Re-Examining the Five Intelligence Articles
Tonight's disquisition will
concern the five articles on intelligence that were sent to me on April 2
by someone who prefers to remain anonymous.
The first of these articles, UNDERSTANDING THE NATURE OF THE GENERAL FACTOR OF INTELLIGENCE: THE ROLE OF INDIVIDUAL DIFFERENCES IN NEURAL PLASTICITY AS AN EXPLANATORY MECHANISM
The author of this paper postulates that intelligence may be modifiable during childhood, when dendrites are making connections and are "wiring up" the brain. After puberty, the author contends, the subject can continue to learn, and can assign different weights at synaptic junctions, but no new connections are formed.
Possible counter-indications are that there is some evidence that structural changes can occur in the brain throughout life as a response to environmental stimuli: Taxi drivers' brains 'grow' on the job . Also, there's an ongoing rhubarb between Yale Univeristy and Princeton University concerning whether new neurons are appearing in the adult primate neocortex. There's no argument over whether new neurons appear in the hippocampus: they do. But Yale has repeated earlier experiments and reiterates that they find no evidence of new neurons in the neocortex ("Read my lips: No new Neurons!"). Liz Gould and others at Princeton say the opposite: they are detecting new neurons in the neo cortex.
Anyway, it isn't clear that no new connections can be made in the adult brain.
The second article, STIMULATION SEEKING AND INTELLIGENCE- A PROSPECTIVE lONGITUDINAL STUDY, deals with stimulation seeking children. And the obvious question is: were the high stimulation seeking three-year-olds already 12 points of IQ brighter than the low stimulation seeking three year olds? Is high stimulation seeking simply an independent earmark of higher IQ, or did the high stimulation seeking children outstrip the low stimulation seeking children as they grew older?
The third article, HUMAN EVOLUTION EXPANDED BRAINS TO INCREASE EXPERTISE CAPACITY, NOT IQ,
revolves around the realization that there are people with head sizes (and
presumably, with brain sizes, that are consistent with the Australopithecines
(e. g., half the brain sizes of modern humans, and brains that aren't much
larger than those of chimpanzeess. For example, Anatole France,
Nobel-Prize-winning author, had a brain size estimated at about 1,000 cc's.,
well within the range of Homo Habilis. One woman had a brain size of
about 760 cc's., but had a Wechsler IQ of 112, did well on the Raven Progressive
Matrices, and was good in math. Another seemingly normal fellow had a brain size
of 624 cc's!
The author then observes that large head size is a challenge in childbirth. Women have evolved to permit the birthing of infants with relatively large heads. But if large heads aren't necessary for intelligence, why do we have them? The author suggests that head size is directly proportional to the capacity to acquire expertise. Of course, this is a testable hypothesis, and he proposes that this question be investigated.
The fourth article, MYOPIA, INTELLIGENCE, AND THE EXPANDING HUMAN NEOCORTEX,
observes that the sizes and weights of U. S.' children's brains have
increased by a standard deviation over the 50-year period from 1920 to 1970. At
the same time, IQ's have also increased by a standard deviation. In particular,
the middle layers of the neocortex have expanded rapidly during the 20th
century. He suggests that an epigenetic kind of rapid evolution has been
occurring in response to environmental requirements.
This is a fascinating paper, but one which I'm unequipped to evaluate.
The fifth paper, THE EVOLUTIONARY PSYCHOLOGY OF PERFECTIONISM, adds that the drive to acquire expertise is just as important as the neurological capacity for it.