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.

Ripped from international headlines, The Hacker Wars takes you to the front lines of the high-stakes battle over the fate of the Internet, freedom and privacy". Get ready to be shuttled between story lines at lightning speed mirroring the disjointed lives of the protagonists and life on the Internet. The Hacker Wars- a film about the targeting of (h)ac(k)tivists and journalists by the US government. Hacktivists are either terrorists or freedom fighters depending on ones perspective on who should control information. Meet weev, infamous hacker; Barrett Brown, journalist and propagandist for the hacktivist collective, Anonymous; and Jeremy Hammond, aka Anarchaos, number one on the FBI's cyber-criminal list. The fourth character is Sabu, the uber-hacker turned FBI informant who ran the FBI's cyber unit for 9 months and is responsible for many arrests. He is the shadowy protagonist in a high-stakes game of espionage and betrayal in the age of the Internet. Barrett Brown, American journalist, is facing 105 years in prison for publicizing information revealed through Jeremy Hammond's epic hacks. Hammond himself has just begun a 10-year prison term. Andrew Auernheimer, known by his hacker handle weev embarrasses large corporations. He was sentenced to 41 months for hacking AT&T, but his conviction was just overturned. He vows to continue doing what landed him in prison in the first place. These hacktivists are the rock stars of the Internetmodern-day folk heroes. Glenn Greenwald (Snowdon Leaks), Pulitzer Prize-winning journalist and others explain why these anti-heroes exposing the security surveillance state are essential to a functioning democracy.

Series concludes with the focus shifting to the United States in the post-war years of the 1950s and beyond. Beginning with arguably the most notorious work of 20th century classical music, John Cage's 'silent' composition 4'33", it looks at how a series of maverick Americans re-invented the sound of classical music into a more simple form, bringing back harmonies and rhythms that made it increasingly popular with audiences across the world. It also examines how this music found its way into a spiritual realm, with the strain of pared-down religious composition that came to be known as 'holy minimalism'. From the Maverick concert hall in Woodstock, New York to an Orthodox cathedral in Estonia to a car park in Peckham, south London, the story is told by a stellar line-up of contributors including Philip Glass, Steve Reich, John Adams, Arvo Pärt and John Tavener.

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.

Even after thousands of years of ice crushing the northern hemisphere and temperatures of 20 degrees lower than those of today, many of the great giants of the ice age still walked the earth. It was only when the world had warmed up again that mammoths, woolly rhinos, sabre-toothed cats, giant ground sloths and glyptodonts finally became extinct. Professor Alice Roberts sets off on her last voyage back to the Ice Age to discover why.

The story of the Viking world's most famous warrior, the legend of Beowulf is the ultimate tale of courage. Pit against thirsty invaders, barbaric monsters and a fire breathing dragon, Beowulf emerges as Norse mythology's greatest hero. But could this warrior have actually been real? Unearthed burial mounds and ancient carvings suggest the myth of Beowulf might have been more than epic legend.