Final answer:
Australopithecus afarensis (Lucy) displayed the human characteristic of bipedalism, evidenced by skeletal structures like a wide and short pelvis. It had small brain size similar to chimpanzees and no evidence for use of fire or advanced tool use.
Step-by-step explanation:
Australopithecus afarensis, nicknamed Lucy, notably possessed the human characteristic of bipedalism. Compared to modern humans, A. afarensis had a smaller brain, and there is no evidence that it used fire or had advanced tool use. The notable morphological features such as a wide and short pelvis and the positioning of the foramen magnum support the bipedal locomotion ability. However, its brain size (approximately 400-500 cc) was relatively small, akin to that of a common chimpanzee, and lack of evidence for the use of fire or advanced tool use supports the assertion that Lucy exhibited bipedalism as the primary human-like characteristic.
Australopithecus afarensis had larger teeth and a more prognathic jaw compared to modern humans, and its arm bones and finger and toe bones were long and curved, indicative of tree-dwelling behavior alongside their bipedal movement. The anatomical differences between A. afarensis and modern humans suggest they did not move in exactly the same way. The human-like features are evidenced more in their skeletal structure adapted for bipedalism than in their cerebral capacity or behavioral traits such as tool use or control of fire.