In the second episode, Professor Iain Stewart discovers how flowers have transformed our planet. He journeys to the remote islands of the South Pacific to track down the earliest flowers. In the deserts of Africa and rainforests of Vietnam, he sees how they brought brilliant colour to the most barren landscapes and sculpted the earth itself. And he learns how they drove the evolution of all animals - kick-starting our human story.

Every 17 minutes in America, someone is killed with a gun. Politicians can't seem to stop the violence. But epidemiologists, psychologists and big data crunchers are discovering that gun crime spreads like a virus -and science may be able to stop its spread.

We live under a billion unblinking eyes - a global surveillance system that solves crime and uncovers terrorist plots. But are we ready for a world without secrets - where not even our homes are off-limits and corporations know our every desire?

Boy or girl? It’s the eternal question. But that question may have more than two answers. Science reveals the line between male and female is blurred. And the battle of the sexes is happening deep within our cells. Are there more than two sexes?

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.

NASA may have just gotten one step closer to the answering the question: are we alone? The Spitzer Telescope has made a groundbreaking discovery of exoplanets that could be similar to our own. And as Kepler also continues its search, our understanding of the universe continues to be redefined.