The foot is a limb that is not given much importance when compared to other vital organs such as the brain or heart. However, the foot is a very complex mechanical structure that is made of 26 bones, 33 joints, and more than 100 muscles and ligaments. About a quarter of the bones in the human body and about a fifth of the joints are found in our two feet. That is why Leonardo da Vinci described the human foot as an engineering and artistic masterpiece.

A healthy person takes about 5,000 steps a day. Given a life of eighty years, a person takes about 150 million steps throughout their life. Assuming that each step is 75 cm, a person walks about 110,000 kilometers throughout his life. This corresponds to walking around the equator about 3 times. Apart from that, a typical person stands for around 2-4 hours a day. During all these activities, the human foot carries the entire body’s weight. In standing position, body weight is supported by two feet while activities such as walking and running are done by only one foot for a certain period of time. While standing, the feet carry 100% of their body weight, while walking, this rate rises up to 150%. While walking, the foot that needs to be lifted from the ground approaches the ground again with an acceleration in the same direction as gravity. Therefore, the impact force at the moment the foot touches the ground corresponds to 150% of a person’s body weight. In cases of severe effects such as running and jumping, this force easily increases up to 5 times the body weight and up to 10 times in some people. For a person weighing 70 kilograms, this force can be 105 kg (or about 1050 Newton) in walking, and easily 350 kg (or about 3500 Newton) in running or jumping. Assuming that a person walking for an hour takes 5,000 steps, the foot pulls a total of about 500 tons of load (5,000 steps x 105 kg). In running, this figure will increase approximately three times.

The foot has been created with a wonderful mechanical and construction design that is able to consistently sustain such high loads. The bones and muscles of the foot add two different belt designs to it. One of them, the structure called the longitudinal belt starts from the heel bone (calcaneus) and ends with its metatarsal bones (Figure 1). Some researchers claim that the long arch is divided into two parts as the inner (medial arch) and the outer arch (lateral arch). However, both structures resemble bridges built in arches. The second arch on the foot is called the transverse arch. This belt is perpendicular to the long belt from the right side of the foot to the left side and is shorter in length (Figure 2).

Therefore, the foot is a marvelous structure consisting of roughly two arches. This structure of the foot can be compared to arch bridges or a dam. The arch structure is known as the strongest structure against steep loads in construction areas due to the robustness of the designs against compression forces in cases of vertical loading. Therefore, hydroelectric dams are constructed in the form of arches or arcs in order to make the most resistant model against hydrostatic pressure.

The arch structure of the foot is very flexible and can also move up and down like a car suspension and acts as a shock absorption. If there was no such structure on the foot, the impact forces during walking and running activities would be higher and cause chronic foot pain. The flatfoot complication is a result of a damage in the arch structure in the foot which comes from birth or develops afterwards. Flatfoot patients are often unable to perform long-term activities and experience foot pain as well as complications in other organs of the body.

Our feet’s arch structure is not the only factor involved in shock absorption that is designed against mechanical forces. The layer of fat on the bottom of the foot also contributes to this process. In a healthy person, this fat layer, which has a height of 2.5 cm under the heel, drops to 5-7 mm in the front part of the foot. It also helps to distribute the vertical and horizontal forces caused by standing or walking evenly on the sole of the foot. At the same time, it serves as a source of heat insulation and helps protect our feet from hot or cold surfaces. In some diseases such as diabetes, in which this fat layer melts or decreases, wounds called foot ulcers can develop because the shock absorption and load distribution get damaged. Mechanical pressure is calculated by dividing the amount of mechanical force by the surface area on which it is applied, meaning that smaller surfaces areas are subjected to more pressure. This is why very tiny needles, despite weighing almost nothing, can pierce our skin and cause pain. Similarly, damage to the fat layer under the foot causes the forces applied under the foot to act on a limited surface area. For example, the reduction of fat in the area just below the heads of the metatarsal bones reduces the “cushioning” effect in this area and causes a pressure in high values. This extra pressure can cause tissue damage along with the aforementioned foot ulcers.

