In the late 1200s, the Ancestral Puebloan people of what is today the Four Corners Region of the U.S. Southwest suddenly vanished. For centuries, the culture—also known as the Anasazi—had grown maize and built elaborate villages and sandstone castles. Then, it was gone. Now, using DNA extracted from ancient turkeys, researchers say they have new insights into where these mysterious people went, though some experts are skeptical of the findings.
“While I think the concept behind the study is a terrific idea, and they present a really plausible case … the evidence is a little weak,” says R. G. Matson, an anthropologist at the University of British Columbia in Vancouver, Canada.
Scientists think they know why the Ancestral Puebloans disappeared. The primary culprit, studies suggest, was a megadrought that would have made it impossible to grow enough food to feed the tens of thousands of people living in the region. That, combined with factors like deforestation and topsoil erosion, led the Ancestral Pueblos to leave their homes at Chaco Canyon and Mesa Verde in search of a better life elsewhere.
Where they migrated to remains a mystery, however. One of the prevailing theories—backed by modern Puebloan peoples’ own narratives and history—is that most relocated to the northern Rio Grande region of northwestern New Mexico, but that has not been conclusively proven by science. “[It] has long been a question in Southwest archaeology,” says Scott Ortman, an anthropologist at the University of Colorado in Boulder and co-author of the new study.
One reason is that scientists haven’t been able to tie the Ancestral Puebloans to other native populations because tribes in the region have been reluctant to give permission to analyze ancient human remains. So Ortman and a team of archaeologists and anthropologists led by molecular anthropologist Brian Kemp at the University of Oklahoma in Norman turned to the next best thing: the DNA of the animals these ancient people domesticated.
They analyzed the mitochondrial DNA—the maternally inherited genetic material that lives in a cell’s energy producing machinery—of hundreds of samples of turkey bones, which are plentiful and well-preserved at the Ancestral Puebloans’ homeland near Mesa Verde in southwestern Colorado. The researchers compared the genetic material from Mesa Verde turkeys to turkeys found in the northern Rio Grande region before and after the Ancestral Puebloans disappeared.
Before 1280, the two turkey populations were unrelated in the maternal line, the team found. But afterward, the northern Rio Grande turkeys carried Mesa Verde “haplogroups”—clusters of genes inherited together as a group—indicating they were descended at least in part from the Ancestral Puebloans’ stock.
The most likely explanation, the researchers argue in PLOS ONE, is that the Ancestral Puebloans left Mesa Verde around 1280 and brought their turkeys with them. This transplanted line of turkeys then replaced those that lived in northern Rio Grande before their arrival.
The implication is that many of the Ancestral Puebloans appear to have joined a smaller population already living in the northern Rio Grande region, says Ortman; their descendants form the Tewa Pueblo population that still lives there today. That conclusion fits previous research that found telling similarities between the face shapes of modern Tewa and Ancestral Puebloans, he says.
“I think our study is a good illustration of the value of curation,” he says. “The people who collected these turkey bones had no idea that one day we would get DNA out of them and use them to answer questions about ancient human migration.”
Matson doesn’t doubt the migration story, but he has concerns about the validity of the DNA evidence in the study. Some of the turkey DNA sequences are incomplete, because of deterioration, and the haplogroups varied depending on how complete the sequences were. “This bizarre difference … creates some doubt about the evidence,” he says.
Bruce Bernstein, a tribal historic preservation officer in the Pueblo of Pojoaque, New Mexico, says the study adds some valuable insight into the lives of Pueblo people’s ancestors. “People don’t need their own history to be verified by archaeology, but they are interested in having science work alongside them, not in spite of them,” he says. “This is a good example of work that fills in some gaps in what Tewa people have talked about.”