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Other DNA Discoveries

Plaque Commemorating the Founding of Harvard College, Cambridge, Massachusetts

Plaque Commemorating the Founding of Harvard College, Cambridge, Massachusetts

I’m still working on the follow-up to my DNA post, but in the meantime I’ve seen a few new reports of interesting research in other parts of the world using techniques similar to what I was talking about. This will provide some context for the Southwest-specific research I’ll discuss later, which is still at a much more rudimentary level that hasn’t yet produced such striking results.

First, commenter ohwilleke, in addition to leaving a long and informative comment about analytical techniques and the usefulness of full-genome sequencing as opposed to mitochondrial studies, points to a recent study of modern inhabitants of Rapanui (Easter Island) that shows clear evidence of prehistoric genetic mixture with people from South America. There have long been theories that there was contact between these populations, but this appears to confirm them with the most solid evidence yet, and provides another glimpse of the complexity of human history. (I’ll address the issue of full genomic sequencing, which has not yet been used on any ancient remains from the Southwest to my knowledge, in the follow-up post.)

Second, there have apparently been two new articles (only one of which I could find, since the news story doesn’t even give the title of the journal the other one was published in) using aDNA techniques on ancient remains from Europe. One study, by a large team including David Reich of Harvard Medical School, found three major sources of ancestry for ancient Europeans: early hunter-gatherers, presumably of African origin; early farmers of Near Eastern origin (which seems to strongly support theories that the spread of agriculture across Europe had migration of people as an important component) who apparently interbred with the hunter-gatherer population to some extent; and a previously unknown group with links to Central Asia and possibly associated with the introduction of Bronze Age material culture. The second study, which looked at remains from later dates than the first, appears to have also found a fourth group that entered eastern Europe during the Iron Age.

Finally, reaching back to a much earlier date, a bone found in a riverbank in Siberia yielded the oldest human genome sequenced to date. Radiocarbon-dated to between 43,000 and 47,000 years ago, the genome is particularly noteworthy because it contains a higher proportion of segments of Neanderthal origin than modern human genomes, which apparently has important implications for theories about the initial peopling of the world by modern humans.

Now, I don’t have access to any of these papers so I haven’t read any of them myself. My comments about them are based on the abstracts and the coverage they’ve gotten in the media, which is of course notoriously unreliable when it comes to highly technical subjects. Still, this should give a sense of the kinds of topics DNA studies are weighing in on. As I said before, DNA research in the Southwest is still at a much more rudimentary level, so don’t expect to see this kind of thing any time soon. It is developing, though, and has great potential to answer important questions of archaeological interest. I’ll explain more about the work that has been done in the next post.

The Evidence from DNA

Dorset Culture Exhibit, Carnegie Museum, Pittsburgh,  Pennsylvania

Dorset Culture Exhibit, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania

To wrap up my series on tracing the connections between ancient Pueblo sites like Chaco Canyon and the modern Pueblos, I’d like to discuss a type of evidence I haven’t discussed much but that people often ask about: DNA evidence. This is the most direct way to tie one population to another, at least in theory, but it’s actually quite difficult to draw any specific conclusions from the work that has been done so far, and that’s not necessarily going to improve as more research is done. Which is not to say that research along these lines has been worthless; it hasn’t revealed anything inconsistent with data from other sources so far, but that in itself is interesting and provides support for the other approaches that have been tried. Because this is such a huge and important topic, I’ve decided to break my discussion of it into two posts, one on the archaeological study of DNA in general, and another on the application of these techniques to the Southwest in particular.

There are many different types of DNA analyses that can in theory be done, but when it comes to archaeological questions, especially those involving connections between ancient sites and modern people, it is generally necessary to analyze remains excavated by archaeologists. This involves studying what is known as “ancient DNA” (or “aDNA” for short), in addition to the DNA of modern populations. As Connie Mulligan of the University of Florida noted in an article published in American Antiquity in 2006, aDNA studies have a lot of potential but also a lot of challenges. Some of the major issues involved in aDNA research are preservation of the DNA, without which any study has no chance of success, and interpretation of the results of a successful analysis of ancient material.

Because DNA, like any other organic material, decays over time, aDNA studies are more difficult and expensive than DNA studies of modern populations, and in some cases there is simply not enough DNA left in archaeological material to do any analysis at all. Preservation is a function, in part, of local environmental conditions, which in the arid Southwest tend to be favorable for preserving organic material, so this is less of a concern in this area than in many others.

Another major consideration in doing aDNA analysis is contamination. The technique that makes aDNA analysis possible is called Polymerase Chain Reaction (PCR), which involves taking a small amount of DNA and exposing it to a chemical reaction that creates billions of copies which can then be analyzed. This can be enormously useful, but the reaction is very sensitive and if any extraneous organic material is introduced it is likely to reproduce its DNA instead of the ancient DNA, which can totally destroy the validity of the analysis. The main concern with aDNA analyses of human remains is modern human DNA from the researchers themselves, and this has been an issue with many studies. These days the major laboratories that do aDNA analysis have elaborate procedures to ensure that modern human DNA doesn’t contaminate their samples, and these are typically spelled out in the papers resulting from this research.

