Scientists in the UK and U.S. have found that men who score higher on intelligence tests have more — and more motile — sperm than their stupider peers, regardless of health habits.
In 1985, scientists at the CDC performed a battery of tests, including of intelligence and fertility, on 425 Vietnam vets between the ages of 31 and 44 as part of a study on the effects of serving in Vietnam. More recently, scientists at King's College London, the University of Delaware and the University of New Mexico looked at how those men's sperm stacked up compared to their intelligence and found that the men who scored higher on the intelligence tests had more and better sperm even if they drank, smoked or were overweight (3 factors that normally affect sperm count and motility).
The researchers think that it might be possible that the genes that affect innate intelligence could be tied to genes that affect sperm count and motility — and study co-author Geoffrey Miller goes even further.
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...
Also, it could explain why male stupidity is sometimes such an effective method of birth control.
Smarter Men Have More Sperm [LiveScience]