Favist: A Homolytic Analysis

Diseases that affect organisms are often seen in negative light. Often, when people hear the word disease they are likely to think of microscopic organisms that harms the host it inhabits. However, scientists like Dr. Sharon Moalem would suggest that the modern day human diseases contributed to the survival of our ancestors. He states that the diseases we still have protected us from other diseases that were much worse. The reason why the diseases are still in existence in modern times is due to the evolutionary advantage it provided to our ancestors, that advantage gave humans the ability to live long enough to reproduce. To show his studies, Dr. Sharon Moalem wrote the book Survival of the Sickest where he explains how diseases like favism,
hemochromatosis, and diabetes allowed for human survival and reproduction. Over 2000 years ago the Greek scholar Pythagoras supposedly said "Avoid fava beans." Although fava beans were associated with politics, legends exist to credit Pythagoras with discovering favism, which is the most common hereditary enzyme deficiency.
The deficiency is carried by the X chromosome which makes the deficiency more common in males. People with favism lack sufficient amounts of the enzyme called glucose-6-phosphate dehydrogenase, also known as G6PD (Dr.Moalem 74). Although G6PD is thought to be present in every cell, it is essential in red blood cells for sustaining cellular integrity and preventing free radicals from destroying them. Thus, favism is a disease that targets red blood cells in the circulatory system . People with favism show symptoms of anemia or hemolytic anemia where there is very little red blood cells or the red blood cells burst. Other diseases that target red blood cells include sickle-cell anemia and thalassemia . J.B.S. Haldane (one of the first people to understand evolutionary pressure and its effects) suggested that sickle-cell anemia and thalassemia, helped its host better resist malaria (Dr.Moalem 89). Haldane's hypothesis was supported by the fact that evolution produces distinct traits in certain populations. In addition, Dr. Moalem states that a map of the world's fava bean
cultivators would correlate with a map of favism carriers. These carriers live mostly in North Africa, Southern Europe, and around the Mediterranean where malaria is common (Dr.Moalem 77). With this evidence, researchers believe that favism, like sickle-cell anemia and thalassemia, could also help its host better resist malaria. To test the hypothesis, researchers turned to use the scientific method - experimenting. According to Dr. Moalem, "In two large case- controlled studies, researchers found that children with the African variant of the G6PD mutation had twice the resistance to P. falciparum, the most severe type of malaria, that children without the mutation had." In addition, laboratory studies found that malaria causing parasites would always prefer infecting a normal red blood cell over ones that lacked G6PD. In 1956, medical researchers managed to diagnose the cause of anemia in African American soldiers and soldiers of Mediterranean descent when they used primaquine (an antimalarial drug used in the Korean War) to the lack of G6PD (Dr.Moalem 74). The drug stressed red blood cells, causing them to burst or prematurely die, and effectively prevented the malaria from spreading. Since favism is a hereditary disease it cannot be cured. But, it is treatable. People with favism should first get diagnosed with a test using fluorescent light that detects the generation of NADPH ; if the blood sample does not florescence under the light, the person may have favism ("Diagnosis and Management of G6PD Deficiency") . When the person is confirmed to have it treatment is to avoid drugs that stress red blood cells as well as avoiding fava beans. Overall, this common deficiency has proved beneficial in helping humanity survive long enough to reproduce without dying from malaria. It has kept our ancestors alive and reproducing that evolution decided to keep the deficiency working in our human genome for future generations. Iron is essential to all living organisms.
No one knows that better than Eugene D. Weinberg, who in 1952, discovered through experimenting that giving iron to bacteria would create massive bacteria growth (Dr.Moalem 6). In humans, however, iron is necessary for a functioning metabolism as well as carrying and bonding oxygen to the bloodstream in the form of hemoglobin. Without iron the immune system would not be able to function properly and the body will experience extreme fatigue. One disease that interferes with the body's ability to manage iron levels is hemochromatosis. Hemochromatosis is a hereditary disease common to people of Western European descent. Nearly one in every three descendents will have one copy of the gene (Dr.Moalem 3). Although many people may have the gene, not all people who have the gene have hemochromatosis; only one in two hundred experience the aliments related to it. Because of the wide range of other variables for it to manifest, it is considered to have a low penetrance rate. The origin for this hereditary disease is believed to be from Vikings that colonized the European coastline. As the Vikings settled, they populated Europe making the disease quite widespread (Dr.Moalem 14). Around 1347, the bubonic plague spread through Europe killing around 25 million Europeans. Those with hemochromatosis managed to survive and thus increasing the chance of passing the gene to the next generation. Those with hemochromatosis have a permanent
