how it functioned, but we can see that it existed.  The evidence is right there in all those potsherds that litter the ground around the sites in the canyon.
Toll, H. (2001). Making and Breaking Pots in the Chaco World American Antiquity, 66 (1) DOI: 10.2307/2694318

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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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