As they dug, they found this palace was rebuilt and remodeled several times by successive occupants from A.D. 500 to 900. At its largest, it measured about 6,500 square feet (600 square meters) and included perhaps 20 rooms with three outside patios, likely where political meetings were held.
The construction and continual remodeling of large palaces like this, with roofed rooms, thick adobe walls, and lime-plastered floors, required a significant investment of local labor and materials. The hilltop palaces were located 1,300 feet (400 meters) above the valley floor and the water sources required for manufacturing plaster and adobe used in construction.
The palace construction started with an underground masonry tomb, where Zapotec elites buried their dead. Inside, the researchers found the bones of three people—some painted with red pigment, which only occurred with bones of the elite, though it's unclear what it signified—along with more than 40 ceramic vessels that may have been filled with food and drink for the trip to the underworld. They also found the remains of a dog.
"Dogs are often placed with burials," explained Feinman. "Part of the larger Mesoamerican ideology is that a dog could lead you to the underworld."
Among the 40 vessels is an exquisite 12-inch (30-centimeter) urn, which features the supernatural figure known as Cocijo, or lightning. In the Zapotec's farm-based economy, Cocijo was the all-important rain god, and Feinman and other experts believe Zapotec nobles dressed up as him to try and ensure a good harvest. The molded figure likely represents someone posing as Cocijo, and the urn's artistic detail is typical of iconic Zapotec ceramics from Monte Albán, suggesting a shared cultural tradition throughout the Oaxaca Valley.
The palace and tomb were occupied at a time when Zapotec economic and political power was shifting away from Monte Albán to El Palmillo and other towns in the region, Feinman said.
An indication of this shift was the addition around A.D. 750 of a ball court adjacent to the grand hilltop palace. The court was used for the rubber ballgame, an important ritual sport that was common throughout ancient Mesoamerica.
"This is a sign that [El Palmillo] was trying to become more of a player in this Valley of Oaxaca, rather than sending its ball players to Monte Albán periodically for an away game, so to speak," Feinman explained.
But El Palmillo's period of local autonomy and rising power was brief. By its fourth occupation, about A.D. 800, the hilltop palace was reduced to just one patio, for example, and then altogether deserted.
Feinman emphasized the abandonment was peaceful and gradual, taking place over about 50 to 100 years. By A.D. 900, signs of occupation were few and far between, raising the question of "what exactly happened," he said.
The answer isn't clear. Feinman and Nicholas suggest the local economy may have collapsed. The declining power of El Palmillo's elite may have precipitated a loss of economic opportunities and options for the local farming and construction labor pool at the same time a breakdown of Monte Albán's central power may have disrupted the intraregional exchange of goods, forcing residents to find opportunities elsewhere.
Drought, Regional Collapse?
The gradual collapse in the Oaxaca Valley paralleled a broad trend throughout Mesoamerica, said Robert Markens, a Canadian archaeologist at the National Institute of Anthropology and History in Oaxaca and expert on ancient Zapotec cities. The great Maya centers within a few hundred miles also crumbled around the same time. But experts disagree on what might have caused the collapse.
Some, like Markens, primarily blame environmental causes. He speculates that an extended drought, documented in lake sediment cores near Mexico City and elsewhere, underpinned the social and political decline.
The Oaxaca Valley's economy was driven by the labor of peasant farmers, Markens noted, so if agricultural production literally dried up, the economy would have unraveled. As cities were abandoned, ceramic representations of the gods and hieroglyphic writing— traditions and skills representative of the elite— also vanish from the archaeological record.
"That tells me there was a crisis of confidence and that the propaganda that supported this social stratification no longer served a purpose," he said.
Kowalewski, the University of Georgia anthropologist, said drought was likely a contributing factor to the Mesoamerican trend of decline, but framed the demise in terms of a collapse of the tightly integrated market economy that had allowed Mesoamerican culture to flourish during the earlier boom years of the Classic period.
As the market economies of Monte Albán and El Palmillo, for example, grew and became ever more interconnected, more and more people depended on them for their livelihoods. Then a combination of factors—drought, political instability, and warfare, for example—could have led to catastrophic market meltdown.
"You have all these people that were dependent on almost everything that they did on the market system," he said. "Then it collapses, and then you're in trouble."
All of this may sound a bit familiar. Indeed, Feinman notes parallels between what happened in ancient Mesoamerica and today's economic crisis, which is also seeing an erosion of an interdependent economy where local and long-distance exchanges play a key role.
"What happens to your neighbor or your co-worker or the group that you do business with has implications for your well-being, too," he said. "And that was probably true in 9th-century Oaxaca as well."
Feinman said the Mesoamerican economic collapse forced people to change their livelihoods and move on. But cities and populations rebound. In the modern world, as in the ancient Oaxaca Valley,
"There will be a turnaround at some point," Feinman said, "although things may not look exactly the same as when the process of decline started."
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