June 27, 2019 | David F. Coppedge

Bare Feet Were Made for Walking

Your feet can become hard against rough ground without sacrificing their sensitivity.

Years ago, Dr Daniel Lieberman, an endurance runner and physiologist, impressed CEH in Nov. 2004 with his findings that humans are the best endurance runners in the animal kingdom. Even though he is an evolutionist, the number of physical adaptations he described that are necessary for endurance running in an upright posture seem to shout “design.” Now, Lieberman and other scientists have investigated barefoot walkers and found new adaptations that make one wonder if we really need shoes.

The human foot is a highly complex apparatus composed of 26 bones, with tendons, ligaments, blood vessels, nerves, skin and sensory organs all integrated and coordinated. One anatomist called it a “biomechanical masterpiece.”

Foot callus thickness does not trade off protection for tactile sensitivity during walking (Holowka et al., with Daniel Lieberman, Nature). This team studied habitually barefoot walkers in Kenya and made the following observations.

Until relatively recently, humans, similar to other animals, were habitually barefoot. Therefore, the soles of our feet were the only direct contact between the body and the ground when walking. There is indirect evidence that footwear such as sandals and moccasins were first invented within the past 40 thousand years, the oldest recovered footwear dates to eight thousand years ago and inexpensive shoes with cushioned heels were not developed until the Industrial Revolution. Because calluses—thickened and hardened areas of the epidermal layer of the skin—are the evolutionary solution to protecting the foot, we wondered whether they differ from shoes in maintaining tactile sensitivity during walking, especially at initial foot contact, to improve safety on surfaces that can be slippery, abrasive or otherwise injurious or uncomfortable. Here we show that, as expected, people from Kenya and the United States who frequently walk barefoot have thicker and harder calluses than those who typically use footwear. However, in contrast to shoes, callus thickness does not trade-off protection, measured as hardness and stiffness, for the ability to perceive tactile stimuli at frequencies experienced during walking. Additionally, unlike cushioned footwear, callus thickness does not affect how hard the feet strike the ground during walking, as indicated by impact forces. Along with providing protection and comfort at the cost of tactile sensitivity, cushioned footwear also lowers rates of loading at impact but increases force impulses, with unknown effects on the skeleton that merit future study.

Why callused bare feet are a better fit than cushioned shoes (Editorial, Nature). The editors describe Lieberman as “an evolutionary biologist with something of an obsession for how we use our feet.” They describe us humans as “quite large, as mammals go,” and since we walk upright, our feet take a lot of punishment. Surprisingly, though, the thick calluses that grow on barefoot walkers do not hinder their sense of touch; “although calluses protect our feet, they transmit tactile sensation almost as effectively as does soft skin.” Tenderfeet (i.e., habitual shoe wearers) know the pain of stepping on a Lego piece in the dark hours of the morning.

As Lieberman and colleagues observe, a person with callused feet would feel that Lego brick just as acutely. But the researchers also find that bare feet offer a better guide to the force with which our feet strike the ground than do artificially cushioned soles, comfy as those might feel. This difference could have untold consequences for the rest of our skeleton.

Barefoot Walking Gives You Calluses That Are Even Better for Your Feet Than Shoes, Study Suggests (Live Science). Christopher Wanjek gives a Darwin-saturated take on the findings, simply assuming that if bare feet exist, they must have evolved. “At its core,” he alleges, “the study is about human evolution.” He claims that calluses are “the evolutionary solution to protecting the foot,” but if that were true, why didn’t we evolve hard hooves, like horses? The actual study reinforces design; here is a structure that can develop thick skin for protection, and yet maintain tactile sensitivity. Shoes rob us of some of the senses that might improve our health:

However, very thick calluses don’t simply act like shoe cushions. The callus thickness can protect against heat or sharp objects, providing comfort and safety, like shoes can. But the sensory receptors in the foot that detect ground surface differences still transmit signals to the brain.

This uninhibited signal — that sensation of feeling the earth — may help the barefoot walker keep balance, strengthen muscles and create a stronger neural connections between the feet and the brain.

