Survival of the Sickest: The Surprising Connections Between Disease
Sharon Moalem, with Jonathan Prince
Harper Perennial, New York, 2007
372 pp., $13.95 paperback
The title, Survival of the Sickest, is certainly an attention
grabber. The author is presumably disputing Charles Darwin's
evolutionary precept, survival of the fittest. The cover features a
quote from a review of the book by Dr. Mehmet Oz, saying this book,
"challenges everything we thought we knew about disease." The
book indeed questions accepted common knowledge. Sharon Moalem is up to
the task of explaining these new concepts. Briefly, his thesis is that
certain nonfatal genetic changes can engender negative metabolic
alterations making the organism weaker but less susceptible to other
acute life-threatening diseases and thus ensuring their survival.
Sometimes the stories are tortuous and circuitous, but the author ties
all the ends together at the close of the chapters.
Dr. Moalem discusses hemochromatosis, a hereditary disease that
relates to iron metabolism. He explains its symptoms, its
pathophysiology, the relationship of iron metabolism to other maladies
and the body's overall resistance mechanism relative to
homochromatic macrophages. He concludes this chapter by detailing how
people with the hemochromatosis mutation were much less likely to die
from bubonic plague in the middle ages, and thus explains the survival
benefit of one potentially harmful gene.
He further relates the scientific benefits of bloodletting as
current medical treatment, and the harmful effects of excess dietary
iron supplements. In another chapter he tells the story of how diabetes
may have helped our ice age ancestors manage the extreme cold.
Four hundred million people have favism, the most common inherited
enzyme deficiency in the world. People with favism who eat lava beans
experience rapid, severe anemia that can sometimes be fatal. Primaquine,
an anti-malaria drug, has the same effect based on the same gene (GP6D)
in people of color of African descent. GP6D deficiency also relates to
sickle cell anemia. The red blood cells of people with favism or sickle
cell anemia are taken out of circulation sooner, and thus disrupt the
life cycle of the parasitic protozoa that causes malaria or sickens
people. People with favism, GP6D deficiency, or sickle cell anemia, have
a significant measure of protection from malaria.
Two chapters in particular make this book worthwhile, Jump Into the
Gene Pool and Methyl Madness: Road to the Final Phenotype.
Jump Into the Gene Pool is a review of genetics, current genome
concepts such as junk DNA, theories of genetic recombination, knockout
gene experiments, scientific revivication of Lamarkian Theory,
transporons or jumping genes, endogenous retroviruses, and parasitic
viruses as the sparks of evolution. It provides a wonderful explanation
of contemporary genetic theory and links together all of the above
Methyl Madness deals with the concept of epigenetics. Epigenetics
is concerned with the study of how children can inherit and express new
traits from their parents without changes in their DNA. Prenatal
maternal nutrition can profoundly alter gene expression without altering
the genes themselves. The exact same genes can produce different
outcomes depending whether they have undergone methylation or not. The
existence of both maternal and paternal methylation effects have been
demonstrated. Epigenetic changes have been shown to pass through the
germ line for many generations.
This information is relevant to dentists. Prenatal nutrition
counseling can have profound effects. Postnatal interaction between
mothers and their offspring have also been shown to provoke the
placement of methyl markers that cause significant epigenetic changes.
It has been demonstrated that breast feeding is good for children.
Cognitive, facial, and physical development are positively affected.
Attention and touch have been shown to improve a child's response
to stressful situations. They can actually change the expression of a
baby's genetic code.
The point of this book is that our relationship with disease is
much more complex than previously thought (craniomandibular
practitioners already knew this) and that evolution as we now understand
it, based on advances in neurogenetics, epigenetics, and methylation may
occur in the time frame of years rather than millennia. Our
understanding of these new developments can significantly impact our
lives, those of our children as well as the way we practice. We highly
recommend this fascinating book.
Allen J. Moses D.D.S., firstname.lastname@example.org and Irving Kittay,