Furthermore, as Mulligan discusses, it’s important that researchers have a clear sense of what questions they are asking and how successful aDNA analyses are likely to be in answering them. For example, DNA analysis is unlikely to be able to unambiguously identify a given set of ancient remains as belonging (or ancestral) to a specific tribal group, since genetic affiliation doesn’t correlate with cultural identity at anything close to that level of specificity. In other words, aDNA analysis can potentially identify remains as being of Native American rather than European origin, but it can’t unambiguously identify remains with any particular modern tribe. On the other hand, it is potentially possible to use aDNA studies to identify migrations and population replacement in the past, if the groups in question are sufficiently distinct genetically. Mulligan actually uses an example from the prehistoric Southwest, which I’ll discuss further in the next post, to illustrate how it can be tricky to interpret differences in genetic characteristics between populations, especially at the level of detail at which these analyses are often conducted.

These concerns aside, DNA analysis can certainly be a  powerful tool for understanding the past, especially when aDNA studies can be integrated with studies of modern DNA. A great example of this is a study that was recently published in Science about the prehistory of the North American Arctic. In this paper, which is available free on the Science website, the researchers report on a combination of aDNA and modern DNA analyses that demonstrate clearly that the people of the mysterious Dorset culture that inhabited Arctic Canada and Greenland from about 800 BC to AD 1300 are not ancestral to the modern Inuit inhabiting the same area, who are instead descended from the people of the Thule culture who immigrated into Canada from northern Alaska around AD 1200. This is solid, careful research that shows what DNA studies can reveal about the human past.

Much of the aDNA research in the Americas has focused on mitochondrial DNA (mtDNA), which is contained in the mitochondria of each cell, as opposed to nuclear DNA, which is contained in the cell nucleus. There are two main reasons for this.

One is that mitochondrial DNA is passed on (generally) unchanged through the maternal line, as opposed to nuclear DNA which undergoes meiosis, the process by which DNA from the mother and father is recombined in the course of creating a new embryo, meaning that any part of the genome that has gone through it cannot be easily traced from generation to generation. Mitochondrial DNA, in contrast, is passed on directly from mother to child, and the only changes are whatever mutations develop over time, which can be used to define specific haplogroups, or genetic groupings sharing certain distinctive mutations that are interpreted as indicating shared descent. Within each haplogroup, further mutations can be used to define various sub-haplogroups, which indicate closer relationship among the haplotypes (individual genetic profiles) that comprise them. The Y chromosome, which is passed on directly from father to son, isn’t affected by recombination during meiosis and can be used to trace descent in a similar fashion. However, mtDNA is more widely used for aDNA studies than Y-chromosome DNA, due to an additional difference between mtDNA and nuclear DNA.  Due to the structure of mitochondria, each cell contains many more copies of its mtDNA than of its nuclear DNA, so mtDNA is much more likely to survive in ancient samples than nuclear DNA. This means there is much greater probability that studies of mtDNA using PCR will identify DNA to be replicated, and the result is that the existing database of mtDNA available for statistical analysis is much larger than that for nuclear DNA, including  Y-chromosome DNA. Most aDNA studies in North America, at least, have therefore used mtDNA as a primary focus for research.

Early research on both ancient and modern DNA identified four main mitochondrial haplogroups among Native American populations. These were labeled A, B, C, and D. (Haplogroups are conventionally identified by capital letters, with more specific sub-haplogroups indicated by sequences of numbers and lowercase letters following the haplogroup letter.) These haplogroups all arose from earlier East Asian haplogroups, which agrees with the traditional interpretation that Native Americans descend from Asian groups that migrated across the Bering Strait. Some modern populations in these early studies showed low levels of an additional haplogroup, X, which had previously only been documented in Europeans. There was some question at first about whether this indicated post-Contact admixture with Europeans or an additional “founding” haplogroup, but it was later found in aDNA, showing clearly that it was indeed ancient in the Americas. The implications of this finding are hard to understand, but the general consensus at this point seems to be that the American examples descend from a very ancient and otherwise unknown Central Asian offshoot of the European X haplogroup. Wherever it came from, however, it is now quite clear that X is one of the founding haplogroups in the Americas.

Much aDNA research in North America, then, has focused on identifying the haplogroups of ancient remains and comparing them to those of other populations, both ancient and modern. Much of this research has involved treating assemblages of ancient remains (either from single sites or across a whole archaeological “culture”) as samples that can be compared statistically to samples from modern tribes. I find this dubious, since the ancient samples are typically small and there’s no way to tell how representative they are of the actual underlying population (however it’s defined). The statistical procedures often used to analyze haplogroup frequencies implicitly assume that these are random samples representative of the population, but there’s no real way to know if this is true and in most cases no particular reason to think it is. In theory it’s possible that the modern samples, at least, are representative of their populations, but I suspect it’s often not the case in practice here either. For both modern and ancient samples, it’s likely that other factors, such as level of preservation and willingness to provide samples, have strongly affected the composition of the samples. These factors may or may not have skewed the representativeness of the samples; the point is that there’s no real way to tell.

