Archeologists studying a forested area in northern Michigan say they've uncovered what is likely the largest intact remains of an ancient Native American agricultural site in the eastern half of the United States.
The researchers used a drone equipped with a laser instrument to fly over more than 300 acres, taking advantage of a brief period of time after the winter snow had melted away but before the trees had put out their leaves.
This allowed the drone to precisely map subtle features on the surface of the exposed ground, revealing parallel rows of earthen mounds. This is what's left of raised gardening beds that were used to grow crops like corn, beans, and squash by the ancestors of the Menominee Indian Tribe of Wisconsin, in the centuries before European colonizers arrived.
The mounds appeared to continue on beyond the surveyed area, the researchers say, showing agriculture at a surprisingly vast scale in a place that wasn't a major population center.
"We haven't even been able to locate any significant settlement sites in this region. There's a couple of tiny little villages," says Jesse Casana, a professor of anthropology at Dartmouth College and one of the authors of a new report in Science. "So it's really shocking in this case to see this level of investment in an agricultural system that would require really enormous amounts of human labor to make happen."
It's especially odd given the relatively poor growing conditions that far north, especially during a period of colder temperatures known as the Little Ice Age, as well as the presence of wild rice right nearby, says Madeleine McLeester, a Dartmouth anthropologist who led the research team.
"Why are they investing so many resources into cultivating maize where it's very, very difficult to cultivate maize?" McLeester wonders. "It's an interesting puzzle, to be sure."
Other experts on ancient agricultural systems say the new find is stunning.
"This astonishing paper shows how much we've underestimated the geographic range, productivity, and sustainability of intensive Indigenous agriculture across North America," says Gayle Fritz, an anthropologist with Washington University in St. Louis.
"The study is outstanding in many ways, one being the long-term collaboration between Menominee tribal members and non-Indigenous archaeologists," she says — with the other being the combination of new technologies plus "old-fashioned, ground-based excavation and survey."
The scale was "unexpected"
While some people may envision historical Native Americans as mostly hunter-gatherers or nomads, "that is very incorrect," says Casana.
"By the time colonists arrived, what they were encountering were a lot of pretty sedentary communities all over North America who were practicing various forms of farming," he says.
It's hard to really know how extensive that farming was, however, because evidence usually isn't well-preserved. European settlers generally took over and developed the most fertile land, eventually erasing signs of past indigenous practices with their own plowing and development.
The site mapped in this new study is part of Anaem Omot, which means the "Dog's Belly" in Menominee. It's an area along the Menominee River on the border between Michigan and Wisconsin, and is of great cultural and historical significance to the Menominee tribe.
The region contains burial mounds and dance rings. It's also known to have agricultural ridges, ranging from 4 to 12 inches in height, because previous work back in the 1990's had mapped some of them.
"These features are really difficult to see on the ground, even when you're walking around, and they're difficult to map," says McLeester.
That difficulty, plus concerns about proposed mining activities in the area, is why the research team — which included the tribe's historic preservation director, David Grignon — wanted to see if new technology could reveal more acres covered with the earthen agricultural rows.
McLeester says they thought they'd find some more rows, but also expected that others would have eroded away since the last mapping effort.
"It was really just a test, more than anything else, to see what could we see, what was still there," she says.
But the drone surveys revealed that the field system was ten times bigger than what had been previously seen.
"Just the scale, I would say, was unexpected," she says, noting that they surveyed less than half of this historic region and the agricultural ridges appear to keep going on beyond the area that they studied in detail. "They just had a huge field system."
Tip of the iceberg
This degree of intensive farming in a very northerly location that's not even farmed much today is probably just "the tip of the iceberg," says Casana.
"One of the interesting things about this study is that it kind of shows us a preserved window of what was probably a much more extensive agricultural landscape," he says.
John Marston, an archaeologist with Boston University who wasn't part of the research team, agrees with that assessment. But if this is the tip of the iceberg, he says, "it may be that the rest of the iceberg has melted."
The only sites comparable to this discovery can be found in arid regions around Phoenix and Tucson in Arizona, he says, where archaeologists have discovered the traces of large-scale irrigation systems used in ancient Native American agriculture.
"That is the only place in which I'm familiar with landscape features of agriculture that are as well preserved at as large a scale as what we have here in this example," he says. "It's really unusual."
Susan Kooiman of Southern Illinois University, an expert on the precontact Indigenous peoples of Eastern North America, says she was "pretty blown away" when she learned of this discovery.
"There's not a lot of remnant agricultural fields in eastern North America in general, just because of modern plowing and ground disturbance and development," she says. "And so to find intact, ancient indigenous agricultural fields in any state, at any level, is very rare."
The size of this particular field system astounded her.
"It requires a lot of labor to create these fields, to clear the forest. This is dense forest, now and then. To clear it, only with stone tools, is a lot of labor, a lot of work," she says, noting that the researchers also did excavation work that shows the ancient farmers were deliberately modifying the soils to improve its fertility.
"The amount of work, and just how far these fields extend, is beyond anything that I think people suspected was going on this far north in eastern North America," she says.
If this same kind of drone technology is used to search other relatively undisturbed areas of forest, Kooiman says, "we may find more remnants of farm fields than we were expecting originally."
There are some historic accounts from European settlers and indigenous groups that describe extensive farming, and researchers know that the city of Cahokia, by the Mississippi River, used intensive agriculture to support ten to twenty thousand people.
The ancestral Menominee community that built the agricultural system uncovered by this new research, however, seems to have been less populous and hierarchical than a place like Cahokia, showing that large-scale agriculture may have been a part of life in very different kinds of societies.
"The question now is, what are they doing with all this stuff they were growing?" says Kooiman. "Who exactly was consuming all of the stuff that they were producing on these fields?"
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