Naked mole-rat queens use a chemical signal to suppress fertility in rivals

Based on analyzing samples taken from hundreds of different mole rats, the team learned members of each colony carried a distinguishable chemical signature. When mole rats from different colonies were placed together, they sniffed each other for about 40 seconds to decide if they were dealing with their nestmate or a stranger. When they sniffed a stranger, they attacked, often with lethal intent. “Naked mole rats are like humans in the sense that they’re very xenophobic,” Lewin said. So, the team tested if depriving mole-rats of smell would purge the xenophobia out of them. It did. When scientists temporarily disabled mole-rats’ olfactory sensory neurons with chemicals, the aggression towards strangers disappeared. “They basically were cool with each other, and there was no fighting,” Lewin said. Besides chemical friend-or-foe signals, researchers found something else in the odor bouquets. There was one compound, an ester called isopropyl myristate, that scientists found in the samples taken from queens and nowhere else. “Breeding females had this particular molecule that non-breeding animals did not have,” Lewin said. Scientists found breeding queens secreted isopropyl myristate from their genitals and smeared it through the tunnels as they roamed their underground kingdoms. Tracking a queen’s output of the compound over her reproductive cycle showed that it rises and falls with her fertility, peaking when she’s in heat or pregnant. “It’s actually a very good marker of whether the queen is capable of breeding, ” Lewin said. On top of that, it has another useful feature. Isopropyl myristate, while volatile, is rather stable once deposited on a surface. Researchers could still detect it in mole-rat cages roughly 24 hours after it’d been applied. Because a colony’s burrow system can run up to three kilometers, a queen has a lot of ground to cover if she wants every subordinate exposed to her scent. “It sticks around for a while, so she has less work to spread the odor around the underground colony,” Lewin said. Pinpointing the queen’s molecule was one thing, though. Showing what it does was another. The queen’s odor bouquet, however, contained many other scents. To be sure they’ve got the right one and that others are not involved in reproductive suppression, the researchers tested what happens when the queen herself is gone, but her royal molecule stays. It turned out the scent alone kept the subjects in check just as well as the real queen did. The team started by taking mating pairs out of a colony away from any queen. Under such conditions, mole rats usually start breeding within four or five weeks. When the team sprinkled their cages with isopropyl myristate daily, though, the animals did not breed—the compound reliably prevented pregnancy. Once the contraceptive effect was confirmed at the individual level, Lewin’s team extended this experiment to the whole colony scale. Removing a queen from an established colony normally sets off the mole-rat version of Game of Thrones. The strongest females fight against each other, often to the death, until a single winner emerges as the new queen. When the researchers removed the queen and dosed the colony with isopropyl myristate every day for three months, there were no attempts at coup d’etat. “Everything was peaceful,” Lewin says. “We had no fights. We had no females emerging as reproductive queens. The molecule was acting as a super contraceptive keeping them all sexually repressed.” To Lewin, these results show that naked mole-rat biology is more closely tied to insect eusociality than scientists expected. Queens in honeybee colonies and other eusocial insects use pheromones to keep worker daughters from developing ovaries. “It’s a relatively simple mechanism that explains a relatively complex behavioral trait,” Lewin says. What we are still not sure about is whether in this shape or another it appeared somewhere else in the mammalian evolutionary tree. Because secreting isopropyl myristate is not something exclusive to naked mole rats. Humans do that too. “Isopropyl myristate has been detected in the breast secretions of lactating human mothers, though its function there is unknown,” Lewin says. “This molecule or similar molecules may have effects on reproduction in species other than naked mole rats, maybe even including humans. We just don’t know that”. Nature, 2026. DOI: 10.1038/s41586-026-10772-5