When Jared Diamond looked for examples of collapse inside the boundaries of the United States for Collapse, he used the Anasazi of the southwest, and Cahokia–the center of the Mississippian culture that once dominated the interior of North America. Slightly over a month ago, Jeff Vail visited Chaco Canyon and was that the National Park Service’s treatment lacked any mention of collapse. In that report, Vail noted that “Chacoan and Mississipian civilizations tend to be overlooked when studying the processes of state formation and possibilities for modes of political organization.” I’m happy to report that Cahokia is much better.

Early European explorers were amazed by the incredible mounds they found in North America. Their racism blinded them to the possibility that such structures were built by Amerindians, leading to the “mystery of the Mound Builders.” The first mounds they discovered tended more towards the east, primarily in what is now Ohio. These were much older, and smaller mounds, the remains of the Hopewell culture. They were burial mounds and ritual sites, primarily. Further west, they discovered an entirely different kind of mound, built by an entirely different kind of culture. While they built some mounds for burial and religious purposes, their most impressive mounds were platforms from which the chief ruled.

The name “Cahokia” was given by the French, after the name of a particular tribe of the Illiniwek Confederacy (also known as the “Illinois”). The city had been abandoned some two centuries before. The Osage Nation, Omaha, Ponca, and Quapaw all descended from the Indians who once lived in Cahokia, yet none of them retained even the slightest hint of memory in any of their folklore. They avoided the city and never spoke of it. All memory of their past there had been wiped out.

Yet, the power and glory of Cahokia is something difficult to deny now. Monk’s Mound is the largest earthen structure of its kind. Named for the Trappist monks who lived there for a short time, the mound is over 100 feet tall, 1,000 feet long, and 800 feet wide–forming a base larger than the Great Pyramid of Giza. Over some three centuries and in several stages of construction, the Cahokians moved 22 million cubic feet of wet earth from swampy borrow pits around the site, to form the massive structure. It is formed out of four terraces, finally leading up to the highest point, where the chief’s hut once stood–a glorious wooden structure that may have risen another 50 feet into the air. From that space today, you can see the Mississippi, and even downtown St. Louis.

Monk’s Mound also commands a view that, while unspectacular now, was no doubt even more important than those vistas in its heyday: a vantage over the entire city of Cahokia, and particularly the 50 acre Grand Plaza that was the beating heart of the Mississippian culture.

Archaeological discoveries at Cahokia show a trade network that stretched across the New World. Items from as far away as Yellowstone and the Gulf Coast have appeared at this site near the banks of the Mississippi. Archaeologists have come to believe that Cahokian power was primarily mercantile in nature–and I certainly have little reason to doubt that contention at present. It may, in fact, support the other pillar of Mississippian civilization: the import of the Mesoamerican triad.

The agricultural cultivation of corn allowed the population of Cahokia to explode. Though the site was first settled around 650 CE, it was not until 1050 CE that we not only see the first mound activity, but a sudden leap in population from around 1,000 to 10,000 to 15,000–and with it, a sudden explosion in complexity. The earmarks of Mississippian politics emerge: the chiefdom, the loss of social equality, the emergence of distinct centers, and the Southeastern Ceremonial Complex (SCC) or “Southern Cult.”

Another import from Mesoamerica may have been beliefs about human sacrifice. Pictured above is the Cahokia Mounds Interpretive Center’s reconstruction of the burial under Mound 72. It was a ridge-top burial mound, and beneath it, archaeologists did not just find the remains of a single noble, nor even lavish grave goods, including 20,000 marine-shell disc beads laid in the shape of a falcon, marking this as the famous “Birdman” of Cahokia, and tying him into a universal shamanic tradition. No, here they also found 250 bodies in mass graves, missing body parts indicating that they were theatrically sacrificed during the burial ceremony.

Many individuals who lived on the periphery of the settlements, and had easier access to the resources in the wilderness, were yet forbidden to use them–they were reserved for the higher echelons of society. In an interview for a fluff piece on Cahokia for MSNBc, Tim Pauketat is quoted as saying, “They didn’t eat the good meat even though they were closer to the source at the woodlands … and may have had some social obligation to send it here.”

Cahokia fell very quickly. While it began its life as a chiefly center around 1050 CE, its abandonment began as early as 1250 CE–to be completed by 1400 CE. After only 250 years, Cahokia began a serious decline. Many of the usual answers have been offered up: environmental degradation, climate change, invasion, political disintegration, etc. Of course, none of these explanations are sufficient in themselves–they are precisely the crises that complexity is supposed to handle. Yet they all integrate well with one another in a model of the diminishing returns of complexity.

When Diamond cites the fall of Cahokia as an example in his book, he is doubtlessly referring to the argument of Cahokia’s collapse that speaks most to Tainter’s model of diminishing returns. The complexity of society stratified that same society. This may well have caused tension, and begun the political fracturing that is currently in vogue as the explanatory framework of Cahokia’s collapse. We certainly see less investment in mounds and other such public monuments, and more investment in defense–such as the wooden stockades, like the ones reconstructed in the photograph above.

These defenses would only have further exasperated the growing timber problem. The forests around Cahokia were being depleted. Timber was the primary raw material in Cahokian construction–even surpassing earth–to say nothing of its use for tools and fuel. The more timber Cahokia consumed, the further Cahokians had to travel to obtain more timber–thus, the cost of timber continued to rise, even as the need for it remained the same. It was a classic example of a diminishing marginal returns curve.

There was a similar crisis involving game. Without domesticated animals, the Cahokian population had to depend on wild game for protein. The more they overhunted to feed a growing population (and keep that population growing), the more difficult it became to hunt.

As the chiefdom began to fail in its ability to provide for the needs of its people, discontent would only have grown–further the process of political fracturing. Greater complexity was likely the response–whatever combination of repression or legitimizing activities was deemed most appropriate by the chief. Either course involved still greater complexity, driving the marginal costs still higher.

If there was an invasion, a force that Great Cahokia might have easily repulsed in its hey-day might have easily overcome the fractured, overworked Cahokians that remained.

In his analysis of Chaco Canyon, Jeff Vail echoed my own beliefs about the history of the southwest, and buttressed them with still more evidence, when he wrote:

Is it possible that as the chaos of the chacoan collapse ensued, the Pueblo people found a rhizome replacement to Chaco’s hierarchy? I find this possibility fascinating: Chacoan and Mississipian civilizations tend to be overlooked when studying the processes of state formation and possibilities for modes of political organization. How much do they have to teach us?

Cahokia seems to provide another case, beyond the southwest. Political disintegration remains the most popular model of Cahokia’s collapse–and such disintegration certainly has a place in a diminishing returns-based understanding. The fact that the survivors of Cahokia’s collapse erased all memory of that important site from their cultural memory certainly suggests that each of these groups were heir to one of the various political factions to emerge from Cahokia. They preserved no memory of those centuries of complexity, inequality, and hierarchy whatsoever. We do not even know by what name they called their city, left instead to call it by the name of the tribe we happened to find there when we first came down the Mississippi. In the end, Cahokia choked on its own complexity, and all that was left of one of the greatest civilizations of the New World was a very big pile of dirt.

Artist rendition of Cahokia by William R. Iseminger, and taken from “A Mississippi Mound Mystery,” published by MSNBC. All other photographs taken by Jason Godesky at Cahokia on 1 October 2005.