The diagram below demonstrates skeletal structures of two ancestors such as Australopithecus afarensis(walker and tree climber) and Homo erectus( walker and endurance runner). It also provides information about their various differences in the physical system.
According to the structure, the head system obtain opposites form, for instance, unbalanced head is structured by tree climbers and balanced head is placed in endurance runners. In the widespread part from shoulders to waist in skeletal systems, tree climbers contain tall and narrow shoulders, wide chest and small and wide waist. Meanwhile, low and wide shoulders, narrow chest and high waist are possessed in the runner’s structure. Comparing Australopithecus afarensis and Homo erectus, the tree climbers have extended femoral necks, and small gluteus maximus , however endurance runners provide short femoral necks and big gluteus maximus.
Regarding the lower leg and foot, tiny hip, knee and ankle joints are placed in tree climbers’ bodies while endurance runners obtain opposite conditions. Short Achilles tendon placed below small heelbone in tree climbers and long Achilles tendon, enlarged heelbone in runners. Additionally, in the left are long toes and in the right partial foot arch in tree climbers, in contrast runners obtained stabilised foot arch and short toes.
To sum up, tree climbers and endurance runners set the opposite skeletal system demonstrating the difference in their body abilities.