The history of the world as explained through objects arrives in North America 2000 years ago and a stone pipe used in ritual. It is one of hundreds of pipes shaped as animals that were found in huge mounds in present day Ohio. Neil MacGregor pieces together the evidence for how these pipes were used. Tony Benn and the artist Maggie Hambling consider the allure of smoking from a modern perspective while Native American historian Gabrielle Tayac describes how the pipe formed a central role in traditional ritual and religious life. Producer: Anthony Denselow