Survival of the Sickest: The Surprising Connections Between Disease and Longevity (P.S.)

Everything out there is influencing the evolution of everything else. The bacteria and viruses and parasites that cause disease in us have affected our evolution as we have adapted in ways to cope with their effects. In response they have evolved in turn, and keep on doing so.There are many dietary diseases that have had an evolutionary advantage in our ancestors but that today do more harm than good. In a person with hemochromatosis, for example, the body always thinks that it doesn't have enough iron and continues to absorb iron unabated. The excess iron can lead to liver failure, heart failure, diabetes, and even cancer.Why would a disease so deadly be bred into our genetic code? Remember how natural selection works. If a given genetic trait makes you stronger--especially if it makes you stronger before you have children--then you're more likely to survive, reproduce, and pass that trait on. People with hemochromatosis have therefore an evolutionary advantage--protection against the bubonic plague!On one set of experiments, macrophages from people who had hemochromatosis and macrophages from people who did not were matched against bacteria in separate dishes to test their killing ability. The hemochromatic macrophages crushed the bacteria. They are thought to be significantly better at combating bacteria by limiting the availability of iron than the nonhemochromatic macrophages. So though hemochromatosis will kill those inflicted with it decades later, they are much more likely than people without hemochromatosis to survive plagues, reproduce, and pass the mutation on to their children.Diabetes also provided an evolutionary advantage to our ancestors by providing superior ability to withstand the cold by eliminating water and driving up sugar levels (like alcohol, sugar is a natural antifreeze). As a theory, it's hotly controversial, but diabetes may have helped our European ancestors survive the sudden cold, including the ice-age.Malaria is an infectious disease that infects as many as 500 million people every year, killing more than 1 million of them. But not everyone who gets bit by malaria-carrying mosquitoes gets infected. And not everybody who gets infected dies. So what's helping the malaria survivors? People with a genetic tendency for sickle-cell anemia, another inherited blood disorder, had better natural resistance to malaria.As you've seen with hemochromatosis, diabetes, and sickle-cell anemia, one generation's evolutionary solution is another generation's evolutionary problem.At the end of the day, every living thing shares two hardwired imperatives: Survive. Reproduce. To achieve this, some organisms have inherited ingenious techniques to manipulate their hosts--the phenomenon that occurs when a parasite provokes its host to behave in a way that helps the parasite to survive and reproduce.Orb weavers are a family of spiders that experience host manipulation. A wasp bites the spider, temporarily paralyzing it, then deposits its egg in its abdomen. The spider then goes on with his life oblivious to the egg in him. The egg then hatches, and the larva slowly feeds off the blood of the spider. When it is ready to cocoon, it injects chemicals into the spider's bloodstream to manipulate the spider into building a special web for it--instead of building circular webs, it goes back and forth building a rectangular web. Once the web is completed, the larva kills the spider by sucking off all its blood, and then throwing its carcass to the jungle floor below. It then uses the specially built web for it to cocoon by hanging on it.A worm that infects ants is a classic example of another host manipulator. As the worms being carried by the ant develop, one of them makes its way to the ant's brain where it manipulates the ant's nervous system. Suddenly, the ant behaves in completely uncharacteristic fashion. At night, it leaves its colony and hangs on the tip of a grass, waiting to be eaten by a sheep. If it does not, it returns to its colony only to resume again its journey at night to the tip of a grass waiting to be eaten. Once eaten by a sheep, the worm would have succeeded in its manipulation, and would grow inside the sheep's stomach, its intended host.The rabies Virus is another interesting host manipulator. It manipulates its host into becoming aggressive, which will make its host bite others and thus also infecting others.Here is one amazing example of host manipulation: One researcher has discovered that women infected with T. gondii spend more money on clothes and are consistently rated as beings more attractive than women without the infection. Infected women were more easy-going, more warm-hearted, had more friends, and cared more about how they looked. However, they were also less trustworthy and had more relationships with men. Infected men, on the other hand, were less well groomed, more likely to be loners, and more willing to fight. They were also more likely to be suspicious and jealous and less willing to follow rules.A normal sneeze occurs when the body's self-defense system senses a foreign invader trying to get in through your nasal passages and acts to repel the invasion by expelling it with a sneeze. But sneezing when you've got a cold? There's obviously no way to expel the cold virus which is already lodged in you. The cold virus has learned this reflex so it can infect your colleagues, family and your friends. Your body is actually being manipulated by the virus into sneezing!The herpes virus may heighten sexual feeling, which will increase the probability of transmission. In other words, sometimes the herpes virus may want you to get some action in order for it to spread to other hosts.So what if we made it easier for a given type of bacteria to survive in a healthy human than to survive in a sick human? Would this create evolutionary pressure against behavior that harms us? In fact there is an evolutionary advantage for the malaria parasite to push its hosts toward the brink of death. The more parasites swarming through our blood, the more parasites the mosquito is likely to ingest; the more parasites the mosquito ingests, the more likely it will cause an infection when it bites someone else. Cholera is similar--it doesn't need us moving around to find new hosts, so there's no reason for the bacteria to select against virulence. The bottom line is that if an infectious client has allies (such as mosquitoes) or good delivery systems (such as unprotected water supplies), peaceful coexistence with its host becomes a lot less important. In those cases evolution is likely to favor versions of the parasite that best exploit its host's resources, allowing the parasite to multiply as much as possible. Some researchers believe that we can use this understanding to influence the evolution of parasites away from virulence. The basic theory is this: shut down the modes of transmission that don't require human participation and suddenly all the evolutionary pressure is directed at allowing the human host to get up and get out. According to this theory, the virulence of a cholera outbreak in a given population should be directly related to the quality and safety of that population's water supply. If sewage flows easily into rivers that people wash in or drink from, then the cholera strain would evolve toward virulence--it can multiply freely, essentially using up its hosts, relying on its access to the water supply for transmission. But if the water supply is well protected, the organism should evolve away from virulence--the longer it remains in a more mobile host, the better its chance of transmission.A series of cholera outbreaks that began in Peru in 1991 and spread across South and Central America over the next few years provide compelling evidence that this theory might actually work. The water supply systems from country to country ranged from relatively advanced to seriously rudimentary. Sure enough, when the bacteria invaded nations with poorly protected water supplies, such as Ecuador, the virus became more harmful as it spread. But in countries with safe water supplies, such as Chile, the bacteria evolved downward in virulence and killed fewer people. The implications of this are huge. Instead of challenging bacteria to become stronger and more dangerous through an antibiotic arms race (which we are currently losing), we could essentially challenge them to get along. If mosquitoes didn't have access to bedridden malaria patients, the microbe would be under evolutionary pressure to evolve in a way that allowed the infected person to remain mobile, increasing the opportunity for it to spread.A series of groundbreaking research has shown that certain compounds can attach themselves to specific genes and suppress their expression. Let's take a look at a few examples. Depending upon the time of year the vole (a type of mouse) is due to give birth, baby voles are born with either a thick coat or a thin coat. The gene for a thick coat is always there--it's just turned on or off depending on the level of light the mother senses in her environment around the time of conception.One species of lizard is born with a long tail and large body or a small tail and small body depending on one thing only--whether their mother smelled a lizard-eating snake while pregnant. When her babies are entering a snake-filled world, they are born with a long tail and big body, making them less likely to be snake food.This is a fascinating book and I highly recommend it. I truly enjoyed reading it and I have learnt things I never imagined! Now that's what I call precious reading!