Barefoot walkers have tough feet but sense the ground just as well (Michael Le Page, BBC News). This less-evolutionary article shares some interesting facts about bare feet that indicate we are missing out on benefits by wearing shoes.

Lieberman noticed that as his calluses grew thicker, his feet got tougher without seeming to lose their ability to sense the surface beneath them. He and his colleagues have now confirmed this by studying the feet of around 100 people in Kenya and the US.

Those who usually went barefoot had calluses up to a third thicker, but could sense vibrations just as well as those with thinner calluses. The reason, the team think, is that hard calluses transmit forces without dampening them – unlike the foam or rubber soles of many shoes.

While this is surprising, it is analogous to guitar players who grow calluses on their fingers but still maintain exquisite sensitivity to touch. It means that the sensors on the skin are able to penetrate the callus and still transmit touch signals to the brain. Lieberman expects to study the physiological benefits of barefoot walking more. He thinks the sensory advantage of bare feet could help elderly people avoid falls, for one thing, and might help everybody avoid joint diseases.

Walking on your sensitive sole (News and Views, Nature). Wading past the typical evolutionary fluff about human ancestors millions of years ago, the reader eventually hears good reasons for the design of the human foot.

Our feet are remarkably sensitive, enabling pleasant sensations such as the feeling when walking barefoot on a beach, but also the experience of pain when stepping on a sharp rock. This sensitivity is useful because our body’s nerves use such information to fine-tune our posture and gait, in a similar way to how our sensitive fingertips enable us to precisely manipulate objects. As part of the system that aids this tactile sensitivity, a variety of mechanoreceptors in our skin sense mechanical stimuli such as pressure. If these receptors don’t work normally, as can occur in disease or during experimental manipulation, people can have problems with their balance or gait.

This article describes the experiments Holowka and Lieberman’s team used to arrive at their findings. They remain ambivalent about the value of bare feet compared to shoes, however, admitting that hard soled shoes can also transmit vibrations pretty well, and are important for added protection in some situations.

More research will be needed to fully understand the effect of shoe soles on gait. Humans are not like machines, in which just one variable at a time can be studied. Human movement is a complex, dynamic system, and changing even one variable, such as shoe-sole stiffness, will probably trigger other physiological and behavioural changes. For example, running when using cushioned soles, compared with running barefoot, triggers changes in how the foot makes contact with the ground (called the strike pattern), and also causes the arch of the foot to behave more stiffly.

So should we take our shoes off? “It makes sense that preserving foot sensitivity is useful, especially if maintaining stability is challenging,” they admit. But for now, “Although this mystery has been solved, much remains to be discovered about what affects how humans walk.”

Feet are amazingly complex features God has given us. They did not evolve. Human feet are so different from ape feet, they are essentially a completely different design. In the book Spacecraft Earth, a Guide for Passengers, Dr Henry Richter spends five pages talking about the human foot. On page 48, he compares it to the ape foot:

The shape of the human foot is much different, clearly adapted for walking upright all of the time. It has a unique bone structure, muscle structure, and sole, with two arches almost perpendicular to each other. The heel and ankle are suited to living on the ground, not in the trees. What chance mutations created such a radical change? Evolutionists often gloss over these details, simply imagining that a change in climate led some ape ancestor to climb out of the trees and start walking. Such things do not just happen. There would be too many things for natural selection to do at the same time. (Richter, p. 48)

The foot is just one of hundreds of wonders our Creator gave us to experience His world. The more we learn about our bodies and minds, the more our gratitude and awe should grow. Evolutionary theory (the Stuff Happens Law) robs God of the honor that is His due.

Exercise: Try barefoot walking when you can. It would take weeks or months to build up the calluses need to walk on rough surfaces, but pay attention to the sensitivity provided through the skin. Does it improve your balance? Are you more aware of the positions of your toes, arches and heel? Compare that with the feeling of walking in soft shoes or hard shoes. What benefits can you find designed into bare feet that can aid your health and enhance your experience of the world?

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