Scientists have struggled for centuries to pinpoint the qualities that distinguish humans from the millions of other animal species with which we share the vast majority of our DNA. In this NOVA scienceNOW program, we explore those traits once thought to be uniquely human to discover their evolutionary roots.

Nova scienceNow (Television program). Originally released by Public Broadcasting Service (U.S.), 2012. Streaming video file encoded with permission for digital streaming by Infobase on December 15, 2015.

Diversity of Species --(2:36) -- Differences in the Skulls -- (3:45) -- Brain Structure -- (3:20) -- Neanderthal Genome -- (2:02) -- Not Extinct, In A Way -- (3:58) -- Origin of Language -- (4:44) -- Tool to Language Hypothesis -- (3:14) -- Broca's Area -- (5:06) -- Laughing Babies -- (3:00) -- Laughing Animals -- (4:35) -- Laughter Makes Us Human -- (2:42) -- Mysteries of Human Evolution -- (6:25) -- Zeray Makes Ethiopia Proud -- (4:16) -- Credits: What Makes Us Human? -- (1:52).