The earliest humans

7 million years ago to 200,000 years ago

How did monkeys evolve into apes? Why did apes come down from the trees and learn to walk on two feet? And do some 3-million-year-old fossilised bipedal footprints and a set of bones found in Africa – the remains of a two-legged creature known as "Lucy" – constitute the first evidence of our very earliest human ancestors?

These are some of the questions that we will be considering in this fourth instalment of our 14-part history of the world and its inhabitants. In purely chronological terms, we have already almost finished our story: if you visualise the history of the Earth as a single 24-hour period, the time has already reached the final minute before midnight. But the story of the human race has yet to begin.

As before, the unique perspective that this series presents – interweaving human history, natural history, geology, biology and much else besides – allows you to see the world in its true complexity.

The remaining instalments appear with The Independent and The Independent on Sunday over the next 10 days and online at giving you a unique reference resource that places in context life, the universe and just about everything else.