Luke Ford

James Thompson writes:

Men’s brains are bigger than women’s, even when controlling for bigger body size, which means they should have higher intelligence, though the evidence for that is conflicting. Most researchers find no notable differences overall, saying that different strengths and weaknesses balance each other out, but Lynn and Irwing (2002, 2004) argued that adult males are almost 4 IQ points brighter than adult females. The authors of the present paper have found one of the largest MRI samples available, each scanned person having done 10 cognitive tests, which is what makes this study particularly interesting. The tests included: Penn progressive matrices, Peabody vocabulary, reading recognition, working memory, pictorial episodic memory, spatial orientation, card sorting, verbal episodic memory, and the Flanker task of inhibition and sustained attention…

I recommend that men pay close attention to the largest sex difference, which plays out in their favour: spatial orientation, in which they have a 6 IQ points advantage. I recommend that women play close attention to Episodic memory in which they have an advantage of 4 IQ points, giving women the upper hand when remembering male transgressions. Those particular findings hold up even when you control for g, so they are very real cognitive sex differences, and are mostly across the board of the abilities measured.

…This study supports the minority position of Lynn and Irwing, that men are about 4 IQ points brighter than women, an across-the-board advantage, plus better spatial ability, and that part of this difference may be attributed to brain size.

… 65% of intellectually demanding occupations will be taken by men, if entry to those occupations is based only on mental ability. If the bar is set higher at IQ 145, then 70.5% of such posts will be taken by men…

When will academic publishing catch up with the pace of modern research? In the meantime, the current suggestion is that the biggest study of brain scans supports a sex difference in intelligence of about 4 points, probably due to larger male brains.

Comments:

* The sex difference at the high end is especially notable, keeping in mind that the study does not even address the extent to which the sexes WANT to do high-end work in math and science. Insofar as women, perhaps innately, are not INCLINED to do cold, abstract sorts of tasks, there will, in the absence of affirmative action, be a sharp difference in the number of male vs. female scientists.

* “Brain size has increased about 350% over human evolution, but we found that blood flow to the brain increased an amazing 600%,” says project leader Professor Emeritus Roger Seymour, from the University of Adelaide. “We believe this is possibly related to the brain’s need to satisfy increasingly energetic connections between nerve cells that allowed the evolution of complex thinking and learning.

“To allow our brain to be so intelligent, it must be constantly fed oxygen and nutrients from the blood.

“The more metabolically active the brain is, the more blood it requires, so the supply arteries are larger. The holes in fossil skulls are accurate gauges of arterial size.”

* Carotid arteries are smaller in women even after adjusting for body and neck size, age, and blood pressure.

* Could the combination of a large brain and insufficient blood supply to it actually mean less brain power? Is the ratio between blood supply (carotid artery diameter) and brain size the true determinant of intelligence/brain power? Of course, a big brain plus sufficient blood supply (wide carotid artery diameter) would then likely mean very high intelligence/brain nerve cell connectivity/activity.

* Rushton seems to be operating with a model of cranial capacity as an index of brain power, like the engine capacity of a car. But there is no neurological reason to “correct” for stature and weight because these are irrelevant, even on his neurological model to the “brain power” of a given brain. Women, have brains, on average 15 percent smaller than men. To deal with this “inconvenient truth” scaling occurs so that when scaled against their smaller bodies the brain size difference disappears. But outside of political correctness, why should such a scaling occur if what we are interested in is “engine capacity”? But even though women’s brains are smaller than men’s, the Wernicke area, a key area for comprehending sounds and word meanings is 30 percent larger in women, and the Broca area, important for the ability to produce fluent and expressive speech, is 20 percent larger. Even here we cannot conclude from these size differences that women’s have a greater verbal superiority to men, as men’s Wernicke and Broca areas may be neurologically more efficient, even if smaller. Even though girls are outperforming boys at school (in an anti-male feminist environment), there is evidence that men’s brain cells transmit nerve impulses faster than women’s. The research was done by Professor Edward Reed of Toronto University, and Philip Vernon and Andrew Johnson of the University of Western Ontario. Males were found to have four times faster nerve conduction velocities than females, a significant sex difference in all test conditions in favour of males. […]
Another problem for Rushton’s theory is the considerable neurological redundancy in the human brain. John Lorber, “Is Your Brain Really Necessary?” Science, vol.210, 1980, p.1232, reported on studies of victims of hydrocephalus (water on the brain). One subject had a respectable IQ of 126 and was a maths honour student, but had “virtually no brain”! All that the neurologist Lorber found in this subject’s head was a thin layer of brain cells only a millimetre in thickness. The rest of the intercranial space was filled with cerebrospinal fluid. This, not only raises problems for Rushton’s theory, but also for reductionist neurology. It is sufficient to note that brain size, at best, is only weakly correlated with IQ. What seems to be more important is the degree of neural connectiveness. Otherwise blue whales would be of a super-intelligence level. Further it has been argued that the degree of fissuring and thickness in the frontal cortical brain layers is more important than the sheer size of the human brain. The Negroid brain is generally less fissured than the White and Mongoloid brain. See C.F. Connolly, “External Morphology of the Primate Brain”, (Thomas, Springfield, 1950); F.W. Vint, “The Brain of the Kenya Native”, Journal of Anatomy, vol.66, 1934; H.G. Garrett, “IQ and Race Differences”, (Howard Allen, Cape Canaveral, 1973), p.14.

Sociobiologists have noted that during the last 20,000 years the upward trend in brain size has been reversed. Modern man has a smaller brain than the Cro-Magnons, by about 100-200 cubic cms. It is usually inferred that the Cro-Magnons were more intelligent than modern man: J.W. Jamieson, “Biological Diversity and Ethnic Identity: Changing Patterns in the Modern World”, The Mankind Quarterly, vol.36, 1995, pp.193-199; B. Chiarelli, “Some comments on the Evolution of Hominid Intelligence” The Mankind Quarterly, vol.37, 1996, pp.29-36. Yet could it be that with modern man evolution departed from pursuing quantity and pursued quality? Perhaps evolution pursued the path of neural efficiency rather than sheer brain size? We will never know the answer to that question because we do not have a Cro-Magnon brain to subject to neurological investigation.”

* Women are morons at their core. Then, their moods outrun their meds. Women were an excellent group to have handed unfettered control of our education system over to. Also Capitol Hill, media, news. Examine all the realms of failed society in the West, the beginnings of failure were infusing our systems of education, law, communications and news with women.

Any other conclusion is politically correct white-knighting.

* The interesting question isn’t really overall brain size, but the relative size of different brain areas. Women are supposed to have a larger hippocampus, which gives them an advantage in some memory tasks. Men have larger parietal lobes which gives them an advantage in spatial intelligence. That leaves the frontal lobes – are the frontal lobes bigger in men, and if so does that give them an IQ advantage? So far, the evidence isn’t very clear.