A US government plan to slash protections for one of North America’s richest and best-preserved archaeological landscapes has prompted a wave of concern among researchers. On 4 December, US President Donald Trump announced that he had cut the Bears Ears National Monument in Utah from 547,000 hectares to 82,000. That removes protections for thousands of Native American cultural sites, some as many as 13,000 years old.

The president’s action leaves the national monument, created last year by his predecessor, Barack Obama, in legal limbo. Although presidents have clear authority to create monuments, many legal scholars argue that only the US Congress can change the areas’ boundaries. Native American tribes and environmental groups have already said that they will sue the government over its attempt to reshape Bears Ears.

The decision to remove protections from the monument comes at a time when people are increasingly encroaching on its cultural treasures. Looting of valuable objects such as ancient pottery has long plagued the Bears Ears area. And as tourism has ballooned in recent years, so have inadvertent damage to sensitive walls and dwellings made of stone and mud, and the disappearance of potsherds and other artefacts.

The greatest vanishing act in prehistoric America

Many archaeologists hoped that designating Bears Ears a national monument would help to mitigate this damage by boosting the budgets of federal land managers — allowing them to hire more staff, collect more baseline data on archaeological sites and do more outreach and education. Now those additional resources may never arrive, even as the publicity surrounding the monument continues to draw bigger crowds to the area.

“This is the worst-case scenario,” says Jason Chuipka, vice-president of Woods Canyon Archaeological Consultants in Cortez, Colorado.

Scientific treasures

Bears Ears’ sandstone canyons and arid plateaus retain deep cultural significance for Native American tribes. Obama established the monument in response to a petition from five groups: the Navajo, the Hopi, the Ute Mountain Ute, the Zuni and the Ute Indian Tribe of the Uintah and Ouray Reservation. But the move was fiercely opposed by some officials and residents in neighbouring counties who are still angry about the government’s creation of the nearby Grand Staircase-Escalante monument in 1996. (On 4 December, Trump ordered that monument to be reduced in size by roughly half.)

“The great research value of the Bears Ears to archaeology is that it’s a relatively undeveloped landscape,” says William Lipe, an archaeologist at Washington State University in Pullman. And perishable goods from ancient communities — including baskets, feather blankets, cobs of maize (corn) and faeces from domestic turkeys — remain intact thanks to the dry climate and the location of some dwellings in alcoves that are sheltered from rain and sunlight.

Much of the material at sites in Bears Ears is more than 1,000 years old, says Chuipka, who calls it “a three-dimensional data trove”. The area is also relatively unexplored: archaeologists estimate that just 10% of the roughly 100,000 sites within the monument have been formally surveyed.

Agriculture insight

The well-preserved ancient goods found in the area have contributed to important scientific discoveries. Earlier this year, for instance, a genetic study of 1,900-year-old maize cobs provided important insights into how tropical maize adapted to temperate growing conditions1.

A team led by Kelly Swarts, a plant geneticist then at Cornell University in Ithaca, New York, sequenced the genomes of 15 cobs. The researchers found that the traits that allowed maize to adapt to cooler climates had always existed in the plant, but it took farmers in what is now the southwest United States 2,000 years to select for them. The cobs provided some of the earliest evidence of maize farming in temperate conditions, and Swarts's findings underscore the vast adaptive capacity of the globally important crop. The work was possible, she says, because “the genetic preservation was excellent in these samples”.

Prehistoric Native Americans farmed macaws in 'feather factories'

The Trump administration’s revisions to the Bears Ears National Monument would fragment it into two units. Two well-known ancient cliff dwellings — Moon House and Doll House — are included as satellites of one of the new units. But the new boundaries exclude Cedar Mesa, a large plateau that hosts the monument's densest concentration of archaeological sites, which were occupied by Ancestral Puebloan farming communities from 500 bc to the mid-thirteenth century ad.

Chuipka says that carving up the monument and cherry-picking popular sites for protection undermines a key reason for creating it: the preservation of an interconnected cultural landscape. Together, says Lipe, the sites within Bears Ears contain a record of “the whole pattern of the way people lived on, made use of, and built their cultural memories into the landscape over thousands of years".

The five tribes that pushed for the creation of the Bears Ears National Monument intend to file suit soon in federal court, where the site's ultimate fate is expected to be decided.