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Tuesday, May 5, 2015

Survival of the sickest‬ - Sharon Moalem - Review

Running into 8 chapters, the first 3 were very attractive. This should make a good reading both for the beginners and non-science readers. Written in a very simple language the book lacks references or foot notes then and there. A few notes are given at the end of the book, but if that was provided in-situ, the readability would have been enhanced.
Some chapters in the end describe what we call "junk science". The junk science is the 'projected-out' views during the course of a research and at times it would mark serendipity as well. Those events that come in the 'context' of a topic cannot be taken to describe the whole. For instance, diabetes that describes increased incidence of sugar in a human is marked 'favourable' for persons living in cold regions for obvious reasons. A person in cold regions needs to burn more sugar to keep himself warm. But this cannot be substituted as 'evolution' phenomenon in the present context where many in tropical region have acquired this as a result of life-style.
Likewise, the author predicts flaw in evolution, which is not agreeable scientifically. The Evolution theory is still debatable and science has not concretely proved it. That warrants no discussion on a topic related to it. The author attributes 'gender' based on evolution and not on more obvious reasons like 'natural selection' and hormones.
On microbes, the writings are interesting, but I felt a negative approach in describing their existance and functionality. Here is what one can summarize on the book:
Ch.1. Ironing it out
Hemochromatosis is an inherited disease in which the body continues to load up on iron because the mechanism regulating iron has broken down. The suggestion is that natural selection is maintaining this genetic defect because it had conferred some benefit in the past.
The long held tradition of bloodletting to fight disease may therefore have had a good basis in fact after all. Starving infectious bacteria of iron by reducing the amount of blood is the surprising benefit that might explain why people believed in the value of bloodletting for so long.
Ch. 2. A spoonful of sugar helps the temperature go down
Diabetes is a disease where the body fails to remove excess sugar from the bloodstream. Dr. Moalem suggests that excess sugar in the blood could have been selected for in the past because sugar could act like antifreeze in times of extreme cold. Now this is not justifiable in the present day scenario.
Ch. 3. The cholesterol also rises
This chapter mentions about Vitamin D and its tremendous benefit in preventing many diseases, not just rickets. There is enough Vitamin D added to milk to prevent rickets. Those living in northern latitudes are at a disadvantage because several minutes of directly overhead sunshine is what is needed to convert cholesterol in our bodies into enough Vitamin D to have an effect. Taking Vitamin D supplements is also an option, as is an ultraviolet B tanning salon or eating fatty fish as the Inuit do.
While the sun makes Vitamin D, it unfortunately destroys folic acid. Skin colour is the adaptation that balances out the effect of the sun. People with dark skin can protect themselves from folic acid depletion, but they need to carry higher amounts of cholesterol to maximize whatever sunlight gets through the skin.
Surprisingly the author asks us to avoid sunglasses while sunbathing. The pituitary gland is involved in helping produce melanin, which darkens the skin. If the pituitary gland does not get signal from the optic nerve (while wearing sunglasses) then the body will not get the right signal about the direct sunlight.
Ch. 4. Hey, bud, can you do me a fava?
Many plants produce toxins to protect themselves from predators. People with favism cannot clear out the free radicals produced by fava beans because of a genetic deficiency. The free radicals attack red blood cells. It turns out that people with this genetic deficiency end up being more resistant to malaria. Does not sound well with the present day scenario on this disease.
Ch. 5. Of microbes and men
The rod of Asclepius — a symbol depicting removal of the Guinea worm parasite is mentioned here. The chapter makes an interesting reading with microbes such as T.Gondii in cats, D. dentriticum in sheep, H. argyraphaga in spider and common sneezing virus bringing out some spine chilling facts. This section has no references for all the incidents mentioned.
Ch. 6. Jump into the gene pool
Large portions of our junk DNA (DNA that does not code for proteins) are made of jumping genes. Empty space? Retroviruses are made of RNA, and can be written into DNA. HIV is a retrovirus, and the drug “cocktail” therapy used to combat HIV
is aimed at stopping the enzyme that helps the retroviruses become part of DNA.
Ch. 7. Methyl madness : road to the final phenotype
Epigenetics is a whole new field in genetics that is concerned with the study of how children can inherit and express new traits derived from their parents without changes in the underlying DNA. This chapter has more of author's views than science and hence one can lose interest given the way exaggerations are made out of the mutations and telomers.
Ch. 8. That’s life : why you and your iPod must die
Again I would disagree with the author on the theory that is put forth in this chapter. That every cell is programmed for a certain number of multiplications (Hayflack limit) and hence death should come only when this limit is reached, does not hold good in a 'thermodynamic' world where everything is dependent on one's life style, environment and food. That would mean every person should live at least 60 years compulsorily!
Points in favour of the aquatic ape theory that are not strong enough:
– humans are the only land animals with fat attached to our skin (like hippos, sea lions, and whales)
– the ability to survive in both land and water environments has tremendous survival benefits against predators
– walking upright helps in venturing into deeper water and so this is how bipedalism may have come about
– we may have lost our fur so as to become more streamlined in the water
– we have downward-facing nostrils, which allowed us to dive
– the extra fat in babies help keeps them afloat
– newborns don’t start breathing until they feel air on their face, which makes birthing in water very safe, and actually easier on
the mother
– newborns reflexively hold their breath, but they also make rhythmic movements that propel them through the water (a behaviour which lasts about four months)–this makes more sense in the aquatic ape theory than in the Savannah theory