Such a situation that will cause pain in a normal person cannot be felt by many diabetics. If diabetes is not well controlled, neuropathy or a “lack of feeling” may occur as a complication. Dead nerve cells become unable to feel pain which can result in people not knowing about harm that is being done to their body. Diabetic patients who develop neuropathy would not feel fatty layer damage and accompanying high pressure values whereas a typical person normally would. Untreated foot ulcers can become infected and can turn into gangrene. Since the gangrenous foot has to be cut, diabetes unfortunately causes a large number of amputations. Such amputations are sadly quite frequent throughout the world due to diabetic neuropathy. Dr. Paul Brand, who studied diabetic foot ulcers, defined pain as a gift from God that no one wanted. Sometimes, what we do not like might be better for us (Qur’an 2:216); likewise, pain can cause a lot of trouble to people but it can also alert us of dangers and harm to our bodies.

Thus, foot care is very important in diabetics. The following three actions are recommended to patients; daily inspection of the foot; daily washing; and control of the inside of the shoes. The pest, pebble, or similar hard object in the shoe that can be very harmful for diabetics with loss of sensation would be removed this way. On the other hand, when such a hard object remains in the shoes, patients may step on them repeatedly without feeling it which will likely lead to an ulcer case.

With its pain that works like a health alarm, extraordinary mechanical loads it carries, heat insulation and shock absorbing features, the human foot is a wonder of art that calls for contemplation.

Original Article: Lieberman, D.E. et al., Nature 463, 531 (2010).

The modern running shoe was not invented until the 1970s. However, the presumption that running barefoot is dangerous and causes pain could be wrong. To explain this phenomenon, scientists studied three groups of people in the United States and Kenya: those who had always run barefoot, those who had always worn shoes, and those who had converted to barefoot running from shod running. They found a striking pattern: the three groups positioned their feet differently; while most shod runner people made initial contact with the ground heel-first (rear-foot striking), barefoot runners used their flat feet (mid-foot striking) or the lateral ball of the feet (fore-foot striking) first. Kinematic and kinetic analyses showed that barefoot runners who used the fore-foot or mid-foot strike generated smaller collision forces than the rear-foot strikers with shoes. This means that it is possible to run barefoot on the world’s hardest surfaces without experiencing the slightest discomfort or pain; all one needs is a few calluses to avoid damaging the skin. It is also clear that running-shoe companies and other footwear designers should pay more attention to how God designed our body and redesign more appropriate shoes for running.

The Molecule with a Thousand Faces

Original Article: Ehre D. et al., Science 327, 672 (2010).

Water freezes at 0 C… or perhaps not? Pure water can remain in liquid form at temperatures down to –40 C, which is known as a “supercooled” state. When agitated by stirring or adding impurities, supercooled water freezes instantly. A team of scientists report that under certain conditions, supercooled water freezes when warmed up (!). Supercooled water can freeze at a higher temperature on a positively-charged surface than it does on a negatively-charged one. Initially, the surface is negatively charged at a lower temperature. The surface becomes positively charged when warmed up and the supercooled liquid water solidifies. Will the day ever come when we will be able to understand the water molecule completely? This is something we just don’t know. What we know for certain though is that water, which is apparently the “most normal” substance around us, has already proven itself ironically as one of the most unusual ones in nature. We take this familiar molecule for granted within our daily routine, but H2O-or water as we know it-still remains a celebrity in the eyes of scientists.

Cancer-Causing DNA Mutations Are Deciphered

Original Articles: Pleasance, E.D. et al., Nature 463, 184 & 191 (2010).

