DEBBIE ELLIOTT, HOST:
Our understanding of one of the world's greatest historic sites recently got a bit of an update.
(SOUNDBITE OF ARCHIVED RECORDING)
UNIDENTIFIED ANNOUNCER: Near Cuzco, the ruins of one of the great Inca cities known as Machu Picchu sprawls across the mountain. The Incas managed to keep secret its location for centuries.
(SOUNDBITE OF MUSIC)
ELLIOTT: Turns out, Machu Picchu is still holding out a few secrets.
NOEL KING, HOST:
Researchers from Yale found evidence that Peru's great hidden city was occupied earlier than previously thought.
Professor Richard Burger led that study of Machu Picchu.
RICHARD BURGER: One of the frustrations is that there are really no written documents from Inca times, except for the quipus, the knotted records. And those can't be read yet.
KING: Until now, historians could only guess the city's age based on documents from the Spanish conquest, which are not the most reliable sources.
BURGER: People were thinking that it dated to about 1450.
ELLIOTT: But Richard Burger's team now has evidence of human habitation dating a few decades earlier, to at least 1420. It involved skeletons discovered at the royal palace at Machu Picchu way back in 1912.
KING: Right. And technology has advanced to where carbon-14 can be dated using even the smallest quantities. And those ancient bones gave the Yale team what they needed.
ELLIOTT: Burger says, their discovery is only a beginning.
BURGER: Some people have often said, well, you know, the Inca empire is so huge and it left so many archaeological remains. Maybe we need a radical revision of the chronology and maybe even push it into, say, the 14th century. Maybe we're completely off base in terms of our estimates.
ELLIOTT: Richard Burger, professor of anthropology at Yale University, unlocking the history of Machu Picchu one secret at a time.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.
