Embark upon a thrilling scientific adventure to discover evidence that could reframe the human family tree.

This is the unexaggerated account of a dangerous expedition into the Earth, in which bold researchers struggle through ancient caves to answer vital questions about who we were, and who we are.

Embark upon a thrilling scientific adventure to discover evidence that could reframe the human family tree.

This is the unexaggerated account of a dangerous expedition into the Earth, in which bold researchers struggle through ancient caves to answer vital questions about who we were, and who we are.

Join National Geographic Explorer Lee Berger on the adventure of a lifetime as he explores South Africa's Rising Star cave system, a treasure trove of ancient findings that could redefine the force of human evolution. These are discoveries that Berger calls "the Rosetta stone of the human mind."

In the summer of 2022, Berger lost 50 pounds in order to wriggle though impossibly small openings in Rising Star to see the remains of Homo naledi, a proto-human likely to have coexisted with Homo sapiens some 250,000 years ago. Though the dark, cramped, dangerous underground spaces could spell disaster for Berger, the answers that might lie with the naledi fossils are too critical. It was time to take the risk.

This exclusive firsthand account by Berger and fellow expedition member John Hawks takes readers inside the suffocating passages of Rising Star to the very places that naledi once traveled. Inside the cave, stand, crouch, and crawl with Berger as he makes shocking new discoveries that expand our understanding of early hominids-discoveries that stand to alter our fundamental understanding of what makes us human.

What does it all mean?