Customer Reviews

Why We Get Sick: The New Science of Darwinian Medicine

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This is a very readable book and an excellent introduction to a subject that has hitherto been sorely neglected. The main argument presented by Nesse and Williams is that disease must be understood from the perspective of evolutionary biology.

The authors begin by asking, "Why, in a body of such exquisite design, are there a thousand flaws and frailties that make us vulnerable to disease?" Through evidence and insights from evolutionary biology, the authors carefully give a detailed answer to this question, which might be summed up thus: The mechanism of evolution fits our bodies for reproduction, not for optimum health. Furthermore the mechanism is imperfect and subject to mutation. Additionally we are in competition with other organisms, e.g, viruses, bacteria, etc., that work toward their fitness, sometimes at our expense (the parasite-prey "arms race"). Noteworthy is the idea that natural selection cares little for the maintenance of the organism after the age of reproduction, and that sexual reproduction actually fosters mechanisms that increase the fitness of youth while neglecting the aged, leading to the phenomena of senescence and death.

Seeing disease from the viewpoint of evolution, the authors argue, helps us to understand disease and the mechanisms involved, which in turn can help us to fight disease. Allergy, for example, is a disease characterized by an over active immune system. Copious amounts of histamine are produced to fight off a few molecules of pollen. Why? The authors make the point that our immune systems operate on the principle that better an overreaction to something harmless than an under reaction to a real threat. It's like jumping at the sight of a piece of rope lying on the ground. It's not a snake, but better this little harmless error than being too slow to get back from the real thing.

Some other interesting ideas: Fever has a purpose. It raises body temperature enough to interfere with the chemistry of some pathogens, thereby killing them. If we take medicines that reduce fever, are we prolonging our illness? In some cases, the authors answer, yes. If we take medicines that suppress coughs and sneezing can that also prolong our illness? Again the answer is in some cases, yes. The point is that in treating the symptoms of disease we need to make a distinction between which are defensive mechanism of our bodies and which are not. Some pathogens, for example, make us sneeze or cause diarrhea in order to better spread themselves to the next victim. The rabies virus makes a dog bite other animals in order to spread itself. But our bodies cause us to cough and sneeze primarily to expel pathogens.

The authors see some of our health problems as the result of genetic "quirks," or evolutionary hangovers. Dyslexia is an example. In the Environment of Evolutionary Adaptation back in the Stone Age, dyslexia was no problem because there were no books to read. Indeed, it might be that the dyslexic approach to some perception problems, is better than the "normal" one, allowing a quicker, better understanding of the objects being viewed. Other genetic quirks include our predisposition to eat too much fat when available because in the EEA there was precious little fat to be had so it made sense to eat as much as possible when it was available. Something similar can be said of alcohol. Before agriculture, and especially before the process of distillation, a predisposition to alcoholism was no danger because there was very little alcohol to be had. These "quirks" are examples of disease caused by "novel environments," much of the modern world being a novel environment to our Stone Age bodies.

Nesse and Williams show that the modern environment, which requires a lot of close work from all of us, especially the reading of books, is the cause of the epidemic of myopia that modern humans experience. I would like to add that it is possible that myopia under some conditions could be adaptive. In the rainforest it would probably be better to see well close at hand than far away (the opposite of what would be valuable on the savannah). Also those people who concentrated on things small and up close might well identify and process food sources overlooked by others.

While this is an excellent book, gracefully written and full of valuable information and insight, it is now a little dated (copyright 1994), and some of the ideas need reworking in light of recent discoveries. For example, while the authors discuss the ill effects of too much fat and sugar in our diets, they say nothing about the carbohydrate intolerance that leads to obesity. This too can be seen as an evolutionary quirk since there were no cultivated fields of amber grain in the prehistory, and the grains that were available were small and required a lot of hand processing so that it was very difficult to overindulge. Consequently there was no need for natural selection to evolve a protection against eating too much. Also their discussion of heart disease and how it is the result of genetic factors and faulty diet fails to mention the idea that heart disease might be caused by a bacteria. (See for example, Plague Time: How Stealth Infections Cause Cancers, Heart Disease, and other Deadly Ailments (2000) by Paul W. Ewald.)

All things considered, though, this is a classic of evolutionary literature, nicely presented to a nonspecialist, but educated public. Now if we can only get the doctors to read it!

Slightly modifying an oft-quoted line by the famous biologist Dobzhansky, Nesse and Williams conclude, "After all, nothing in medicine makes sense except in the light of evolution." In this lucidly written book, the authors make this assertion throughout. They lay out principles for interpreting aspects of human health from an evolutionary perspective. For example, some of the body's responses can be viewed as adaptive defenses (e.g. fever), others the products of novel environments (e.g. Sudden Infant Death Syndrome, or SIDS). The authors raise intriguing examples, from adaptive withholding of the body's iron stores to pregnancy sickness, that put flesh on the bones of these principles. This book does a fine job of overviewing the ways in which an evolutionary perspective can contribute to a richer understanding of medicine than the more proximate (e.g. what are the chemical and genetic bases to schizophrenia?) focus alone can provide. For this reason, it may long be seen as a seminal contribution.

