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Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease

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If you're a fan of books like The Tipping Point and Freakonomics, I highly recommend Survival of the Sickest. It's full of the same kinds of fascinating insights that make for great cocktail party conversation. As a parent, I was particularly fascinated by the chapter on how what you eat during pregnancy can influence the way your children (and even their children) metabolize their food. And as a health conscious person, you'll get practical, actionable ideas on how to think about personalizing your diet based on your background.

You don't need a degree in evolutionary biology to understand Survival of the Sickest. This book gives you a peak into how evolution can actually select for disease, and makes a compelling case for why and how understanding this can shape the way disease is treated in the future. It also explains some fascinating facts - like how some Americans are immune to HIV because they have a mutation and how a person can rust to death but be saved by giving blood. It'll leave you thinking completely differently about your body, and - in some cases - like when it advises that you should take your sunglasses off for a few minutes when you get into the sun so that your eyes can "tell" your skin to be on guard against it, it'll actually affect the way you act.

This book about genetics, evolution and disease is a genuine page turner, that's how deeply interesting it is, and how well it is written. The basic premise runs like this: The environment puts pressure on all living things, including humans, to evolve characteristics that help us survive long enough to reproduce and pass on our genes. Over the millenia, various conditions such as drought, ice ages and other climate changes have sparked genetic mutations that enhance our abilities to survive. These include some biological conditions that are advantageous in the short term, but sometimes detrimental in the long term.

For example, today we consider diabetes mellitus a serious disease because it raises human blood sugars to dangerous levels that can result in loss of limbs and sight, among other problems. However, in an ice age, when temperatures were significantly lower than they are now, having extra sugar in the blood may have enabled our ancestors to survive the cold because sugar lowers the temperature at which we freeze to death. Similarly, Sickle Cell Anemia may have evolved to help people resist malaria.

What's especially interesting is that this theory would explain why ethnic groups that are prone to diabetes -- Scandinavians and people from the British Isles, for instance -- originally came from northern areas that were at one time covered by glaciers. And the ancestors of those groups that tend to carry the genes for Sickle Cell generally originated from climates in which malaria was prevalent.

Another intriguing idea is that some "sicknesses" only become serious problems when an individual is older and past his or her prime reproductive years. So if one of our ancestors had, for instance, a chronic disease like diabetes, it probably wouldn't kill him/her until after the person had children.

There are many such fascinating observations and facts in this relatively short book and I highly recommend it to anyone who wonders how things and people got to be the way they, and we, are today.

I read this book in one sitting - it is fascinating and remarkably accessible. Moalem takes a unique and optimistic approach towards investigating the purpose of disease as a way to really understand its role in evolution. The book is packed with insightful anecdotes and leaves the reader less alarmed by disease, and instead with a deeper understanding of its purpose. Most remarkable, the book takes the reader along a journey that connects us to our ancestors.

From the second I picked up this book, I realized I was in for a fun ride! A unique look at evolution and genetics is mixed with humor and fun facts. You may never look at The Plague, baby fat,alcohol,vikings,or your very own medical problems in the same way. This book is an entertaining trip into our history and future -- a must read!!!

We're used to thinking of disease as the enemy, as a malicious force that makes our lives shorter and more miserable. That may be exactly what "disease" is on an individual basis--but its value to the species as a whole is a different matter.

Dr. Moalem elegantly explains why medical conditions that are deemed to be diseases today often helped our ancestors survive and reproduce in difficult environments. Take hemochromatosis, a hereditary condition that causes iron to accumulate in a person's internal organs, eventually leading to death. Although the gene that causes hemochromatosis was once thought to be rare, research completed in 1996 found that it's actually surprisingly common. Why wouldn't such a terrible disease have been "bred out" of our species long ago? The answer is that hemochromatosis reduces the amount of iron available to iron-loving bacteria, such as the bubonic plague that depopulated Europe in the mid-1300s. A person living in the Middle Ages with the hemochromatosis gene would have eventually died from iron build up, but in the meantime would have have had a smaller chance of dying from the plague and other iron-loving infections--in an age when few people lived past the age of 50, the disease resistance conferred by hemochromatosis far outweighed the disadvantage that would have materialized if the person carrying the gene had lived to old age. People with hemochromatosis reproduced and passed the gene one to their heirs; those without it died of the plague, without children.

"Survival of the Sickest" is filled with similarly surprising observations. Anemia may be the body's way of reducing iron available to bacteria--giving an iron supplement to a malnourished population may be a bad idea and ironically (so to speak) medical bloodletting may not have been such a bad idea. Type II diabetes may have been a condition that conferred an advantage on northern Eurpoeans during the ice age, when an increase in sugar in the bloodstream and frequent urination would have reduced the risk of freezing to death. Similarly, sickle cell anemia offers protection from malaria. In the "good old days," a genetic condition that kept a person from dying before reproducing would have been a boon, even if the condition would have turned killer if the person managed to reach old age.

