Fossils of Ardipithecus ramidus, a 4.4-million-year-old species nicknamed 'Ardi', reveal humans evolved from African ape-like ancestors. Its ankle bone had a 14.5° talar angle, which is the highest among fossil hominins and similar to that of modern apes. The talus and calcaneus showed Ardi could climb and walk upright; human ancestors were already skilled in various forms of locomotion.