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Controlling for age, physical maturity, and mother’s education, a significant curvilinear relationship between intelligence and coital status was demonstrated; adolescents at the upper and lower ends of the intelligence distribution were less likely to have sex. Higher intelligence was also associated with postponement of the initiation of the full range of partnered sexual activities. An expanded model incorporating a variety of control and mediator variables was tested to identify mechanisms by which the relationship operates.

Conclusions: Higher intelligence operates as a protective factor against early sexual activity during adolescence, and lower intelligence, to a point, is a risk factor. More systematic investigation of the implications of individual differences in cognitive abilities for sexual activities and of the processes that underlie those activities is warranted.

Even very “early” behaviors, such as holding hands and kissing, are inversely related to PPVT scores, suggesting that higher intelligence is associated with a generalized delay in the onset of all partnered sexual activities.

The peak crime rate occurs in the IQ range from 75 to 90; this is approximately the same range in which the probability of having sex is highest in the Add Health sample (using AHPVT scores standardized to an IQ metric). Although many factors influence adolescents’ sexual behavior, just as many factors influence delinquency, it is clear that higher intelligence is a protective factor and lower intelligence, to a point, constitutes a risk factor.

The idea that brighter adolescents postpone holding hands and kissing because they believe that such activity will start them down the path to coitus (and toward the negative consequences that coitus may entail) implies an extremely far-sighted concern with a “slippery slope” that is hard to take seriously.

More intelligent adolescents do evidence a stronger attachment to conventional values and institutions, and higher expectations about goal attainment. For example, they make better grades in school, they have higher expectations about attending college, they believe their parents are more disapproving of sexual activity, they report higher religious attendance, and they are more likely to be involved in structured activities such as school clubs. Each of these factors is also associated with sexual postponement and appears to play a role in the protective effect of intelligence.

Previous analyses on measures of sexual interest, sexual motivation (e.g., masturbation), and conservatism of sexual attitudes from the Biosocial Factors data indicate that higher intelligence is not associated with lesser sexual interest, just with a postponement of acting on that interest.

The inclusion of multiple control and mediator variables yielded no change in the relative odds of having sex among adolescents who score very low on the AHPVT. This suggests that the elements and dynamics of the protection process differ for adolescents who fall at opposite ends of the intelligence distribution.

For males with IQs under 70, 63.3% were still virgins, for those with IQs between 70-90 only 50.2% were virgin, 58.6% were virgins with IQs between 90-110, and 70.3% with IQs over 110 were virgins.

Each additional point of IQ increased the odds of virginity by 2.7% for males and 1.7% for females.

By the age of 19, 80% of US males and 75% of women have lost their virginity, and 87% of college students have had sex. But this number appears to be much lower at elite (i.e. more intelligent) colleges. According to the article, only 56% of Princeton undergraduates have had intercourse. At Harvard 59% of the undergraduates are non-virgins, and at MIT, only a slight majority, 51%, have had intercourse. Further, only 65% of MIT graduate students have had sex.

The student surveys at MIT and Wellesley also compared virginity by academic major. The chart for Wellesley displayed below shows that 0% of studio art majors were virgins, but 72% of biology majors were virgins, and 83% of biochem and math majors were virgins! Similarly, at MIT 20% of 'humanities' majors were virgins, but 73% of biology majors. (Apparently those most likely to read Darwin are also the least Darwinian!)

While still consistent with pregnancy fears and competing interests, lower sex drive seems like a better fit. In fact another revealing finding from the Counterpoint survey was that while 95% of US men and 70% of women masturbate, this number is only 68% of men and 20% of women at MIT!

But lower sex drive and anxiety about sex's consequences can't be the whole story either. Half Sigma also showed that the smartest men in the GSS (approx. IQ >120) were also more likely to visit a prostitute. (Hardly indicative of cautiousness) This may suggest intelligent men are less able to find willing sex partners. Are smart men less attractive to women? Perhaps in some ways. For instance HS found that smart men were less likely to be athletic, and this paper shows, unathletic men and women have fewer sex partners. Athletic men, with more willing sexual partners are also less likely to visit a prostitute. Athletic activity gives men more masculine bodies, which are more attractive to women. A more masculine physique correlates with (PDF) an increased number of sex partners.

So intelligent people have lower libidos and less masculine physiques. What hormone is responsible for both sex drive and masculine builds? That's right: testosterone.

And two new papers suggest that testosterone may depress IQ. One team found that salivary testosterone levels were lower for preadolescent boys with IQs above 130 and below 70. (the same two groups most likely to be virgins in adolescence)

Tags: science, grad school, sex