The Arctic is the harshest environment on Earth: little food grows, it's dark for months on end, and temperatures stay well below freezing for much of the year. Yet four million people manage to survive here. Human Planet tells remarkable stories of extraordinary people who make their homes in nature's deep freeze. In springtime, Amos and Karl-Frederik set out across the sea ice with their dogs to catch a real-life sea monster: a Greenland shark! Inuit mussel-gatherers venture underneath the sea ice at low tide for a perilous race against time as they gather their food. And the children of Churchill, Manitoba, set out on the most dangerous trick or treating Halloween in the world: they risk coming face-to-face with deadly polar bears on the streets of their town. Who'll get the tastiest snack?

Grasslands feed the world. Over thousands of years, we humans have learned to grow grains on the grasslands and domesticate the creatures that live there. Our success has propelled our population to almost seven billion people. But this episode reveals that, even today, life in the 'Garden of Eden' isn't always rosy. We walk with the Dorobo people of Kenya as they bravely attempt to scare off a pride of hungry lions from their freshly caught kill. We gallop across the Steppe with extraordinary Mongolian horsemen who were 'born in the saddle'. And in a perfect partnership with nature built up over generations Maasai children must literally talk to the birds! The honeyguide leads them to find sweet treats, but they'll have to repay the favour.

Are the wealthy just born in the right place at the right time? Are the poor victims of a system designed to keep them down? Or do physics and biology determine who is rich and who is poor? Throughout history, distribution of wealth is governed by hidden forces: DNA, environmental stress, patterns of human migration and even the laws of thermodynamics! Nature seems to demand winners and losers in life. But does this mean greed is king, and the rich can take what they want? Or is cooperation – between microorganisms, monkeys, and humans – more essential to survival of a species?

We all agree lying is shameful. Yet we still deliberately deceive each other constantly. Are our brains wired for lying from a young age? The brains of pathological liars may provide insights. Will technology make it easier for us to be dishonest, or could it someday instantly reveal someone is lying? Perhaps we are deceitful because our limited senses prevent us from seeing the real truth. Scientists say our own memories deceive us, and have managed to implant false memories. Other scientists look for ultimate truth in the subatomic world … only to end up turning reality on its head.

The 24th July 2010... 80,000 Lives... 4,500 Hours of Footage... 2 Award winning Filmmakers... Now one incredible motion picture event. What began life as a startling cinematic experiment becomes the must see movie experience. Created entirely from footage uploaded by YouTube users, Life in a Day is a film first: exhilarating, moving and very, very funny. It is the story of our world. Told by us. Ridley Scott produced the film and edited the videos into a film with director Kevin Macdonald and film editor Joe Walker

Chinese 'Cockblock'. In China, where marrying-age men outnumber women by the millions, discover the lucrative business catered to matchmaking and the bachelors who use such services. 'European Meltdown' With their economy in the toilet and no jobs to be had, Europe's youth are taking to the streets to demand radical changes.