Artists, academics, and critics discuss the historical origins, original reception, and slow climb to critical acclaim for Eugene Delacroix's painting commemorating the Revolution of 1830, 'Liberty Leading the People.'
A woman of the people with a phrygian cap personifying the concept of Liberty leads the people forward over a barricade and the bodies of the fallen, holding the flag of the French Revolution – the tricolour, which again became France's national flag after these events – in one hand and brandishing a bayonetted musket with the other. The figure of Liberty is also viewed as a symbol of France and the French Republic known as Marianne.

The next instalment focuses on dietary needs and how different species have evolved beaks to suit their individual requirements. The latter come in a multitude of forms. Blue tits and goldfinches have beaks akin to tweezers, with which to extract seeds, while the hawfinch's razor-like bill can deal with a cherry-stone. However, the crossbill is the only finch that can twist its mandibles in opposite directions. Jays store acorns for winter by burying them in the ground, whereas woodpeckers can keep up to 60,000 of them in one tree trunk. Sap is also desirable, and there are a variety of methods used to obtain it. The hoatzin is the only specialised leaf-eater, and accordingly has a digestive system more akin to that of cattle. Plants recruit birds to aid pollination, and offer nectar as a reward. Hummingbirds eat little else, and the sword-bill's beak is the longest of any bird in relation to its body. Insects are also highly prized, and Galapagos finches are shown to possess some ingenuity as they not only strip bark, but also use 'tools' to reach their prey. Crows are hailed as being among the most intelligent birds, and one is shown using a twig to spear a grub within a fallen log. The robin is an opportunist, and Sir Attenborough observes one seizing morsels as he digs a patch of earth. In South America, a cattle tyrant sits atop an obliging capybara and uses its vantage point to spot passing food that may be dislodged by its grazing partner.

Fourth episode examines how plants either share environments harmoniously or compete for dominance within them. Attenborough highlights the 1987 hurricane and the devastation it caused. However, for some species, it was that opportunity for which they had lain dormant for many years. The space left by uprooted trees is soon filled by others who move relatively swiftly towards the light. The oak is one of the strongest and longest-lived, and other, lesser plants nearby must wait until the spring to flourish before the light above is extinguished by leaves. Tropical forests are green throughout the year, so brute force is needed for a successful climb to the top of the canopy: the rattan is an example that has the longest stem of any plant. As its name suggests, the strangler fig 'throttles' its host by growing around it and cutting off essential water and light. Some can take advantage of a fallen tree by setting down roots on the now horizontal trunk and getting nutriment from the surrounding moss and the fungi on the dead bark. The mountain ash (eucalyptus regnans) grows so tall, that regeneration becomes a considerable problem. It is easily flammable, so its solution is to shed its seeds during a forest fire and sacrifice itself. It therefore relies on the periodic near-destruction of its surroundings in order to survive. Attenborough observes that catastrophes such as fire and drought, while initially detrimental to wildlife, eventually allow for deserted habitats to be reborn.

Having explained the science behind global warming, and addressed the arguments of the climate change sceptics earlier in the series, Dr Iain Stewart concludes the series by looking at the biggest challenge now facing climate scientists - Just how can they predict exactly what changes global warming will bring?
It's a journey that takes him from early attempts to model the climate system with dishpans, to supercomputers, and to the frontline of climate research today: Greenland. Most worryingly he discovers that scientists are becoming increasingly concerned that their models are actually underestimating the speed of changes already underway.

Richard Rudgley goes in search of evidence of the barbarians of the dark ages, people whose names have for 1500 years been bywords for mindless brutality. The real truth about the barbarians who marched across Europe during the Dark Ages is more shocking than what you may know. Where did they come from? Who are their descendants? Are any of their techniques and inventions still used? Richard discovers the secrets of forgotten empires, and of mighty clashes throughout Europe. The art, society and cultural legacy of the barbarians are shown to have shaped and moulded the destiny of Europe even more than the Roman Empire.
In the first part of the journey through the Dark Ages we will be tracing the legacies of the Huns, Vandals and Goths, to ask whether the 'dark ages' represent a resurfacing of much older tribal lines. Sites in Austria show how sophisticated pre-Roman communities had become with evidence of stunning craftsmanship and sophisticated farming techniques which defy the image of a mindless rabble we have come to accept without challenge.

The film is a intimate diary of Bob Dylan's 1965 tour of Britain, chronicling reactions as his tunes caught the nation off-guard, but ultimately won him critical acclaim and worldwide fame and fortune. Featuring interviews with various Sixties cult figures, including the man himself, his then-girlfriend Joan Baez and poet Allen Ginsberg.