Cannabis is the world's favourite drug, but also one of the least understood. Can cannabis cause schizophrenia? Is it addictive? Can it lead you on to harder drugs? Or is it simply a herb, an undervalued medicine? Addiction specialist Dr John Marsden discovers that modern science is finally beginning to find answers to these questions. John traces the cannabis plants' birthplace in Kazakhstan; finds the origins of our sensitivity to cannabis in the simple sea squirt; and finds out just what it does to our brains. He meets people who have been changed by this drug in drastically different ways - from those whose lives have been shattered to those who lives have been revived.

Journey through the long-vanished corners of prehistoric North America, beginning when man first entered the vast, unspoiled continent some 14,000 years ago, in this appealing BBC documentary. Witness ancient beasts, mammoths, mastodons, giant bears, and sabre-toothed cats, and see the legacies each has passed to their modern successors. Computer animation and digital effects bring to life mammoths, saber-toothed cats, giant ground sloths, short-faced bears, glyptodonts, and a plethora of smaller animals in a lush Ice Age mosaic.

Southern Africa is a riot of life and colour because of two great ocean currents that sweep around the continent's Cape. To the east, the warm Agulhas current generates clouds that roll inland to the wettest place in southern Africa. To the west is the cold Benguela current, home to more great white sharks than anywhere else. Moisture laden fog rolls inland, supporting an incredible desert garden. Where the two currents meet, the clash of warm and cold water creates one of the world's most fabulous natural spectacles - South Africa's sardine run. This is the greatest gathering of predators on the planet, including Africa's largest, the Bryde's whale.

In February 2009, Michael Moore issued an appeal to people who worked for Wall Street or in the financial industry to share first hand information, requesting, 'Be a hero and help me expose the biggest swindle in American history'. He uncovers the social costs of corporate interests pursuing profits at the expense of the public good.

The story of America's most notorious gangster, Al Capone, starts on the streets of Brooklyn. In 1913, at the age of 14, Capone starts running errands for local gangsters - just one of many immigrants struggling to survive. One day, young Al Capone gets caught in a police raid. He quickly grabs what money he can, evades police, and runs to the headquarters of mob boss Johnny Torrio. Torrio rewards Capone for his quick-thinking. When Torrio recognizes Capone's intelligence and drive, he takes him under his wing.

Caravaggio's approach to painting was unconventional. He avoided the standard method of making copies of old sculptures and instead took the more direct approach of painting directly onto canvas without drawing first. He also used people from the street as his models. His dramatic painting was enhanced with intense and theatrical lighting. Caravaggio's fate was sealed when he killed a man in a duel in 1606. He fled to Naples where he attempted to paint his way out of trouble, he became a Knight, but was then imprisoned in Malta and then finally moved to Sicily. He was pardoned for murder in 1610, but died of a fever when attempting to return to Rome. For me the power of Caravaggio's art is the power of truth, not least the truth about ourselves. If we are ever to hope for redemption we have to start from the recognition that the Goliath competes with the David in all of us."