the final episode deals with plants that live in hostile environments. Attenborough visits Ellesmere Island, north of the Arctic Circle, to demonstrate that even in a place that is unconducive to life, it can be found. Algae and lichens grow in or on rock, and during summer, when the ice melts, flowers are much more apparent. However, they must remain close to the ground to stay out of the chilling wind. In the Tasmanian mountains, plants conserve heat by growing into 'cushions' that act as solar panels, with as many as a million individual shoots grouped together as one. Others, such as the lobelia in Mount Kenya, have a 'fur coat' of dense hairs on their leaves. The saguaro cactus in the Sonoran Desert flourishes because of its ability to retain vast amounts of water, which can't be lost through leaves because it has none. Many desert dwellers benefit from an accelerated life cycle, blooming rapidly within weeks after rainfall. Conversely, Mount Roraima is one of the wettest places on Earth. It is a huge sandstone plateau with high waterfalls and nutrients are continuously washed away, so plants have to adapt their diet if they are to survive. A bladderwort is shown invading a bromeliad. Inhabitants of lakes have other problems to contend with: those that dominate the surface will proliferate, and the Amazon water lily provides an apt illustration. Attenborough ends the series with an entreaty for the conservation of plant species.

Anthropologist Wade Davis and river advocate Robert F. Kennedy Jr journey down the Colorado River on a two-week expedition to highlight water conservation issues. Traveling by rafts, kayaks and wooden dories, they are accompanied by their daughters and guided by Shana Watahomigie, a Native American National Park ranger. Filmed with a 350-pound 3D camera, it involved the cooperation of three Indian nations, the National Park Service, film sponsor Teva’s team of kayakers and more than a dozen experienced river guides. The film explores America's drought and freshwater shortages, the impact on the river of damming, and human water supply needs. Grand Canyon Adventure: River at Risk was directed by Greg MacGillivray and narrated by Robert Redford.

Professor Jim Al-Khalili sets out to discover whether nuclear power is safe. He begins in Japan, at the former Fukushima nuclear plant, where he meets some of the tens of thousands of people who have been evacuated from the exclusion zone. He travels to an abandoned village just outside the zone to witness a nuclear clean-up operation. Jim draws on the latest scientific findings from Japan and from the previous explosion at Chernobyl to understand how dangerous the release of radiation is likely to be and what that means for our trust in nuclear power.

As he tries his hand at baking, brewing and braising, acclaimed food writer Michael Pollan explores how cooking transforms food and shapes our world. In the first espisode, with help from Aboriginal hunters and a barbecue pit master, Pollan shows how fire shaped human gastronomy, and weighs our duty to the animals we eat.

Technology is opening up new possibilities for physical, sexual and romantic relationships with astonishing speed. But is seeking human connection virtually a positive step forward or are we stunting our intimate lives? In the first episode of this series, meet a cyber BDSM couple who use tracking technology to fulfill their master slave relationship; an eligible bachelor in Japan who has fallen in love with a virtual girlfriend; and a revenge porn victim whose life was upended when her private naked photos were published online.

Heart disease is the number one cause of deaths worldwide, killing more than eight million people each year. Cardiac infarction, more commonly known as a heart attack, can happen without warning, killing heart muscle cells immediately. Even if the patient recovers, the damage to their heart may not.
But there are researchers frantically working to change that. Meet the people inventing the future of cardiac health, from new ways of imaging the body, to the possibility of 3D printing a functioning heart.