…intelligence is a vital predictor of life outcomes, correlating with school results at 0.7, university performance at 0.5, and postgraduate performance at 0.4. It correlates with salary at 0.3 and is an important predictor of occupational status. It has been found that those in less-selective professions, such as nurses, have an IQ of about 110, while the average is 120 for doctors and lawyers, and higher still for those who rise to the top of these kinds of profession. The average PhD student in an education department has an IQ of around 117, while the average PhD student in a physics department has an IQ of 130. The more intelligent are more likely to engage in civic activities such as voting, and are less likely to endorse extreme political parties or opinions. They are, presumably, less extreme because they are better able to foresee the negative consequences of extreme action and are better at perceiving nuance. They are more likely to engage in civic activity because they are more cooperative and trusting. They can also better understand the positive outcomes of doing so, such as living in a nice environment or being politically free.
* It has been calculated that in the US white American single mothers have an average IQ of 92, whereas it is 105 for women who are childless or married with children. We have seen that education level is a proxy for intelligence. Research from the USA has found that women with no high school education are 20 times more likely to end up as single mothers than are women with a high school education.
* Interest rates can be regarded as a marker of intelligence because they measure time preference. We have already seen that ‘time preference’ is associated with intelligence. More intelligent people are more focused on the future than are less intelligent people. As such, a smaller reward, given relatively further into the future, is sufficient to persuade a more intelligent person to postpone immediate gratification.
* Interest rates, then, are a marker of intelligence. Clark’s research has shown that between 1200 and 1800 in England interest rates significantly fell. Based on land return and rent return, interest rates in the year 1200 were over 10% and, in fact, in 1150 they were around 15%. By 1800, they had fallen to just 5%.
* An appetite for violence and cruelty is often a reflection of low intelligence. As we have discussed, the less intelligent are less able to empathise with the feelings of others. Accordingly, we would expect to see a rise in intelligence parallel a decline in barbarity. Although this is difficult to measure, a case can be made that this is precisely what we see. A good example can be seen in the cruelty inflicted on criminals.
* We have already seen that democracy is associated with relatively high intelligence at the level of individuals. Those of low IQ are less likely to vote for democratic parties or sustain democracy at all. This is because democracy involves cooperation, low corruption, trust, and future orientation, all of which are associated to some extent with high intelligence. This being the case, we would expect to observe a process of greater democratisation and political stability as we move towards the 18th century.
* Rushton showed that the Big Five (and Big Three) are all co-correlated, and could all therefore be reduced to a single personality variable, which he called the General Factor of Personality (GFP). The GFP can be understood as the single foundational dimension of personality, corresponding broadly to social effectiveness—or the ability to effectively read people and social situations and to behaviourally regulate oneself. This underlies the more specific personality traits—akin to how general intelligence or g underlies all the specific cognitive abilities, as we have already explored. With personality, you have the ‘aspects’ or ‘facets’—lots of very specific traits such as ‘courage’ or ‘jealousy’. These can be reduced down to the Big Five and these, in turn, yield a Big Two comprised of a broad Stability factor (encompassing Conscientiousness, Agreeableness, and Emotional Stability) and a Plasticity factor (comprising Extraversion and Openness-Intellect). The Big Two always correlate. This gives rise to the g factor of personality; the ‘General Factor of Personality’. So the General Factor of Personality (GFP) can be conceptualised as the degree to which a personality is socially desirable and socially effective. GFP describes a basic personality dimension, high levels of which (it is suggested) evolved as an adaptation in complex and stable societies so that people would ‘get along together’. So a person with high GFP would be socially extraverted, be empathic and concerned with the feelings of others, conscientious and self-disciplined in pursuit of socially-approved goals, have stable emotions, and be open to new ideas. The existence of the GFP is also why people say things like ‘She has a nice personality’, or ‘He’s shallow!’: the idea being that people intuitively understand that there is one ‘core’ personality trait with socially desirable and undesirable poles—and that paying attention to this in choosing mates and allies likely would have had significant evolutionary pay-offs. Unsurprisingly, the GFP predicts likeability and employability, and is substantially correlated with (and is essentially the same thing as) Emotional Intelligence. This is the ability to ‘know’ yourself and take command over your emotions, which, as was discussed earlier, is sometimes touted as a sort of ‘second’ intelligence, but is really a mixture of general intelligence and the GFP, with such traits properly belonging in the ‘personality realm’.
