How would you define your life for people living thousands of years in the future? Here’s the catch: you can’t use words. For scientists who study fossils, their job is to decode and understand the lives of creatures from thousands of years ago from the fossilized remnants they unearth.

“What we live in today is just a glimpse of time,” ETSU geosciences professor Dr. Blaine Schubert said. “We need to look at our deeper history to better understand our place in it.”

Last week, an episode of “Nova” featuring Schubert aired on PBS. The special called “First Face of America” profiles the oldest and most complete human skeleton that’s been found in the Americas. Her remains are 13,000 years old, discovered in an underwater cave in Yucatán.

What might her life have been like? That’s what Schubert and many other scientists working in these caves are trying to find out. Schubert heads up the Center for Excellence in Paleontology. His primary focus since becoming involved with the project in 2016 is on the animal fossils that have been found in these caves.

“The animals we find alongside [the human] tell a more complete story of what life what like for people living at that time,” Schubert said. “It was a difficult place to live.”

According to Schubert, the caves weren’t always underwater. The people and animals of the late pleistocene era could once walk right into them—and fall to their deaths in numerous pits, leaving their fossils to be found in present day. There’s almost no fossil record of Central America because tropical climates aren’t ideal for preserving remains, but as the ice age ended, the water flooding these caves made it possible.

In the past, scientists had only found fragments, but now the discovery of these caves has revealed complete skeletons of short-faced bears, sabertooth cats and giant ground sloths.

“There’s still so much to discover,” Schubert said. “Just when you think you understand something about the animals, the plants and the world—then all of a sudden, you’re shown something completely different.”

You can watch the “Nova” special at pbs.org.