Every year, over a thousand climbers try to reach the summit of Mount Everest, with the annual record for successful attempts currently standing at 633. But of that number, nearly half were Sherpas - the mountain's unsung heroes. Yet the Sherpa community has remained secretive about their nation, culture and experiences living in the shadow of the world's highest mountain. Now, for the first time, they open the door into their world. Without the expertise of the Sherpas, only the hardiest and most skilful climbers would succeed. Every day they risk their lives for the safety of others, yet they seek neither glory nor reward, preferring to stay in the background. Following the stories of four such Sherpas - Phurba, Ngima, Ngima Tenji and Gelu - this film reveals the reality of their daily lives, not just up the mountain, but with their families after they return home.

Stonehenge is an icon of prehistoric British culture, an enigma that has seduced archaeologists and tourists for centuries. Why is it here? What is its significance? And which forces inspired its creators? Now a group of international archaeologists led by the University of Birmingham and the Ludwig Boltzman Institute in Vienna believe that a new state-of-the-art approach is the key to unlocking Stonehenge's secrets. For four years the team have surveyed and mapped every monument, both visible and invisible, across ten square kilometres of the sacred landscape to create the most complete digital picture of Stonehenge and the surrounding area over millennia. Known monuments have yielded more data than ever before, revealing hidden structures within, and new finds are revolutionising the very timeline of Stonehenge. The film takes the viewer on a prehistoric journey from 8000 BC to 2500 BC as the scientists uncover the very origins of Stonehenge, learning why this landscape is sacred, preserved and has been revered by following generations. Evidence of war and conflict, as well as the cultivation of ideas and industry, is explored to reveal complex communities with international trade links as far-reaching as Spain and central Europe.

25 million years ago the biggest land mammals of all time, the indricotheres, stalked the Earth. Up to seven metres tall and weighing 15 tonnes, adults were too big to be eaten by any predator of the time. Only in the first few years of its life was indricotheres vulnerable. The programme follows the fate of a calf from his traumatic birth to see whether it can survive droughts, killer hogs and hyaenodon - a predator the size of a rhino with jaws that could crush a rock.

Moving on to the Late Eocene period 36 million years ago and mammals have prospered and are now the largest creatures on land and sea. This is an era of animals like andrewsarchus, the biggest mammal carnivore ever to walk on land, and the brontotheres, small-brained herbivores. It is in the sea, however, that the most monstrous mammals of all can be found. We follow the fate of a female basilosaurus, a huge serpent-like early whale, but nothing like the gentle filter feeding whales of the 21st century. Four times the length of the great white shark, with jaws to match, she is every inch a killer.

The series takes place after the extinction of the dinosaurs 65 million years ago and recreates animals of the Cenozoic with computer-generated imagery and animatronics. The first episode starts 49 million years ago, when Earth has fully recovered from the dinosaur extinction and is covered in a mysterious forest. This is a time that the world has almost forgotten - Germany was a hot sweaty jungle, birds ruled the earth and preyed on miniature horses and whales walked on land.

Ant colonies are one of the wonders of nature - complex, organised and mysterious. This programme reveals the secret, underground world of the ant colony in a way that's never been seen before. At its heart is a massive, full-scale ant nest, specially designed and built to allow cameras to see its inner workings. The nest is a new home for a million-strong colony of leafcutter ants from Trinidad. For a month, entomologist Dr George McGavin and leafcutter expert Professor Adam Hart capture every aspect of the life of the colony, using time-lapse cameras, microscopes, microphones and radio tracking technology.