Thursday, March 31, 2011

Cacao in the Southwestern U.S.

The Journal of Archaeological Science has published online an article reporting the discovery of cacao residues in a significant number of ceramic vessels from Ancestral Puebloan and Hohokam sites in the southwestern United States.

Washburn, D.K., Washburn, W.N., Shipkova, P.A. The prehistoric drug trade: widespread consumption of cacao in Ancestral Pueblo and Hohokam communities in the American Southwest, Journal of Archaeological Science (2011), doi: 10.1016/j.jas.2011.02.029.

The lead author, Dorothy Washburn, is best known for applying the techniques of symmetry analysis, from crystallography, to the formal analysis of designs on archaeological artifacts.

Many of the the vessels studied come from eleventh century deposits at Pueblo Bonito and Pueblo del Arroyo in Chaco Canyon, while the remainder come from the fourteenth century deposits at Los Muertos. Although this is not the first time that cacao residues, primary theobromine, have been identified in Ancestral Puebloan pots, the sample tested in this study was much larger (75 vessels) and from a wider variety of contexts (i.e., both elite and non-elite). The results were astonishing: 50 of the 75 vessels tested (67%) revealed evidence of cacao. Thus, it appears that trade in cacao, which must have come from Mesoamerica, was much more widespread than previously believed.

Great stuff!

Where else should we be looking for cacao?

Saturday, March 26, 2011

Report on Pre-Clovis Occupation in Central Texas

A rich cache of articles on archaeology appeared in this week's issue of Science. The most
important for us is a report from Texas A&M on the excavation and dating of a Pre-Clovis
complex in central Texas. Here's the citation:

Michael R. Waters, Steven L. Forman, Thomas A. Jennings, Lee C. Nordt, Steven G. Driese,
Joshua M. Feinberg, Joshua L. Keene, Jessi Halligan, Anna Lindquist, James Pierson, Charles T.
Hallmark, Michael B. Collins, James E. Wiederhold (2011). The Buttermilk Creek Complex and
the Origins of Clovis at the Debra L. Friedkin Site, Texas. Science 331:1599-1603.

The Friedkin site appears to be well-preserved and displays a high degree of stratigraphic integrity. Lead author Michael Waters is a distinguished geoarchaeologist and, surprise!, the description of the soils, stratigraphy, and geomorphology are outstanding. The site has a long occupational sequence, from Pre-Clovis through Clovis, Folsom, Late Paleoindian and Early Archaic cultures, representing a span of roughly 6,000 or 7,000 years, all sandwiched into about a meter of alluvial and colluvial sediment.

The key issue is the definition and dating of the Pre-Clovis Buttermilk Creek Complex. Because
the excavators could not recover any carbon from the site, making radiocarbon dating impossible, they relied upon optically stimulated luminescence (OSL) dating instead. This technique is somewhat less desirable than radiocarbon dating because OSL depends on local conditions, such as soil moisture content and ambient radiation rates, that can be difficult to estimate. Nevertheless, I'm inclined to believe the results in the case because the many dates form a clear, properly ordered, and internally consistent series that correlates appropriately with known information from other sites. So even if the adjustments for local conditions are not perfect, the essential fact would not change: there is a Pre-Clovis component that is many hundreds or even a couple of thousand years older than Clovis stratified below it. The OSL dates for the Buttermilk Creek Complex are reported by the authors to be 13.2-15.5 kya (kya=thousands of years ago).

Unfortunately, as at Monte Verde in Chile, the excavators did not find any really distinctive
diagnostic artifacts associated with the Pre-Clovis complex. So we still don't have any easy and
obvious means to identify other such occupations at other sites.

These finding contribute to the already significant evidence for Pre-Clovis occupation of the

Monday, March 21, 2011

2012 News

Something must be wrong when you find information related to your professorial duties posted on News of the Weird (Professional Edition, no less!). But that's where I found a reference to a guy who was in jail for making bombs because he believed the world was ending in 2012. The full story is at the Louisville Journal-Courier.

This should serve as a reminder that the apparently silly bunk about 2012 can be deeply pernicious. However ridiculous, inane, or childish they seems to us, these outrageous fabrications can trouble people and might even push troubled people over the edge.

This is not a unique incident. I seem to remember reading somewhere about a Mayanist who took a call from a credulous person who wanted to know if he or she should kill himself before the world ended.

I want to collect stories like these. Please send me any you find.


Friday, March 4, 2011

Bruce Dahlin Photo

Here's my favorite photo of Bruce and me: sitting on the stoop in Tecoh, Yucatan, after a hard day's work. It was taken by Marilyn Masson. Thanks to Marilyn for letting me post it.