The book is filled with other "big ideas, briefly discussed." Instead of battling bacteria with antibiotics (which is only making them tougher), perhaps we could manage their evolution so that they thrive by inconveniencing their host (like a cold) instead of by flooring it (like malaria). And, although Dr. Moalem seems to agree that natural selection is the big driver of evolution, he observes that perhaps Lamarck wasn't so far off after all--jumping genes, retroviruses and methylation all suggest that an organism's life experiences can in certain circumstances affect future generations. As for aging--perhaps our bodies are designed by natural selection to limit the number of times a cell can reproduce (thus insuring that we will all die from old age if something else doesn't get us first), the alternative being an excess of cells without such a limit (in other words, cancer).

On the whole, "Survival of the Sickest" is readable, surprising and filled with "ah-ha!" moments. If you enjoyed "The Tipping Point" or "Freakonomics," you'll probably be intrigued by Dr. Maolem's often counter-intuitive observations.

Survival of the Sickest, by Dr. Sharon Moalem, with Jonathan Prince -- Hardcover 267 pages with Notes and Index

Most of us probably think of evolution in terms of the ancient past when ape-like creatures were morphing into human form or earlier when one-celled animals were gradually changing into the next higher forms of animals, or even when dinosaurs evolved into birds. Some have likely included the domestication of plants and animals as an agricultural arm of evolution, and may have considered the mutating of a retrovirus like HIV/AIDS to be an aspect of evolution.

But if you read Survival of the Sickest, you will likely come away with a very different appreciation of the wonders of evolution. Dr. Moalem takes us on a journey of discovery, a journey that started in his young life as a search for a cause for his grandfather's, and his own, as it turned out, disease of hemochromatosis (dangerous levels of iron in the blood and organs). This quest led to an answer and more questions--many, many more questions--about the true nature of the physical influences in our lives--and why we need diseaase.

Dr. Moalem writes with tongue firmly in cheek as he makes his points with vigor. Survival of the Sickest tells, if not a different story of life, then certainly one that has an uncommon emphasis. He says, "... life is in a constant state of creation. Evolution isn't over--it's all around you, changing as we go. ... nothing in our world exists in isolation. We--meaning humans and animals and plants and microbes and everything else--are all evolving together and our relationship with disease is often much more complex than we may have previously realized."

"So to be crystal clear: 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. They have evolved in turn, and keep on doing so. All kinds of environmental factors have affected our evolution, from shifting weather patterns to changing food supplies--even dietary preferences that were largely cultural."

Dr. Moalem puts this all into perspective with this poetic summation: "It's as if the whole world is engaged in an intricate, multilevel dance, where we're all partners, sometimes leading, sometimes following, but always affecting one another's movements--a global, evolutionary Macarena."

Much of the book concerns the genetic interaction of the DNA of bacteria and viruses with ours. "DNA is not destiny--it's history. Your genetic code doesn't determine your life. Sure, it shapes it--but exactly how it shapes it will be dramatically different, depending on your parents, your environment, and your choices."

As an illustration of the dynamic nature of the science of evolution, he goes well beyond established DNA understanding with a discussion of the possibility that Lamarkian theory (individual behaviors can result in genetic modification in an individual and that trait be passed on to offspring) could be coming back in vogue.

There is a lengthy discussion of what the young science of epigenetics is discovering about the effects that "methylation" has on our genome. It seems that methylation is some communication media that attaches to particular genes within an individual and modifies the on/off switch and even the strength of its expression without actually modifying the DNA.

I found rather fascinating the claim that the behaviors of a prospective mother can alter the expression of genes in her baby, but she can influence development even before her fertilized egg has implanted in her uterus. Even more amazing, and, I think, not fully substantiated in the book, is the claim that behaviors of the baby's grandmothers, and even of its father and grandfathers can influence gene expression in the developing fetus. He does admit, however, that the jury is still out on some of this research.

I loved this existential summary: "Your genes are the evolutionary legacy of every organism that came before you, beginning with your parents and winding all the way back to the very beginning. Somewhere in your genetic code is the tale of every plague, every predator, every parasite and every planetary upheaval your ancestors managed to survive. And every mutation, every change, that helped them better adapt to their circumstances is written there."

Survival of the Sickest is a fun read. I found myself smiling at the author's use of metaphor and expression, and at a few puns he sprinkled here and there. You'll get a different perspective on the utter pervasiveness of evolution, on how this universe operates at the biologic level, and of how we fit within it. I highly recommend it.

This is a great little book to tote along wherever you go and have a few minutes to spend on insights into the fascinating and intelligent ways our bodies and, really, Nature, work in our best interests. It leaves the reader in awe of the universe and all its complexities. And because each chapter is a separate topic, it's very easy to pick up and put down and still get a sense of an overall thread. Moalem loves a mystery, a challenge - and has shared his enthusiasm with his readers. His style is engaging, accessible, and fun. As he has a conversation with you, he takes you through the logic of the process with an amusing metaphor (eg: "When you try to move one dancer with a bulldozer, you're pretty darn certain to scoop up more than one Rockette.") You don't become confused because he explains details in an interesting, and totally uncondescending way. The chapter on epigenetics is fascinating: who knew that a woman's lifestyle habits can actually change the fetus' genes? We used to think that her habits could change the baby's health, but the genetic code? That's kind of like saying if you swim a lot when you're pregnant, the baby will show a predisposition to swimming. But it's true in a sense (read the chapter "Methyl Madness" to find out). Moalem is one who would put some credence in old wives' tales because he believes that long-held beliefs can often be accurate in a weird way (bloodletting, for example). This is a must-have book for anyone curious about little known and groundbreaking knowledge of the human body.

