Nature vs. Nurture: "Rationality"

Pro Case:C1: The Flynn Effect. [1][2]Over the past 60 years or so, the average I. Q. score has steadily risen in the modern countries where it has been tracked. The increase has been so rapid that we have had to periodically update the standards of what constitutes an "average" score (~100. ) Each generation has seen an increase of between 5 and 25 general I. Q. points. It is useful to immediately note that there is a distinction made, however, between something called "fluid intelligence" and something else, called "crystallized intelligence. " Essentially, "fluid" intelligence is the ability to reason independently of any previously existing knowledge, in order to solve abstract problems. Each generation has, on average, experienced a 15 point rise in "fluid" I. Q. for the past 60 years. On the other hand, "crystallized" intelligence is the aggregate of our knowledge in specific areas, and the level of skill we have in applying that information. Each generation has, on average, experienced a 9 point increase in "crystallized" intelligence. This is counterintuitive. We might think that, with the passing of each generation, their main advantage would be in having a more detailed and advanced pool of knowledge to draw on, and to learn from. This is partially true, apparently. However, the increase in abstract problem-solving ability is surprisingly more significant. I account for it by one, or both, of two factors: 1) Educational systems have improved the manner in which they teach children how to think on their own, and more importantly, 2) Our everyday environment has become increasingly abstract, complex, and fast-paced. What cannot explain these changes is any inheritable genetic factors, because the timeframe is simply too brief. My favored explanation agrees with that of Flynn, who "favors environmental factors," and who Restak indirectly quotes as saying that, "The direct effect of genes on I. Q. accounts for only 36% of I. Q. variance, with environmental differences making up the remaining 64%. .. "C2: Neuroplasticity. [1][3][4][5]For quite some time brain researchers thought that the brain was static. They believed that it was as unchangeable as skin color, height, or eye color. Recently, however, that trend has been broken and research increasingly finds evidence that the brain is a dynamic, adaptive organ that "wires" and rewires itself in response to our habits and environment. This process is referred to as "neuroplasticity. " It follows two fundamental rules, worded very rhythmically as, 1) "Use it, or lose it," and 2) "Cells that fire together, wire together,"1) Use it or lose it:The maximum number of neurons our brain will ever have is achieved at the end of our most critical period of brain development, the 2nd trimester of our gestation period. By the time we are born, this number has already decreased. A newborn, however, still has significantly more neurons than an adult. In infancy, as the number of neurons drops, the number of connections between neurons -- synapses -- increases. A synapse is literally a physical manifestation of learning. The infant immediately starts using its high neuronal potential to "make connections" (i. e. learn) about its new environment. It logically follows that if an infant's environment provides more opportunities for learning and positive stimulation, then that particular infant will carry more of those synapses out of infancy with them. And if they continue to live in a stimulating environment, and/or maintain cognitively challenging habits, then they will probably avoid much of the full 40% loss, by adulthood, of synaptic connections that people experience on average.2) Cells that fire together, wire together:Another paradigm shift in neuroscience has lead to the revelation that people who practice distinct skills have distinctive brains. In other words, a neuroscientist can tell the brain of a musician from that of a circus juggler. Both activities, by the way, that they would recommend to improve your brain's performance, and increase neuroplasticity (i. e. the ability to make new connections. ) As another example, they have also found distinctive changes in the brains of meditators, which highly correlate with the number of years practiced. Meditators, especially experienced ones, it is especially worthy of noting here, are masters of conscientiousness. The most interesting and recent development in this area is a study conducted that demonstrated that, for one thing, the I. Q. of individual teenagers can vary (it can go up or down) by as much as 20 points in four years. For another, it demonstrated that these changes can happen in both verbal and non-verbal intelligences. And finally, it demonstrated that specific changes in verbal I. Q. were associated with changes in the verbal circuitry of the brain, while changes in non-verbal I. Q. were associated with the non-verbal movement circuitry of the brain. It is unlikely that these specific, physical brain changes were predestined by the genes, and therefore it can be concluded that they were probably a result of changing environmental influences in the children who did experience the biggest changes in I. Q. C3: Early education improves I. Q. and success later. [6][7]The "Abecedarian" project intervened in the lives of low-income families, putting half of their babies into high-quality day care programs. The study reported that these children were four times more likely to graduate college (23% v. 6%) than the controls, they were more likely to have consistent employment (75% v. 53%), and less likely to use public assistance. Norway extended their compulsory middle school attendance by two years in 1955. What they found was a 3.7 point increase in I. Q. for each additional year of school. Taken together with the abecedarian study, this strongly suggests that both I. Q. and conscientiousness can be significantly affected by positive environmental influences. And that the earlier, the better. C4: Nature vs. Nurture: There can be only one! Well, almost. .. [8][9]A study of the genes of surviving elderly Scottish people, aged 65 and older, who had taken I. Q. tests at age 11, has been carried out along with a re-testing of the group. The study used advanced genetic testing, referred to as genome-wide complex-trait analysis, to determine the influence of genes on lifelong cognitive change. The study's conclusion is that genes account for 24% of I. Q. variability across a person's lifetime. Therefore, about 76% of the changes in our I. Q. can be accounted for by environmental influences, which means that the smarter we are about selecting that environment, the smarter we are likely to become. [1]Restak, Richard. Think Smart: A Neuroscientist's Prescription for Improving Your Brain's Performance. New York: Penguin, 2009. Print. [2]. http://www.indiana.edu...[3]Doidge, Norman. The Brain That Changes Itself. New York: Penguin, 2007. Print. [4]. http://online.wsj.com...[5]http://www.sciencedaily.com...[6]http://www.newsobserver.com...[7]http://www.bbc.co.uk...[8]http://online.wsj.com...[9]http://www.nature.com...