Survival of the Sickest: Part I

My daughter Kate has similar tastes in books as I do. We like non-fiction, but it needs an edge so it is not too dry of a read. This time, Kate has loaned me a 2007 book by Dr. Sharon Moalem, called Survival of the Sickest. It is a good read, but then again, I like things like this-hypotheses that make sense, have some scientific evidence to support them, but are not totally proven or accepted as fact. To me, this is the fun of science-it is the big 'What If' that allows you to wonder about coincidences and explore connections between seemingly odd things. I believe that there are no coincidences in life, and I believe that all things are connected.

"DNA isn't destiny, it's history", writes Moalem, and that quote reminds me of a conversation I had a while back with my friend James, who is oft irritated by those who use genetic predisposition as an excuse for continuing unhealthy behaviors and lifestyles. Moalem's quote is important to remember. We have to study history so as not to repeat it, but just because history tends to repeat itself doesn't mean that the future is locked in. When it comes to disease, there are so many variables and triggers that it is possible to be predisposed to a disease and have a high probability of contracting it, but never actually contracting it because one lived a life avoiding the potential or known genetic triggers, like smoking or eating a diet low in fiber, etc. Later in the book, when discussing epigenetics, Moalem writes "DNA is destiny--until you get out the old methyl Magic Marker and start rewriting it." You see, it is actually possible to change your DNA by your actions. What you do can initiate certain genes, formerly thought of as junk DNA, now thought of as jumping genes, to fasttrack mutations and speed up evolution. So yeah, Lamarckian was correct after all and the concept of jumping genes, while not fully understood, can explain things like why a small percentage of Australian Shepherds are now being born with naturally docked tails, and why some lizards are born with larger bodies and tails if the mother smells a certain snake while she is pregnant, versus a small bodied lizard if no danger is sensed. Scariest of all, is that my smoking habit may have switched on cancer genes for my daughter AND granddaughter, even if they never smoke. Get this: since I smoked when I was pregnant with my daughter, and she was born with every egg she will have, essentially, my cells passed epigenetic signals to my granddaughter while she was still an egg in my daughter's ovary, while my daughter was still a fetus inside of me. This stuff is wild, and it goes to show that Heinlein was right and the universe is not just stranger than we imagine, it is stranger than we can imagine.

At any rate, the book is about history, genetics, and human evolution, and it is fascinating. He starts off by talking about the disease called hemochromatosis then moves on to diabetes, then blood lipids. I took notes because I am increasing suffering from CRS, a middle age affliction known colloquially as Can't Remember Sh*t. I won't spoil the entire book, but in this post, I do want to talk about his first talking point-the relationship between iron and disease and how that may have helped mankind survive.

Hemochromatosis is a disease where the body locks up and stores iron. Yes, iron is a good thing, but too much iron can cause organ damage. The body has chelators, proteins which lock up iron, and they are very important in the immune response. Egg white, albumin, is full of chelators, as is breast milk. Bacteria multiply unimpeded in iron rich environments, so if you can bind up iron, as chelators do, you can starve bacteria and allow the immune system's other defenses to work.

Bubonic plague affects lymphatic system, causing glands to swell and even rupture through the skin...survival rate is 33% Airborne plague has a survival rate of 10% Those that survived the plague probably had hemochromatosis, a disease where chelating agents lock up iron in the body making it inaccessible to bacteria or were anemic. Today, the hemochromatosis mutation is seen in those whose ancestors came from Western Europe. The downside is that the disease can eventually kill people by the organ damage the iron causes, but because the body's iron is locked away, bacteria starve. The same type of effects are seen in populations that are anemic, like Somali nomads who were exposed to TB, malaria, brucellosis and other diseases, yet did not become sick. In the old days, bloodletting may have helped those with hemochromatosis. It would reduce the iron load. In modern times,people with this disease often give blood more than others. It literally, physically, makes them feel good.

This idea about iron and bacteria requires more study by me. Moalem mentioned what he called the Geritol Solution to Global warming. There was an experiment in 1995 near the Galapagos Islands where massive quantities of iron were dumped into the clear blue(basically barren) ocean. The result was that there was an increased phytoplankton growth and the ocean turned green with life. The plankton and bacteria feasted on the iron, and in doing so, sucked carbon dioxide right out of the atmosphere. I'd like to read more about this, but it sure makes me like the idea of ships as artificial reefs a lot more than I did at one time.

I'll make a few more blog entries on this book, but as a teaser, here's a couple of things you might find interesting:

ACHOO syndrome: Autosomal dominant Compelling Heliopthalmic Outburst syndrome is uncontrollable sneezing when someone is exposed to light after being in the dark...response is a leftover immune response from the days when people lived in caves, and upon emerging into the sunlight, cleared their nasal passages of molds, microbes, etc. that they might have picked up in the cave.

Most adults are lactose intolerance because after a child is weaned, their bodies no longer produce the enzyme that breaks down lactose. People who are descended from tribal or farming communities where animal milk is regularly consumed perhaps have a mutation that allowed continued lactase production after weaning, and therefore would not be lactose intolerant.