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MIT Work Recasts Archaeologist's Thinking About Peoples of Ancient West Mexico

CAMBRIDGE, Mass.-In work that recasts archaeologists' thinking aboutpeoples living in the western region of ancient Mexico, MIT researchershave shown that these people had a significant impact on other culturalgroups by producing large numbers of metal artifacts and distributing themto centers as far south as Belize.

Because the majority of these artifacts, such as bells andtweezers, were symbols of sacred and political power, by exporting them theWest Mexican peoples not only affected economic systems but also influencedreligious and ritual behavior.

"They were exporting a religious ideology," said Dorothy Hosler,Associate Professor of Archaeology and Ancient Technology in the Departmentof Materials Science and Engineering. Professor Hosler and Andrew W.Macfarlane, a research affiliate in the department and an associateprofessor at Florida International University, are authors of an article onthe work in the September 27 issue of Science.

West Mexican peoples were one of many cultural groups, includingthe Aztec and Maya, who lived in a region archaeologists call Mesoamerica.This region encompassed central and southern Mexico, Guatemala, Belize,western Honduras, and El Salvador. Until now, archaeologists had thoughtthat the West Mexicans were relatively isolated and had little impact onother Mesoamerican peoples.

The new work, which links copper and bronze artifacts excavated atmany sites in Mesoamerica to West Mexican ore deposits, "is the firstevidence we have that West Mexican peoples were interacting intensivelywith other Mesoamerican groups," Professor Hosler said. "So it alters ourthinking about the economic and social networks in this period [~A.D.1200-1521]."

In the summer of 1995 Professor Hosler spent two months in Mexicocollecting ore samples from 15 deposits in West Mexico, Oaxaca, and EasternMexico (Veracruz). With a permit granted by Mexico's National Institute ofAnthropology and History, she also took samples of 171 copper artifactsfrom a variety of Mesoamerican archaeological sites. "I came back to MITwith boxes and boxes of artifact and ore samples," said Professor Hosler,who is also a member of the MIT Center for Archaeological Materials.

The researchers then determined the ratios of lead isotopes in eachsample (isotopes of an element have different atomic weights). Lead isotopeanalysis, a standard technique, "can be used to identify ore sources forartifacts made from copper and copper alloys by matching the isotopicsignatures of ore lead to those of the artifacts," the researchers write inScience.

Professor Hosler notes that MIT undergraduate Jennifer Pinson, nowa junior in materials science, played a key role in the analysis. "Sheworked all last year on the project; at one point she went to Florida tohand-deliver ore samples to Professor Macfarlane because we were afraid wemight lose them if we shipped them." (The samples were analyzed atProfessor Macfarlane's lab.)

The lead-isotope results showed that most of the Mesoamericanartifacts sampled were indeed made of metal smelted from West Mexican ores.These analytical data combined with historical and archaeological evidencetherefore show that the West Mexicans were exporting artifacts throughoutthe Mesoamerican region.

Among the archaeological evidence that supports this conclusion isthat "as far as we know, other Mesoamerican peoples did not develop thetechnical expertise to make these artifacts," Professor Hosler said. Shenoted that West Mexican bells, for example, are difficult to cast. "Last January, MIT Professors Sam Allen, Linn Hobbs, and I led a class in ancientMexican bell casting. The students spent two weeks trying to cast copies ofthese bells, and we don't have it exactly right yet."

Professor Hosler concluded that although she had suspected that theWest Mexicans played a major role in the production and distribution ofmetal artifacts, "until the lead isotope analysis we had no way ofsubstantiating what we thought might be true."

For more information about MIT research on the history ofmaterials, go to:<>.

The work reported in Science was supported by a grant from GrupoMexico (Industrial Minera Mexico), American Smelting and Refining Company,and Southern Peru Copper.

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