Some men make themselves less fertile while trying to look more attractive
In an ironic twist, some men are compromising their fertility by going to harmful extremes to attract mates. This phenomenon is referred to as the Mossman-Pacey paradox, named for the scientists who first discovered it.
Dr. James Mossman, who is now at Brown University, was studying for his doctorate in Sheffield when he turned his attention to steroid abuse.
“I noticed some men coming in to have their fertility tested and these guys were huge,” Dr. Mossman told the BBC. “They are trying to look really big, to look like the pinnacles of evolution. But they are making themselves very unfit in an evolutionary sense, because without exception they had no sperm in their ejaculation at all.”
Anabolic steroids are commonly used by bodybuilders to enhance muscle growth. These drugs are synthetic variations of the male hormone testosterone. The steroids cause the brain’s pituitary gland to stop producing two hormones that are critical for yielding sperm.
“Isn’t it ironic that men go to the gym to look wonderful, for the most part to attract women, and inadvertently decrease their fertility,” said Professor Allan Pacey from the University of Sheffield.
According to the researchers, treatments intended to prevent baldness can also be damaging to male fertility. The drug finasteride affects the way that the body metabolizes testosterone, and side effects include erectile dysfunction. Although it is not thought to permanently impact fertility, finasteride is known to lower sperm counts and sperm motility while it is being taken.
“I would say more anabolic steroid users are likely to become sterile than you would think – 90% probably,” Professor Pacey told the BBC. “Baldness is a bit more hit-and-miss, but sales are going through the roof and that makes it an increasingly common problem.”
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