Analysis of 3,000-year-old pottery shards from the ancient Olmec capital of San Lorenzo and other sites contradicts the notion among some researchers that the Olmec civilization was the "mother culture" that laid the foundation for the Inca, Maya and other civilizations of Central and South America.
     Many researchers believe that the Olmec were the primary culture of the region, ultimately raising the other chiefdoms to the level of civilization. A key role in this process was played by pottery, these researchers say, which the Olmec made and gave away, incorporating many of their cultural beliefs into the decorations. But a chemical analysis by researchers from the University of Wisconsin indicates that pottery was produced throughout the region and exchanged in trade among sister states, the team reports in the Proceedings of the National Academy of Sciences.
     "The Olmec were big and numerous and made impressive stone monuments, but they were not the source of all known ideas," said archeologist Kent Flannery of the University of Michigan, one of the report's authors.
     The Olmec people, who called themselves Xi (pronounced "shee"), were among the earliest cultures in the Americas, emerging around 1200 BCE. Their capital was what is now San Lorenzo, near Veracruz on the Gulf Coast of Mexico. There they built massive pyramids and plazas with ceremonial buildings and elite residences. Among their chief legacies are massive stone heads carved in the image of their rulers.
     In a paper published in Science magazine this year, chemist Michael D. Glascock of the University of Missouri used a technique called neutron activation analysis to monitor the elemental composition of pottery shards from San Lorenzo and other sites in the region. Glascock concluded that all of the shards were produced at San Lorenzo. He and colleagues concluded that the containers were shipped to other cities, spreading culture in the process.
     In the new studies, geologist James B. Stoltman of the University of Wisconsin used a technique called petrography to study a similar set of shards. Stoltman studied thin slices of the shards to determine what minerals were used in production. The minerals, usually from crushed local rock, were added to the pottery clay to provide plasticity and to help pots survive shrinking and drying. Stoltman concluded that the shards were produced at a variety of sites. Some, for example, contained the sedimentary rock, such as limestone and sandstone, that underlies San Lorenzo. Others contained volcanic rock, such as that found at Oaxaca. Stoltman identified seven types of materials in the shards, suggesting a similar number of production sites.
     Five of the samples dug up in the Olmec capital "were unambiguously from Oaxaca, demonstrating that some of the pottery in San Lorenzo was made elsewhere," Stoltman said. That "contradicts recent claims that the Gulf Coast was the sole source of pottery" for the region. "It’s difficult to give primacy to one culture," Stoltman says. "In many ways, the Olmec culture was unique," but it may have only been one part of the cultural equation of the day.

Sources: Innovations Report, Los Angeles Times (2 August 2005)