The final part reveals how our knowledge of cells has brought us to the brink of one of the most important moments in history. Scientists are close to repeating what has happened only once in four billion years - the creation of a new life form.

1917. People have had enough of the war. Behind the scenes, uprisings are brewing, like the one that toppled the Tsar in Russia; on the front soldiers begin to mutiny as they did at Chemin des Dames in France. German submarine attacks in the Atlantic will finally pull the Americans into the war, but they arrive too late to help prevent the carnage of the Battle of Passchendaele.

It's 3.5 million years ago and in East Africa a remarkable species of ape roams the land. Australopithecus afarensis has taken the first tentative steps towards humanity by standing and walking on two legs. The rift valley was forming, and the rain forests dying as Africa dried out - turning the landscape into a mosaic of scattered trees and grass. In this new environment afarensis found it more efficient to move about on two legs rather than four.

The BBC has made an extraordinary new documentary, presented by Sir David Attenborough, which will reveal the discovery of a fossilised skeleton that may be a vital ‘missing link’ in human evolution. The centrepiece of the programme is the unveiling of the first-ever complete skeleton of an extinct animal called an adapid

In this final episode, Mary Beard delves even deeper into ordinary Roman life by going behind the closed doors of their homes. She meets an extraordinary cast of characters - drunken housewives, teenage brides, bullied children and runaway slaves - and paints a more dynamic, lusty picture of Roman family life. Mary uncovers their preserved beds, furniture and cradles, tries on Roman wedding rings and meets some eccentric wives like Glyconis, praised by her husband for liking a drink or two, and Allia Potestas, who lived in a Roman menage a trois. Mary explores Roman parenting, childbirth and children, including Sulpicius Maximus, an 11-year-old schoolboy who was worked to death by his pushy parents, and Geminia Mater, a 5-year-old tomboy. Finally, Mary paints a more nuanced picture of Roman slavery and asks why if it was such a brutal institution did many Romans choose to be buried with their servants - living cheek by jowl in death, as in life