But the biggest predictor of being smarter in old age is rather obvious, and perhaps somewhat disheartening: being smarter in childhood.
However you want to measure it – and the best measures of class will take into account many different factors – your score on an intelligence test will correlate with your social class: smarter people tend to end up in higher social classes.
people with higher ability do tend to end up in jobs where their skills can be put to good use.
large-scale studies have shown that those with lower intelligence test scores are more likely to be hospitalized for psychiatric conditions (Gale et al., 2010).
The researchers who found these links have suggested that higher-IQ people are better at noticing and responding to risks, making them less likely to get caught up in life-threatening situations.
Another type of creativity that has been studied with regard to IQ is scientific and mathematical creativity: the sort of insight that leads to a ‘Eureka!’ moment when working on a problem. It seems that higher spatial ability – measured by, among other things, the ‘mental rotation’ task we encountered in Chapter 2 – seems to be particularly helpful (Wai et al., 2009). The kind of abstract visualization that’s required to manipulate shapes in one’s mind seems to be essential for thinking through new scientific questions.
What’s surprising to many is that, taking into account all the data from twin studies, the shared environment appears to have a very small effect on intelligence. If you measure intelligence in adulthood, almost all of the variance is explained by a combination of genes and the non-shared environment.
Outside of cases of abuse or neglect, the things that parents do don’t seem to have a strong effect on their children’s intelligence, in the long run (Harris, 2009). To put this another way, the main reason smart parents tend to have smart children is because of the genes they pass on, not because of their parenting decisions.
Another important finding from functional imaging relates to brain efficiency. Compared to those with lower ability, the brains of higher-IQ people tend to show less, rather than more, activity when completing complicated tasks: this suggests that their brains can more efficiently work through the problems.
they have usually found no effect of Mozart at all. In 2010 scientists collected together all the data on the Mozart Effect, and the unusually frank title of their paper nicely sums up their opinion: ‘Mozart Effect – Schmozart Effect’.
Peter Singer (1995). If your belief in equal rights and opportunities for all – and against racism, sexism and other kinds of discrimination – is based on there being no biological differences between people, then you’ll find it very hard to know what to do if clear evidence of biological differences actually appears. If a hundred scientific papers were published tomorrow providing bulletproof evidence that women had higher general intelligence than men, or vice versa, would this justify sexism? Of course not. It makes better sense to base one’s moral beliefs on ethical principles that are informed by, but not shackled to, the vagaries of the scientific evidence.
There are many others: interested readers should investigate the works of long-time IQ critics such as Leon Kamin and Steven Rose, and see for themselves how their arguments stack up against the scientific research recounted in this book.
100 Ideas This 100 ideas section gives ways you can explore the subject in more depth. It’s much more than just the usual reading list.