Why humans walked upright

 The necessity of carrying more of scarce, high quality resources may have prompted human beings to adapt to walking upright, a study reveals.

The team from the US, England, Japan and Portugal investigated the behaviour of modern-day chimps to learn what prompted a large ape, which resembled the six-million-year-old ancestor we shared with living chimps, to walk on two legs.

“These chimpanzees provide a model of the ecological conditions under which our earliest ancestors might have begun walking on two legs,” said Brian Richmond, of the George Washington University.

“Something as simple as carrying — an activity we engage in every day — may have, under the right conditions, led to upright walking and set our ancestors on a path apart from other apes,” said Richmond.