Australopithecus afarensis, the early human who lived about 3.2 million years ago, walked upright, according to an "evolutionary robotics" model.
The model, which uses footprints to predict gait, suggests "Lucy", as the first fossil afarensis was called, walked rather like us.
This contradicts earlier suggestions that Lucy shuffled like a bipedally walking chimpanzee.
The research is published in the Royal Society Interface journal.
"I think it is very interesting work," Professor Chris Stringer, head of human origins at the Natural History Museum in London, told the BBC News website. "There was controversy as to whether these prints where showing a human pattern. And it looks like they do."
A team of scientists from around the UK have used computer robotic techniques to work out the most energy efficient gait for afarensis based on Lucy's skeleton and the Laetoli footprint trails.
They claim to have cleared up the debate by finding that, based on their model, Lucy almost certainly did walk tall.
"Assuming that the early human relative Australopithecus afarensis was the maker of the Laetoli footprint trails, our study suggests that by 3.5 million years ago at least some of our early relatives - despite their small stature - could sustain efficient bipedal walking at absolute speeds within the range shown by modern humans," co-author Weijie Wang from Dundee University told the Scotsman newspaper.
However, Professor Stringer believes the controversy will not vanish overnight.
"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," he told the BBC News website.