Once life arrived in the Galapagos, it exploded into unique and spectacular forms. David Attenborough investigates the driving forces behind such evolutionary innovations. We learn that life must be able to adapt quickly in these ever-changing volcanic landscapes. It has resulted in species found nowhere else in the world, such as giant whale sharks and marine iguanas that can spit sea-salt from their noses, dandelion seeds that grow into tree-sized plants and spiders that can blend perfectly into the darkness. Adaptation has been the key to survival in these islands so far, but the story of life in the Galapagos doesn’t end here. The catalyst that triggers these explosions of life remains in place.

The second part, Nothing, explores science at the very limits of human perception, where we now understand the deepest mysteries of the universe lie. Professor Jim Al-Khalili sets out to answer one very simple question - what is nothing? His journey ends with perhaps the most profound insight about reality that humanity has ever made. Everything came from nothing. The quantum world of the super small shaped the vast universe we inhabit today, and Jim can prove it.

Scientists investigate the way the Sun builds its power -- through fusion -- hoping to find a way to use fusion as a less dangerous and less radioactive waste-producing path to energy than fission. But there are some major difficulties along the way. Fusion really is the perfect way to make energy. We have millions of years worth of fuel. It produces no long-lived radioactive waste. If we can solve the engineering challenges, energy will become cheaper, more available for everybody.

Moving on to Ethiopia 3.2 million years ago, we witness the beginnings of mankind via a group of australopithecus - a type of ape which, like us, walks upright on two legs. But unlike us, these early members of the human family weren't predators, they were prey. Things get worse for the group as they are hunted by a sabre-tooth cat called dinofelis and fall victim to other dangers such as malaria, rival australopithecus and a rampaging 14-tonne deinotherium.

Travelling forward in time to 30,000 years ago, it's the middle of an ice age. The landscape is dominated by mighty mammoths, living side-by-side with woolly rhinos, giant deer and two separate species of human. The programme follows the fate of a herd of mammoths in their annual struggle against the harsh ice-age conditions. Every summer they spend on the grassy plains of what will one day become the bottom of the North Sea, but every winter they are forced to head for the less exposed valleys further south. It is a journey fraught with danger: mammoths can get trapped in frozen bogs, and the herd must run the gauntlet of hunters like cave lions and the deadly Neanderthals.

In the last episode, Al-Khalili turns detective, hunting for clues that show how the scientific revolution that took place in the 16th and 17th centuries in Europe had its roots in the earlier world of medieval Islam. He travels across Iran, Syria and Egypt to discover the huge astronomical advances made by Islamic scholars through their obsession with accurate measurement and coherent and rigorous mathematics.He then visits Italy to see how those Islamic ideas permeated into the west and ultimately helped shape the works of the great European astronomer Copernicus, and investigates why science in the Islamic world appeared to go into decline after the 16th and 17th centuries, only for it to re-emerge in the present day. Al-Khalili ends his journey in the Royan Institute in the Iranian capital Tehran, looking at how science is now regarded in the Islamic world