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The history of life can be best understood using the analogy of a tree. All living things, be they animals, plants, fungi, bacteria, or viruses are on the outside of the tree, .but they are all descended from a common ancestor at its base. The evolutionary history of all these living forms is represented by the branches within the tree. Modern humans are at the end of a relatively short twig. There is reliable genetic evidence to suggest that our nearest neighbor on the Tree of Life is the chimpanzee, with another African ape, the gorilla, being the next closest neighbour. The combined chimp/human twig is part of a small higher primate branch, which is part of a larger primate branch, which is just a small component of the bough of the Tree of Life that includes all animals (Figure 1.1).

This chapter deals with the recent evolution of the human foot. Its scope is more limited than Chapter 1. Instead of spanning approximately 400 million years it covers only 8 million years, and instead of dealing with the vertebrate branch of the Tree of Life it considers just one of the many small terminal twigs, or clades, that make up the primate part of the Tree of Life. We focus on a series of extinct mammals called hominins that through time, and in fits and starts, accumulate morphology more similar to modern humans and less like that of the other great apes. Researchers have differing views about how many branches the twig has, and they also disagree about how reliably we are able to reconstruct the branching pattern within the twig. We try to reflect these different views in our discussion.

This chapter is a review of how we have reached our present state of knowledge of the human foot. The gross structure of the foot was known long before there was an understanding of how it functioned. These insights only started in the nineteenth century. They continue to be pursued thanks to the growth of biomechanical studies by orthopaedic surgeons and sports scientists.

The patterns of activity of newborn mammals are appropriate to the environment into which they are born. In this respect mammals can be divided into four classes: herd animals, such as the horse, cow, and whale; nest animals, such as the lion, dog, and mouse; mother-clinging animals, such as primates, bats, and finally marsupials. Herd animals must be born in a state of relative ‘maturity’ to be able to follow the herd shortly after birth. When an animal is born into the security of a nest, there are advantages in birth at an early stage of development because a large bulk will be a handicap. A large baby needs more energy and this is difficult to obtain from diet alone. The young need only to feel their way to the mother’s nipples for milk and for this purpose do not need a full complement of sensory apparatus nor full powers of locomotion.

It happened one day about noon, going towards my boat, I was exceedingly surprised with the print of a man’s naked foot on the shore, which was very plain to be seen in the sand. I stood like one thunderstruck, or as if I had seen an apparition, for there was exactly the very print of a foot, toes, heel and every part of a foot.

This chapter deals with some of the many varieties of human activity in which the function of the foot is tested to the extreme and used with maximal skill, such as running, ballet dancing, kicking, and for swimming, tightrope, and firewalking. These various skills are due to central neurological control. In contrast in microgravity the role of the foot is changed with consequences that are described.

An individual’s response to partial or total loss of a limb depends, to some extent, on the age when it occurs. Children adapt rapidly but most adults stoically accept the situation and make the best of it. Those who are liberated from chronic pain are only too pleased to become mobile again. As stated by a psychiatrist, James Parkes [1],