It’s difficult to define the point when our ancestors became ‘human’, but one important milestone occurred when the human lineage diverged from that of our closest living relatives: chimpanzees. The last ancestor we shared with chimps lived about 7 million years ago – a relatively short time ago in the 2 billion odd years since life first appeared on Earth. Since then there have been 15-20 different species of early hominid. Another key chapter in human evolution was the beginnings of bipedalism – the ability to walk on two feet. Australopithecus was the first genus to accomplish this feat around 4 million years ago in eastern Africa. It wasn’t until 2.4 million years ago that the Homo genus appeared. Their distinguishing feature was a bigger brain and they were the first of our ancestors to use stone tools. Homo sapiens are only about 200,000 years old, emerging in Africa before migrating across the globe.