-Why We Get Sick- is a discussion on novel way of thinking about sickness, an epiphany on the perseverance of human vulnerability. The book addresses whre disease come from and why we get such diseases. Nesse and Williams carefully state 6 major causes of diseases: Defenses, infection, novel environments, genes, design compromises, and evolutionary legacies. Our immune system is the frontier battefield of any intruders. Studies have shown that at the first point of contraction, the immune system proliferate T-cells against the HIV virus. These immune cells fight the best they can to prohibit HIV settling onto the CD-4 cells. The only reason the immune system loses is because the HIV virus is simply too smart that they mutate into other forms and fool the T-cells. The first sign of the cold virus triggers series of defensive action-fever and sneezing are actually not illness, but defensive/immunological responses against the virus.

Bacteria can evolve as much in a day as we can in a thousand years, and this gives us a grossly unfair handicap in the arms race. That's right, according to the authors of this book, we are in an ever-lasting struggle with bacteria and virus because they evolve so much faster than we can imagine. TB disappeared more than 40 years ago after the discovery of antibiotics. TB is now coming back with an even more potent form-a kind that no longer can be treated by the old antibiotics. Evolution of the virus plays a significant role here. The possibile treatment would be chemical mimetics, synthesizing structurally similar compound to treat the new strain.

The more I read the more I'm refreshed by the authors. They discussed the cause of allergy and why some people are so allergic to plants and pollen while others are completely immune to them. The book also makes distinction between virus and toxins. How does the body identify novel toxins? What is the sinificance of maleness and femaleness? These are questions we all address but of which we never consider in the evolutionary point of view. The authors do not argue that evolution is the main cause of why we have allergy, AIDS, influenza and gene defects, but they have done a brilliant job in exploring the matter in this side of the argument.

Both authors are scientists of the highest caliber, and "Why We Get Sick" is a marvelous, important, and valuable read. The book's purpose is to include functional evolutionary explanations into ordinary medicine, a project that is only slowly coming to be. The key to unlocking so many mysteries behind so many diseases is to look beyond proximate causes and look instead for functional, often evolutionary, causes of disease and dysfunction. This requirement demands that we don't stop at signs and symptoms of disease, but that we understand how the disease disrupts the function of organisms. Only by a functional understanding of disease, which requires an evolutionary perspective, can we both prevent and treat disease more quickly, accurately, and thoroughly.

The classic case is fever. Hopefully, we all know that most fevers are generally good for us (to a degree), namely that it is the body's own defense mechanism to raise the body's temperature to help kill pathogens. Some fevers, obviously, need to be treated with aspirin, but by doing so, you may actually prolong the disease. If we understand that fevers play a vital evolutionary role in helping us ward off pathogens, we'll not want to reduce a fever unless absolutely necessary (e.g., very high temperatures). Our body's own immune system is a marvel of evolution at work; and we need to learn to work with it, not work around it, much less against it. Certainly we ought not be taking antibiotics for viral infections, yet patients demand it, and doctors give in. There are health consequences to this slipshod type of medicine.

If we understand, similarly, that being biped is relatively recent in our evolutionary history, and we understand how our visceral girdle is designed for quadrupeds, not bipeds, then the fact that so many of us get back pain should not come as a surprise. And, the more sedentary and unexercised this girdle becomes, the more prone to back disorders (e.g., herniated discs) we become. Part of the evolutionary scheme of things is preventative as well as curative, so rigorous exercise of our midriff girdle will do much to prevent back disorders resulting from flabby girdles. By taking the evolutionary function into account, we are better able to prevent as well as treat most disorders.

These are just two examples of a plethora of diseases that, when given their functional aetiology, give a fuller account of what steps are necessary to keep us healthy and which steps are necessary to treat illnesses. The authors maintain that we must get to the true, real, and functional cause of most disorders before we have a real grasp of disease itself, thereby opening the door to both conventional and evolutionary prevention and treatment. I can't possibly do justice to the depth and breadth of this very important work. While I believe it should be in every doctor's library (like "Darwinian Psychiatry" should be in every psychiatrist's library), it is also one book most health consumers need to understand. Some parts are challenging reading, but it's worth it.

I do have several criticisms. First, the book is not the finest in scientific writing for the layperson. Many doubly compound sentences (and subjects) would have been better developed with a shorter, simpler sentential writing style. Second, no footnotes; there are notes at the end of the text, and no bibliography. Third, the organization and presentation in the first part of the book could be better, with implications made explicit. These criticisms, while not major, do affect the overall rating of the book.

