In part two, Professor Al-Khalili looks at the 19th century chemists who struggled to impose an order on the apparently random world of the elements. From working out how many there were to discovering their unique relationships with each other, the early scientists' bid to decode the hidden order of the elements was driven by false starts and bitter disputes. But ultimately the quest would lead to one of chemistry's most beautiful intellectual creations - the periodic table.

Professor Robert Bartlett explores how the Normans developed from a band of marauding Vikings into the formidable warriors who conquered England in 1066. He tells how the Normans established their new province of Normandy -'land of the northmen' - in northern France. Under the leadership of Duke William, they conquered England. The Battle of Hastings marked the end of the Anglo-Saxon aristocracy and monarchy. The culture and politics of England would now be transformed by the Normans.

Professor Robert Bartlett explores the impact of the Norman conquest of Britain and Ireland. Bartlett shows how William the Conqueror imposed a new aristocracy, savagely cut down opposition and built scores of castles and cathedrals to intimidate and control. He also commissioned the Domesday Book, the greatest national survey of England that had ever been attempted. England adapted to its new masters and both the language and culture were transformed as the Normans and the English intermarried. Bartlett shows how the political and cultural landscape of Scotland, Wales and Ireland were also forged by the Normans and argues that the Normans created the blueprint for colonialism in the modern world.

Professor Robert Bartlett explores the impact of the Normans on southern Europe and the Middle East. The Normans spread south in the 11th century, winning control of southern Italy and the island of Sicily. There they created their most prosperous kingdom, where Christianity and Islam co-existed in relative harmony and mutual tolerance. It became a great centre of medieval culture and learning. But events in the Middle East provoked the more aggressive side of the Norman character. In 1095, the Normans enthusiastically answered the Pope's call for holy war against Islam and joined the first crusade. They lay siege to Jerusalem and eventually helped win back the holy city from the muslims. This bloody conquest left a deep rift between Christianity and Islam which is still being felt to this day.

We are the only species on earth that cooks its food - and we are also the cleverest species on the planet. The question is: do we cook because we're clever and imaginative, or are we clever and imaginative because our ancestors discovered cooking? Horizon examines the evidence that our ancestors' changing diet and their mastery of fire prompted anatomical and neurological changes that resulted in taking us out of the trees and into the kitchen.

Dr Thomas Dixon delves into the BBC's archive to explore the troubled relationship between religion and science. From the creationists of America to the physicists of the Large Hadron Collider, he traces the expansion of scientific knowledge and asks whether there is still room for God in the modern world. He looks at what happens when new scientific discoveries start to explain events that were once seen as the workings of God, and explains how some of our most famous scientists have seen God in the grandest laws of the universe. Finally, he finds intriguing evidence from brain science which hints that belief in God is here to stay.