determinism - the idea that behavior and personality is determined and cannot be changed
telomere - the sequence of TTAGGG at both ends of the DNA strands
retrotransposons - a viral genome that has the ability to copy itself and insert them anywhere in the chromosome
eugenics - selective breeding especially in humans to create better offspring
Summary
Around the turn of the century, the scientists working on the Human Genome Project managed to map part of the human genome. In Matt Ridley's Genome , the author discusses the discoveries of those scientists and what they could imply. The scientists discovered that only 3% of the human genome is actually genes, which is a surprisingly small amount. Ridley goes on to discuss each genome in detail, inferring that language is an instinct caused by several genes, including one on chromosome 7 and one on chromosome 11. Those with changes in those genes have specific language impairment (SLI) and Williams syndrome, respectively, which are genetic conditions affecting one's speech and ability to understand grammar. Also, viral genomes that jump from person to person make up a big part of the human genome, about 1.3%. Also, there are 'retrotransposons' which are viral genomes as well. The difference between them is that retrotransposons do not try to go from person to person, but rather stay on the genome and can reproduce itself and attach it onto the human genome. Because of this unique ability, it can copy itself many times and now makes up about 14.6% of the human genome. Ridley also discusses the way cortisol, the chemical released when one is stressed, suppresses the immune system. He does not know why this happens and no one does. Also, Ridley argues that personality, or at least part of it, is based on genes. On chromosome 11, there is a gene named D4DR that controls the dopamine receptor in the brain. When there is a little dopamine in the brain, the person is quiet and reserved, and when there is a lot, that person is adventurous. The scientists discovered that all the genes for making body parts in flies, mice, and humans, called the Hox clusters are all in a row. In addition, scientists think that they have found the reason that people age. When copying DNA, polymerases do not start from the ends of the strand, but rather a tiny bit from the end. So, each time it copies, it leaves off a little bit from the beginning and the end. That is why there are telomeres, the sequence TTAGGG repeated about two thousand times on each end of the strand. It is meaningless, but as we get older, the amount of telomere decreases and soon when it copies, the polymerase is cutting off actual genes, which explains how we get old. Finally, Ridley discusses that the behavior and personality of a person is determined right from the start, in a paradoxical way. He says that some against determinism argue that society is what makes a personality, but that is not able to change, so that is as deterministic an idea as being determined by genes. But people know they have free will; they can move as they like and think as they like. Behavior is "unpredictable, but not undetermined." Discussion
I think Ridley inferences and the scientists' discoveries are very interesting. When they find the genes that cause certain disorders, they can treat people genetically, rather than using either using damaging treatments or no treatments at all. Also, scientists could develop a way to make people not age as fast and to fix birth defects, as well as other imperfections. It is fine to fix flaws that could be detrimental to the person in life, but we do not want a repeat of the early 1900's with a craze about eugenics, where thousands of people with slight disabilities were convinced by their doctors to be sterilized. Genetic treatments could be used to cure many diseases, especially cancer, where current treatments are extremely inefficient and harmful. Genes could be used to explain many things, including personality, which surprised me.
Questions
Eventually, when human beings are able to alter their genome to have the traits they want, would it be accepted as morally right?
Can one gene code for multiple traits, for example an eye color gene and a receptor trait being represented by the same gene?
Resources
Ridley, Matt. Genome. N.p.: Harper Perennial, 2006. Print.
http://www.biojobblog.com/uploads/image/dna_500.jpg
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