Given this sampling issue, I think the most conservative and defensible approach is to treat haplogroup distributions as nominal-level data: the most we can really say about a given haplogroup in a given sample is whether it is present or absent. That’s not very helpful, though, and it may be reasonable to take a further leap and treat the distributions as ordinal-level data: this allows us to make use of the fact that some haplogroups are much more common in a given sample than others to make some broad conclusions about haplogroup distributions on a larger scale. What isn’t justified, however, is treating the frequencies of haplogroups in a sample as interval/ratio-level data: using the actual numbers as if they are meaningfully representative of the underlying population, and plugging them into elaborate statistical formulas to compare them to other samples/populations. Not all aDNA studies do this sort of thing, but it’s common enough that I think it’s important to emphasize that it’s a problematic approach at best, and that any conclusions regarding probable relationships between populations based on this method shouldn’t be taken very seriously.

A better way to go beyond the crude data of haplogroup assignment is to sequence additional portions of the mitochondrial genome that are known to contain mutations that define sub-haplogroups within the assigned overall haplogroup. Enough research has been done at this point that quite a few sub-haplogroups are known, and when they show up in multiple samples, either ancient or modern, that provides a much firmer basis for hypothesizing meaningfully close relationships than statistical comparisons of haplogroup distributions among whole samples. Furthermore, since the mutations that define sub-haplogroups can be grouped hierarchically, it’s possible to construct trees showing how individuals in a given sample, or even across samples, that belong to the same haplogroup relate to each other. (Note that this isn’t quite the same as showing how the people were actually related, since we don’t know when the mutations that define these groups actually occurred or how the people whose remains were sampled were related to the people in whom the mutations originally occurred.) There’s a probabilistic aspect to this type of evidence, since there are multiple ways a particular set of mutations could have ended up together in the same haplotype, and determining the most likely sequence of events can require modeling and simulation. The more samples are analyzed, the larger the database of known mutations and sub-haplogroups becomes, and the more reliable the conclusions that can be drawn about relationships are.

So that’s the basic outline of how ancient DNA analysis works and the methodological concerns that need to be kept in mind when evaluating it. In the next post, we’ll look at some of the specific studies that have applied these methods to the Southwest, and what their results can and can’t tell us about Southwestern prehistory.
ResearchBlogging.org
Mulligan, C. (2006). Anthropological Applications of Ancient DNA: Problems and Prospects American Antiquity, 71 (2) DOI: 10.2307/40035909

Raghavan, M., DeGiorgio, M., Albrechtsen, A., Moltke, I., Skoglund, P., Korneliussen, T., Gronnow, B., Appelt, M., Gullov, H., Friesen, T., Fitzhugh, W., Malmstrom, H., Rasmussen, S., Olsen, J., Melchior, L., Fuller, B., Fahrni, S., Stafford, T., Grimes, V., Renouf, M., Cybulski, J., Lynnerup, N., Lahr, M., Britton, K., Knecht, R., Arneborg, J., Metspalu, M., Cornejo, O., Malaspinas, A., Wang, Y., Rasmussen, M., Raghavan, V., Hansen, T., Khusnutdinova, E., Pierre, T., Dneprovsky, K., Andreasen, C., Lange, H., Hayes, M., Coltrain, J., Spitsyn, V., Gotherstrom, A., Orlando, L., Kivisild, T., Villems, R., Crawford, M., Nielsen, F., Dissing, J., Heinemeier, J., Meldgaard, M., Bustamante, C., O’Rourke, D., Jakobsson, M., Gilbert, M., Nielsen, R., & Willerslev, E. (2014). The genetic prehistory of the New World Arctic Science, 345 (6200), 1255832-1255832 DOI: 10.1126/science.1255832

Primary Sources: Free!

Smithsonian Institution, National Museum of National History

Smithsonian Institution, National Museum of Natural History, Washington, DC

I’ve been diligently working on the DNA post, but it looks like I may not be able to finish it tonight, and I’d hate to let a whole month go by without a post. So I’ll just do a quick post here to mention some resources I’ve recently found where the full text of important primary sources on Southwestern archaeology are available for free. Keep in mind that in general these are just scans of the print documents converted to PDFs, which means the files are very large and can take a long time to download.

First, the Smithsonian has done a lot of work recently on digitizing its old publications, but they aren’t very easy to find. The publications most relevant to archaeology are the Smithsonian Miscellaneous Collections and the Bulletins of the Bureau of American Ethnology, both of which are available in the Biodiversity Heritage Library. The BAE Bulletins are listed under Bulletin / Smithsonian Institution, Bureau of American Ethnology, while Miscellaneous Collections are listed under Smithsonian miscellaneous collections. Both of these series include important primary sources on Southwestern archaeology, including Neil Judd’s reports on Pueblo Bonito and Pueblo del Arroyo in the Miscellaneous collections and Frank H. H. Roberts’s reports on Shabik’eshchee, Kiatuthlanna, and the Village of the Great Kivas in the BAE Bulletins. The Bulletins in particular also include a huge amount of other research on American anthropology, and it’s really amazing to have all that available for free online. There’s probably other useful stuff in the Biodiversity Heritage Library that I haven’t found yet; its collections go well beyond the Smithsonian publications.

Secondly, the American Museum of Natural History in New York has put its Anthropological Papers online. The most important of these for Chacoan purposes are George Pepper’s report on Pueblo Bonito and Earl Morris’s reports on Aztec Ruin. Again, there are a lot of other reports of general anthropological interest in this series, so it’s well worth checking out.