I love this book! It's a fascinating read that anyone can enjoy because you don't need a scientific background to get it. I recommend it to patients all the time. Understanding how sunlight causes the conversion of cholesterol in the skin into Vitamin D, alone makes the book worth reading. This is important because we are being "sold" cholesterol lowering drugs daily. The premise of the book is that disease itself provides the environmental stimulus which lead to genetic mutations that allow for "survival". They don't argue that disease is good, but rather explain why it came about. What we are today calling genetic diseases are, in fact, the result of adaptive response to conditions which would have otherwise resulted in death. For example, people who today carry the gene for sickle cell disease are the offspring of people who lived in Malaria prone regions of the world. While many of their fellow men and women were dying of malaria, some individuals developed genetic mutations that made their red blood cells sickle in the face of the malaria parasite. These people survived and passed this gene on to their offspring. Present day offspring still have this gene, whether they live in a Malaria prone region or not; but you can see that the very existence of this genetic variation was a strategy for survival in the face of an environmental threat. So, if you carefully research a genetic disease you should find some environmental circumstance that drove that particular genetic adaptation which allowed for the survival of that exposure; whether it's from an infection; toxic plants or whatever. Another example is that people whose ancestors lived in places where there are a lot of toxic plants have evolved the capability of rapid metabolizing various drugs by their liver. [The relevance of this is that today people often have adverse drug reactions that are due to their unique genetically driven metabolism that dictates how they process drugs. Consequently, even when using a medication in appropriate doses; for the correct reason; in the correct timing can still result in adverse reactions due to these unique genetic variations. This makes it difficult to always prevent adverse medication reactions. These reactions are usually labeled as "errors". For example hospitals put in check and balances and redundancies to prevent "errors", but how do you mitigate against an individual's unique genetic variations?] This book is filled with all sorts of examples of this nature. With a little imagination you can come up with plenty of additional circumstances where you can apply the premise on your own.

Most of us grew up thinking that genes are just something that we inherit from our parents and pass on to our offspring, but otherwise genes just sit around inside of our cells. The subject of epigenetic has changed that thinking. Our genes can and do actually change from an environmental demand!! This is HUGE guys!! It is such a big deal that for most of us it takes a while for the significance of this concept to sink in. Consider the environmental pressure of constant famine; a genetic response may be the capability of surviving on very little food.

All of us are "survivors" of ancestors who faced some sort of threat (just like those discussed in the book) and therefore we all have these little quirky gene variations. Considering where on the globe and the environment that your ancestors came from can help you understand why you may be at risk for various diseases, but it can also help you see why your genes may protect you from others.

You don't need any knowledge of science to love this book; all you need is a curious mind.

Maxine J Thomas, MD

Sharon Moalem is indeed the maverick he claims to be. The first few chapters of the book questions and attempts to explain why natural selection did not eliminate hereditary conditions that are potentially or even ultimately fatal.

First described, is the condition of hemochromatosis where the body just keeps absorbing iron way beyond what is needed until liver failure and heart failure set in. An advantage which an individual with hemochromatosis has over others is that his macrophages are virtually iron-free. Pathogens engulfed by these macrophages are starved and easily inactivated. This makes the individuals resistant to a number of illnesses like bubonic plague which killed more than 25 million people in Europe. For this reason, the gene for hemochromatosis is passed down, making it most common in Western Europeans. The only way to prolong the life of a person with hemochromatosis in modern times? Bloodletting. Moalem further postulates that anemia, a seemingly undesirable condition, may actually protect people who live under harsh conditions.

The next subject is juvenile diabetes, a deadly inherited condition which, according to the author, could have helped humans lived through the Ice Age!

The next part of the book tells us how parasites affect the evolution of their hosts, not just by controlling host behaviour, but also by incoporating themselves into the host's DNA. Part of the human genome is of viral origin! If that's not enough, check out his theory about aquatic apes which evolved into hairless humans!

Apart from these bizarre theories, there is also some valuable information on how cancer cells can get around the Hayflick limit of cell division with the use of telomerase. There are also some unbiased facts about gene methylation and how the future of medicine may involve treatment at genetic level. The author is honest enough to tell us that medical science is still not able to determine exactly how to turn a gene on or off. This should serve as a good warning to anti-aging specialists who claim they know how to turn the aging genes off with nutritional supplements.

If you have a background in the life sciences, this book will certainly make you sit up. It takes a very open-minded reader to finish this book before calling it rubbish. Personally, I find Moalem's arguments pretty cogent. The book is highly readable and well-organised, but all these extraordinary theories really need some extraordinary proof. I admire the author's creativity which may help solve some scientific puzzles for us in the future.