It will go down as one of the most amazing archeological discoveries in history. Homo naledi - a new species of human-like fossils found in South Africa - is already rewriting the story of human evolution. These 15 skeletons are the largest cache of pre-human bones ever found. But so far, scientists don't know how old they are, or why they were placed in this burial site. Grad student Alia Gurtov describes the perilous crawl into the cave, which narrows to 7 inches at one point, in order to retrieve the fossils. And paleoanthropologist John Hawks explains why the discovery overturns decades of assumptions about our ancestry.
What's it like to look at the 30,000-year old paintings in Chauvet Cave? "You're just awe-struck," says renowned filmmaker Werner Herzog, who finds direct connections between these ancient paintings and modern art. The Chauvet paintings also inspired Kim Stanley Robinson to write his novel "Shaman," which is set in the paleolithic era when humans co-existed with Neandertals. Michelle Paver is another novelist who writes about the Stone Age. Her big question: What kinds of stories were told by the greatest storytellers?
In our last segment, we shift gears and reflect on 9/11 and the battles that followed with one of the world's great war photographers. James Nachtwey nearly died taking photos at Ground Zero as the World Trade Center collapsed, and he's waded into war zones around the world.