Since these documents are generally scans of printed versions, many of them hundreds of pages long, the files are huge and may take a long time to download. It’s also important to note that these are not popularizations of research in any sense; they really are original reports, and are likely to strike the general reader as quite dry. For those of us with a serious interest in the details of this research, however, they are both fascinating and invaluable, and I applaud their publishers for making them available.

Old Bonito from Above

Old Bonito from Above, Including Northern Burial Rooms

So far in this series of posts on “tracing the connections” between ancient Pueblo sites like Chaco Canyon and modern Pueblos, I’ve discussed evidence from linguistics and folklore, but of course if the issue is determining which modern groups are physically descended from which ancient ones it’s hard to beat evidence from actual physical remains. Physical anthropology has been somewhat less emphasized in the history of Southwestern anthropology, especially compared to archaeology and ethnography, but there has been a fair amount of this kind of research over the years and it is clearly at least potentially useful in answering these questions.

These days when people talk about physical evidence of genetic connections they often mean DNA, and there have been several interesting recent studies of the DNA of both ancient and modern Southwestern populations that are relevant to my present concern. That topic deserves its own post, however (which I am working on), so for now I’m going to focus on a more “traditional” type of physical anthropological study: the statistical comparison of skull features and measurements.

This sort of study generally takes the form of measuring various attributes of skulls from different archaeological excavations and comparing them statistically to see which ones pattern together. (There are also studies of non-metric features that work somewhat differently, but here I’m going to focus on studies of metric features.) I’m always a bit dubious about the relevance of these studies, since I’m not sure how clear it is that the traits they’re measuring really do correlate with genetic relatedness, but this is a well-established and longstanding field of inquiry so for now I’ll take it as given that the underlying theoretical assumptions are well-founded.

Old Bonito from West Plaza Showing Plaza Kivas in Foreground

Old Bonito from West Plaza Showing Plaza Kivas in Foreground

Turning to Chaco specifically, the most influential studies along these lines are those done by Nancy Akins as part of the Chaco Project in the 1970s and 1980s. It was her work that famously concluded that the two main burial populations in Pueblo Bonito, in the northern and western parts of the site, were most similar not to each other but to two different small house sites elsewhere in the canyon. This was an important finding, in that it implied that the population inhabiting the canyon in its heyday was physically diverse in ways that didn’t necessarily pattern with geographical settlement patterns. This in turn implies that there may have substantial diversity in ethnic and linguistic backgrounds among different Chaco residents as well, an implication that some other lines of evidence also support.

Akins only compared populations from within Chaco Canyon, however. To evaluate the connections between Chaco and later Pueblo sites, comparable measurements needed to be made of remains from later Pueblo sites and compared to Akins’s Chaco data. The most extensive study along these lines that I know of is in a short article by Michael Schillaci and Christopher Stojanowski published in 2002. Interestingly, this article was actually a comment on an earlier article by Peter Peregrine arguing that Chacoan society was matrilocal based in part on the fact that some modern Pueblo groups, such as the Hopis and Zunis, are matrilocal. (Matrilocality is the practice of newly married couples living with the wife’s parents, and it is apparently very uncommon cross-culturally compared to patrilocality, where couples live with the husband’s parents.)

Schillaci and Stojanowski argue that while it’s certainly possible that the matrilocal western Pueblos of Hopi and Zuni are descended in part from the Chacoans, it’s not at all obvious that they have a better claim to such descent than the eastern Pueblos of the Rio Grande Valley, which are generally either patrilocal or bilocal (couples live with either set of parents). To test this idea, they take Akins’s data from Chaco and compare it to measurements made according to the same protocol on several other contemporaneous and later Pueblo populations. These include Village of the Great Kivas, a Chacoan outlier in the Zuni area, as well as Hawikku, a much later ancestral Zuni site. They also include several samples from the Rio Grande area, both contemporary with Chaco and later.

As expected from Akins’s results, Schillaci and Stojanowski found that the different samples from Chaco don’t particularly pattern with each other. Interestingly, in their analysis the northern burials at Pueblo Bonito stand somewhat apart from all the other samples. This could potentially be evidence that these, the richest burials ever found in the Pueblo Southwest, represent a group that was genetically distinct from most other Southwestern populations, but it’s important to keep in mind that the number of samples being compared here is relatively small and there’s no way to know how representative it is, so sampling error is always a strong possibility when patterns like this show up. (Other studies have found that these remains are well within the range of variation typical of Southwestern populations, so the fact that they stand apart from the other groups in this study probably doesn’t imply that they were immigrants from outside the region or anything.)

Western Burial Rooms in Old Bonito

Western Burial Rooms in Old Bonito

Of the other Chaco samples, the western burials at Pueblo Bonito cluster most closely with those from both Hawikku and the ancestral Tewa site of Puye in the Rio Grande Valley. The burials from the small sites in the Fajada Butte area at Chaco pattern most closely with the ancestral Tewa site of Tsankawi, and in fact these two form a somewhat distinct group compared to most of the other samples. Finally, the burials from the small sites of Bc 51 and Bc 53, on the south side of the canyon across from Pueblo Bonito, pattern closely with those from Picuris, a Northern Tiwa Pueblo which is still occupied, as well as with those from the ancestral Tewa sites of Sapawe and Pindi.

