Survival of the Sickest: The Surprising Connections Between Disease and Longevity

Survival of the Sickest: The Surprising Connections Between Disease and Longevity
Jonathan Prince

Dr Sharon Moalem

In this groundbreaking and absorbing book Dr. Sharon Moalem, delves back into the evolution of man to offer a radical perspective on survival, the human body, and our understanding of disease. Survival of the Sickest will change the way you think about your body.Dr. Moalem investigates peculiar and puzzling features of human biology to reveal the answers to such provocative questions as:• Why do we need to pee when we’re cold?• Can a person rust to death?• Why are Greeks hairier than Africans?• Can the tanning salon lower cholesterol?• Why are leeches back in vogue?• Can sunglasses cause sunburns?• Who gets drunk faster – Europeans or Asians?In considering the question of why diseases exist, Dr Moalem proposes that most common diseases came into existence for very good reasons. Diabetes, hemochromatosis, cystic fibrosis and sickle cell anemia may all exist because, at some time in our past, they helped our ancestors survive some grand challenge to human existence. In turn, he also discovers that genetic and cultural differences have led to each race having different and unique ways of reacting to their environment and subsequently how they become susceptible to certain diseases.Survival of the Sickest is a book about life – yours, ours and every little living thing under the sun. About how we all got here, where we're all going and what we can do about it. Revelatory and written in an utterly engaging fashion, Sharon Moalem's book will change the way you think about your body.

SURVIVAL

OF THE SICKEST

THE SURPRISING CONNECTIONS BETWEEN

DISEASE AND LONGEVITY

DR. SHARON MOALEM

with Jonathan Prince

DEDICATION (#ulink_2878c3b8-f4de-5b31-9bc0-139e3df54f28)

To my grandparents Tibi and Josephina Elizabeth Weiss, whose lives served to teach me the complexities of survival

CONTENTS

Cover (#uecb74959-3d6a-598c-a8bb-28775219e542)

Title Page (#uf93971d2-4f1a-5e2c-8df9-e296f3a8aa74)

Dedication (#ufdbd1824-ce3b-5d51-bb34-9b3bdce29564)

Introduction (#ue23abc6e-4470-5c06-9d82-9af8a2f017d0)

Chapter One: Ironing It Out (#u0d9cd7c5-4446-51b1-8759-49ef3647cf35)

Chapter Two: A Spoonful of Sugar Helps the Temperature Go Down (#u8a7af0ed-e5c9-55b0-b8be-d893b19a45b0)

Chapter Three: The Cholesterol Also Rises (#u9b060441-cf4e-52f7-aa95-5351e72c54b2)

Chapter Four: Hey, Bud, Can You Do Me a Fava? (#litres_trial_promo)

Chapter Five: Of Microbes and Men (#litres_trial_promo)

Chapter Six: Jump into the Gene Pool (#litres_trial_promo)

Chapter Seven: Methyl Madness: Road to the Final Phenotype (#litres_trial_promo)

Chapter Eight: That’s Life: Why You and Your iPod Must Die (#litres_trial_promo)

Index (#litres_trial_promo)

Acknowledgments (#litres_trial_promo)

About the Author (#litres_trial_promo)

Notes (#litres_trial_promo)

Copyright (#litres_trial_promo)

About the Publisher (#litres_trial_promo)

INTRODUCTION (#ulink_f4defdc4-86b8-51e4-8798-8a7e033f8683)

This is a book about mysteries and miracles. About medicine and myth. About cold iron, red blood, and neverending ice. It’s a book about survival and creation. It’s a book that wonders why, and a book that asks why not. It’s a book in love with order and a book that craves a little chaos.

Most of all, it’s a book about life – yours, ours, and that of every little living thing under the sun. About how we all got here, where we’re all going, and what we can do about it.

Welcome to our magical medical mystery tour.

When I was fifteen years old, my grandfather was diagnosed with Alzheimer’s disease. He was seventy-one. Alzheimer’s – as too many people know – is a terrible disease to watch. And when you’re fifteen, watching a strong, loving man drift away almost before your eyes, it’s hard to accept. You want answers. You want to know why.

Now, there was one thing about my grandfather that always struck me as kind of strange – he loved to give blood. And I mean he loved it. He loved the way it made him feel; he loved the way it energized him. Most people donate blood purely because it makes them feel good emotionally to do something altruistic – not my grandfather; it made him feel good both emotionally and physically. He said no matter where his body hurt, all he needed was a good bleeding to make the aches and pains go away. I couldn’t understand how giving away a pint of the stuff our lives depend on could make someone feel so good. I asked my high school biology teachers. I asked the family doctor. Nobody could explain it. So I felt it was up to me to figure it out.

