All posts by ChrissyS

Survival of the Sickest- Part IV

What Did You Think About the Reading?

Because the entirety of this book was so intriguing, it made reaching the end a little sad. The last two chapters contained some of the most captivating topics because this was something that concerns everyone- How our behavior in our lifetime can actually affect the health of our children and even grandchildren later on.  That really makes us think twice (or even three times!) about our actions- Once for our own health, once for our future children, and once for our children’s children! Although some parts of the book could be all over the place and a little hard to understand, I am very glad that I picked this book for the summer project.

What Did You Learn?

One of the most interesting facts that I learned dealt with gene expression; namely, how we can actually turn genes on and off (almost deliberately) in our children. The process of switching this gene on and off is known as methylation because it is a methyl group that binds to the gene to alter its expression. This discovery was first found in mice in a research conducted by Duke University. There were fat yellow mice (that came from a long line of fat yellow mice) that mated together. Normally, they would produce more fat and yellow mice. When the scientists gave the fat yellow mice some extra vitamins (vitamin B12, floci acid, betaine, and choline), however, their offspring turned out thin and brown. When analyzed further, it was found that the thin brown mice had the same genes as their parents. The only difference is that the agouti gene (the gene that gives them a pale coat and tendency towards obesity) in the thin brown mice was suppressed the gene from being expressed. Not only was it discovered that vitamins can alter gene expression but even the environment can influence the offspring’s phenotype! This was found by researching voles (a type of rodent that resembles a mouse).  They found that the gene for having a thick coat is always present in the vole but is either suppressed or not suppressed depending on the environment (the amount of light) the mother experiences during pregnancy (160).

For human implications, it was found that epigenetics may play a part in our rise in childhood obesity. The junk food that we are constantly putting into our bodies is literally junk- it is high in calories and fat but not in nutrition. When pregnant women eat a lot of junk food during their pregnancy, it sends messages to the fetus that there is not a lot of nutrition around. In response, the fetus develops a “thrifty metabolism”, meaning that it can retain energy more efficiently than those who do not develop a thrifty metabolism. This thrifty metabolism eventually leads to retaining weight and becoming overweight.

Another interesting fact about infant health was actually found after the child was born. The more a mother nurtures her young, the more the methyl markers were influenced and the more significant epigenetic changes occurred. In rat pups, those who were given more attention by their mothers (even if they were “adopted” by different mothers) had methyl markers removed from the gene that stops the brain from developing. This means that the nurtured pup’s brain can now develop even further than it would have if the methyl markers were still present.

Sometimes, the cells are pre-programmed to die early. This is manifested in diseases like progeria and Werner syndrome. In these heart breaking illnesses, the victims have cells that age much more rapidly than normal cells- sometimes aging 10x faster than normal cells. Recent research has isolated where these disease mutations take place- on a protein called lamin A. Lamin A is used for support in the nuclear membrane. In patients who have illnesses such as progeria or Werner syndrome, lamin A is impaired, causing cells to depreciate much more quickly. A disease that programs people to die early makes scientists wonder: Are we made just to die?

Although this question is rather gruesome to say the least, the effects of aging are crucial to surviving and evolving. The author compared it to selling electronic products that seem to have a limit to how long they last: Once a consumer’s product breaks, they are now in the market to buy a new, upgraded version of the old model. When used in the sense of humans, new “models” make it possible for change and, therefore, evolution. The second advantage the author gave for aging is that, those individuals who have illnesses or parasites will protect the group by leaving it (that is, dying). Gruesome, yes, but there’s no way around death.

And speaking of evolution, how did we evolve to look the way we do and have such a difficult birthing process? One theory is known as the savanna hypothesis. This hypothesis explains the phenomenon as such: Our apelike ancestors left the African forest and moved to a grassy plain. It was more challenging to obtain food in the savanna so the males had to hunt for their met. In order to improve their hunting skills, they started walking on two legs to travel faster, became more erect in order to see the animals better, and lost their hair so they could cool down. However, someone by the name Elaine Morgan contradicts this theory and wrote down her own thoughts in a book called The Descent of Woman in 1972. To her, it didn’t make sense that we would evolve to bipedalism in order to become faster- most of the quadrupeds can out run us, anyhow. And males losing hair to cool down doesn’t explain why women have even less hair than men do or why there are no other animals living in the savanna that are hairless. The only hairless mammals are those that live in the water or play in the mud. A very similar theory by Alister Hardy says that we evolved the way we did because a group of apes got isolated on an island. On this island, they started swimming in the water and learned to hold their breath under water to help them catch fish for food. By living on both land and water, the aquatic apes had more food resources and more places to find safety when being chased by predators. Also, this theory explains why we have fat on our skin, similar to aquatic animals. The fat helps us move smoothly through the water and, for infants (who have a lot of fat), it helps them to float in the water. This last bit of information has some interesting effects in today’s world. When women give birth while sitting in a tub of water, giving birth was a lot easier and less painful. Also, it lessens the risk for babies to get infections from the birthing residue that sometimes get on their face or in their mouth. For the aquatic ape supporters, this is just another piece of evidence that supports their theory.

What Questions do You Still Have?

Some of the questions that I still have include: Could it ever become conceivable to create a remedy for cancer that looked at telomerase activity? On page 188 Dr. Moalem said that scientists are working on a test for cancer that uses telomerase activity. Could scientists ever force cancerous cells to submit to the Hayflick limit? Another question I have is about stem cells. Since stem cells are immortal and are not subject to the Hayflick limit either, they could aid tremendously in scientific research. I am sure, however, that the places where we get these stemm cells would no doubt raise disputes about ethical rights.