Mossman-Pacey Paradox: Men Trying to Look like the 'Pinnacles of Evolution' Risk Becoming Sterile, Scientist Warns

man gym fitness working out stock getty
The Mossman-Pacey paradox describes the phenomenon of men's quest for aesthetic perfection damaging their fertility. Getty Images

Men are risking their fertility by pumping their bodies with steroids in a quest to look like the "pinnacles of evolution," scientists have warned.

The phenomenon, where men unwittingly damage their fertility by taking pills to prevent balding or dosing themselves with steroids to build muscle, has been named the Mossman-Pacey paradox after the scientists who first identified it, BBC News reported.

James Mossman is a research associate in the Department of Ecology and Evolutionary Biology at Brown University and Allan Pacey is professor of andrology at the University of Sheffield in the U.K.

Mossman told BBC News that the potential effects of such products on fertility dawned on him after he noticed a pattern of "huge" men having their fertility tested while he was studying for his PhD at the University of Sheffield.

Newsweek subscription offers >

"They are trying to look really big, to look like the pinnacles of evolution," he said. "But they are making themselves very unfit in an evolutionary sense, because without exception they had no sperm in their ejaculation at all."

Professor Allan Pacey told BBC News: "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."

Some gym-goers looking to build muscle take anabolic steroids which act like the male hormone testosterone. Users can inject the drugs into their muscles, take them orally or as topical creams. These steroids are linked with side effects in men including addiction, reduced sperm count, infertility, shrunken testicles, erectile dysfunction, acne, and stomach pain. Some men may also develop breasts, and increase their risk of developing prostate cancer. These drugs are commonly referred to as gear, juice, roids, and stackers.

Anabolic steroids can make the pituitary gland stop producing the hormones FSH amd LH, which help to create sperm. Similarly, the drug finasteride, which is sold to prevent balding, can trigger erectile dysfunction and reduce fertility, according to the scientists.

Newsweek subscription offers >

Pacey said he believes around 90 percent of anabolic steroid users are at risk of becoming sterile, with "hit-and-miss" side effects on fertility for users of drugs to combat baldness.

The warning comes as scientists try to understand another hit to male fertility, and answer what caused an apparent 50 percent reduction in sperm quality between 1938 and 2011.

In a study published in Scientific Reports earlier this year, a separate team of scientists posited that DEHP, a chemical used to make plastic and found in such items as furniture, flooring, carpets, upholstery, toys and shoes, could be to blame. They found similar results in dogs, too.

Richard Lea, lead author of the study and associate professor and reader in reproductive biology at the University of Nottingham School of Veterinary Medicine and Science, said in a statement at the time: "Our findings suggest that man-made chemicals that have been widely used in the home and working environment may be responsible for the fall in sperm quality reported in both man and dog that share the same environment."

Mossman-Pacey Paradox: Men Trying to Look like the 'Pinnacles of Evolution' Risk Becoming Sterile, Scientist Warns | Health