Scientists have confirmed that our ancient ancestor, Australopithecus afarensis, did indeed walk upright as had been previously believed. Archaeologists in Ethiopia have unearthed an arched fossilized foot bone which shows that these human ancestors, which included the famous fossil Lucy, had arched feet and therefore walked upright. Lucy and her kin walked the Earth 3.2 million years ago.
The arch in the foot would have provided leverage for Lucy so that she could push off the ground at the start of a stride and then help absorb shock when the foot met the ground again, in the same way our feet do. Our apes cousins have flatter, more flexible feet with a big toe for grasping tree branches, features that do not appear in A. afarensis. This is very significant as we now have a greater understanding of when our ancestors left the safety of trees and started to walk upright.