I convinced my father to take me to a medical library, where I spent countless hours searching for an answer. I don’t know how I possibly found it among the thousands and thousands of books in the library, but something steered me there. In a hunch, I decided to plow through all the books about iron – I knew enough to know that iron was one of the big things my grandfather was giving up every time he donated blood. And then – bam! There it was – a relatively unheard of hereditary condition called hemochromatosis. Basically, hemochromatosis is a disorder that causes iron to build up in the body. Eventually, the iron can build up to dangerous levels, where it damages organs like the pancreas and the liver; that’s why it’s also called “iron overload.” Sometimes, some of that excess iron is deposited in the skin, giving you a George Hamilton perma-tan all year long. And as we’ll explore, giving blood is the best way to reduce the iron levels in your body – all my grand-father’s blood donations were actually treating his hemochromatosis!

Well, when my grandfather was diagnosed with Alzheimer’s, I had a gut instinct that the two diseases had to be connected. After all, if hemochromatosis caused dangerous iron buildups that damaged other organs, why couldn’t it contribute to damage in the brain? Of course, nobody took me very seriously – I was fifteen.

When I went to college a few years later, there was no question that I was going to study biology. And there was no question that I was going to keep on searching for the link between Alzheimer’s and hemochromatosis. Soon after I graduated, I learned that the gene for hemochromatosis had been pinpointed; I knew that this was the right time to pursue my hunch seriously. I delayed medical school to enter a Ph.D. program focused on neurogenetics. After just two years of collaborative work with researchers and physicians from many different laboratories we had our answer. It was a complex genetic association, but sure enough there was indeed a link between hemochromatosis and certain types of Alzheimer’s disease.

It was a bittersweet victory, though. I had proved my high school hunch (and even earned a Ph.D. for it), but it did nothing for my grandfather. He had died twelve years earlier, at seventy-six, after five long years battling Alzheimer’s. Of course, I also knew that this discovery could help many others – and that’s why I wanted to be a physician and a scientist in the first place.

And actually, as we’ll discuss more in the next chapter, unlike many scientific discoveries, this one came with the potential for an immediate payoff. Hemochromatosis is one of the most common genetic disorders in people descended from Western Europeans: more than 30 percent carry these genes. And if you know you have hemochromatosis, there are some very straightforward steps you can take to reduce the iron levels in your blood and prevent the iron buildups that can damage your organs, including the one my grandfather discovered on his own – bleeding. And as for knowing whether or not you have hemochromatosis – well, there are a couple of very simple blood tests used to make the diagnosis. That’s about it. And if the results come back positive, then you start to give blood regularly and modify your diet. But you can live with it.

I do.

I was around eighteen when I first started feeling “achy.” And then it dawned on me – maybe I have iron overload like my grandfather. And sure enough, the tests came back positive. As you can imagine, that got me thinking – what did this mean for me? Why did I get it? And the biggest question of all – why would so many people inherit a gene for something potentially so harmful? Why would evolution – which is supposed to weed out harmful traits and promote helpful ones – allow this gene to persist?

That’s what this book is about.

The more I plunged into research, the more questions I wanted answered. This book is the product of all the questions I asked, the research they led to, and some of the connections uncovered along the way. I hope it gives you a window into the beautiful, varied, and interconnected nature of life on this wonderful world we inhabit.

Instead of just asking what’s wrong and what can be done about it, I want people to look behind the evolutionary curtain, to ask why this condition or that particular infection occurs in the first place. I think the answers will surprise you, enlighten you, and – in the long run – give all of us a chance to live longer, healthier lives.

We’re going to start by looking at some hereditary disorders. Hereditary disorders are very interesting to people like me who study both evolution and medicine – because common conditions that are only caused by inheritance should die out along the evolutionary line under most circumstances.

Evolution likes genetic traits that help us survive and reproduce – it doesn’t like traits that weaken us or threaten our health (especially when they threaten it before we can reproduce). That preference for genes that give us a survival or reproductive advantage is called natural selection. Here are the basics: If a gene produces a trait that makes an organism less likely to survive and reproduce, that gene (and thus, that trait) won’t get passed on, at least not for very long, because the individuals who carry it are less likely to survive. On the other hand, when a gene produces a trait that makes an organism better suited for the environment and more likely to reproduce, that gene (and again, that trait) is more likely to get passed on to its offspring. The more advantageous a trait is, the faster the gene that produces it will spread through the gene pool.

So hereditary disorders don’t make much evolutionary sense at first glance. Why would genes that make people sick still be in the gene pool after millions of years? You’ll soon find out.

From there, we’re going to examine how the environment of our ancestors helped to shape our genes.