Humanity's earliest ancestors did not drag their knuckles along the ground before mastering life on two feet, but learned to walk upright while still living in the trees, according to a team of British scientists. The claim challenges the belief that humans evolved from chimp-like creatures that descended from the trees to roam the savannahs of east Africa, using their knuckles for support, before slowly rising to the upright posture of more modern humans.

The theory marks a dramatic twist in evolutionary thinking that suggests some of our earliest ancestors may have begun walking on two legs up to 24m years ago, rather than shortly after the human lineage split from chimpanzees around 6m years ago. It suggests early humans adapted rapidly to open landscapes by honing the basic walking skills they developed to move around the forest canopy.

The team, led by Robin Crompton at Liverpool University and Susannah Thorpe at Birmingham University, claim our tree-dwelling ancestors learned to walk on two feet because it helped them edge along outer branches while having their hands free to grasp ripe fruit. The tactic also enabled them to clamber between neighbouring trees without having to descend to the forest floor.