Anthropologist Donald Johanson looks at how our human ancestors of two million years ago made their living. Contrary to popular myth, scavenging was a more lucrative living than hunting – and may have contributed to the development of human intelligence.

NOVA visits the most cigarette-addicted nation in the world, China. Western advertising and trading practices have exacerbated the fatal romance with smoking in the world's most populous country, where lung cancer cases are beginning to strain the nation's health care system.