Schillaci and Stojanowski conclude from this that there is no good reason to conclude that Chacoan society was matrilocal based on the practices of the likely descendants of the Chacoans, among whom they have identified both eastern and western Pueblos practicing various forms of postmarital residence. They do acknowledge that they weren’t able to include any Hopi samples in the analysis, so the western Pueblos are represented only by the two Zuni-area sites, which leaves open the possibility that the Hopis are closely connected to Chaco, which would strengthen Peregrine’s position and weaken theirs. On the other hand, other lines of evidence suggested somewhat weaker ties to Chaco among the Hopis than among most other modern Pueblos, so this probably isn’t a major problem. In his response, Peregrine notes the possibility that bilocality among the eastern Pueblos is a post-contact development related to declining population and therefore not necessarily relevant to the prehistoric evidence. He doesn’t challenge the overall validity of the analysis, however, which is our main concern here.

This is an interesting study, and it identifies some later sites with at least a high probability of including people descended from the Chacoans, but the facts that these sites don’t particularly pattern with each other and that there was considerable diversity within Chaco itself point to how complicated the picture seems to be. Overall, this evidence seems to support the idea that most of the modern Pueblos include at least some people who are descended from the Chacoans, and it provides particular support for such ties among the Zuni, Tewa, and Northern Tiwa. It also supports the previously existing evidence for considerable population diversity at Chaco itself. As we’ll see in the next post, this is not very different from where the DNA evidence leads.
ResearchBlogging.org
Schillaci, M., & Stojanowski, C. (2002). A Reassessment of Matrilocality in Chacoan Culture American Antiquity, 67 (2) DOI: 10.2307/2694571

Southeast Corner of Pueblo Bonito

Southeast Corner of Pueblo Bonito

Today is the summer solstice, on which I typically make posts about archaeoastronomy, so I’m going to take a break from my very gradual series of posts on tracing the connections between ancient and modern Pueblos to speculate a bit about the role of astronomy at Chaco. Briefly, what I’m proposing is that the rise of Chaco as a regional center could have been due to it being the first place in the Southwest to develop detailed, precise knowledge of the movements of heavenly bodies (especially the sun and moon), which allowed Chacoan religious leaders to develop an elaborate ceremonial calendar with rituals that proved attractive enough to other groups in the region to give the canyon immense religious prestige. This would have drawn many people from the surrounding area to Chaco, either on short-term pilgrimages or permanently, which in turn would have given Chacoan political elites (who may or may not have been the same people as the religious leaders) the economic base to project political and/or military power throughout a large area, and cultural influence even further.

I don’t have any specific research papers to discuss on this topic because as far as I know no one has really looked at it quite this way. It’s similar in some respects to the theories of the Solstice Project, although I don’t buy that astronomical alignments were quite as important in the Chacoan system as they propose. There is also some overlap with the theories of various archaeologists, but none of them have put the pieces together in quite this way. This may be because it’s demonstrably wrong, but if it is I haven’t seen the evidence that disproves it yet (but would be very interesting in doing so).

This theory first occurred to me when I was reading about Tiwanaku in Bolivia, which was a prehistoric society that, like Chaco, left very impressive physical remains in a very isolated location with few obvious economic advantages. As I noted in my post on Tiwanaku, the similarities actually go well beyond that, extending also to the shifting interpretations by archaeologists and the evidence for astronomical alignments. Most relevant in this context is the theory of John Janusek at Vanderbilt, whose theory of Tiwanaku is the model for the theory I’m suggesting here for Chaco. As he wrote in one paper, which I also quoted in the earlier post:

Tiwanaku’s long rise to power in the Andean altiplano was predicated on the integration of diverse local ritual cults and various symbolic dimensions of the natural environment into a reasonably coherent, supremely elegant and powerfully predictive religion. The shifting physicality of Tiwanaku’s religious monuments attests the construction and ongoing transformation of an urban landscape that not only visually expressed the altiplano’s ‘natural’ forces and cycles, but, via recurring construction and ritual, simultaneously shaped new social practices and Tiwanaku’s ever-increasing political influence and productive coordination, intensification and expansion. Tiwanaku was an imperfect and potentially volatile integration of religious cults, productive enterprises and societies. The material objectification of a seductive religious ideology that infused the monumental centre with numinous natural forces and simultaneously projected those forces across distant Andean realms helped drive Tiwanaku’s very worldly imperial mission.

Tiwanaku was apparently the first society in the altiplano to develop the level of astronomical skill which allowed it to develop such a “powerfully predictive” religion, and my application of a similar theory to Chaco relies on it also being the first place that developed a comparable knowledge of astronomy in the Southwest. I hadn’t really thought about this before reading Janusek’s work, but as far as I can tell it does in fact seem to be the case. Ray Williamson’s somewhat dated but still very useful book on Native North American astronomy (which I reviewed here) doesn’t mention any evidence of Southwestern astronomical knowledge predating Chaco, and I haven’t seen any other publications that do either. Granted, some of the evidence for astronomical evidence comes from rock art which is difficult or impossible to date, but at least when it comes to building alignments, which are more securely datable, the Chacoan great houses seem to be the earliest manifestation of detailed astronomical knowledge. Some earlier sites do show general alignments to cardinal directions and so forth, but the precise alignments to solstices and lunar standstills that are characteristic of Chacoan buildings do really seem to be innovative. I’m not totally certain that there aren’t counterexamples out there, though, so if anyone knows of any I’m very interested in hearing about them.

