During the evolution of humans, from walking on all fours to upright walking, the functions of the hands and feet gradually differentiated. The hands were freed from their supporting and grasping functions and became organs capable of performing more complex and dexterous movements, while the feet assumed the functions of bearing weight and walking. The skeletal structures of the hands and feet are similar, but their mobility differs greatly, which is closely related to their structures.
The mobility of the feet is controlled by the ankle joint, with an angle of flexion and extension towards the dorsal side of the foot of about 65°, and a limited degree of inward and outward rotation (or pronation and supination) in the lateral direction. In contrast, the wrist joint of the hand can flex and extend by up to 150°, with a range of approximately 60°, providing a greater range of motion than the feet. In terms of length, the fingers of the hand are slender and can flex and extend further than the toes of the foot, allowing them to wrap around the palm and grasp objects. The toes of the foot, however, are relatively shorter and can only flex but not reach the sole of the foot. The slender five fingers of the hand spread out in a fan shape, with a distance of 18–20 cm from the thumb to the little finger, and strong fingertips. In contrast, the toes of the foot have a limited range of spread and weaker fingertips, making the foot less dexterous than the hand. The big toe of the foot lies on the same plane as the other toes, allowing it to only make contact with adjacent toes for pinching actions, lacking the thumb-to-finger specialization of the hand.
However, although the feet lack flexibility, they offer greater stability and serve as reliable supports for the body. While praising the dexterity of the hand, we should not forget that the dexterity of the hands and feet depends not only on their structural characteristics but also on acquired training, so the differences between individuals can be significant.