Animal Study: Stress Might Induce Human Infertility
This pregnant naked mole-rat is 15 years old.
Credit: Rochelle Buffenstein/City College of New York.

In African naked mole-rat colonies, the queen is the only reproducing female — a feat she accomplishes by bullying around her fellow blind, tunnel-digging companions.

The candy-bar-sized rat’s behavior could reveal how stress cripples human fertility, zoologists said today at the European Society of Human Reproduction and Embryology’s annual meeting.

“The queen exerts her dominance over the colony by, literally, pushing the other members of the colony around. She shoves them to show who’s boss,” said Chris Faulkes, a zoologist at the University of London.

Faulkes explained that the stressful domination reduces fertility hormone levels — effectively suppressing puberty in young mole-rats, lowering sperm counts in males and even turning off the female ovulatory cycle.

“The queen also seems to exert control over the breeding males, so that concentrations of their testosterone are suppressed except when she is ready to mate,” he said.

But naked mole-rats aren’t alone in their odd ways, Faulkes noted. “Social suppression of reproduction in marmoset monkeys is very similar to that in naked mole-rats,” he said, “and as these are primates the applications to understanding human stress-related infertility aren't so far fetched.”

Faulkes thinks stress and fertility areas of the brain are closely related in most mammals, so careful comparisons of mole-rats to humans could reveal how genes, environment, up-bringing and culture contribute to human infertility.