And then, about 300 B.C., their civilization vanished. No one knows why. But they left behind some of the finest artworks ever produced in ancient America, the most spectacular of which will be on display at the National Gallery of Art in Washington starting next week. Titled "Olmec Art of Ancient Mexico," the exhibition is the first comprehensive survey of Olmec artifacts, ranging from palm-size jade carvings to a 10-ton, monumental stone head. For the next four months, visitors will be able to see treasures that have never before been permitted to leave Mexico. "It's amazing," says one of the show's curators, Peter David Joralemon of Pre-Columbian Art Research Associates in New York City. "The only major Olmec objects left in Mexico are the ones that are too fragile to travel."
For historians the artworks are much more than gorgeous museum pieces. If the Olmec ever had a written language, all traces of it have disappeared. Even their bones are gone, rotted long ago in the humid rain forest. Virtually everything that scholars know about them is based on the remains of cities and on comparisons between their artifacts and imagery and those of later civilizations. It isn't surprising, therefore, that while the experts have plenty of theories about the Olmec's origins, social structure and religion, few of these ideas are universally accepted.
What scholars do know is that the ancestors of the Olmec, like those of all Native Americans, were Asian hunter-gatherers who crossed into the Americas at least 12,000 years ago, at the end of the most recent ice age. Bits of ancient garbage and the remains of mud buildings hint that by about 2000 B.C., some of their descendants had settled in what is now the Mexican states of Veracruz and Tabasco, living in small fishing villages along the region's rivers.
By then, says Richard Diehl, an Olmec expert at the University of Alabama-Tuscaloosa, "we know that they had adapted to the environment and probably supplemented their diet with cultivated plants, such as maize and beans. And we know they became more and more dependent on agriculture, perhaps because the population was increasing."
But archaeologists don't know what transformed a society of farmers into the class-based social structure of the Olmec, with their leaders and commoners, bosses and laborers, artisans and priests. Diehl theorizes that it was population pressure and that as the pre-Olmec villages grew, they naturally stratified. "A new elite class probably asserted its leadership through charisma, control of trade networks and control of people, all of which led to the evolution of a complex society and, eventually, the art style we call Olmec."
It's a plausible scenario, at least. But whatever the reason, Olmec society was in full flower by 1200 B.C., at a place known as San Lorenzo, on a fertile plain overlooking the Chiquito River. Like all the known Olmec sites, San Lorenzo is much less impressive than the Mayan cities that dot the Yucatan peninsula to the east. One reason: it supported only a few thousand people, rather than 100,000 or more. The major buildings and plazas were little more than earthen mounds covered with grass, lacking any sort of masonry facade and probably topped with pole-and-thatch houses.
The sites were also built on a fairly modest scale: the Great Pyramid at La Venta, a site that arose around 800 B.C., is just 100 ft. high, about half the size of the tallest Mayan pyramid at Chichen Itza. Still, each Olmec site was laid out according to a preconceived plan, a fact that reflects both the people's religious beliefs and a fairly sophisticated knowledge of engineering. All the mounds at La Venta, for example, are oriented precisely 8 west of north.
San Lorenzo shows clear evidence of class structure, according to Ann Cyphers, an Olmec scholar at Mexico's National Autonomous University, with more elaborate housing for the upper classes and simpler accommodations for the middle class and the poor. There were also, observes Cyphers, workshops for producing artifacts, and irrigation and drainage systems. "All these things show a society of great complexity," she says.
That complexity, however, may not have extended to Olmec politics. Rather than a single, unified state, says one school of archaeological thought, the Olmec were little more than a glorified collection of chiefdoms. Indeed, Diehl prefers the term Olman instead of Olmec to avoid implying that there was a single linguistic or political entity. "There just isn't any evidence for this," he insists. "There were probably a number of different populations, forming groups that rose and fell over time and shifted alliances. I don't think there was any political integration." No one knows whether the major cities--San Lorenzo, La Venta and Tres Zapotes--traded with one another, or even co-existed.
Art historians and archaeologists agree, however, that the Olmec produced the earliest sophisticated art in Mesoamerica and that their distinctive style provided a model for the Maya, Aztec and other later civilizations in the region. According to Joralemon, small-scale Olmec objects made prior to 900 B.C. tend to be ceramic, whereas later pieces were often fashioned of jade and serpentine, rare materials that required great skill to carve. The vast majority of Olmec artifacts are sculptures--figurines, decorated stone stelae, votive axes, altars and the like--some of which were polished to a mirror-like shine.
Human figures from the earliest period tend to wear simple, understated costumes, while later ones are more embellished. The purpose of the objects changed as well. The ceramics were simply sculptures, while the jade pieces were often intended for rulers to wear. Explains Joralemon: "They were clearly a display of personal wealth, an indication of status and prestige"-- evidence, he suggests, that the society may have been growing increasingly stratified.
Recurring images in Olmec art--dragons, birds, dwarfs, hunchbacks and, most important, the "were-jaguar" (part human, part jaguar)--indicate a belief in the supernatural and in shamanism. Olmec-style human figures typically have squarish facial features with full lips, a flat nose, pronounced jowls and slanting eyes reminiscent (at least to early travelers in the region) of African or Chinese peoples. Archaeologists have found household objects as well, but they tend to be broken. As a result, laments Joralemon, "we know relatively little about the common Olmec."
The most famous Olmec artifacts are 17 colossal stone heads, presumed to have been carved between 1200 B.C. and 900 B.C. Cut from blocks of volcanic basalt, the heads, which range in height from 5 ft. to 11 ft. and weigh as much as 20 tons, are generally thought to be portraits of rulers. Archaeologists still have not determined how the Olmec transported the basalt from quarries to various settlements as far as 80 miles away--and, in San Lorenzo, hoisted it to the top of a plateau some 150 ft. high. "It must have been an incredible engineering effort," Joralemon says. "These people didn't have beasts of burden, and they didn't have wheels. We don't know if they floated the blocks on rafts or traveled over land."
There is still hope that archaeologists can solve this mystery, as well as dozens of other unanswered questions about the Olmec. Most of the sites have barely been studied, and with good reason. Annual floods smother the land with thick layers of silt that dry into impenetrable clay. What's more, says Diehl, "about 80% of the entire Olmec territory in southern Mexico has been converted in the past 20 years from jungle to cow pastures and sugar-cane fields. There's so much vegetation on the surface that you can't just pick up pottery. Generally, you can't even see the ground." Beyond that, the hot, humid climate makes the work extremely unpleasant.
Still, in the past five or 10 years researchers have managed to uncover a number of key sites, including the monument-strewn ruins of Teopantecuanitlan in the Mexican state of Guerrero, and the sacred shrine at El Manati, whose murky springs yielded the first examples of wooden Olmec statuary and the earliest known evidence of child sacrifice in Mesoamerica. Heat and hardship notwithstanding, the prospect of understanding the still shrouded origins of Mesoamerican civilization--and the haunting beauty of the items on display at the National Gallery--makes it all seem worthwhile.