In the last episode, Iain discovers the remarkable impact of just one plant: grass. On the savannah of South Africa he sees how grass unleashed a firestorm to fight its greatest enemy, the forests. He shows how cutting your finger on a blade of grass shows us how it transformed life in the oceans. In Senegal, he meets the cleverest chimps in the world. And, in the ruins of the oldest temple on Earth, he tells the extraordinary story of how grass triggered human civilisation.

For more than 80 years, Solenopsis Invicta has been on a ceaseless march across the United States, racking up six billion dollars every year in crop damage, equipment repair, and pest control. They have conquered more than 320 million acres in 13 states and killed at least 80 people. And the invader is still on the move. Globally. Now, scientists are cracking the ant's ancient secrets to success and breeding winged assassins to hunt them down. Stunning 3D macro photography explores the secret world of the fire ant and the cutting-edge research into stopping it

Bob Clewell's helicopter crew comes under intense fire in one of the final operations of the war. Joe Galloway returns to Vietnam and in Washington, D.C., Barry Romo throws down his medals in protest. The last American troops return home and POW wife Anne Purcell awaits word of her husband's fate. The fall of Saigon brings the unification of Vietnam.

Just 92 elements made up the world, but the belief that were only four - earth, fire, air and water - persisted until the 19th Century. Professor Al-Khalili retraces the footsteps of the alchemists who first began to question the notion of the elements in their search for the secret of everlasting life.He reveals the red herrings and rivalries which dogged scientific progress, and explores how new approaches to splitting matter brought us both remarkable elements and the new science of chemistry.

We are the only species on earth that cooks its food - and we are also the cleverest species on the planet. The question is: do we cook because we're clever and imaginative, or are we clever and imaginative because our ancestors discovered cooking? Horizon examines the evidence that our ancestors' changing diet and their mastery of fire prompted anatomical and neurological changes that resulted in taking us out of the trees and into the kitchen.

We will nvestigate the first skeleton that really looks like us –Turkana Boy– an astonishingly complete specimen of Homo erectus found by the famous Leakey team in Kenya. These early humans are thought to have developed key innovations that helped them thrive, including hunting large prey, the use of fire, and extensive social bonds. The program examines an intriguing theory that long-distance running –our ability to jog– was crucial for the survival of these early hominids. Not only did running help them escape from vicious predators roaming the grasslands, but it also gave them a unique hunting strategy: chasing down prey animals such as deer and antelope to the point of exhaustion. Birth of Humanity also probes how, why, and when humans' uniquely long period of childhood and parenting began.