Friday, February 11, 2011

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

Rating: (150 reviews) Author: Sharon Moalem ISBN : 9780060889661 New from $6.00 Format: PDF
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Joining the ranks of modern myth busters, Dr. Sharon Moalem turns our current understanding of illness on its head and challenges us to fundamentally change the way we think about our bodies, our health, and our relationship to just about every other living thing on earth. Through a fresh and engaging examination of our evolutionary history, Dr. Moalem reveals how many of the conditions that are diseases today actually gave our ancestors a leg up in the survival sweepstakes. But Survival of the Sickest doesn't stop there. It goes on to demonstrate just how little modern medicine really understands about human health, and offers a new way of thinking that can help all of us live longer, healthier lives.

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  • Series: P.S.
  • Paperback: 304 pages
  • Publisher: Harper Perennial; 1 Reprint edition (March 18, 2008)
  • Language: English
  • ISBN-10: 0060889667
  • ISBN-13: 978-0060889661
  • Product Dimensions: 8.1 x 5.3 x 0.7 inches
  • Shipping Weight: 8.5 ounces (View shipping rates and policies)

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

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.
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.

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