It is virtually impossible to conceive of the vastness of Earth time: in an attempt to illustrate the planet’s lifespan, Michio Kaku travels from the West to the East coast of America, each millimetre representing a single 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 which 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.