What did you think about the reading?
I thought the last couple of chapters gave the book a satisfactory resolution. To conclude, Dr. Moalem discussed how humans evolved from “aquatic apes” and transitioned that into how science has evolved because of the questions we ask. Chapter seven was about phenotypic expression and methylation. This chapter discussed how environmental influences shape our development. Chapter eight analyzed aging and how it relates to disorders like progeria and cancer. It also considered our evolutionary past to determine what makes us human and why. Overall, I found this book to be very intriguing. Everything in nature is interconnected, and Dr. Moalem did an exceptional job of getting this point across to his readers.
What did you learn?
Epigenetics is the subdiscipline of genetics that focuses on the expression of new traits in children without changes in the DNA. The Greek prefix epi- means in addition. Epigenetics is Lamarckian; that is, without changing the DNA of the germ line cells, offspring can inherit it’s parents’ acquired traits. This was extremely fascinating to me. Here’s an experiment conducted at Duke University. Two fat yellow mice were bred to produce a skinny brown mouse. How is this possible? Vitamins were given to the pregnant mouse and they have the ability to override the agouti gene responsible for pale fur and obesity. Methyl markers were added to the agouti gene. Other studies show that when a rat is nurtured by a caring mother, it’s personality is more calm and relaxed when compared to a rat whose mother was ignorant. This is another significant epigenetic change. In this case, the grooming of rats removed methyl markers in genes responsible for brain development. To prove the Lamarckian nature of epigenetics, fathers who smoke before puberty tend to have overweight children, and even grandchildren of those involved in the Dutch famine of 1944 and 1945 tend to be overweight since they were born so small (due to a malnourished pregnant mother).
The final chapter of this book opened with the discussion of progeria, a disease that causes rapid aging. Those with progeria die very early since they age ten times as fast as those without it. This disease suggests that aging is preprogrammed. Dr. Moalem then studies telomeres and discusses how they control the lives of normal cells (Hayflick limit) and extend the lives of cancerous cells (active telomerase). Telomeres may be the key to a longer life. The human pelvis is cleverly shaped; it’s “twisted” in the middle and there’s a tight squeeze when trying to give birth. Unlike the typical primate pelvis, it has to support the weight of your entire upper body. This trait, along with fatty skin, ability to swim well, no fur, prominent nose, etc., could only have been brought about by an aquatic or semi-aquatic past. This theory was created by Alister Hardy and is heavily supported by Elaine Morgan which contradicted the conventional savanna hypothesis (which only focused on males). Additionally, water births are easier to endure for humans.
Do you have any questions?
While reading, I was wondering why the savanna hypothesis was so heavily supported. Obviously, evolutionary patterns only held true for males, leaving the evolutionary history of females completely unanswered. However, I believe that the semi-aquatic human past shows an evolutionary process that is more species oriented (rather than gender oriented). Additionally, I wanted to know if there could ever be a key to longevity without causing cancer. I would assume that the activation of telomerase in every body cell would lead to cancerous tumors, and it seems as if there is no other way to suppress the aging process without promoting the proliferation of cancer cells. Other than that, I really enjoyed reading this book; it definitely changed the way I look at the world.