The journey continues into Asia, the world's greatest land mass, in a quest to discover how early hunter-gatherers managed to survive in one of the most inhospitable places on earth - the Arctic region of Northern Siberia. Alice also explores what may have occurred during human migration to produce Chinese physical characteristics, and considers a controversial claim about Chinese evolution: that the Chinese do not share the same African ancestry as other peoples.

When ancient Greece fell into decline, mathematical progress stagnated as Europe entered the Dark Ages, but in the East mathematics reached new heights. In the second episode, Du Sautoy explores how maths helped build imperial China and discovers how the symbol for the number zero was invented in India. He also looks at the Middle Eastern invention of algebra and how mathematicians such as Fibonacci spread Eastern knowledge to the West.

Austrian director Michael Glawogger travels to five countries to focus on some of the worst jobs imaginable: Ukrainian miners crawl into tiny cracks in old coal pits to scratch out a few bags of winter fuel; Indonesian workers trudge long distances carrying baskets with hundreds of pounds of sulfur chunks extracted from a steaming mountain; Pakistanis risk explosions and burial under tons of scrap iron as they dismantle huge carrier ships. The visuals are everything here. Despite the hardships depicted, many sequences have a dreamlike beauty. In addition, the director has a bone-dry sense of irony; during the Ukraine scenes, he frequently cuts away to a statue of Stakhanov, the "hero" lauded by the Soviets for his superhuman work habits. He also shows us an old German smelting works that's been converted into a theme park.

Intrepid adventurer Michael Palin travels through Pakistan's North-West Frontier Province, starting on the Khyber Pass and ending five miles from K2 on the Pakistan/China border. He passes through Darra, visits a street dentist in Peshawar, goes bull racing with a Pakistani aristocrat and is almost trampled to death, and finally crosses over the Lowari Pass into the buffer state of Chitral.

Following the Yangtze along Tiger Leaping Gorge into Yunnan in China, Palin reaches the easternmost end of the Himalayas. He gets a medical check-up before exploring medieval Lijiang with the director of the local orchestra. Heading over Myanmar to Nagaland in India he rides the steam train to Tipong Coalmine. In Assam he rides an elephant and then stays in a strange monastery.

The magnificent ancient city of pyramids at Caral in Peru is a thousand years older than the earliest known civilisation in the Americas and, at 2,627 BC, is as old as the pyramids of Egypt. Many now believe it is the fabled missing link of archaeology - a 'mother city'. If so, then these extraordinary findings could finally answer one of the great questions of archaeology: why did humans become civilised?" For over a century, archaeologists have been searching for what they call a mother city. Civilisation began in only six areas of the world: Egypt, Mesopotamia, India, China, Peru and Central America. In each of these regions people moved from small family units to build cities of thousands of people. They crossed the historic divide, one of the great moments in human history. Why? To find the answer archaeologists needed to find a mother city - the first stage of city-building. Caral, is so much older than anything else in South America that it is a clear candidate to be the mother city. It also is in pristine condition. Nothing has been built on it at all. Instead laid out before the world is an elaborate complex of pyramids, temples, an amphitheatre and ordinary houses. Scientists developed a number of theories. Some said it was because of the development of trade, others that it was irrigation. Some even today believe it was all because of aliens. Gradually an uneasy consensus emerged. The key force common to all civilisations was warfare. Crucially, there is not the faintest trace of warfare at Caral; no battlements, no weapons, no mutilated bodies. Instead, Ruth's findings suggest it was a gentle society, built on commerce and pleasure. In one of the pyramids they uncovered beautiful flutes made from condor and pelican bones. They have also found evidence of a culture that took drugs and perhaps aphrodisiacs. Most stunning of all, they have found the remains of a baby, lovingly wrapped and buried with a precious necklace made of stone beads.