The foot is composed of three main elements that provide arch support and function: the keystone bone, wedge-shaped bones, and ligaments. The bones must be present or else the arch will fail to support and balance the weight of the body. The ligaments are essential in keeping the bones together and creating firmness and flexibility providing stability and the ability to walk, run, and jump in the vertical posture.
Conversely, apes do not have arched feet—they utilize their feet just like hands to grip things such as branches. The amazing arch is an irreducibly complex and must be there in its entirety in order for optimal upright performance. When we observe a sole we can be reminded of our faithful Creator’s love for our soul, which He formed in His image.
(Source: Stuart Burgess – The Origin of Man: The image of an ape or the image of God? 2004 pp.24-18)