Lucy may well be the world’s most famous fossil hominid. She is the best-known specimen of the species Australopithecus afarensis, and her partial skeleton, found in 1974, revealed that she and her kin could walk upright....

Now, a fossilized foot bone from Hadar, Ethiopia, reveals that A. afarensis had arched feet, as do modern humans, and was fully committed to walking upright. The species lived between 3.7 million and 2.9 million years ago....