Living primates like this western lowland gorilla hold a wealth of untapped knowledge about what our ancestors were like (Image: Holly Harris / Stone / Getty) Two australopithecine fossils. Top: a gracile australopithecine, Australopithecus africanus known as “Mrs Ples”. Bottom: a robust australopithecine, A. robustus (Image: John Reader / SPL)

Explore our interactive timeline of human evolution

DAYBREAK, and a group of apes are dancing around a rectangular monolith so dark it seems to suck light in. Inspired by this mysterious object, one of them grabs a bone and begins to wield it as a tool – then as a weapon. The armed ape goes hunting, makes a kill and eats flesh for the first time. Next day, he drives a rival group of apes from a watering hole and murders their leader. This, according to Stanley Kubrick’s sci-fi masterpiece 2001: A space odyssey, is the dawn of humankind.

If only it were that simple. Anyone trying to understand our origins soon realises that no one thing pushed our ape ancestors across the threshold of humanity. It is difficult to pin down what makes us human anyway. We walk upright on two legs, with disproportionately large brains held high, communicating in spoken languages, navigating the complexity of human social life, producing sophisticated tools and artefacts, and creating culture. The story of how we became human is woven from many strands.

Attempts to unravel that tale have until recently relied on the hard evidence of fossilised bones. This has allowed us to make inferences about certain aspects of our ancestors: how big they were, how they moved and their cranial capacity. But …