If this is in fact the case, it opens up several additional lines of inquiry. First, if Chaco was in fact the first place in the (northern?) Southwest to attain detailed astronomical knowledge, where did that knowledge come from? Many discussions of Chacoan astronomy have assumed, implicitly or explicitly, that the answer is “Mexico,” but I’m not so sure. There is definitely extensive evidence of contact with Mesoamerica at Chaco, but it’s all fairly indirect and there are lots of important aspects of Mesoamerican culture that are noticeably lacking. Mesoamerican astronomical knowledge was certainly impressive, and certainly predates the rise of Chaco, but given the general context I think it’s still an open question whether the Chacoans got their knowledge from contacts to the south (either directly or via the Hohokam and/or Mogollon) or developed it independently. This is an area that would definitely benefit from further study.

Secondly, why Chaco rather than somewhere else in the region? This is sort of the key question hanging over everything about Chaco, and so far no one has come up with a broadly convincing answer. I don’t have one either; the astronomy theory I’m proposing here answers the “how” of Chaco but not the “why.” It could be that, as some archaeologists have proposed, the physical setting of the canyon had unique attributes within the region that contributed to its ritual importance from an early period, which from my perspective would have provided the impetus for the development and/or integration of new astronomical knowledge into existing belief systems. Alternatively, as other archaeologists have argued, there could have been economic advantages to the location, which are not obvious to modern eyes but were sufficient to give Chaco an important role in the region, which may have made it a promising place for new ideas to develop or be introduced. And finally, maybe it’s all just a matter of historical contingency: this was where people happened to figure this stuff out, and that’s what made it attractive to others for both religious and economic reasons.

Another question is when this would have happened. Chaco was occupied for hundreds of years, but its florescence as a regional center was relatively brief, lasting roughly a century from AD 1030 to 1130 or so. One natural conclusion would be that the development of new astronomical knowledge happened at the start of this period, but I suspect it actually began earlier, probably during the period (roughly the late ninth and tenth centuries, or the late Pueblo I period) when Chaco was just one of several “proto-great-house” communities in the San Juan Basin that were more or less equal in size and influence. Over time, the advantages of the Chacoan rituals over the others would have become apparent, perhaps through fortuitous stretches of good weather and/or military successes by Chacoan warriors. This would have set the stage for Chacoan influence to expand on a vast scale during the eleventh century.

As the reference to military success in the previous paragraph suggests, I don’t see the expansion of Chacoan religious influence fueled by astronomical knowledge as having necessarily been entirely peaceful. Here again, the parallel to Tiwanaku is instructive. Note Janusek’s reference to Tiwanaku’s “very worldly imperial mission” in the quote above. I suspect what we would today see as “religious” and “secular” impulses were much more intertwined at Chaco, as indeed they have been shown to be in many societies.

All that said, I’m not totally convinced by this theory myself, and there are many strands of the Chacoan record that it doesn’t really seem to account for in an obvious way. I figured this was a good opportunity to toss it out there, though, to see whether it’s worth pursuing further.
ResearchBlogging.org
Janusek, J. (2006). The changing ‘nature’ of Tiwanaku religion and the rise of an Andean state World Archaeology, 38 (3), 469-492 DOI: 10.1080/00438240600813541

Original Plaster and Whitewash at Chetro Ketl

Original Plaster and Whitewash at Chetro Ketl

Given the obvious continuity in material culture between ancient and modern Pueblos, one potential source of information on the connections between prehistory and history in the region is the traditions of the modern Pueblos themselves. The florescence of Chaco was about 1000 years ago, so the events since then that led to the modern distribution of Pueblos are more recent than that, and potentially within the time depth for which the accuracy of oral traditions has been demonstrated in other parts of the world. Furthermore, the Pueblos do indeed have extensive oral traditions documenting how the various groups now residing in a given Pueblo got there, where they lived before, and what made them move. This seems on the face of it like an ideal situations, and indeed anthropologists at various points in the past hundred years or so have tried to match up the events in the oral traditions with what the archaeology shows. The efforts of Jesse Walter Fewkes with the Hopis in the early twentieth century, Florence Hawley Ellis with the Rio Grande Pueblos in the 1950s and 1960s, and various archaeologists associated with the Center for Desert Archaeology (now known as Archaeology Southwest) in the past few years with the western Pueblos are particularly noteworthy along these lines.

However, there are some big challenges to this type of work. First, it’s not clear how accurate the oral traditions are, and many anthropologists have distrusted them. Elsie Clews Parsons in the 1920s and 1930s pushed back strongly against the approach taken by Fewkes and others, pointing out that the traditions include many obviously mythical or legendary elements that must be brushed aside to treat them as “history” in the Western sense. Similarly, the rise of the “New Archaeology” in the 1960s and 1970s led to a tendency to downplay this kind of research on the archaeological side in favor of more “scientific” types of research focused on ecological factors. Lately the pendulum seems to be swinging back again, and many archaeologists as well as sociocultural anthropologists have begun to take oral traditions seriously as a source of information that can bridge the gap between prehistoric archaeology and the ethnographic present. Personally, I think these researchers are on the right track; the difficulties pointed out by Parsons and others are real, and the traditions can’t be accepted uncritically as fact, but they do very likely contain much information that is useful for historical reconstructions when interpreted carefully in context.

