We can survive for weeks without food, but only days without water: it is the essential element of life. Yet many millions of us live in parched deserts around the world. In the second episode of Human Planet, we discover how the eternal quest for water brings huge challenges - and ingenious solutions - in the driest places on Earth. Battling through a sand storm in Mali, Mamadou must get his cows to a remote lake but desert elephants have arrived first. Can he find a safe way through the elephant blockade? Alone for weeks on end, Tubu women and children navigate the endless dunes of the Sahara. How does young Shede know where to find the last oasis, three days walk across the sea of sand? At the height of the drought we witness a spectacular frenzy: two thousand men rushing into Antogo Lake to catch the fish trapped by the evaporating water. When the rain finally arrives in the desert it's a time for flowering and jubilation - and love. The Wodaabe men of Niger put on make-up for an intoxicating courtship dance and beauty contest.

David Attenborough comes face-to-face with a baby rhino and asks what the future holds for this little one. He meets the local people who are standing side-by-side with the wildlife at this pivotal moment in their history. We discover what it takes to save a species, hold back a desert and even resurrect an entire wilderness - revealing what the world was like before modern man.

The great flood in the Okavango turns 4,000 square miles of arid plains into a beautiful wetland. Elephant mothers guide their families on an epic trek across the harsh Kalahari Desert towards it, siphoning fresh water from stagnant pools and facing hungry lions. Hippos battle for territory, as the magical water draws in thousands of buffalo and birds, and vast clouds of dragonflies. Will the young elephant calves survive to reach this grassland paradise? The experienced mother elephants time their arrival at the delta to coincide with the lush grass produced by the great flood.
In a TV first, the programme shows the way they use their trunks to siphon clean water from the surface layers of a stagnant pool, while avoiding stirring up the muddy sediment on the bottom with their feet. Lechwe swamp deer, zebras, giraffes, crocodiles and numerous fish and thousands of birds arrive in the delta. And, in a phenomenon never before filmed in the Okavango, thousands of dragonflies appear - seemingly from nowhere - within minutes of the flood arrival, mating and laying eggs. As the flood finally reaches its peak, elephants and buffalo, near the end of their epic trek across the desert, face the final gauntlet of a hungry pride of lions. In a heart-wrenching sequence, a baby elephant is brought down by a lion in broad daylight.

Dr Alice Roberts re-traces the greatest ever journey taken by our ancestors. Thousands of years ago one small group of our species, Homo sapiens, crossed out of Africa and into the unknown. Their descendants faced baking deserts, sweat-soaked jungles and frozen wildernesses and risked everything on the vast empty ocean. Within 60,000 years they colonised the whole world... How did they do it? Why do we, their descendants all look so different?

In the second episode, Professor Iain Stewart discovers how flowers have transformed our planet. He journeys to the remote islands of the South Pacific to track down the earliest flowers. In the deserts of Africa and rainforests of Vietnam, he sees how they brought brilliant colour to the most barren landscapes and sculpted the earth itself. And he learns how they drove the evolution of all animals - kick-starting our human story.

Planet Earth has been home to humankind for over 200,000 years, but with a population of 7.3 billion and counting and limited resources, this planet might not support us forever. Professor Stephen Hawking thinks the human species will have to populate a new planet within 100 years if it is to survive. With climate change, pollution, deforestation, pandemics and population growth, our own planet is becoming increasingly precarious. In this landmark film Professor Hawking, alongside engineer and radio astronomy expert Professor Danielle George and a former student, Christophe Galfard, join forces to find out if, and how, humans can reach for the stars and relocate to different planets. Travelling the globe, they meet top scientists, technologists and engineers who are working to answer our biggest questions: is there another planet out there that we could call home? How will we travel across the vast distances of space to get there? How will we survive the journey? And how will we set up a new human civilization on an alien world? Travelling the globe, they meet top scientists, technologists and engineers who are working to answer our biggest questions: is there another planet out there that we could call home? How will we travel across the vast distances of space to get there? How will we survive the journey? And how will we set up a new human civilization on an alien world? Taking in the latest advances in astronomy, biology and rocket technology from the Atacama Desert to the wilds of the Arctic, viewers will discover a whole world of cutting edge research. This programme shows that Professor Hawking’s ambition isn’t as fantastical as it sounds - and that science fiction is closer to science fact than we ever thought.