Every ten years, the U.S. Census tries to get a count of the country's population, recording shifts in demographics as people move from place to place. But to get a count of people who lived more than a thousand years ago, only archaeological evidence can tell the story. In this Science Update, you'll hear about a 20-year effort to learn what happened to the ancient residents of the American Southwest.
A migration mystery. I'm Bob Hirshon and this is Science Update.
In Colorado's Mesa Verde National Park, visitors can see the ancient cliff dwellings of the ancestral Pueblo people, who lived in the region between 600 and 1300 A.D. Exactly what happened to them over this seven-hundred-year period has been a mystery. That's according to Mark Varien, Director of Research at the Crow Canyon Archaeological Center in Cortez, Colorado.
There's a common perception that the occupation of the region was characterized by consistent but gradual growth, and that it ended with this sudden and single abandonment. And our research looks in greater detail at that.
To determine how long families stayed at certain sites, Varien measured the amount of cooking pottery left behind. He also looked at the timbers of excavated buildings, counting tree rings to figure out how long entire communities lasted.
What I found was that the seven centuries of occupation is actually characterized by two cycles of occupation: one from about A.D. 600 to 900, and another from 1000 to 1300.
So rather than abruptly abandoning the Mesa Verde region, Varien says the Pueblo people moved in and out over the centuries—finally leaving for New Mexico and Arizona, where their descendants live today. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
Mesa Verde National Park is just a small part of the Mesa Verde archaeological region, which spans from southwestern Colorado to southeastern Utah, north of the San Juan River. It was the ancient home of the ancestors of the modern Pueblo people. When European Americans first entered the area, they saw so many empty cliff dwellings—many tens of thousands—that they assumed that the entire area had just been abandoned all at once.
To get a more accurate, detailed picture of the Pueblan occupation of the area, Varien examined the communities on three scales of time and size. First, he looked at individual dwellings (by examining the cookware). By dating the cookware, he could infer how long the dwellings were occupied. His conclusion was that individual dwellings were occupied continuously for between 8 and 50 years. Generally, they were occupied for longer periods of time in later centuries.
Next, he stepped back to the community level, by looking at the tree-ring data. There, he found that some communities stayed together for as long as three centuries. Combined with the pottery data, a picture begins to emerge not of a whole population setting up camp and then leaving, but of a society more like our own, in which communities remained relatively stable as individual dwellings were constantly being moved in and out of.
Finally, stepping back to look at the entire region, the picture of the two large cycles of occupation start to emerge. Varien says the two cycles share similar characteristics: they each started with relatively thin population scattered around the area, then build to a system of densely populated villages, and then end with people gradually moving out.
Not only does this sound a lot like the growth patterns of many European-American communities—it also matches up well with the centuries-old oral tradition of the Pueblo people themselves. Varien says that archaeologists are finding that these unwritten folk histories can serve as surprisingly accurate windows to the past.
Now try and answer these questions:
- How was the history of the Pueblo people in the Mesa Verde area investigated?
- What were the main findings of the study?
- Why is this information useful? What could this knowledge be applied to?
- How is archaeology like detective work? What patterns of thinking are needed to conduct investigations like these?
Mesa Verde National Park is near the site of Varien's research, and home to some of the best preserved archaeological sites in the United States.
The Crow Canyon Archaeological Center is devoted to the archaeological study of Native American cultures.
The University of Michigan's Online Public Library features this Pueblo Pottery Exhibit.