Pueblo Display at Chaco Visitor Center

Pueblo Display at Chaco Visitor Center

That more general issue aside, there are a lot of specific characteristics of the existing narratives that make them hard to work with, especially in the case of Chaco. For one thing, there aren’t that many of them that have been documented, and those that have overwhelmingly come from the western Pueblos of Hopi and, to a lesser extent, Zuni. The eastern Pueblos, which on geographical and other grounds are the ones most likely to have close ties to Chaco, have produced far fewer narratives, and those that are available are much less detailed and relevant. There are two main reasons for this, both stemming from the much more intense experience of Spanish colonization in these areas versus Hopi and Zuni:

  1. The Rio Grande Pueblos, especially, have been in such close contact with Spanish colonists that many traditions have been lost due to population loss and cultural change, and those that have been preserved have been influenced to some extent by European folklore elements. This is probably less of a concern with origin and migration stories than with more “informal” folktales.
  2. Due to the extreme repression of Native religion and culture by the Spanish missionaries, the eastern Pueblos are much more reluctant to share whatever traditions they have with white anthropologists than the western Pueblos are. This is probably the biggest reason for the lack of eastern Pueblo data, but its scale is impossible to estimate because we just don’t know how many traditions there are that have never been shared.

As a result of these two factors, we don’t have anything comparable to the extensive and detailed accounts of Hopi clan migrations that have been collected by numerous researchers, starting with Fewkes. There are a fair number of general creation stories from the eastern Pueblos, including those collected from the Tewa by Parsons and from Keresan Pueblos of Acoma and San Felipe by C. Daryll Forde and Ruth Bunzel respectively. These tend to be somewhat abbreviated, and sometimes also confusing in a way that suggests important parts have been omitted. Migration stories are much rarer, but a few have been recorded at least in a general fashion. George Pradt gave a brief overview of a western Keres migration tradition in introducing a story about Acoma:

THE oldest tradition of the people of Acoma and Laguna indicates that they lived on some island; that their homes were destroyed by tidal waves, earthquakes, and red-hot stones from the sky. They fled and landed on a low, swampy coast. From here they migrated to the northwest, and wherever they made a long stay they built a “White City” (Kush-kut-ret).

The fifth White City was built somewhere in southern Colorado or northern New Mexico. The people were obliged to leave it on account of cold, drought, and famine.

Now this is of obvious interest in discussing Chaco and Mesa Verde connections to modern Pueblos! The first part is of unclear relevance and likely has little or no historical content, but the part about moving around and building a series of communities, the last of which was in “southern Colorado or northern New Mexico” (i.e., north of Acoma and Laguna and in the general area of Chaco, Mesa Verde, and other important late prehistoric Pueblo sites), matches up pretty well with what is now known of the archaeological record. Furthermore, the “White City” or “White House” concept recurs in other Keres-speaking Pueblos as well. Here’s the San Felipe version recorded by Bunzel, starting just after the Emergence:

Then the people came out and walked towards the southwest. There they built a little town, Kackatrik (White House). This was their first village. Then from there came every nation. All the different kinds of Indians had their language and their songs and their ceremonies. There were many people there. Then the people were starving. There was no food to eat at this time. Then they had a meeting to talk about it. “Why are we starving?” all the head men said, “We have stayed here a long time. We should move on to some other place.” So then they started to move again. There were all different kinds of people, and they had all different kinds of languages. So then from there they scattered. Some went to the east and some went to the west, and some came through the middle.

Again, this is pretty consistent with the archaeology of Chaco, and to some extent of Mesa Verde as well. The “White House” story seems to be specific to the Keres, which implies a particularly strong connection between that groups and the ancient sites of the Four Corners, as many anthropologists have concluded. That’s not to say they were the only ones up there, however. There’s also evidence among some of the other groups’ traditions indicating an origin in this area.

White House/Black Market, Santa Fe, New Mexico

White House/Black Market, Santa Fe, New Mexico

For the Tewa, Scott Ortman has done extensive research using several lines of evidence, including what little is known of Tewa migration traditions, to conclude that Tewa-speakers migrated to the Rio Grande Valley from the Mesa Verde region. He has a new book, which I have not yet read, making this argument in detail. He could well be right, in which case there may have been both Keres- and Tewa-speakers in the Mesa Verde region, and perhaps at Chaco as well given the close but complicated ties between the two areas. This would be similar to the modern situation in the central part of the Rio Grande Valley, which is also divided between Keres- and Tewa-speaking Pueblos.There are also clear ties between Chaco and the Zuni area, which has an unusual degree of settlement continuity extending to modern times compared to other Pueblo areas, which may imply that Zuni-speakers were involved in Chaco as well. Ties to the Hopis are more tenuous despite the larger corpus of Hopi traditions, which tends to trace most Hopi clans to the south or west rather than the east (with the exception of clans from other Pueblo regions that moved to Hopi and became assimilated to Hopi culture fairly recently).