* By the time they reach adulthood, women are higher in Agreeableness and Conscientiousness than men: they have higher impulse control and they are kinder. This would make women better carers for children and men higher in competitive drive and aggression. This should be borne in mind when people bemoan the fact that high-stakes, money-oriented professions like finance or even politics are male-dominated, but nursing and school teaching are female-dominated, as these differences are precisely what male–female differences in personality would predict. Women are also higher in Neuroticism than men, as already noted, which would mean a greater proneness to suffering from stress. They are higher in some Extraversion facets than men, more likely to be outgoing, for example. The differences on Openness-Intellect are at the facet level. Women are higher in ‘Aestheticism’; men are higher in ‘Intellect’. So, you would predict that women would be more interested in the arts and men more interested in the sciences.
* An unstable, dangerous childhood will tend to increase mental instability, and those who experience it will learn to see the world as a perilous place—and this may have a lasting effect on their behaviour. For instance, when childhood is unpredictable and dangerous, children will tend to ‘live for the now’, so displaying lower Conscientiousness, and they may be suspicious of other people, leading to lower Agreeableness. Another example is that girls who have grown up in sexually-unstable situations seem to adopt a short-term sexual strategy. They have children with a large variety of men and these men are chosen because they are macho, not for their ability to remain committed to the relationship and/or provide resources over the long term. To put it in slang terms, girls from unstable homes seem to exhibit a preference for ‘cads’ rather than ‘dads’.
* Darwin argued that as societies become more advanced they become more compassionate towards their weaker members. This makes sense because, as we have already seen, the ability to solve social problems is modestly correlated with intelligence. Furthermore intelligence makes you more able to put yourself in the position of others. In other words, it increases your ability to empathise; it makes you nicer.
* Darwin wrote, in 1871, verbatim: ‘With savages, the weak in body or mind are soon eliminated; and those that survive commonly exhibit a vigorous state of health. We civilised men, on the other hand, do our utmost to check the process of elimination; we build asylums for the imbecile, the maimed, and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilised societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race; but excepting in the case of man himself, hardly any one is so ignorant as to allow his worst animals to breed.’
In conversation with Alfred Russell Wallace (1823–1913), shortly before Darwin’s death, Darwin expressed extreme pessimism about the future of humanity, telling Wallace, ‘It is notorious that our population is more largely renewed in each generation from the lower than from the middle and upper classes.’ Darwin also spoke of the large number of children of what he called ‘the scum’ and the inevitable deterioration, as a consequence, of the qualities that were needed to build up civilisation.
* welfare recipient families require far less money than they are given but, rather than putting money aside for their children, they seem to spend the money on unnecessary luxuries such as alcohol, cigarettes, and electronic equipment instead. Perkins also presents evidence showing that children raised on welfare are far more likely to be neglected than those who are not.
* Perkins concentrates on personality and argues that the welfare state is, in effect, causing those with an ‘employment resistant personality’—low in Agreeableness and low in Conscientiousness—to be more fertile than those with a work-oriented personality, and he notes the heritability of personality.
* People of relatively low intelligence, such that they are unable to hold down all but low-paying jobs, are likely to be intelligent enough to rationally calculate that they are better off not working as long as they have lots of children. They can then fritter away the ‘child support’, to which these children entitle them, on their own pleasures, investing as little of it in the children as they can.
* The final factor that is reducing average intelligence in developed countries is by far the most controversial. That factor is immigration from less developed countries.
* Lynn and Vanhanen have shown that the average IQ of a country strongly predicts how highly it will score on pretty much every measure of civilisation that you can think of: educational attainment, average earnings, democracy, lack of corruption, nutrition, life expectancy, low infant mortality rate, access to clean water and sanitary conditions, low levels of crime, liberal attitudes, rational attitudes, and even happiness.