What is it, exactly, that makes humans "human"? This three-part PBS documentary program revisits the fascinating evolution of mankind, which over the course of billions of years, at last produced a very specific variation of the species that permitted us to separate ourselves from our animal brethren and achieve a lasting dominion over the entire planet. Alan Alda hosts. 180 min. Widescreen (Enhanced); Soundtrack: English Dolby Digital stereo.