The question of our human origins is one of the most controversial science has wrestled with. This is the story of how scientists came to explain the beauty and diversity of life on earth, and reveal how its evolution is connected to the long and violent history of our planet. Featuring ocean adventurers, eccentric French aristocrats, mountain climbers, a secret Victorian publisher with 12 fingers, a ridiculed German meteorologist, and only a brief hint of Charles Darwin.

The theory of Némesis, a star that orbits the Sun and causes catastrophic events is explored. Nemesis is a hypothetical red dwarf or brown dwarf, originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU (1.5 light-years) somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years.

Hanging in the Barnes Foundation in Philadelphia, Seurat’s Les Poseuses is probably his least-known painting. It is also a picture brimming with codes and hidden meanings. It shows three nudes in the artist’s studio, but included in the background is Seurat’s famous masterpiece, A Sunday Afternoon on the Island of La Grande Jatte. Why is it there? What is it trying to say? Why two pictures at once? Waldemar Januszczak investigates.

Jeremy Clarkson decides to become a naturalist. 'In just 30 years, insect numbers have dropped by 25% and they're still falling. Without insects, all life on Earth ends. Everywhere where insects like to live is disappearing and I've decided to do something about that. My plan is to make my hedgerows, my valleys, my woods, and my streams more attractive to creepy crawlies. In essence, I am going to leave chunks of the farm completely alone. I'm going to put Mother Nature in the driving seat. It's a process called wilding.'

Six videos the Rolling Stones have selected from their files. Including Mick and Keith interviews where they explain why this particular selection.

It is one of the most baffling questions that scientists can ask: how big is the Universe that we live in? Follow the cosmologists who are creating the most ambitious map in history - a map of everything in existence. And it is stranger than anyone had imagined - a Universe without end that stretches far beyond what the eye can ever see. And, if the latest research proves true, our Universe may just be the start of something even bigger. Much bigger.