The design of the human body has fascinated evolutionary biologists for over 100 years. The short toes of humans are designed in a way that we can cover long distances. The human foot and its features are also in a way that we can walk upright with great and remarkable ease.
A quick observation of the human feet shows some instant peculiarities in the appearance. The phalangeal section of the forefoot is very short when compared to the body mass of human beings. The distribution of this pedal fraction is believed to have evolved in the concept of bipedalism, but the advantages of shorter toes when it comes to walking or even running have not been fully comprehended.
Scientists trying to explain the running, walking and evolution of short toes for the purpose of walking. This has not even been studied properly before. The proposal from these scientists includes a biomechanical model of the function of the toes alongside bipedal locomotion, all of which alludes to the fact of shorter pedal phalanges which improve the locomotor performance via the reduction of digital flexor force and mechanical work which can lead to the decrease of the metabolic cost of the flexor force generation during movement.
Humans have the distinction of being the unique bipedal primate in the animal kingdom, having developed a very sophisticated foot that has not just the skeletal apomorphies found in the metatarsals and the tarsals but also the very outstanding and unique proportions of the phalanges. When a comparison is done with the other hominids (now extant) and the earlier hominins like Australopithecus, the lateral pedal phalanges seen in human beings are straight and very diminished in length in comparison with the body size.
The evolution over time also led to the adduction of the hallux, which is more prominent and almost of the same length as the lateral digits. Overall, these apomorphies have established a decreased phalangeal part of the forefoot in which the motion of the digits does not go beyond the extension and flexion across the transverse axis of the metatarsals and the phalanges.
This morphology of the phalanges is unique and has been seen to be properly adaptive for bipedal locomotion of animals and there have also been studies relating to the function of toes when humans are running or walking. Studies examine a biochemical performance advantages via the reduction of mechanical work output and force of the digital flexors needed for the maintenance of joint stability when the subject is in a regular stance.
The evolution of short toes in human beings has stance during walking to be classified into three stages. The first one is called contact and it covers 0 to 25% of the stance and it is called such because it happens when the plantar surface of the foot is in contact with the ground. Then there is the midstance phase which is 25 to 65% of the overall stance and it is in this phase where the center of the mass of the body is positioned over the foot in the stance mode.
The third stage is called propulsion and covers 65 to 100% of the stance itself. It is in the third stage that the subject has no period in which the two feet are contacting the ground. When in the stance mode, the different ground reaction forces stemming from the force of gravity and accelerations on the body segment can be applied directly to the surfaces of the toes and foot.
Evolution of the short toes in humans has led to the provision of traction, particularly the digital flexors which assist in the control of forward motion when the body is in propulsion. It is in this phase that the body can pitch in a forward direction and that is known as forward falling.