Her retrospective “volunteers” were former American soldiers enrolled in what was known as the Vietnam Experience Study. In 1985 almost 4,500 veterans of that war volunteered for extensive medical and mental examinations. Some of them gave semen samples that were analysed for sperm concentration (ie, number of sperm per cubic centimetre), sperm count (ie, total number of sperm in the ejaculate) and sperm motility.
Ms Arden found 425 cases where samples had been collected and analysed from unvasectomised men who had managed to avoid spilling their seed during the collection process and had answered all the necessary questions for her to test her hypothesis, namely that their [intelligence test] values would correlate with all three measures of their sperm quality.
They did. Moreover, neither age nor any obvious confounding variable that might have been a consequence of intelligent decisions about health (obesity, smoking, drinking and drug use) had any effect on the result. Brainy men, it seems, do have better sperm.
Hmmm. File this one under facts that would not have been predicted by observing the average academic department.
Via The Economist.