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Survival of the Sickest: A Medical Maverick Discovers Why We Need Disease    by Dr. Sharon Moalem & Jonathan Prince order for
Survival of the Sickest
by Sharon Moalem
Order:  USA  Can
William Morrow, 2007 (2007)
Hardcover, Audio, e-Book

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* * *   Reviewed by Hilary Williamson

I love reading books that tilt my view of life, and Survival of the Sickest is one such volume. I read it in one sitting. The (popular science) style is witty and engaging, and the information presented is far-ranging and utterly fascinating. Of the authors, Dr. Moalem holds his Ph.D. in physiology, neurogenetics and evolutionary medicine, while Jonathan Prince's writing credentials include being a Senior Advisor and speechwriter in the Clinton White House.

In their Introduction, the authors welcome readers to their 'magical medical mystery tour' and go on to confound us with ideas that seem (only at first) counter-intuitive, including a rational cause for a deadly disease to evolve in our genetic code. 'Hemochromatosis is a hereditary disease that disrupts the way the body metabolizes iron', its gene common to people of Western European descent. Why would natural selection retain a gene that predisposes many to die early? Because, at a time when the plague devastated Europe, 'It's the only thing that will stop you from dying tomorrow.' Apparently, in hemochromatic people, macrophages (a kind of white blood cell) aren't loaded with iron, making them more effective.

Next the authors explore a relationship between diabetes, sugar, and extreme climate change. They discuss humanity's survival during the last ice age (Younger Dryas), citing evidence that its onset took only a decade or so - a crisis that would have been at least as devastating as the Black Death. They introduce the wood frog, which freezes solid every winter and thaws to continue life in the spring, doing so by turning its bloodstream 'into a kind of sugary antifreeze.' The authors postulate that diabetes, characterized by water elimination and high blood sugar, 'may have helped our European ancestors survive the sudden cold of the Younger Dryas.' They remind us that every evolutionary adaptation is a compromise, aimed at increasing chances for survival in the current environment, and that 'one generation's evolutionary solution is another generation's evolutionary problem.'

The book continues on from the plague and Ice Ages to address the relationship between sunshine, cholesterol, and evolutionary pressure for different skin shades around the globe. They continue with genetic variations related to resistance to alcoholism - based on whether one's ancestors boiled water for tea or fermented it to kill microbes. Next come 'some people's deadly reaction to fava beans', related to how plants attract the right predators (those who will properly spread their seeds), and resistance to malaria. From plants, this medical mystery tour takes us to diseases and how they manipulate their hosts to help them spread and reproduce (anyone sneezed recently?) They introduce the intriguing notion of directing the 'evolution of infectious agents away from virulence and towards harmlessness'.

Next we jump into genetics, where the authors explain how as much as a third of our DNA is from viruses, and how the recent discovery of jumping genes (which effect a kind of intentional mutation and look very like a type of virus) 'have reshaped our understanding of mutation and evolution.' It's been suggested that 'a challenge to survival triggers the organism to throw the mutation dice, hoping it will land on a change that will help' and that jumping genes helped species survive 'large environmental shifts', also described as 'evolutionary exclamation points'. The authors conclude that we've long been in 'partnership with viruses' which has sped up our evolution. In one of the best lines in the book, they throw out, 'Infectious design, anyone?'

Complicated - but fascinating - stuff. And it gets even more so with methylation, a process in which a compound binds to a gene and changes the effect of that gene without changing DNA. This is part of a young discipline called epigenetics - which we're told is 'in a bit of a the-more-we-know-the-less-we-understand phase' - to do with 'how children can inherit and express seemingly new traits from their parents without changes in the underlying DNA.' Scary notions, but also with a great potential for control of health - and also for adverse unintended consequences. The book ends with a discussion of the interrelationship between aging research, the Hayflick limit and cancer - aging (and 'planned obsolescence') being beneficial for the species, rather than the individual. There's also a nice connection between the aquatic ape and human birthing methods.

The authors advocate for continuing to ask the questions that bring new insights into 'the miracle of evolution', which is all around us, 'changing as we go'. They remind us that we're all in it together - people, animals, plants, and microbes - and have certainly convinced me that human knowledge is moving in remarkable directions. I'm looking forward to the sequels to Survival of the Sickest!

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