I was on the right track last time but I got the details about 80% wrong. Take that as a cautionary tale. This is an overview of the 2.0 theory.
Thesis: White matter is the seat of kenntnis, gray matter is the seat of wissenschaft.
Races with large crania in absolute terms correlate to healthy white matter production and a nonverbal cognitive slant (i.e. specifically the draw-a-man IQ subtest), whereas having high encephalization and large social group sizes corresponds to healthy gray matter production (i.e. most academic and cognitive tasks).
Yeah, this is mostly backwards from before. The pattern-matching was good but my knowledge base was weak. This happens when your instincts are much better than your brain.
To understand the two German words I’m stealing, I recommend reading two sections from the book Boys Adrift that address the difference between wissenschaft (academic knowledge) and kenntnis (intuitive/experiential knowledge): The Tree of the Knowledge of Good and Evil, and How Is a Child Different from a Programmable Computer, pages 27-35. They’re available in the Google books preview.
It’s reasonable to ask why such a handwavy generalization is even necessary. I claim it’s necessary to understand
1) recent, post-neanderthal human evolution,
2) the extreme right-tail outliers we occasionally see in nonverbal IQ subtests which otherwise defy modeling, and
3) part of the reason that extreme intelligence predicts disparate social outcomes (contra the hierarchical theory of g). That is, we would expect extremely smart people to also be extremely social and extremely emotionally balanced, but this is only true about half of the time.
If we take this model as true and reasonably predictive, then we would predict late neanderthals and early cro magnon hybrids thereof to have average nonverbal IQs of approximately 120. To understand the significance of this, compare it to the average Ashkenazi IQ of ~110 and the over-representation of this tiny population in the upper echelons of academic and social success. Because they are not particularly big-brained, we would expect these Ashkenazim to have thicker cerebral cortices.
I claim the disparity in ability types derives from the same sort of systemic building-blocks as somatotype: some bodies are better at putting on muscle than others by nature, and some are better adapted for long-distance running. Though we expect that a person’s ability to lift heavy weights and run long distances are correlated in the normal ranges of physical fitness, at the extreme upper end we begin to see a bimodal split in specialized abilities due to different underlying structures.
The neocortex is very deep in the frontal lobe, being composed of six layers. Whereas in ancient regions of the brain, the cerebral cortex is only two layers deep. If you have a thick cerebral cortex, it inhibits your ability to dream and draw. The echidna is an example of a mammal with an outlandishly thick cerebral cortex in the frontal lobe:
The Australian anteater, Echidna, is a prosimian low down on the mammalian family tree. Its tremendously developed frontal cortex is far larger than that of primates, our much closer relatives. If we had frontal lobes as massive as the spiny anteater’s per unit volume of brain we would have to carry our heads in front of us in an extra-large wheelbarrow. This contradiction of a simple animal with a proportionately huge frontal cortex suggests an evolutionary strategy that went down a dead end. Having more analytic space for more computations does not make an efficient brain nor one that is especially smart.
The Australian anteater also appears not to dream, illustrating the general principle that for every gain there is usually a loss elsewhere. It is as if the anteater paid for its massive frontal lobes of cortex by forfeiting limbic function. The evidence is this. All other mammals dream, and when we do we emit an electroencephalographic signal in REM sleep called the theta rhythm, which is particularly prominent in the hippocampus of the limbic system. The anteater has no theta rhythm and presumably does not dream.
The Man Who Tasted Shapes (p. 160)
The same is true of most adult humans, until old age when the cortex begins to decay and mental function declines (psychosis is also possible here in cases of pathological decline). So it stands to reason that, if gray matter suppresses limbic function (that is, the mind suppresses emotional impulsivity), a thicker cerebral cortex in the frontal lobe also creates time preference.
The Enlightenment can be conceptualized as an ideology which encourages the suppression of the limbic system in favor of the abstract thought inherent to the cerebral cortex. Which is why it’s so interesting that coffee increases blood flow to the brain, and similarly why aerobic activity produces high mental energy and a concomitant suite of mental traits that Steve Sailer talks about here.
This supports my contention that the Enlightenment was a result of coffee. That is, Voltaire was just rationalizing his habit :-).