Through a mix of crime-lab science, archeology, and history, this NOVA/National Geographic special presents new evidence that is changing what we know about the final days of the once-mighty Inca Empire. This probing story of archeological discovery begins in a cemetery crammed with skeletons that offer tantalizing clues about a fierce 16th-century battle between warriors of the collapsing Inca Empire and Spanish invaders. Now, the long-accepted account of a swift Spanish conquest of the Inca—achieved with guns, steel, and horses—is being replaced by a more complete story based on surprising new evidence, including what may be the first gunshot wound in the Americas.

The first hour examines the factors that caused the split from the apes. The film explores the fossil of “Selam,” also known as “Lucy’s Child” — an amazing, nearly complete child fossil that helps shed light on our ancestors’ early development and how we began to depart from that of chimps.

In gripping forensic detail, the second program in “Becoming Human” investigates the first skeleton that really looks like us — “Turkana Boy” — an astonishingly complete specimen of Homo erectus found by the famous Leakey team in Kenya.

The final program examines the roots of our own species, Homo sapiens, which new evidence pinpoints to southern Africa some 200,000 years ago. New discoveries are upending old ideas and suggesting that our exodus from Africa was far earlier than previously thought.