DNA mutations are changes in the DNA code caused by external or internal agents known as mutagens. Scientists have identified mutations from lung cancer and skin cancer and have compared them to normal samples in order to find the mutations that lead to these cancers. They have identified ~23,000 mutations in lung cancer (small-cell lung cancer) and ~33,000 mutations in skin cancer (melanoma). The researchers revealed that most of these mutations are single-base DNA changes, suggesting that they are a direct cause of the carcinogens in tobacco smoke and UV light. Under normal conditions, our cells are equipped with a “DNA repair mechanism” which detects any changes in the DNA code and repairs it. However, when excess amount of mutations occur due to tobacco smoke in our lungs or to too much exposure to sunlight in our skin cells, the DNA repair mechanism cannot repair all of the mutations. Accumulations of these mutations lead to cancer-a state in which cell division has gone out of control. Scientists have calculated that every 15 cigarette causes one mutation in the DNA. These studies will be immensely useful for understanding the reasons behind the genetic changes in cancer and more importantly they will provide a comprehensive catalogue of mutations that can be used for cancer diagnosis and treatment.

Scientists Inspired by the Spider Web

Original Article: Zheng, Y. et al., Nature 463, 640 (2010).

Even though spiders may not be the most appealing creatures living on earth, they are one of the most intriguing predators in the animal kingdom. For centuries the intricate ways that spiders hunt, their (relatively) enormous appetite, their strong senses and extraordinary craftsmanship have been fascinating research topics for scientists. In this study, researchers wondered why and how spider webs become decorated with pearl-like drops of water in humid weather conditions. At nanometric scales, the group revealed that the fibers which constitute the web of Uloborus Walkcenaerius-a non-venomous spider-change conformations after interacting with water. When the web becomes wet the fibers condense into knot-like structures which are distributed evenly along the entire silk. The geometric structure of the web results in surface-energy gradients that drive water particles towards the knots. Concentrating water molecules at the knots may help to keep the rest of the web dry, which is a necessary factor to capture prey. This extraordinary finding has inspired the building of an artificial spider silk, which exploits the same geometric trick, trapping and transporting water droplets. In the near future, such “green” materials could be used in a wide variety of applications, such as filtering substances out of chemical reactions without need for a catalyst.

Self-Sacrificing Mother Yeast Cells

Original Article: Liu, B. et al., Cell 140, 257 (2010).

Humanity has always searched for the fountain of youth. Yet, the process of aging is still a poorly understood concept in biology. How ironic that the budding yeast, a mere single cellular organism, has a fascinating way of keeping its offspring young and healthy. It was previously shown that protein aggregates appear within the cytoplasm of yeast cells as they age. These protein aggregates are thought to be toxic to the cells and thus potential risk factors to both mother and daughter cells. Researchers demonstrated that these aggregates are consistently transported to the mother cell, thereby allowing the daughter cells to make a fresh start to life. Polymerizing actin filaments, which are nucleated from the polarisome in the daughter cell, bind to these aggregates and push them towards the mother cell cytoplasm. In addition to being an amazing biological process, these self-sacrificing mother cells which keep their offspring healthy form a controversial issue. The common understanding in biology is that all organisms struggle for their own survival. However, why a simple organism like yeast prefers to have a healthy daughter cell and to jeopardize its own life is unclear and shows the existence of a mother’s mercy, even at the single-cell level.

Honey Bee Collapses

Original Article: Ratnieks, F.L.W. & Carreck, N.L., Science 327, 152 (2010).

Throughout history an extensive loss of honey bee colonies has occurred in many different locations; however, in North America, particularly after 2006, there has been an increase in the disappearance of adult honey bees from hives, in which they abandon their food and brood; this has been coined a “Colony Collapse Disorder” (CCD). The most likely cause of the syndrome is seen to be the presence of a parasitic mite Varroa destructor. It is not the mite that causes bee death, but rather the number of bee viruses which it carries, such as the Israeli acute paralysis virus; it was previously thought that these were insignificant to honey bee biology. It has also been suggested that CCD is not caused by a previously unknown pathogen, but rather a combination of factors, which only have subtle effects on bee health if considered separately. The health of honeybee colonies is vital for agriculture. In 2000, the total U.S. crop value wholly dependent on honey bee pollination was estimated to exceed $15 billion. The sudden disappearance of honey bees and the complexity of the causes behind CCD remind us of the delicate balance that exists in nature.