The episode is a journey through the human gut and the process of turning food into energy to keep the body going. Humans have turned eating into culture, a way to celebrate our roots, to bring us together. But food is really just one thing: Fuel. It's where you get the power to live your life. Even when you're sitting completely still, your body needs a lot of energy to stay on. But nowhere is the need for fuel more apparent than when you push yourself to the absolute limit. And the microbiome, the bacteria living in our gut, plays a great role in all this.

Master Chef judge Gregg Wallace and mathematician Dr Hannah Fry take over a restaurant and invite five special guests to enjoy a dinner party with a difference, where they will be scored on the carbon footprint of every dish they choose. Food accounts for a third of all greenhouse gas emissions, so making informed choices about what we eat is more important than ever.
Gregg is with the kitchen team preparing delicious dishes and uncovering tips and tricks we can all use to cook more sustainably. Hannah is working with environmental scientists to reveal the carbon footprint of every single item on the menu and uncovering the latest research that can help us enjoy the food we love that doesn't cost the Earth.

Deep in the twisted roots of a giant strangler fig tree, hidden from view, lives perhaps the most bizarre nighttime creature of all. The spectral tarsier, tiny primates barely larger than a tennis ball. As darkness falls, a family of these small primates in Sulawesi ventures into the jungle to find food while protecting their babies.

With a million species at risk of extinction, Sir David Attenborough explores how this crisis of biodiversity has consequences for us all, threatening food and water security, undermining our ability to control our climate and even putting us at greater risk of pandemic diseases.
Everything in the natural world is connected in networks that support the whole of life on earth, and we are losing many of the benefits that nature provides to us. The loss of insects is threatening the pollination of crops, while the loss of biodiversity in the soil also threatens plants growth.
Last year, a UN report identified the key drivers of biodiversity loss, including overfishing, climate change and pollution. But the single biggest driver of biodiversity loss is the destruction of natural habitats. Seventy-five per cent of Earth's land surface (where not covered by ice) has been changed by humans, much of it for agriculture, and as consumers we may unwittingly be contributing towards the loss of species through what we buy in the supermarket. Human activities like the trade in animals and the destruction of habitats drive the emergence of diseases. Disease ecologists believe that if we continue on this pathway, this year’s pandemic will not be a one-off event.

At the end of each Antarctic summer, the emperor penguins of the South Pole journey to their traditional breeding grounds in a fascinating mating ritual that is captured in this documentary by intrepid filmmaker Luc Jacquet. The journey across frozen tundra proves to be the simplest part of the ritual, as after the egg is hatched, the female must delicately transfer it to the male and make her way back to the distant sea to nourish herself and bring back food to her newborn chick.

Across the world, rising demands for food, water and materials have pushed resources to the limit. Many parts of the world have major challenges over fresh water. A lot of soils have a lot of residual pesticides and herbicides. At the same time waste is piling higher. All this demands a new wave of innovation. The challenge is to make more of the things we need without the environmental cost.