This first-person narrative about an archaeological discovery is rewriting the story of human evolution. A story of defiance and determination by a controversial scientist, this is Lee Berger's own take on finding Homo naledi, an all-new species on the human family tree and one of the greatest discoveries of the 21st century.

In 2013, Berger, a National Geographic Explorer-in-Residence, caught wind of a cache of bones in a hard-to-reach underground cave in South Africa. He put out a call around the world for petite collaborators--men and women small and adventurous enough to be...