This series illuminates unique and bizarre evolutionary journeys that have brought forth some of the world’s most impressive animals. We unearth a 50-million-year-old mystery mammal sought out a new source of food in the water, starting a spectacular evolutionary journey so that today it looks like a fish. How did a creature built for land become master of the ocean?

Around 30% of the land's surface is desert, the most varied of our ecosystems despite the lack of rain. Unravel the secrets of desert survival and experience the ephemeral nature of this dynamic environment. Watch Saharan sandstorms nearly a mile high and desert rivers that run for a single day. In the Gobi Desert, rare Bactrian camels get moisture from the snow. In the Atacama, guanacos survive by licking dew off cactus spines. In the USA, the brief blooming of Death Valley triggers a plague of locusts 65km wide and 160km long. A unique aerial voyage over the Namibian desert reveals elephants on a long trek for food and desert lions searching for wandering oryx.

In August 2014, ISIS militants raided a Yazidi village in Syria, kidnapping thousands of men, women and children. Hundreds of the kidnapped men were killed or forced to convert to Islam; the women and children were sold as sex slaves or to marry ISIS fighters. Many were raped or became victims of other forms of sexual violence. Escaping ISIS depicts 34 of those captured by militants last year — mostly women and young children — reuniting with their families as they escape to freedom". Some victims were brought to freedom through underground networks, guides inside ISIS and resistance fighters. Women contacted the resistance fighters, begging for rescue; some said the alternative is committing suicide. Many escapees walk for several days with little food and water, often barefoot, risking getting recaptured and killed. One resistance fighter was shot in the back of the head in ISIS territory after they found out that he was working against them. The documentary shows parts of this treacherous journey to freedom.

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.

It is time to see if personalised dieting will work in normal life. The volunteers have been given one of three diets to follow - based on their genes, their hormones and their psychology. But now they are back at home, trying to stick to their personalised diets with all the stresses and temptations of real life. Dr Chris van Tulleken and Professor Tanya Byron discover how our genetic makeup can make temptation difficult to resist, how understanding the brain reveals what makes us comfort eat and what science can tell us about why we make disastrous food choices.

Of the four elements, air is the most elusive because we can't see it. There's something very magical about it. One of the ways we transform food is by getting air into it. Think of the soufflé, think of the loaf of bread. These things are elevated by the fact that they now contain air. They're ethereal. Visit food labs and Moroccan fields as Michael Pollan delves into the science of bread-making and the nature of gluten.