Megan Sullivan
Ms. Huntemann
AP Biology
The Making of the Fittest Writeup
1. “We are no longer savages staring at passing ships” (34).
This quote from chapter one means that our growing technology has given us
humans the ability to grasp the process of evolution. For over a century, scientists did not
have much evidence of evolution because they could only use anatomy of structures and
observe external changes in species. However, with the discovery of the DNA record, we
now have concrete evidence of evolution. We are now able to fully understand exact
changes in the DNA record over long periods of time to show the fullness of evolution.
With this development in science, we have gained new insight into the process of
evolution.
2. “The functions of immortal genes are central to fundamental, universal processes in the
cell” (79).
Despite a certain lack of similarity between species in different domains,
immortal genes are the five hundred genes that exist in all of the domains of life. These
immortal genes date back over a billion years to the Archaea and bacteria, and the genes
have withstood mutation over this long period of time. Immortal genes have vital roles in
all organisms, and these include the making of proteins and the decoding of DNA and
RNA. Organisms depend on their immortal genes for processes that are necessary to their
survival and success. Although immortal genes have gone through minor mutations, they
have withstood the test of time and preserved for the success of every organism.
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3. “The pattern of evolution of genes under purifying selection is one of ‘running in place’”
(82).
This quote means that although certain base pairs in a triplet may be changing over time due
to mutation, their overall translated meaning does not change. Therefore, two different triplets
might code for the same protein, and the purifying selection provides a safety net for the DNA
code. Although certain base pairs may change or “run” over a period of time, selection makes
sure that these changes do not alter the protein’s function or sequence. Thus, the genes are
“running in place.”
4. “These broken pieces of yesterday’s code reflect the adaptation of species, including
humans, to new ways of life” (119).
Fossil genes are links to former ways of life and ancestors. They reflect the
adaptation of species to new ways of life because they are evidence of the shifting of
habitats or environments for species. The phrase “Use it or lose it” fits with the idea of
fossil genes because certain genes are no longer needed as the habitat changes for an
organism. Selection on certain genes is relaxed if the genes are no longer needed, which
then leads to a buildup of mutations that causes the genes to become inactive. Thus, fossil
genes are created. Fossil genes are evidence to scientists about the previous lifestyle and
ancient ancestors that the species once had. Therefore, fossil genes provide a connection
to the past.
5. “The variation in predator and prey sets the stage for a ‘co-evolutionary’ arms race”
(166).
Arms races occur between predator and prey in the matter of “survival of the fittest.” In the
example of the newt and garter snake, the newt’s skin is loaded with a toxin called TTX that can
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be fatal. However, the garter snake has developed a resistance to the newt’s TTX. The natural
selection leads to increasingly toxic newts and increasingly resistant garter snakes. This
escalation in the arms race shows evolution at a fast pace in the present. Species are in the
process of evolution as they struggle to survive in the predator vs. prey encounter. In the matter
of life or death, both species strive to out-do the other and become successful.
Before reading this book, I never fully grasped the idea of evolution. I memorized key
terms in order to pass the tests in Honors Biology, but I didn’t understand the amount of
evidence and facts that are present in the evolutionary theory. Sean Carroll’s The Making of the
Fittest gave me a better understanding of the idea of natural selection and descent with
modification. He used terms that I am familiar with, and he went step-by-step in his
explanations. Carroll not only gave the big picture of evolution, but he also showed tiny details
of evidence.
Overall, I enjoyed this book greatly. Carroll gave ample evidence for each idea. This was
done with paragraphs in each chapter, mathematical calculations for the probability of mutations,
and many pictures. At times, Carroll might’ve even given too many pieces of evidence.
Nonetheless, the book delved into all parts of the evolutionary theory and helped me to better
understand it. For the first eight chapters, he gave all the details of evolution such as fossil genes,
mutations, and natural selection. He then touched on the significance of evolution and the critics
of it.
My favorite part of The Making of the Fittest was the ending. The last chapter did not end
on a positive note as Carroll explained how human activities have destroyed many species and
habitats. Due to ecosystem disruption and climate change, many species around the world are on
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the verge of extinction. I loved how the last paragraph challenges us as humans to make a
difference in the world and stop this destruction.
Questions:
1. What are synonymous and non-synonymous mutations, and what is the significance of
them?
2. Are fossil genes related to vestigial structures?
3. What would the common ancestor of most species look like?