A team of scientists have used robotics to predict how our early relative Australopithecus afarensis would have walked.
The most famous skeleton of Australopithecus afarensis, known as 'Lucy', is 3.2 million years old, and was discovered in Ethiopia in 1974.
Some scientists have argued that Lucy walked more like a chimpanzees' shuffle than in a fully human manner.
By studying proportions of the Lucy skeleton with some 3.5–3.6 million-year-old Laetoli fossil footprints, scientists created a computer model that predicted the most efficient way Lucy would have walked.
The results strongly suggest Lucy walked upright in a human manner.
Professor Chris Stringer, human evolution expert at the Natural History Museum in London, told the BBC News website 'I think it is very interesting work. There was controversy as to whether [footprints purported to be from afarensis] were showing a human pattern. And it looks like they do.'
But there is also a remaining question as to whether the Laetoli footprints belong to afarensis.
'There are still some people who argue that, looking at the anatomy of the foot bones of afarensis, that they were unlikely to have made the Laetoli footprints,' Chris adds.
'So it doesn't end the argument because there is still the possibility that there were also different creatures around at the time.'
The research is published in the Royal Society journal.