This book offers a stimulating challenge to medicine and a thoughtful discussion of how (Darwin) evolution theory applies to us. Mr. Nesse and Mr. Williams provide a careful survey about how evolutionary factors can shape and affect human health - the causes and effects are being discussed in a plain-language manner. Have you ever thought about how the sneezing, the fever, and the coughing are all front-line responses of our immune system? Why do you think the once-eradicated TB come back with a more potent strand? The book provides a refreshing yet convincing view that bacterial resistance to antibiotics is an everlasting arm race.

As a bright artistic type who is basically scientifically illiterate, I often find myself unable to get through more than a third of my organic chemist husband's science books. Why We Get Sick is written for both the scientist and those who are just plain interested in knowing about things, i.e. people like me. Like all theories, what is presented here could be flawed. However the authors present a very intriguing point of view about health and the human body. Well worth tripping over a few unfamiliar words.

This book is extremely readable, and hard to put down. The authors make a very compelling case for the usefulness of a evolutionary perspective in medicine. I have a couple minor complaints (but don't let this discourage you). The authors seem to move freely between fact and speculation, without making clear distinctions. Not a problem if you're paying attention, but they may sometimes give the impression that their is more data to support a contention than there actually is. Anyway, I highly recommend this book - it's easy to read, stimulating, and bound to make you look at illness and health in a new way.

"If you are starving in a rain forest, eat the camouflaged frog that is hidden in the vegetation, not the bright one sitting resplendent on a nearby branch."

At first glance, this quote from WHY WE GET SICK wouldn't seem to be relevant to the topic. But since the hypothesis of the book is that evolution and natural selection govern the senescence of aging and the physiological responses to diseases and mortally competitive environments, the fact that the gaudier frog has evolved with potent internal poisons that (should) signal "danger" to any potential predator makes the connection vis-a-vis both the amphibian's toxin and the starving hiker whose internal defense mechanisms may at least cause vomiting and diarrhea if frog's legs make it onto the dinner menu.

As authors Randolph Nesse and George Williams summarize:

"First, there are genes that make us vulnerable to disease ... Most deleterious genetic effects ... are actively maintained by selection because they have unappreciated benefits that outweigh their costs ... Second, disease results from exposure to novel factors that were not present in the environment in which we evolved ... Third, disease results from design compromises, such as upright posture with its associated back problems ... Fourth, ... natural selection ... works just as hard for pathogens trying to eat us and the organisms we want to eat. In conflicts with these organisms, as in baseball, you can't win 'em all. Finally, disease results from unfortunate historical legacies ... the human body must function well, with no chance to go back and start afresh ... Susceptibility to disease ... cannot be eliminated by any duration of natural selection, for it is the very power of natural selection that created them."

Under the umbrella of natural selection, the authors include everything from the obvious and non-arguable, such as fever as a mechanism to kill invading pathogens with heat, to the less obvious and perhaps debatable, such as the instinctive desire of small children to remained unweaned from mother's breast, which serves to prolong lactation and ensures that Mom won't become pregnant with a potential rival. Other examples fall into the category, Gee, Why Didn't I Think of That, including the morning sickness of pregnancy, which serves to prevent Mom from ingesting toxins during that vulnerable period when the unborn child is experiencing peak organ formation, and the causative agent of gout, uric acid, the build-up of which also protects the body from the aging effects of oxidative damage. Then there's cancer, which wouldn't be a problem had we not tissue cells that grow and regenerate. And did you know that premature ejaculation in the male is ostensibly selective, in an evolutionary sense, for those men that can get the gene transfer job done, so to speak, and then flee before the female's alpha male partner shows up to brain the interloper with a knotty pine cudgel?

Nesse and Williams lucidly present an unconventional paradigm of medicine, a different perspective from which to view disease and aging, that's only accasionally preachy. They rue the fact that it's not part of the mainstream, and argue for its inclusion in the curriculum of the country's medical schools. They fail to mention what I think is the more practical route to widespread acceptance, i.e. when it can make the medical industry lots of money.

Hey honey! How about some frog legs for dinner? I see a bright green one with yellow and red speckles perched in the carrotwood out back!

This book is about the exciting field of Darwinian medicine. In this book the authors describe why (and not how) we suffer from various diseases. Looking at diseases from an evolutionary viewpoint gives us tremendous insight and offers innovative ideas for treatment and prevention. Though I tend to treat radical new ideas with skepticism, I found most of the arguments in this book very convincing. Apart from being ingenious, this book is also very entertaining and easy to read. In my opinion this is the science 'Book of the decade'

PROS: It helps you understand why some illnesses are good for you. Well written and easy to read.

CONS: It's a dated. Medical advances and knowledge have come a long way in the last 15 years.

CONCLUSION: I would suggest reading "The Survival of the Sickest" instead. It's more up to date and has better writing than this book.