Evolution of the Human Foot
The human foot has an interesting evolutionary history. Understanding this history can be helpful in assessing foot and ankle problems, because there is a theory that many humans have retained some elements of foot characteristics of our evolutionary ancestors (atavistic traits). These traits may lead to conditions such as flatfeet and bunions, which alter the way that the foot absorbs force when we walk. This, in turn, can lead to a propensity to develop symptomatic foot conditions (ex. metatarsalgia, acquired adult flatfoot deformity, bunions, plantar fasciitis, etc). This idea was initially proposed by Dudley Morton (different from the Morton who described Morton’s neuroma). Morton was an anatomist at Columbia University who wrote a book entitled The Human Foot: Its Evolutionary Development, Physiology and Functional Disorders in 1935.
Here are some ideas associated with the role of the importance the evolution of the human foot:
1. Humans are one of the “Great Apes”
Along with Chimpanzees, Pygmy Chimps (Bonobos), Gorillas, and Orangutans. From a genetic point of view, humans are closely related to the other great apes sharing over 95% of our DNA. Chimpanzees share 97.3% of their DNA with humans. From a genetic point of view, it has been suggested that chimpanzees are more closely related to humans than they are to gorillas.
2. The other great apes all have opposable first rays i.e. they can grab things with their feet
Morton proposed that humans have evolved to have a stable arch on the inside of their foot. They cannot grab things with their big toes the way the that other great apes do (Figure 1), and the way humans do with their hands. Having a stable arch of the foot makes it much easier to walk upright. However, some humans may have retained some extra motion in the inside part of their foot (medial column). These individuals often have flatfeet and bunions -and usually have a strong family history of these foot conditions.
Figure 1: Baby Gorilla using feet to grab
3. Chimps, Gorillas, and Orangutans all have pronounced gastrocnemius equinus contractures.
Have you ever watched a chimp or gorilla walk upright? They walk with their knees bent. This occurs because the outer calf muscle (the gastrocnemius) is very tight. It starts above the knee and is therefore under tension when the knee is straight. Only by bending their knees can the other great apes get their feet flat on the ground. When you straighten their knees, their feet point down and they are unable to bring their feet up to a right angle unless they bend their knees. Morton argued that some humans have retained a tight gastrocnemius –although no where near as tight as that seen in gorillas and chimps. An “equinus contracture” forces the foot to accommodate to the extra tightness of the calf muscle by flattening out the arch and increasing the load through the front. This can lead to the development of a variety of foot conditions including flatfeet, bunions, metatarsalgia, and Achilles tendonitis.
Edited October 8th, 2025
