Mind over Computer 31
high IQ. Functional MRI scans show intelligent people use more neurons when tackling a given mental task, perhaps bringing to bear greater raw horsepower, but this is not really an explanation. It is akin to saying Usain Bolt runs faster because he gets more power to his legs. This is obvious. What we want to know is how.
The problem with looking at brains for a common cause is the variation from brain to brain. We all have different genes and life experiences. On top of this, we really only see brains post mortem and this tends to confound comparisons of brain structure. One way to minimize the variation is to use separated identical twins. Twins have identical genes so their fundamental hardware is the same. We should be able to see features of the brain that are common to smart sets of twins but absent in less smart pairs. If a feature is not shared it can be discounted as something accidental, caused by disease, environment, or the like.
When we examine smart twins, they appear to have greater myelination of their neurons. Myelin is a flat protein that acts as an insulating sheath, wrapping the nerves and the neurons in our brain. Myelination appears to be part of the mechanism involved in laying down long-term memory — more myelin, more memories. It may also help sustain signals and allow them to move faster over a longer distance: the increased insulation allowing the brain to include information from more distant parts of the brain within a given thought. But increased myelination may be an effect of higher intelligence rather than a cause. The brain is responsible for a significant part of our overall energy consumption so insulating the neurons might simply help with energy conservation. This is an active area of research.
Evolution also gives a clue to the causes of intelligence. Humans, nonhuman primates, and dolphins all share spindle neurons. These spread across the brain and appear to help us coordinate complex actions between the different parts. The high function intelligence that characterizes these disparate species requires a great deal of cooperation between different areas of the brain. Take playing a musical instrument. This uses physical coordination (motor cortex), sound processing (auditory cortex), rhythm (another part of the motor cortex), along with emotional interpretation (amygdala). Humans have more spindle cells than other animals so this might explain our superior ability in performing these complex tasks.
However plausible these ideas, they are all hardware arguments. It is like me saying my word processor is better than yours because it has gold plated connectors. That might be true — it might allow the machine to run a little faster without electrical errors creeping in, but we all know
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