Perhaps the rumours of strange newcomers were true after all. Certainly the slender stone blade in front of the young Neanderthal had been fashioned by someone with skills that surpᴀssed any he had seen before. The snap of a twig broke his reverie. He spun round, and found himself face to face with two men every bit as strange and exotic as the tool they had evidently returned to claim. Their skins were unusually dark, their eyes the colour of the sky.

IT WAS possibly curiosity or wonder that the young Neanderthal felt during his first encounter with our species. Arguably, it should have been fear: a chance meeting like this could easily have happened about 45,000 years ago in a forest somewhere between Poland and England. When it did, it would have marked the dawn of a new human conquest.

Until that point, Europe had been the exclusive playground of Neanderthals. Homo sapiens, meanwhile, had left Africa, marched across Arabia into East and South-East Asia, sailed to Australia. One group was on its way to Siberia, the Bering Strait and the promise of a New World. But what of Europe?

Not too long ago, that story appeared beguilingly simple. Our species arrived 45,000 years ago from the Middle East, outcompeted the Neanderthals, and that was that. Now, an explosion of studies is using fragments of DNA pulled out of ancient bones…