Humans have an arc in the foot as a need to bear more weight due to bipedalism, apes on the other hand have flat feet
The human foot evolved to act as a platform to support the entire weight of the body, rather than acting as a grasping structure, as it did in early hominids. Humans therefore have smaller toes than their bipedal ancestors. This includes a non-opposable hallux, which is relocated in line with the other toes. Moreover, humans have a foot arch rather than flat feet. When non-human hominids walk upright, weight is transmitted from the heel, along the outside of the foot, and then through the middle toes while a human foot transmits weight from the heel, along the outside of the foot, across the ball of the foot and finally through the big toe. This transference of weight contributes to energy conservation during locomotion.