Narrator in “Unfinished Business”

[about Australopithecus] A type of ape has evolved that clearly shows the first signs of becoming more human. What makes them closer to us than other apes is not their brains, which are only one third of the size. It's not their skin, which is hairy. It's something they do that other apes just don't. Something that will one day lead them to be described as a missing link. These apes walk upright!