Being able to walk upright on two legs is considered one of the most important milestones in human evolution. However, how the body adapted to this new habit was, until now, a mystery. Harvard researchers conclude that the origin lies in two changes in the pelvis, the cornerstone of vertical locomotion. More than any other part of our body, this bone structure has been radically altered over millions of years to allow our ancestors to be bipedal and roam the planet. a study published in the magazine Nature, scientists reveal the key genetic changes that reshaped the pelvis between 5 and 8 million years ago, when human ancestors diverged from African great apes.