Survival of the Sickest Part 2

What did you think of the reading?

Especially in chapter three, the reading discussed a broad spectrum of traits, unlike how chapter one focused solely on hemochromatosis and how chapter two focused solely on diabetes. The main focus of this chapter, however, was on how cholesterol and vitamin D production relates to different races and ethnic backgrounds. In chapter four, Dr. Moalem discusses the dangers (or in this case, wonders) of the fava bean in certain populations and how plants use chemical weapons, such as toxins, as protective measures. As expected, I was extremely fascinated by the information presented in part two, and I cannot wait to continue reading.

What did you learn?

Chapter three started out by introducing cholesterol and how it is used to manufacture vitamin D. Vitamin D is used to facilitate levels of calcium and phosphorus in the blood; thus, it ensures proper bone health. I also found it very interesting that cholesterol levels are generally higher in winter months, since the sun is not able to convert it into vitamin D. The chapter then goes on to discuss skin, pre-disposition to diseases, and genetic anomalies that relate to certain races. My favorite fact of the chapter is that the optic nerve transmits signals to he pituitary gland when it senses bright sunlight. As a result, the pituitary gland tells the melanocytes to produce excess melanin (to prevent sunburns). However, when you are wearing sunglasses, the optic nerve can’t sense the sunlight (and can’t send signals for melanin production), so you are more likely to get sunburned while wearing sunglasses. Furthermore, in dark-skinned populations (where there is too much sunlight) and in populations of Northern Europe (where there is not enough sunlight) there is a gene called ApoE4 that cranks up cholesterol levels so sunlight can be used efficiently.

In the next chapter, Dr. Moalem discussed the effects of plants’ defense mechanisms. When raw, cassava contains a precursor to cyanide, and the Indian vetch contains a neurotoxin that causes paralysis. In extreme cases, poor farmers resort to eating the vetch to avoid starvation during a drought. In raw habanero peppers, capsaicin is used to prevent the digestion of the peppers’ seeds by mammals by causing a burning sensation and degeneration of neurons. Interestingly, capsaicin is sticky so it can’t just be washed away with water. This chemical is used because seeds are destroyed when digested in mammals, but in birds, the seeds pass through undamaged. As a result, birds are not affected by capsaicin (birds help spread seeds to new locations through feces). Iit seems as if everything presented in this book has advantages and disadvantages (it goes back to the quote in part one about taking a pill that will kill you in forty years but will save you tomorrow). This is definitely shown when Dr. Moslem discusses fava beans. Fava beans release free radicals in the bloodstream. The G6PD enzyme is responsible for clearing up the free radicals. In those with favism (caused by a sex-linked mutation on the X chromosome), there is a G6PD deficiency and anemia is the final result. The weird part about this is that on a map, those with favism live in areas that cultivate the most fava beans (Africa and the Mediterranean). This is because fava beans provide a resistance to malaria (which is common in these areas) by making the blood cells a less hospitable place for P. falciparum (severe malarial parasite).

Do you have any questions?

I really enjoyed reading about the different genes/traits presented in different races from adaptations to the environment, and it made me think about traits in children with parents from different races. For instance, my dad’s side of the family descended from Russia and my mom’s is from Cuba/Spain. Would that mean that I have increased chances of getting cancer and heart disease (European descent) as well as diabetes, liver disease, and infectious disease (Latino descent)? Additionally, I was wondering if there were any interesting cases regarding over-consumption of certain plant toxins, and I also wanted to learn more about how medicines are produced from plants.


4 thoughts on “Survival of the Sickest Part 2

  1. You present a very interesting question about having increased chances in diseases due to your parents being of different race. I am no expert but if I were to guess, I believe the possibility of having an increased chance may exist. Then again, it depends on your family’s history of these diseases. Your question made me think, if I have both parents of the same race, then would I have more chances of these diseases rather than if I had only one? Regarding the cases of other plant toxins, I would believe they exist considering the amount of plants around the world that produce these types of toxins. I truly enjoyed reading your insight on these chapters!

  2. You pose a good point regarding having both parents of the same race. I’m not sure how the genetics work, but if both of your parents pass down the same allele for the trait, I would assume you would get it. If this allele is for predisposition for a disease, it would certainly make you more likely to get it as a result.

    1. If the traits such as insulin production was affected by several genes, and therefore the amount of insulin in the human population was a wide spectrum, you may have an average chance of having many diseases. But as David said, family history is probably a more important factor that racial background.

  3. The question regarding having parents of certain descents increasing your chances of disease is quite interesting and probably true. And I completely agree about the plant toxins, if we overdose on certain plants it probably does have an interesting effect. The ‘interesting cases regarding over-consumption’ would probably include the belief that eating too many carrots would turn you orange.

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