The last episode examines the fragile interdependence that exists between forests' wide variety of residents, including bald eagles, hunting dogs and Siberian tigers.
Over half of all the world's trees, evergreen and deciduous, stand in great assemblies. For many of us, they are places of mystery and darkness. They are key to our climate, and home to countless unique species. The boreal forest contains 750 billion trees, and it stores over 40 percent of the world's carbon, making it a vital element in the fight against climate change. In the past, we have destroyed them without hesitation. Yet, forests do have an astonishing ability to recover. If we choose to give forests time and space, they could reclothe the earth with much of the rich and varied communities of animals and plants of which we have, so recently, robbed it. A future with more forests is key to the resilience of our planet.

'Stangest Things' series examines those hidden gems that have been tucked away in museums, laboratories and storage rooms around the world. Experts use the latest technology to investigate these incredible artifacts of history.
A bizarre find called Copper Scroll is one of the famous Dead Sea Scrolls, but it's unlike any of the others; this strange relic might hold clues to a long-lost treasure, and cutting-edge science may finally reveal answers to this billion-dollar mystery.

As the world enters a phase of aggressive competition over untapped ocean floor resources, countries are scrambling to stake their claims. The vast economic potential on offer has made the seabed the ultimate frontier in a new Age of Exploration. China's research vessels in particular have been active in waters right across the globe. Through our exhaustive analysis of huge volumes of Chinese ship tracking data, from sand dredgers to survey vessels, we piece together a puzzle that reveals a new hidden power struggle over increasingly critical submarine resources.

What makes us human is the squishy triple-pounder inside our heads. It lets us build skyscrapers, and lift a special few of us into space. We are the only species on this planet that can construct realities in our mind and then go actually build it. The story of how our mind evolved on this one strange rock is one of chance, coincidence and impossible odds.
This episode is an investigation into the mystery of the human brain and the chain of events that produced the anomaly of human intelligence.

The Obsidian Mirror is a mysterious artefact crafted from volcanic rock, and it's said to be a device used to communicate with supernatural beings; experts use cutting-edge tech to discover who made this strange relic and why.
A golden disc can answer the biggest mystery of all: Are we alone in the universe? The Voynich manuscript is one enormous puzzle. What secrets are hidden in this bizarre 600 year old book that nobody can read?

Feast your eyes on a reconstruction of the mega-city and its amazing buildings. Alexandria, built in the middle of rancid marshland, had become in less than a century, the greatest city of the Mediterranean. An ideal position at the crossroads of east and west, and one that brought her great riches. Huge, modern, gleaming white and cosmopolitan, like no other in antiquity, it created its own identity.
While the beauty of its planning, its great arteries, its temples and its ports would be equalled only by its openness to the rest of the world. And the monumental achievements of its sovereigns, still shrouded in mystery, we'll never cease to fire our imagination for millennia to come.