My Opinion of Survival of the Sickest: Author: Dr. Sharon Moalem: By Carlos TopherThis book is very interesting, it is about diseases, history and the creation of life. It also explains how what we think of as sickness may have benefited our ancestors, leading us to things we can do about it. From the past to now, our genetics have been affected by diseases and the environment. This book explains some of these factors have affected our genetic history.The Moalem says that people with diabetes can survive lower temperatures and this is because the sugar acts as an anti-freeze. During the Ice Age, people who had diabetes survived better against the cold, and this book explains the possible benefit to our ancestors.Also, the author has a theory that humans used to live in water. He explains that water birth could be more comfortable for women. They could stand up in the water and give birth safely, by themselves with less pain. The safety he noted by the fact that babies don't breathe under the water until they feel the air on their cheeks.To further support the theory that we once lived in water, our bodies have less hair than most other mammals. We are like dolphins in the hairlessness of our bodies and they live in water. Additionally, mammals who live in water have fat attached to their skin as we do too.Sun light is both good and bad. It is good because your body can use it to make vitamin D. Vitamin D is necessary to construct bones and to prevent Rickets. Sun light helps to convert cholesterol into vitamin D. Too much sun light could be harmful because it could burn your skin. Melanin protects the skin from burning and gives it a darker color. The author explains why we have different skin colors, reminding us that lighter-skinned people were favored in areas where there is less sun light, and darker skinned people were favored in places where there is more sun light. Today people who find themselves in the wrong light zone can correct a vitamin D deficiency with supplements, this explains why they put vitamin D in the milk.This book is also about the creation of life, it explains that every virus, bacteria, plant, animal and human, has to live long enough to reproduce in order for its offspring to survive. Reproduction, the author explains, is the main goal of a life form. It is even more important than the individual survival, introducing the idea that we have to die in order to allow our offspring to improve. Another reason for dying, the author explains, is that older individuals die so that their parasites die with them, to protect the young.You might think that "Survival of the Sickest" would be a boring book, but it is not. In a fact this book is good and I recommend it. Dr. Moalem explains how diseases may have helped our ancestors get through several historical events, such as an ice age. The author introduces the idea that humans once lived in water, with evidence like our hairlessness, and I think that it is amazing. I believe that this book would help you understand the relationship between vitamin D and sun light. Additionally this book talks about the nature of life, reproduction and death.

