By Guy Gugliotta
Washington Post Staff Writer

Scientists presented new evidence yesterday that the fabled Olmec, sculptors of ancient Mexico's colossal stone heads, were the region's first dominant civilization, a "mother culture" that served as the hub of lesser settlements.

For decades, a debate has raged between scholars favoring the mother-culture hypothesis and those who argue that the Olmec were just one of several "sister" cultures that developed simultaneously.

George Washington University's Jeffrey P. Blomster, leader of the team that examined pottery samples from Mexico and Central America, said at a news conference that chemical analysis of the clays and potsherds suggested that while other ancient settlements made pottery with symbols and designs in the "Olmec style," only the early Olmec themselves -- at San Lorenzo near Mexico's Gulf Coast -- exported their pottery.

Local pottery did not have the prestige, Blomster said: "Higher-status houses [at other sites] had more access to the Olmec pottery. The difference was in having the real thing or a knockoff."

The new research appeared in this week's edition of the journal Science and drew cries of foul from sister-culture proponents. Blomster's research team "has demonstrated that pots were traded," said archaeologist David C. Grove, a professor emeritus at the University of Illinois at Urbana-Champaign. "They did not demonstrate that trade sent Olmec religious and political ideas" around the region as well.

The University of Michigan's Kent V. Flannery, a leading sister-culture proponent, suggested in an e-mail that the Blomster team had sampled only pottery that looked as if it might have come from San Lorenzo. "It is simply not true that nobody else's ceramics show up in San Lorenzo."

The Olmec arose more than 3,000 years ago near the present-day Mexican Gulf states of Veracruz and Tabasco. Known for spectacular sculpted basalt stone heads as much as 11 feet tall, the Olmec are regarded as the first Middle Americans to develop the region's monumental architecture.

Besides the key Olmec settlements at San Lorenzo and La Venta, evidence of "Olmec-style" imagery and design is reflected in pottery at other contemporary sites. At a famous meeting of Olmec scholars in 1942, Mexican archaeologists suggested the Olmec were a "mother culture" whose ideas, religion and iconography were adopted and imitated by surrounding peoples.

Later, however, other scholars described this view as overly simplistic. They said the surrounding cultures were as sophisticated as the Olmec, and as "sister cultures" had developed similar pottery styles and iconography from what Grove described as a regional "root style of unknown origin."

Blomster and co-researchers -- Hector Neff of California State University at Long Beach and Michael D. Glascock of the University of Missouri -- did elemental analysis of 725 pottery and clay samples from San Lorenzo and six other sites prominent during the "late formative" Olmec period -- between 1,500 B.C. and 900 B.C.

The analysis showed that all seven sites had Olmec-style pottery made from local clays, and all seven also had pottery made at San Lorenzo. But San Lorenzo had nothing from any of the other sites, and the other sites had nothing from one another -- only from themselves and San Lorenzo.

Blomster described the results as a "really striking" demonstration that the Olmec in San Lorenzo "had something to offer that was of great interest."

"The Gulf Coast Olmec created and synthesized their symbolism and disseminated it," he said.

Grove, however, said that the study proved nothing and committed the sin of granting primacy to the Olmec when the evidence does not exist. "If the Olmec were so influential," he said in a telephone interview, "why didn't the sites they allegedly 'influenced' also borrow monument-making?"

Precisely, countered Blomster, because only the San Lorenzo Olmec had the sophistication and organization to handle multi-ton building projects: "The elites can control massive amounts of labor. Other sites didn't have that kind of social differentiation."

© 2005