The bones tell stories about the health of the Incan people. The metal tools hint at the society's technological advancement. The artifacts help scientists reconstruct ancient trade routes.
Archaeologists say they've even learned that the Incan diet revolved not around the Peruvian staple of potatoes, but was based largely on maize. All this from restudying a collection that's nearly a century old.
The government of Peru wants it back, saying it never relinquished ownership when Yale scholar Hiram Bingham III rediscovered the city in 1911 and began exporting artifacts from what has become one of the world's most famous archaeological sites.
Peru demanded that Yale return the relics this fall. Then, after a compromise broke down that would have divided the them among museums in both countries, Peru said it intended to sue. No lawsuit has been filed and Yale administrators say they remain confident a deal can be worked out that will resolve the dispute amicably.
Many of the relics are on display at Yale's Peabody Museum. But the collection, which include mummies, ceramics, tools and human bones, has more scientific than aesthetic value, Yale anthropology professor Richard L. Burger said.
"It's not a collection of art objects," Burger said. "If you want to see the most beautiful Incan art objects, you go to the Inca Museum in Cusco."
The Incas ruled Peru from the 1430s until the arrival of the Spaniards in 1532, constructing incredible stone-block cities and roads and developing a highly organized society that extended from modern-day Colombia to Chile.
The ruins at Machu Picchu, located on a mountaintop above a lush valley 310 miles southeast of Lima, are Peru's top tourist attraction.
Bingham, a Yale archaeologist, became the first foreigner to reach Machu Picchu in 1911 and returned to the site in 1912 and 1914. Yale said artifacts from the 1914 expedition were returned long ago and said the current dispute focuses on relics from the 1912 trip.
The Peruvian government maintains that, while Bingham had approval to remove the artifacts, they were essentially on loan to Yale and the country never relinquished legal ownership.
Peru's first lady, Elaine Karp, has pushed hard to have the relics returned, Burger said. Her husband, President Alejandro Toledo is not eligible for another term, however, and a new government took over after a June 4 runoff election.
Burger said he hopes the new government will resume negotiations.