Final answer:
The cranial capacity of Australopithecus afarensis was about 380 to 450 cc, similar to that of modern chimpanzees, while Australopithecus africanus had a larger brain size of around 500 cc.
Step-by-step explanation:
The cranial capacity, or brain size, of Australopithecus afarensis ranged from 380 to 450 cubic centimeters (cc), which is roughly equivalent to that of a modern chimpanzee. This species, which is known from fossils like the famous "Lucy," demonstrated a mixture of bipedal movement and arboreal activities, inferred from their longer arms and the shape of their pelvis. On the other hand, Australopithecus africanus, which lived slightly later, had a cranial capacity of approximately 500 cc, indicating a slight increase in brain size over time. These species are key to understanding the evolution of early humans and their cognitive abilities, notwithstanding the overall smaller brain sizes compared to modern humans.