Saturday, August 4, 2007

Book Reiview No. 2: Survival of the Sickest

I saw this book while I was researching Natalie Angier's book, The Canon. Before I even read the insert, I was hooked - the title was enough for me. It is a quick read (only took me about 4 days) and very intriguing.

Dr. Sharon Moalem wrote this book based on a very interesting topic – why the human population needs disease. Before you begin to assume that this book is about disease being a method to eradicate the weak and thin out the herds of genetically inferior, please take a deep breath… because it has nothing to do with that. But he begs the question - why are there genes still being inherited that are painful and potentially deadly? His hypothesis: some of the diseases that effect humans (diabetes, high cholesterol and even sickle cell anemia) have actually evolved to help humans survive.

For example, there is new evidence that there was a very recent (in geological standards) Ice Age called the Younger Dryas, and it came about very rapidly. So rapid in fact that some animals froze to death while in the middle of enjoying dinner – so how did humans survive this deep freeze? Why, have you ever heard of ice wine? Or cryonics (biostasis), thanks to Ted Williams? When your blood or grapes freeze, the water inside your arteries expands and literally tears your blood vessels to shreds – therefore, cryogenics cannot possibly work just yet. With ice wine, grapes rid themselves of much of the water they carry, thereby increasing the sugar levels within the fruit, making it harder to freeze. Do you see where this is headed? Our ancestors who were diabetic were able to adapt to their extremely cold environments… here’s how:

When you live in a very cold environment, your body stores what is called brown fat. When your blood sugar is delivered to a brown fat cell, instead of being stored for future energy as it is in a regular fat cell, the brown fat cell converts it to hear right on the spot. The brown fat process creates heat without muscle movement; shivering is only good for a few hours and can cause you to become more exhausted. Brown fat can go on generating heat for as long as it is fed and it doesn’t need insulin to bring sugar to cells.

Back then, food was probably limited, so dietary blood-sugar load would already be low, and brown fat would convert most of that to heat, so the ice age “diabetic” blow sugar, even with less insulin, might never reach dangerous levels. Modern-day diabetics, on the other hand, with little or no brown fat, and little or not exposure to constant cold, have no use therefore no outlet for the sugar that accumulates in their blood.

So today, diabetes is not a useful adaptation. But it was useful at one point in human history. Isn’t it odd that the Pima Indians of the southwestern U.S. and people of Northern European descent are more likely to have diabetes than the rest of the world?

In one word?


I truly enjoyed this book because I love studying evolution and the symbiotic relationships we foster with the rest of the living world. From plants to parasites to beneficial microbes, we are influencing and reacting to one another. Another interesting topic which Dr. Moalem touched upon was the subject of epigenetics – how there are literally genes upon our existing genes that can be turned on and off based on your environment as well as the choices your grandparents made. Weird, huh?

From cancer to hemochromatosis, Dr. Moalem writes with incredible insight and current research to bring forth a book that is both understandable and fascinating to anyone who reads it. He reveals a different and unique perspective on how we view disease and the human body. I strongly suggest this book to anyone – regardless of profession – who might be slightly interested in how human survival has adapted through time. This book will open your eyes to how the choices you make today will affect your grandchildren – before your own children are even born.

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