Field of Science

Good Books Gone Bad

I have been meaning to comment on Sharon Moalem's Survival of the Sickest for a while now, but I have been stymied by the real world. In short, I think this book is based on a truly interesting premise, but in presentation does a tremendous disservice to said premise. The idea behind this book is that many of the mutations that cause or predispose people to disease are actually beneficial mutations that were selected for in the distant past. One thing I took away from this book is that while I am a definite adaptionist, Dr. Moalem makes me look like a structuralist.

Now the idea that harmful mutations are really beneficial mutations in a different light is not new nor wrong. In fact the hallmark example for this is likely known to everyone reading this. It is sickle cell anemia. Sickle cell anemia is a blood disorder in which the classic concave red blood cell (the cell that transports oxygen from the lungs to the rest of the cells of our bodies) as shown to the left and taken from here, has a sickle shape to the right. Now this shape in and of itself, is not a bad thing. The problem lies in the fact that these oddly shaped cells cannot move through blood vessels effectively, thus depriving tissues of much need oxygen. This causes lots of problems, not the least of which can be demonstrated as a 30 year decline in life expectancy. In case you were wondering, or need a refresher, sickle cell anemia is cause by a point mutation in the DNA (a single nucleotide change) that leads to a single amino acid substitution in the protein sequence of hemoglobin (by the way, most of a red blood cell is composed of hemoglobin). This mutation, causes hemoglobin sub-units to polymerize into fibers, which distorts the red blood cell, leading to its sickle cell shape.

Holy crap Batman! This sounds bad and should be selected against.

Indeed Robin, however, let's look at where this mutation is most often found. Yes boy wonder, Sub-Saharan Africa. Notice that malaria is prevalent in that area as well. What? You're wondering if there is a link? Damn Boy Wonder is you aren't just the cats meow (and by that I mean smart, yet pathetic). Indeed there is a link! You see, human beings who carry the sickle cell mutation (in other words have a normal copy and a mutant copy) or are homozygous for sickle cell (have 2 mutant copies and 0 normal copies) are more resistant to malaria.

Holy defecation Batman, that rocks! But if sickle cell anemia is bad, what the fuck? I mean that doesn't make sense.

Indeed it does Boy Blunder, I mean Wonder (wonder I don't kick his ass out of the Justice League). However, think about this. Malaria will sicken everyone, but kills children in the less than 5 year old range. Whereas, sickle cell anemia, while debilitating tends to kill 40+ year olds. So, if you live in a malarial invested area, its better for you to have the sickle cell mutation survive childhood, be hawt and reproduce, and die at 40 rather than not having the sickle cell mutation and dying in childhood.

Now while the evidence linking malaria/sickle cell anemia is well established, the scenarios described by Dr. Moalem are weaker. There is the  pubonic plague vs. iron overloading, diabetes and ice age (recent ice age not ancient), high cholesterol (which your blogmaster is dealing with) vs. vitamin D, and the list continues. Now I will not dispute any of the potential claims made by Dr. Moalem, but I will remain highly skeptical primarily because Dr. Moalem does a fantastic job writing to the lay public and an atrocious job writing to a scientist. Phrasology (if I can make up a word) such as "in the prestigous journal..." or the fact that nothing in science is understood until some asshat working on a mouse recapitulates what's been known in yeast and plants for decades (epigenetics).  Pounding the Barbara McClintock was relegated to the back burner mythology because MDs couldn't understand the importance of her work, although she worked alongside other seminal molecular biologists such as Salvador Luria and Max Delbruck, not to mention the fact that Dr. McClintock was elected to the National Academy of Sciences in 1944. Nope. The value of Dr. McClintock's work was not appreciated until mouse geneticists realized she was right.

Suffice it to say the idea behind the book is outstanding and deserves more intellectual consideration. However, the delivery of the book, after the first 1-2 chapters, reads more like any general woo-meister cook book rather than a scientific analysis. Worth it from the Barnes and Noble bargain bin, but only if you get the 10% member discount.  

4 comments:

SnapperGas said...

What?!?! Now, you expect MD's to understand basic science? Most of us are too busy being deluded. Did you see this?



*hangs head in shame

SnapperGas said...

Sorry, bad link, try here.

The Lorax said...

Thanks for the link, like I didn't have enough to rail against! Although it does sound fairly familiar

Petronella said...

Good post.