The ancient remains of a teenage girl found in an underwater Mexican cave have established a definitive link between the earliest Americans and modern Native Americans.

An international team of researchers discovered the remains of the girl called Naia, estimated to be between 12,000 and 13,000-years-old, in a pit called Hoyo Nego, meaning "black hole" in Spanish. The skeleton was found in an underwater cave on the Yucatán peninsula.

Now an international team of researchers have identified a nearly complete Paleoamerican skeleton with Native American DNA that dates close to the time the race first entered the New World.

The findings have major implications for our understanding of the origins of the Western Hemisphere's first people and their relationship with contemporary Native Americans.

North America oldest skeleton
A cave diver inspects the newly-discovered skull of Naia in a submerged cave on the Yucatan peninsula of Mexico Daniel Riordan Araujo

Eastern Asia, Western Asia, Japan, Beringia and even Europe have all been suggested origination points for the earliest humans to enter the Americas because of apparent differences in cranial form between today's Native Americans and the earliest known Paleoamerican skeletons.

The study was conducted by researchers from 13 institutions, including Deborah Bolnick, a professor of anthropology at the University of Texas in Austin.

Researchers in separate labs independently examined the tooth's mitochondrial DNA, which is maternally inherited. They found that the ancient girl belonged to a genetic lineage shared only by Native Americans.

This is the first time researchers have been able to match a skeleton with an early American (or Paleoamerican) skull and facial characteristics with DNA linked to the hunter-gatherers who moved onto the Bering Land Bridge from northeast Asia between 26,000 and 18,000 years ago. They spread southward into North America sometime after 17,000 years ago.

Morphologically, Naia does not look like a contemporary Native American, but mitochondrial DNA testing carried out at Washington State University showed that she has a D1 haplotype.

This is consistent with the hypothesis that her ancestors' origins were in Beringia, a now partially submerged landmass including parts of Siberia, Alaska and the Yukon.

"The Hoyo Negro girl was related to living Native Americans and has ancestry from the same Beringian population," Bolnick says. "This study therefore provides no support for the hypothesis that Paleoamericans migrated from Southeast Asia, Australia or Europe."

"Instead, it shows that Paleoamericans could have come from Beringia, like contemporary Native Americans, even though they exhibit some distinctive skull and facial features. The physical differences between Paleoamericans and Native Americans today are more likely due to changes that occurred in Beringia and the Americas over the last 9,000 years," Bolnick added.

The study was led by Mexico's National Institute of Anthropology and History, and coordinated by James Chatters, owner of Applied Paleoscience, an archaeological and paleontological consulting firm in Bothell, Wash.

The research was published in the journal Science.