Cahokia’s downfall has been blamed on a variety of culprits. A corn-based, protein-poor diet might have sent urban dwellers west in search of buffalo. A centuries-long cold spell could have crippled the region’s agricultural productivity. Deforestation of the uplands would have choked downstream water supplies with silt and exacerbated flooding. Or the cause could have been those same intangibles invoked by latter-day theorists to describe Cahokia’s rise: a shift in belief systems or the balance of power. Certainly the sprawling pacts that Cahokian chiefs may have forged with nearby villages would have challenged any lasting centralization of power.
“The typical life history of a chiefdom is that it comes together, it has its heyday, and it falls apart, all within a couple of generations,” says Emerson. “The interesting thing about Cahokia is that it managed to hang together. The fact that it didn’t go on forever isn’t unusual at all.”
One of Cahokia’s chiefs appears to be buried in Mound 72, which lies a half mile south of Monks Mound. It is a modest hillock by comparison, but the site holds far grimmer implications about Cahokian society. During excavations there in the late 1960s, Melvin Fowler of the University of Wisconsin at Milwaukee uncovered the remains of more than 250 people. One middle-aged male had been laid on a shelf of 20,000 seashell beads arranged in the shape of a bird. Near him were the bones of six other people, a cache of more than 800 flint arrowheads, a rolled-up sheet of copper, and several bushels of unprocessed mica—all seemingly placed in tribute to the Beaded Birdman.
In other parts of the mound, skeletons of more than 100 young women clearly indicate human sacrifice, and another grouping of four men with no hands or heads denotes the same. Another 40 bodies seemed to have been tossed into a grave haphazardly. Other mass burials in Mound 72 show varying degrees of respect and carelessness—and seem to reflect some sort of social hierarchy as yet undeciphered. Human sacrifice, for example, can be a sign of a coercive society or of a cultlike mentality. “Mound 72 is an ancient text with its own set of Rosetta stones and is slow to give up its secrets,” Fowler wrote in Cahokia, a book he coauthored with Biloine Whiting Young.
The cause of Cahokia’s demise is no more certain, but at least one expert links it to the Toltec civilization of south-central Mexico some 1,400 miles away. Although no Mexican artifacts have ever been found at Cahokia, similarities in the monumental and ornamental styles are conspicuous—and far from accidental, according to anthropologist Stephen Lekson of the University of Colorado at Boulder. Lekson and anthropologist Peter Peregrine of Lawrence University in Wisconsin believe that the mound cultures of the American East, the pueblo cultures of the American Southwest, and the pyramid cultures of the Mexican highlands were not only familiar but possibly even integrated with one another. There’s plenty of evidence for such an exchange at Chaco Canyon, where copper bells, macaw feathers, pyrite mirrors, and other Mexican goods turn up. But Chaco was a wannabe compared with Cahokia—much smaller, far less populous, and without a centuries-long tradition preceding its development. Cahokia, with its central location, entrenched culture, and extensive trade network, didn’t need Mexican trinkets to bolster its stature, Lekson says. “If someone from Cahokia showed up in any major town in Mexico, he’d be taken seriously,” says Lekson. “But if someone from Chaco wandered in, they’d ask him if he had an appointment.”
The Toltec, Chaco, and Cahokian societies all collapsed at very nearly the same moment, and Lekson believes that that, too, is no accident. Events in Mexico may have rippled up the Gulf Coast to the Mississippi and thence to Cahokia. “I’m not saying that Mexico is pulling everybody’s strings,” says Lekson. “But [the cultures] are more alike than not, and it’s interesting to ask why.”
Interesting as it might be, a continental perspective doesn’t yield an explanation, because no one’s sure what caused the Toltec regime to fall, either. It may be that if scientists ever determine why Cahokia fell, they may be able to help explain what happened elsewhere in the Americas. At present it’s still anyone’s guess. “We are telling stories that will fall apart in the future,” says Pauketat. “But we can’t ignore the evidence, either. You could make the mistake of saying this is a coercive society, based on Mound 72. Or you could look at the outlying villages and say, ‘This is a peaceful community.’ They must have wanted to build Cahokia. The truth may be somewhere in between. We don’t really know what happened here.”