Illustration of Lucy, a young female Australopithecus afarensis hominid. Lucys skeleton was discovered in the Afar region of Ethiopia in 1974. She dates back to approximately 3.3 million years ago and is one of the earliest links in the human fossil record. Australopithecus afarensis existed between 3.9 and 2.9 million years ago. This early human relative had a projecting face and an upright posture, featuring a blend of both ape-like and human-like characteristics. Adult individuals stood between 1 to 1.7 meters tall and weighed between 25 to 64 kilograms, with females being significantly shorter and lighter than males. Their diet consisted mainly of grasses, fruits, and leaves. When this small-bodied, small-brained hominin was discovered, it proved that early humans habitually walked on two legs.