Planets beyond our solar system are known to astronomers as exoplanets. They are at trillions of miles from Earth and yet, it might be possible to detect a faint signature of life in them. From the light of the stars they orbit that passes through the atmosphere of an exoplanet, it is possible to capture the chemical fingerprint of the elements in that atmosphere.
The fictional world Eden is orbiting not one star, but two. The light from its twin stars powers photosynthesis, pumping more oxygen into the atmosphere than in Earth, allowing life to thrive. Grazers are constantly alert to danger, because the canopy is home to predators perfectly evolved to live among the trees. In Episode 3, another topic are fungi and the role they could play on exoplanets. Ecologist Thomas Crowther talks about the role mycelial networks play in the Rothiemurchus forest in Scotland.

Brian asks how, from a lifeless cosmos, it is possible that a planet can produce the more than eight million species we know of.

No two islands in the Galapagos are the same. The imperceptible drift of a continental plate keeps each island biologically isolated. David Attenborough explores this evolutionary crucible, encountering tortoises that weigh up to half a tonne, finches that use tools and lizards that communicate using press-ups; for Darwin, this was all evidence for his theory of evolution. We see the final footage of the world famous tortoise fondly known as Lonesome George, the last survivor of his species. David Attenborough was the last person to have ever filmed with him. Darwin’s famous visit had a downside – the arrival of man. David investigates the impact we’ve had in these islands, as our influence is a double-edged sword. We’ve disrupted the natural balance but he also believes Darwin would be thrilled with the advances we have made in science. We’re also now uncovering evidence that evolution is more rapid than Darwin could ever have imagined. Whatever wonders the Galapagos Islands hold today, they are only a hint of what awaits them in the future.

What triggered the incredible diversity of life on Earth, and how have complex life forms, including humans, evolved? Is there direction to evolution? And is human intelligence inevitable? This program focuses on evolution's 'great transformations' —among them the development of a standard four-limbed body plan, the journey from water to land, the return of marine mammals to the sea, and the emergence of humans. Driven by a combination of opportunism and a genetic 'toolkit', these astounding leaps forward define the arc of evolution. And they suggest that every living creature on earth today, and every species that has ever existed, is a variation on a grand genetic theme—a member of one, and only one, tree of life

Survival of the fittest: Raw competition? Intense cooperation? Both are essential. Interactions between and within species are among the most powerful evolutionary forces on Earth, and understanding them may be a key to our own survival.

Brian travels across the US and encounters some astonishing creatures that reveal how the senses evolved. It is a story that takes him through life's journey, from single-celled organisms to sentient beings.