50，000 years ago， we were not the only species of human in the world。 There were at least four others， including the Neanderthals， who occupied Europe， the Near East and parts of Eurasia; the enigmatic Homo floresiensis， or 'Hobbits'， from the island of Flores in Indonesia; and Homo luzonesis， found in the Philippines， and less than four feet high。 And then there are the elusive Denisovans， discovered thanks to cutting-edge science in 2010 in a cave in Siberia。

At the forefront of this ground-breaking discovery was Oxford Professor Tom Higham。 In The World Before Us he follows the scientific and technological advancements - in radiocarbon dating and ancient DNA， for example - that allowed these discoveries to be made and enabled us to better predict not just how long ago these other humans lived， but how they lived。 Could they make art， recall their dreams or joke？ Did they play music， or use medicine？ What might Homo sapiens have learned from them？

It is likely that we will find even more species of these other humans， and thanks to recent scientific advances， we might not even need to find a skeleton。 We interbred and their DNA lives on in us， so we know which human groups today share which ancestors' genes and the impact this has; from Denisovan genes helping people cope better with living at high altitude， to Neanderthal genes increasing the risk of developing severe COVID-19 symptoms。 The implications of these - and future - discoveries for us today are profound。

We have always thought of ourselves as unique， but in evolutionary time， our uniqueness did not exist until yesterday - and yet now it is only us。 What happened？ Was it a given that we'd conquer the world， or might， under different circumstances， a Denisovan or Neanderthal population be the only ones left？ This is the story of us， told for the first time with its full cast of characters。