So, tentatively, the limited information available from oral traditions suggests particularly strong ties to the Four Corners among the Keres, which makes sense since they are still the closest Pueblos to the area geographically. There is some evidence for connections to the area among the Tewa and Zuni as well. Little is known about Tiwa or Towa (Jemez) traditions, but it is noteworthy that Jemez is the only Pueblo that has not claimed cultural affiliation with Chaco under NAGPRA, which implies strongly that Jemez traditions point to a different history. The Hopi connection seems to be more distant, and primarily through groups that were not originally Hopi-speaking but immigrated to Hopi from other areas further east in recent centuries and became assimilated over time.

I think there’s a lot of potential for further research along these lines, mostly using the scattered and fragmented eastern Pueblo traditions collected decades ago. Individually each of these may not be very enlightening, but piecing them together may reveal some useful connections. It’s very unlikely that any of these groups will reveal any more of their traditions to outsiders; many are still angry at the early anthropologists who recorded and published traditions revealed surreptitiously by individual community members at considerable personal risk. Parsons comes in for particularly harsh criticism for publishing the names of her informants in some of her early work. It’s possible that in the future the relationship between anthropologists and the eastern Pueblos will improve to the point where the Pueblos are more comfortable revealing information, but we’ve got a long way to go.
ResearchBlogging.org
Pradt, G. (1902). Shakok and Miochin: Origin of Summer and Winter The Journal of American Folklore, 15 (57) DOI: 10.2307/533476

Kachina Fast Tax, Winslow, Arizona

Kachina Fast Tax, Winslow, Arizona

As I mentioned in the last post, I don’t think the linguistic relationships among the modern Pueblo languages shed much light on the details of the relationships between ancient and modern Pueblo groups. However, that’s not to say that linguistics is totally useless in addressing this issue. There’s another type of linguistic evidence which has received less attention from researchers but has a lot of potential here: contact linguistics, especially loanword studies.

Due to the close historical connections and cultural similarities among the Pueblos, they form what linguists call a “Sprachbund”: a linguistic area where borrowing of both words and other linguistic features is common among unrelated (or distantly related) languages. Oddly, however, there hasn’t been a whole lot of study of this phenomenon among the Pueblos. Individual loanwords from one Pueblo language to another have been pointed out in descriptive accounts of the specific languages, and instances of unusual lexical or grammatical influence from one Pueblo language to another have been noted. There has been some research on loanwords from Spanish and English into various Pueblo languages (e.g., Hopi), mostly in the 1950s and 1960s when the process of acculturation was a major topic of anthropological interest. Nevertheless, there has still never been a systematic, comprehensive study of linguistic contact between Pueblo languages. My discussion here will therefore have to be limited to pointing out individual instances of contact that have been noted in the literature and suggesting possible implications for prehistoric relationships.

Known examples of loanwords tend to relate to ceremonial  concepts, and often are from Keres into other languages. For example, and of interest for the question of the origins of the kachina cult, the word kachina itself is apparently a loan from Keres into Hopi. That’s not necessarily evidence that the Keres originated the kachina cult, but it could be interpreted as evidence that they transmitted it to the Hopi, which would argue for an eastern rather than western origin for the cult. On the other hand, the Zuni word for “kachina,” koko, is apparently a loanword from a Piman language, which would seem to argue for a western origin of the cult, possibly even outside the Pueblo world itself. Teasing apart the implications of the various terms associated with the kachina cult in different languages would be a promising way to try to address the issue of origins, but it would be a huge and difficult task, and as far as I know no one has attempted it yet.

Similarly, I’ve previously mentioned Jane Hill’s argument from alleged Uto-Aztecan loanwords in Proto-Kiowa Tanoan that agriculture was introduced to the Southwest by migrants from the south speaking a Uto-Aztecan language. In that case the evidence for borrowing is more tenuous and less widely accepted than in the kachina case, but it’s still an interesting approach that could be fruitful if applied more broadly to both this and other puzzles of Southwestern prehistory.

It’s not clear if either of these examples sheds much light on Chaco or its relationship to the modern Pueblos, however. The introduction of agriculture, however it happened, was thousands of years before the era of the Chaco Phenomenon (although recent evidence has shown that agriculture at Chaco itself began much earlier than previously thought). The kachina cult, on the other hand, is generally thought to have originated in the post-Chacoan era, perhaps as one of many societal responses to the chaotic conditions in the aftermath of the decline of Chaco. There are some archaeologists who see some form of the kachina cult as having existed at Chaco, in which case the linguistic evidence about kachinas would be more important for understanding it, but I haven’t been convinced by their arguments.

So what can loanword and other linguistic contact evidence tell us about the relationship between Chaco and other prehistoric sites and the modern Pueblos? Given the limited research along these lines so far, not much. As I said above, though, there is still a lot of potential for studies of this issue, so I wanted to highlight it as a separate line of evidence from the more commonly used evidence from linguistic relationships.
ResearchBlogging.org
Dockstader, F. (1955). Spanish Loanwords in Hopi; A Preliminary Checklist International Journal of American Linguistics, 21 (2) DOI: 10.1086/464324

Hill, J. (2008). Northern Uto‐Aztecan and Kiowa‐Tanoan: Evidence of Contact between the Proto‐Languages? International Journal of American Linguistics, 74 (2), 155-188 DOI: 10.1086/587703

Shaul, D., & Hill, J. (1998). Tepimans, Yumans, and Other Hohokam American Antiquity, 63 (3) DOI: 10.2307/2694626

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