Mac scientist helps tell tale of 13,000-year-old Mexican skeleton

A McMaster University scientist played a key role in verifying the age of a pristine 13,000-year-old skeleton submerged in a Mexican cave that is being heralded as an unprecedented glimpse into the history of early inhabitants of the Americas.

The skeleton of the teenaged girl scientists call Naia was covered in 40 metres of water in the Yucatán Peninsula, which helped to preserve the remains, but made dating the bones problematic.

Eduard Reinhardt, a micropaleontologist at McMaster, constructed an "environmental story" of the caves that was used in conjunction with carbon dating done on a tooth of the girl's skull.

"Getting a reliable age out of waterlogged skeletons is a bit of challenge," he said.

Reinhardt studied the area around the remains and was able to "help verify the radio carbon results. I was able to provide a context as to as to why Naia was going into the cave."

He said he was able to determine the varying water levels within the cave system over time to figure out "when people and animals could actually get into the cave system."

It is believe the girl fell into the cave at a time when it was relatively dry.

"We provided an environmental framework of the cave system and then the dating of the water-level rise helped us check ages we were getting from the skeleton. It gives us confidence in radio carbon ages."

Reinhardt says there are two scenarios about how Naia ended up in the cave: She willingly walked in and became trapped, perhaps after being injured. Or she maybe fell through a hole in the ground to become trapped in the cave that was beneath the ground.

She likely starved to death and through time the cave flooded with water, preserving her skeleton and remains of numerous animals, including a sabre-toothed tiger, giant ground sloths and cave bears. The animal remains, Reinhardt said, are going through numerous studies.

Naia's remains were discovered in 2007 by three Mexican cave divers who reported their find to the National Institute of Anthropology and History in Mexico. A group of 16 scientists and cave explorers from Mexico, the United States and Canada was formed in 2011 to photograph and document the site, and to collect fossilized samples for testing.

- thespec.com