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Welcome to the discussion group for Making of the Fittest by Sean Carroll. Prompts and posts are student generated. This is a collective effort to engage in discussions that connect the theory of evolution with the biological concepts and themes discussed in our course throughout the year.
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2009
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04/05 - 04/12
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- Can evolution expain all traits?
- Detrimental Diseases helping Life pg. 174
- Treating Cancer
- Censoring Science
- Humans Changing Selective Conditions
- Coral Reefs
- Quotes
- Fossilizing Genes in Humans?
- Humans Outwitting Natural Selection
- Deja Vu
- Evolution Designed?
- Ultimate Arms Race
- "Different Means to Similar Ends"- pg. 151
- Coloring of Organisms
- Taxonomy
- Number of Opsins
- Climates of the World
- Plutarch's quote
- Eww...Pathogens...
- Vision and Hearing abilities
- Owl monkey
- Nonbelievers
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In Plutarch's quote, I first focused on the part where he says "numerous coincidences should spontaneously occur". This, in biological terms, is basically saying that mutations will constantly and randomly occur throughout all of time. Some of those mutations are point mutations, so only one base pair is changed. Substitutions can also occur, the two types being missense and nonsense mutations. As a review, missense mutations are when the mutated codon is still coding for an amino acid, but the amino acid coded for may not be the correct amino acid. Nonsense mutations are when a codon is changed so that the codon signals for a premature stop signal. Insertions, deletions, and frameshift mutations are also kinds of mutations. For example, in the Antarctic ice fish (pg. 23-25), mutations have caused two genes that have the DNA for the globin part of a hemoglobin molecule to no longer function properly. This lack of hemoglobin cause the fish to have white blood. Also, the myoglobin protein was mutated through insertion of five letters of DNA.
ReplyDeleteThe Plutarch quote later describes (in biological terms) how if mutations can always occur in every single species of life, then it is easier for species success to exist. Going back to the icefish example, it was possible, because of mutations, for the icefish to survive without hemoglobin and myoglobin in the ice-cold waters of the Antarctic by the invention of "antifreeze" proteins. These antifreeze proteins were formed by mutations from a gene for a digestive enzyme. For the icefish, mutations allowed the species to adapt to the surrounding environment and for the species to survive.
I personally liked the quote by Honore de Balzac on page 215.
"It is no great wonder if in the long process of time, while fortune takes her course hither and thither, numerous coincidences should spontaneously occur. If the number and variety of subjects to be wrought upon be infinite, it is all the more easy for fortune, with such an abundance of material, to effect this similarity of results."
ReplyDelete-Plutarch, Life of Sertorius
Carroll p 139
In layman's terms: It's no surprise that somewhere along the infinite course of time coincidences should occur. With so many opportunities and so much time, it is only natural that chance brings us some coincidences.
Plutarch is saying that we should not be surprised by coincidences. With so much time and so many situations in which coincidences could occur, it is only natural that some of these situations do indeed have coincidences. In biological terms, Plutarch would not be surprised by the evolutionary convergence we see happening all around us to different species in similar situations. However, whereas Plutarch would attribute these convergences to chance, we know that the convergences are actually the result of natural selection. In the example of developing (and redeveloping) trichromatic color vision; for the howler monkey and for the ancestor of all higher primates (Old World Monkeys, apes, and humans), having color vision provided an advantage such that individuals with full color vision were able to survive and reproduce better than individuals without full color vision (144). Where Plutarch and biology would agree is that the mutations leading to the development of color vision were chance, and their happening again was indeed a coincidence, however inevitable due to the steady rate of mutation. Of course, the mutation occurring in Howler monkeys is not the same one that occurred in the ancestor of Old World primates, but the end result is the same - development and consequent favorment of color vision.
In regards to the de Balzac quote on page 215, I think that it is a great representation of how we humans unraveled the mystery of evolution: bit by tiny bit. We could only see the results of evolution (effect), and from there had to work to the cause (DNA), and even from there had to work to find the reason for particular sequences of DNA, reasons that we're still finding today.
Though this quote is rather less philosophical, I found it equally striking as the one by Plutarch:
"'How extremely stupid not to have thought of that!' exclaimed the great biologist Thomas Huxley after reading On the Origin of Species."
- Carroll p 29
Coming from the genius biologist Thomas Huxley, whose theory was at the time widely accepted as THE method by which evolution occurs; by saying this, he conceded to Darwin's own genius. If perhaps the next comment could discuss this quote in greater detail....
In the quote from Plutarch in the beginning of Ch. 6, I thought it was interesting how he kept referring to evolution and the changes as "fortune". Fortune is usually seen as a good, successful thing so this is exactly what Darwin talks about when he refers to natural selection. The changes in the environment caused evolution which is seen as "good fortune" for the species that is now able to survive and reproduce in the new environment.
ReplyDeleteAnother interesting quote I found was from Pasteur on pages 216-217.
"Imagination should give wings to our thoughts but we should always need decisive experimental proof, and when the moment comes to draw conclusions and to interpret the gathered observation, imagination must be checked and documented by the factual results of the experiment".
This shows how our imagination and questioning should lead to experimentation to prove our curiosities and observations. But our imagination is also limited by what the results show.
To me, this was the difference between the works of Huxley and Darwin. Huxley knew that evolution existed but he did not seem to perform many experiments which led him to conclude that evolution is a rapid process (45). On the other hand, Darwin experimented and researched many years with many different species, such as pigeons, birds, and peas, to come up with the Darwinian Theory that includes the idea of gradual change over time.