Two shown systems illustrate differences between modern and ancestor bodies. Overall, from the first sight, it is clearly seen that there are a lot of dissimilarities.
Australopithecus afarensis had an unbalanced head with a long snout and high and narrow shoulders, a wide upper body, long arms, small hips, and knees. It can be due to necessities to support a family, try to be alive as much as possible, and be gutsy enough to find some food. His toes were much longer than those of a present-day person. Homo erectus, in his turn, has a balanced, tall, and thin torso. Moreover, shorter hands and feet with good stability, which help him to walk straightly and confidently.
The comparison between two bodies demonstrates that a historical person used to live as a wildman because of his body structure, even so the modern one differs a lot and adapted to have sufficient needs without any hard efforts.