Horizon reports on the resurgence in research on psychedelic drugs in the 1990's.

In this documentary, Horizon investigates obesity in Britain, following a woman, Heather Osborne, who weighs 322 pounds. We watch her progress through a stomach stapling operation and explore reports on a so-called fat free fat and two new drugs which have been marketed as the ultimate cure for obesity.

Horizon follows the investigations into the origins of a 16th century shipwreck discovered off of the coast of the Channel Islands.

This episode of Horizon presents a profile of the inventor Sir Frank Whittle and his idea for the first jet engine which changed the nature of air travel.

In this episode, Horizon reports on the last lab samples of smallpox destined to be destroyed. But do we still have much to learn from this virus?

In this episode, Horizon investigates an amazing new sign language developed solely by deaf children and explores if we copy language from what surrounds us.

Horizon reports on a radical new theory by Professor Polly Matzinger about the human body's immune system.

Horizon investigates the real impact that oil pollution has on our environment during a 12 month study.

Horizon reports on the technical and logistical struggles of teams trying for the first time to circumnavigate the earth by balloon.

Horizon investigates the theory that a comet impact in the Gulf of Mexico was responsible for the mass extinction of the dinosaurs.

Horizon reports on how mainstream science is now looking at whether the brain can affect the immune system.

In this episode, Horizon presents new findings about the dates for the arrival of people in Australia and the invention of art.

Horizon presents a documentary about scientists who now believe that viruses that can kill bacteria, known as bacteriophage, might win the fight against super-germs.

Looks at Ian Waterman, who at 19 caught a virus that destroyed half of his nervous system and who, in spite of medical assertions that he would never walk, feed or move again, managed by sheer will-power to get back some mobility. Examines the question of how far the brain can over-ride disease or physical problems.

This Horizon documentary is about how and why, a sheep named Dolly, became the first cloned copy of an adult mammal.