For men only! If you think you’re smart, but you’re still shooting blanks, then perhaps you should take an intelligence test. A recent study has found significant positive correlations between intelligence and sperm quality, sperm count and how well they swim (motility).
Researchers at King’s College London, the University of Delaware and the University of New Mexico recently compared results from five intelligence tests given to 425 Vietnam War vets in 1985 as part of the U.S. Centers For Disease Control and Prevention’s Vietnam Experience Study. These vets, aged 31 to 44, also provided sperm samples.
The smarter the men were, the more sperm they produced and the better their sperm swam — and it didn’t matter how old the men were or whether they smoked, drank or were obese.
But why might these two seemingly unrelated traits be linked? Why would smart men produce better sperm?
Turns out that intelligent people are generally healthier than their less-clever peers — studies have shown that more intelligent people are, for instance, less likely to suffer from heart disease and Alzheimer’s. Scientists have suggested that smart people may score less stressful jobs in safer places and that they may make better lifestyle choices, for instance by exercising more and eating better. In other words, maybe bright people actually listen to the health experts.
But these newest findings, to be published in an upcoming issue of the journal Intelligence, found that negative habits had little effect on sperm quality.
The researchers instead speculate that intelligence might be passed down as part of a larger package of good attributes. One gene can influence multiple traits, so the genes involved in smarts may somehow improve sperm quality — and perhaps other characteristics as well.
This could help explain, then, why intelligence can be so sexy: It could simply be an indicator that a person has a lot of good genes and traits, says study co-author Geoffrey Miller, a psychologist at the University of New Mexico.
Also, it could explain why male stupidity is sometimes such an effective method of birth control.
Ardena, R., Gottfredson, L. S., Miller, G. & Pierce, A. (In press). Intelligence and semen quality are positively correlated. Intelligence, 37.