Very insightful read. Would recommend!

Despite the rather gimmicky American title (and the somewhat sleazy hardback cover featuring a nurse) this is an intelligent and well-constructed book. I'm fascinated by evolution so I loved it. I did feel a bit cheated though: I was looking forward to another hour or two at least, with my Kindle showing 68% read, when it suddenly stopped. Of course I was expecting notes, but 32% of the book? Some of that is an index.I tend to shy away from science books on Kindle because images will be poor. But you can relax with this one - it doesn't have or need any. I wish Amazon would make an effort to handle images better.They should also provide better information about publication dates. The Kindle edition of this book quotes 2014, but as far as I can tell the text has not been updated since the original publication in 2007. So don't expect the science to be right up-to-date. (The book looks forward to more from a favourite of mine, Elaine Morgan, who sadly died in 2013. If only.)

If you're into genetics (epigenetics) or curious as to why we get diseases and ailments in the first place, this is a great book that explains everything to you. I was volunteering my time for over 5 years for a clinical research charity reading through research proposals on genetic methylation and this book helped me finally make sense of not only what I was reading, but about my own body, my family's and generally why we are all different.

Some good ideas in here which make it an interesting read, but also some 'controversial' ideas which are a bit weak, eg aquatic apes - pretty silly idea. But worth a read.

This is a brilliant read!Dr Sharon Moalem has a easy going and humorous approach to what could be a complicated subject. Well articulated.A real page turner.More please!

This is a book with countless deeply interesting facts about biology. After reading it I feel that I have a much much stronger grasp on how evolution works.However if you want to read something that will help you with your biology classes this isn't it. You will only gain generic knowledge, the kind of which will entertain a group of friends during a dinner party.All in all this is a extremely interesting book that mainly consists of a collection of unbelievable facts about biology, not a textbook. You will go through it as easily as if it was a Agatha Christie!