Skeleton reveals Native American history

A teenage girl who fell into a hole more than 12,000 years ago in Mexico's Yucatan Peninsula is offering new clues about the origins of the first Native Americans.

Named "Naia" by scientists, her skeleton is among the oldest known and best preserved in the Americas.

Her remains were found in 2007, submerged in an underwater cave along with the bones of sabre tooth tigers, giant sloths and cave bears, some 41 metres below sea level.

At the time she fell, some 12,000 to 13,000 years ago, the area, called Hoyo Negro, or Black Hole in Spanish, was dry and above ground.

Melting glaciers caused sea level rise that covered the pit with water for the last 8000 years.

The girl was aged 15 to 16 and may have slipped into what appeared to her to be a watering hole.

Her pelvis appears to have broken on impact, suggesting she died quickly after her fall, said Jim Chatters, an archaeologist and forensic anthropologist in Bothell, Washington.

Her skull shows she had a small, narrow face, wide-set eyes, a prominent forehead and teeth that jutted outward.

Her appearance was "about the opposite of what Native Americans look like," Chatters told reporters on Thursday.

But a genetic marker found in the girl's rib bone and tooth shows that her maternally inherited lineage was the same as that found in some modern Native Americans.

The report in the journal Science suggests she descended from people who migrated from Asia across the Bering Strait, over a land mass that was known as Beringia.

"What this study is presenting for the first time is the evidence that paleo-Americans with those distinctive features can also be directly tied to the same Beringian source population as contemporary Native Americans," said Deborah Bolnick, an assistant professor at the University of Texas at Austin.

That goes against theories held by some experts that Native Americans were descendants of people who migrated later, perhaps from Europe, southeast Asia or Australia.