Social scientists at the universities of Aberdeen, Bristol, Edinburgh and Glasgow in Britain tested the IQs of 900 boys and girls at the age of 11 and then checked on their rates of marriage 40 years later. They found that higher IQ increases the chances a man will marry but high IQ causes an even greater decrease in the chances that a woman will marry. (same article here)
"The finding that IQ in early life appears to be associated with the likelihood to marry is important because factors in childhood may determine a person's marital status in adulthood, which may in turn influence future health and mortality," says the study, to appear in the Journal of Personality and Individual Differences.
For boys, there is a 35% increase in the likelihood of marriage for each 16-point rise in IQ. For girls, there is a 40% drop for each 16-point increase.
One possible cause of this result is that many smarter women find it beneath them to be wives. Or perhaps they are too choosy in wanting higher status men whereas the men are not as choosy about status of females and hence can find a suitable mate from a much larger pool of women. Men are more driven to seek physical beauty and youth as a result of selective pressures to seek fertile mates. Whereas natural selection favored a female preference for higher status men as better providers.
For the lower status and less intelligent women the smart successful men (and smart men are more successful on average) look like great catches that allow the women to move up in status and in creature comforts. They might also see smarter men as likely to treat them more thoughtfully (at least on average - though there are smart and callous men of course).
Another possible cause in the reduction in marriage rates for higher IQ women is that they spend more time in school than lower IQ women and therefore delay marriage past the point of their maximum attractiveness and maximum fertility. This is certainly consistent with a study on the Australian Twins Registry found that higher education reduces reproductive fitness of women. It would be interesting to look at the women in the most recent study to see if higher IQ still lowered marriage rates once educational attainment was adjusted for.
Go back and read the comments of my previous post Men Prefer Subordinate Women For Long Term Relationships. Note that some people really took issue when I advanced the argument that smarter women are at a disadvantage in finding a mate. Here is social science data that really proves the common intuition. Anyone still want to dispute this argument?
Here is what I want to know: Are genes for higher IQ being selected against? If smarter men are marrying more are they having more kids to compensate for the fact that smarter women are having fewer kids? My guess is that there is a net dysgenic effect. However, in America there is one higher IQ group that has a higher fertility rate: Higher income Republicans have more children than lower income Republicans and various groups of Democrats. So the selective pressures on genes for IQ are hard to tease out. We need cheap DNA sequencing which will probably come along in 5 to 10 years and settle this question.