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	Michio illustrates how old the Earth is, using one millimetre to represent one year    Using the same scale of one millimetre equal to one year, Michio shows the relatively short time humans have inhabited the Earth

In the 17th century an Irish bishop used the scientific method and the Bible to calculate a date of creation - approximately 6000 years ago. It was a remarkable achievement, but he was wrong. Michio climbs down the layers of rock from which the Grand Canyon is carved to discover that the world must be much older. Meteorites hold the ultimate clues to the formation of the Earth - a staggering 4.6 billion years ago. Michio reveals that, far from being fixed, the Earth has been reshaped with incredible violence. It's usually too slow to witness directly, but inhabitants close to the world's most active volcano, Kilauea, on Hawaii know the Earth's forces all too well as they recover their homes from volcanic ash.

It's almost impossible to conceive of the vastness of Earth time: in an attempt to illustrate the planet's lifespan, Michio travels from the West to the East coast of America each millimetre representing one year. But where do we fit in? Our time seems so insignificant, but we're part of perhaps the greatest story ever told - the story of life itself. The programme looks at bacteria that have been brought to life from a time capsule of rock after 250 million years, encounters creatures in which evolution can be seen in action, and explores the ultimate biological clock - DNA. Michio has his own DNA tested to reveal his ancestral journey all the way back to our first human ancestors in Africa. Finally, the episode concludes with a look into the future to ask where we are ultimately going.