Heritable IQ is Boosted by Environment, Just Like Height

hough it’s not easy to pinpoint the causes of the rise in IQ scores, it’s no paradox that a heritable trait can be boosted by changes in the environment. That’s what happened with height, a trait that also is highly heritable and has increased over the decades, and for some of the same reasons: better nutrition and less disease. Brains are greedy organs, consuming about a fifth of the body’s energy, and they are made of fats and proteins that are demanding for the body to produce. Fig...

 Different Measure of Intelligence Peak at Different Ages

One potential concern with cross-sectional data is that it may be subject to cohort effects. Our findings in Experiment 2 are consistent with the possibility that people born in 1945 have unusually large vocabularies, people born in 1980 have unusually good working memory, and people born in 1990 have unusually fast processing speed. Such concerns can be mitigated by converging results from cross-sectional datasets collected at different times (Schaie, 2005). Here, we compared results derived...

 Scientific Reasoning Explains Increases in IQ

The bombshell is that the Flynn Effect is almost certainly environmental. Natural selection has a speed limit measured in generations, but the Flynn Effect is measurable on the scale of decades and years. Flynn was also able to rule out increases in nutrition, overall health, and outbreeding (marrying outside one’s local community) as explanations for his eponymous effect.241 Whatever propels the Flynn Effect, then, is likely to be in people’s cognitive environments, not in their genes, d...

 The Biggest Gains in g

It is one thing if a child’s IQ is elevated over time because she is drilled daily on vocabulary and basic number facts (two of the subtests of major IQ batteries). But Flynn and others have shown that these are not the areas where IQ has risen much. It is in what Flynn refers to as “on-the-spot reasoning” about relations between objects that are either totally familiar to everyone, hence no one can be claimed to have a prior advantage (e.g., arranging familiar pictures so they tell a c...

 <em>g</em> Presumes Unidimensionality

 In a multidimensional set of interrelations among tests, one axis can be found that accounts for as much of the interrelatedness as possible, even when it is known that more dimensions are required. The g-men have defined that largest dimension as g. They haven’t discovered it, as they are fond of saying, any more than the Greenwich Meridian was discovered by the International Meridian Conference in 1884. Any set of interrelated tests has to have a largest dimension, so under this d...

 Solving Xenophobia

The in-group-vs.-out-group double standard, which had and has such catastrophic consequences, could in theory be eliminated if everyone alive were considered to be in everyone else’s in-group. This utopian prospect is remote, but an expansion of the conceptual in-group would expand the range of friendly, supportive, and altruistic behavior. This effect may already be in evidence in the increase in charitable activities in support of foreign populations confronted by natural disasters. Donor...