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Introduction: First Face of America (03:33)

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Divers discover prehistoric bones at the bottom of a flooded Mexican cave system. The bones of a girl will provide insight into the first humans to arrive in the Americas.

Hoyo Negro (04:27)

Cave divers prepare to explore a system of cenotes in the Yucatan Peninsula in Mexico. The dangerous system of underwater tunnels stretches for hundreds of miles; it flooded at the end of the last Ice Age 10,000 years ago. Divers come upon a vast black pit; they see bones at the bottom.

Prehistoric Bones (03:29)

Alex Alvarez and Alberto Nava find over twenty partial skeletons at the bottom of Hoyo Negro: a human pelvis, broken femur, skull of a cave bear, a skeleton of a giant sloth, and a thigh bone of an extinct elephant. The divers send the bones to Pilar Luna, Director of Subaquatic Archeology at Mexico’s National Institute of Anthropology and History. She sends a CD of photos to James Chatters who says the human bones are of an adolescent female they later named Naia.

Radiocarbon Dating (03:15)

Chatters extracts protein containing carbon from bones and tooth fragments. From the Carbon 14 in Naia's tooth enamel, Chatters learns that her bones are about 13,000 years old, making her one of the oldest humans found in the Americas.

Clovis People (03:29)

Homo sapiens moved from Africa 80,000 years ago and spread through the Middle East, Europe, Asia, and Australia. Sea levels fell, and a land bridge that spread 1,000 miles wide connected Siberia to Alaska. In the 1930s, people discovered stone tools and spear points in Clovis, New Mexico. The bones of a child, found in 1968, provided the first solid link between Clovis technology and a human.

Naia's Skull (06:45)

Naia and five other partials are the only skeletons older than 12,000 years. Chatters travels to Mexico, organizes a dive to retrieve Naia’s skull, and talks with Susan Bird about how to handle the delicate bones she is going to collect. Bird, Alvarez, and Nava dive to get the brittle bones, and have to take three decompression stops on the way back up to avoid the bends.

Naia's Age (03:10)

Chatters takes Naia’s skull to the labs at the National Institute of Anthropology and History in Campeche, Mexico and performs a CT scan and places the skull in a bath of chemicals to protect it from air. The remainder of Naia’s skeleton is brought to the surface for forensic analysis. After Naia’s skeleton is assembled, Chatters learns that she was 15 or 16 years old, and she gave birth when her pelvis was not prepared to produce a child.

Entering the Cave (02:36)

Chatters says in the time Naia was alive, the area was dry, and people likely had to find water in the recesses of caves, especially in a dry season. Many animals use caves for denning, which makes them dangerous for people. Naia's muscle development is evidence of a high level of physical activity; it is more like that of a modern 35 year old male than a teenage female.

Naia's Abuse Fracture (02:14)

Chatters explains there was a lot of interpersonal violence and extreme male aggression in hunter-gatherer populations because there were fewer women than men. Women died in their early twenties, and men died in their mid to late 30s. The Kennewick Man’s skeleton shows signs of trauma likely from fighting as seen by head injuries, broken bones, and a healed spear wound in his pelvis.

Difference in Skull Structure (02:43)

The Kennewick Man looks very different from modern Americans. Naia's skull along with those found in Kennewick, Washington; Sprit Cave, Nevada; and Horn Shelter, Texas are more ruggedly built with heavy brows, large muscle attachments, and more projecting in form. Modern Native American males have smaller heads and finer features with more roundness in the back of the skull, a longer face, and with the face more tucked back.

Difference in Tools (03:42)

In the Tennanah Valley of Central Alaska, archeologist Ben Potter and his team discover campsites of early nomads from Siberia. Beringia, the 1,000 miles wide land bridge that connected Asia and America, was home for early immigrants from Asia. Tools found from these people are stored at The University of Alaska Museum in Fairbanks, and they are very different from the tools and spear points found from the Clovis People.

Connecting Ancestors (03:30)

Potter finds the grave of two infants near the Upward Sun River in Alaska. They were buried carefully with symbolic artifacts and red ochre. Potter sends samples to Danish geneticist, Eske Willerslev, in Copenhagen, where he extracts DNA and finds the ACTG genetic marker that links ancestors to living descendants.

American Indian People (02:05)

Willerslev discovers that the Upward Sun People, or the Beringians, are ancestors of all ancient and modern Native Americans. The genomic analyses indicated a single existence of Ancient Asian hunters in Beringia 25,000 years ago. Shane Doyle from the Crow Tribe says that people who met at the Bering had unique genetic profiles; they had children together, and produced a new group of people who make up all Native Americans. There is no Native American DNA in the world except in the Americas.

First Native Americans (02:28)

About 15,000 years ago, Native Americans moved south from Beringia and developed new tools and weapons that became the distinctive Clovis People culture. Chatters says Naia’s people were new to the area as indicated by the growth patterns showing that there were periods of malnourishment. Through the teeth and jawbone of Naia, he can see that one season every year, she did not eat enough protein, which shows they did not know how to obtain it.

Death of Naia (04:27)

Chatters shows Naia’s skull having a jagged fracture, which indicates it lead to her death. Chatters speculates that she entered the cave, possibly lost her light source, wandered for a long time trying to leave the cave, and took a fatal step, falling 100 or more feet to her death. The sea levels rose, the Hoyo Negro cave system flooded about 10,000 years ago, and the water preserved the bones at the bottom until they were discovered.