We have gotten taller primarily because of better nutrition. IQ scores have also increased because of environmental factors. The problem is that people are trying to pretend that IQ scores are some kind of genetic measure for intelligence, which is without merit.We have gotten taller during that time period, why is not feasible that IQ scores increased as well?
"Skeletons and written records show that human beings today are inches taller than humans just a century or two ago."
Its not a calibration issue. The Flynn effect is solid proof that IQ tests have unknown environmental variables influencing the outcome. It is unacceptable to claim causal relationships between race and IQ based on correlative experiments with significant unknown variables altering the results. That doesn't even get into the fact that the racial categories for such tests is based sloppy measurements like self-identification, not genetics.And the racial gaps don't close. It's a calibration issue.
As for the canard that all the measure is how well one takes tests, only an ignoramus working on superficial knowledge would make that statement.
When international IQ comparisons are done they have to compare "like to like." For instance, Japan can do a national IQ test and decide to normalize their population at 100 so that they can use the results for internal purposes and see what's going on in the country. When it comes time to compare Japan to the US then they need to move their societal mean up from 100 to about 105-108 so that it is in line with the white American norm of 100. This is because when the tests are compared side by side, the Japanese score higher than white Americans.
The upshot is that the US mean IQ is about 98, Canada's mean IQ is about 99, Norway's mean IQ is 100, China's mean IQ is 105 and Hong Kong's is about 108.
- MRI-based studies estimate a moderate correlation between brain size and intelligence of 0.40 to 0.51;
- Genetic modelling has shown that g and grey matter volumes depend on the same set of genes (the genetic correlation is about 0.25);
- g is significantly linked to differences in the volume of frontal grey matter, which were determined primarily by genetic factors;
- The volume of frontal grey matter had additional predictive validity for g even after the predictive effect of total brain volume was factored out;
- The linkage between volume of grey matter and g is mediated by a common set of genes;
- Neural activity in several areas, measured by a positron emission tomography (PET) scan, was greater during high-g than low-g tasks;
- Studies using electroencephalograms and event-related potentials indicate that the speed and reliability of neural transmission are related to higher intelligence;
- Monozygotic twins raised separately following adoption show a correlation of 0.72 for intelligence; that is, one twin’s intelligence strongly predicts the other’s, despite their different rearing environments;
- For 48 identical twin pairs separated in early infancy and reared apart, Bouchard et al. found remarkably high between-twin correlations for verbal scores on the WAIS (0.64) and for the first principal component of special mental abilities (0.78);
- Psychometric g has been shown to be highly heritable in many studies, even more so than specific cognitive abilities (h2 = 0.6–0.8);