condition where chelators, or iron-locking proteins, are constantly locking away iron. The iron is distributed throughout the body but not quite reaching the macrophages, which are white blood cells responsible for isolating invasive bacteria. When the bubonic plague hit people with the disease, the macrophages would isolate the bacteria and prevent its growth due to the lack of iron. As observed from the plague, hemochromatosis seems to target the macrophages of the immune system. People with the disease may display symptoms of joint pain, arthritis and even diabetes. Originally, the disease was unknowingly treated by bloodletting or phlebotomy, which was a common practice of bleeding patients that had any illnesses (Dr.Moalem 18). But, it was never diagnosed. Today, the disease is diagnosed using blood tests like total iron binding capacity or TIBC that test for iron levels and DNA tests that test either both parents or the patient for genes for hemochromatosis (Dr.Moalem 211). If the person does have hemochromatosis they would be treated by bleeding. Therefore, the disease provided humans the evolutionary advantage of surviving the plague by passing on the gene to their offsprings. Today, the impact on humanity isn't as positive as it was for our ancestors surviving the plague, instead not many may be diagnosed with the situation early enough before they start displaying the symptoms of iron overloading. Glucose is known as a body sugar used to supply fuel to the brain, an ingredient used to produce proteins and overall a source of energy. Diabetes also known as diabetes mellitus , one of the most common chronic diseases, is a disease that interferes with the body's glucose levels (Dr.Moalem 24). Unlike favism and hemochromatosis, diabetes is subcategorized into two major types: Type 1 and Type 2. Both types are not solely based off genetics but other factors such as diet and environment. In a typical human body a hormone called insulin (made by the pancreas) helps to absorb and convert blood sugar. In Type 1 diabetes, the body incorrectly identifies insulin as a threat and eliminates all insulin from the body; today Type 1 diabetes are treated by daily doses of insulin injections and a strict diet as well as exercise. People with Type 2 diabetes, however, still are able to produce insulin but the body becomes resistant to it; it is treatable through medication and close monitoring of health, diet and exercise (Dr.Moalem 25). Since the disease interferes with a hormone, diabetes targets the endocrine system and its glands like the pancreas. Symptoms of diabetes is a high level of unregulated blood sugar due to the absence of insulin; thus to diagnose whether or not a person has diabetes, doctors usually test for sugary urine. Similarly in the past, Chinese physicians would diagnose a patient by seeing if ants were attracted to their urine (Dr.Moalem 24). Even the discovery of the first documented diabetic symptoms in Egypt of the year 1552 BC consisted of frequent urine that ants were attracted to ("The History of Diabetes"). To scientists like Dr.Moalem, they state that diabetes helped our ancestors survive the sudden ice age nearly 13,000 years ago. To understand how it helped, it is useful to know that pure water freezes at 32 degrees Fahrenheit and that any impurities, like sugar, lowers the freezing point and makes freezing harder. With the sudden change in temperatures, people with diabetes benefited in having lots of sugar in their blood because it meant it would be harder for them to freeze to death. But, the disease wasn't widespread enough to save everyone from the cold and that's why there was a steep decline in human population in Northern Europe when the cold hit (Dr.Moalem 34). Diabetes in the ice age actually helped people survive, therefore there was no treatment for it. Today, diabetics are not often exposed to freezing temperatures, but they are exposed to lot of foods high in sugar, so the advantage isn't as beneficial. As Dr. Moalem used the scientific method to observe diabetes, he also found out that more diabetics were diagnosed during colder months, which suggests that diabetes had impacted the human body's response to cold. Therefore, diabetes may have been helpful in surviving the cold in the past, but today diabetes are more harmful than beneficial to human health due to our sugary diets. Dr.Moalem has reoriented my opinion on diseases. Like many others I didn't think of diseases as a beneficial thing even though I knew that human DNA is comprised of some viruses that used to harm us. The most interesting thing Dr.Moalem has taught me is that diseases don't all have the same goal. Maybe some diseases do want us dead tomorrow, but some allow us to survive longer and that's the plus side. From favism, Dr.Moalem has opened my eyes that a single fava bean (or maybe a few) can kill you. From hemochromatosis I've learned that turning into iron man can kill you because too much of a good thing becomes a bad habit. But perhaps the most eye-opening, jaw-dropping and mystifying thing I've learnt is about diabetes. Unlike the other diseases, I've heard about diabetes and how people have lost limbs to the disease and succumbed to it. Yet, Dr. Moalem has surprised me with the fact that research on diabetes can help with bringing the dead back to life. In his book he explained the relationship with the cold and diabetes and the little wood frog. With enough researching and experimenting I hope that we would be able to reanimate life to the dead. Of course not many people would be in favor of raising people from their graves, but surely they'll be interested in saving lives. By studying how the cold can help preserve the wood frog and how impurities can lower freezing temperatures, organ transplants maybe more successful. Many people lie on hospital beds waiting for a donor, only a few find an organ donor that matches them and when they do that organ needs to be preserved till it reaches the surgeon table. Some of the organs may have failed to come on time and therefore not suitable for transplant. But what if organs were to be able to be preserved for however long and thawed out when needed without damaging it? Science has managed to turn lots of "what if's" to reality, perhaps one day this will happen, it's only a matter of time.