Naked mole rat queen scent suppresses reproduction
The scent that silences a colony
For decades, researchers watched a puzzle unfold underground. In naked mole rat colonies, only one female ever gives birth. The queen reigns for decades, sometimes longer than a human lifespan. Meanwhile, every other female remains reproductively frozen. They have ovaries, but those ovaries never release eggs. Their bodies produce high levels of the hormone prolactin, a substance that suppresses fertility. Yet these females are not sterile by birth. Remove them from the colony, and they can become pregnant within weeks. The mystery was not whether the queen suppresses reproduction — it was how she does it without constant physical confrontation.
The prevailing explanation was simple: the queen is larger and more aggressive. She pushes, shoves, and bites subordinates into submission. But Gary Lewin, a neuroscientist at the Max Delbrück Center for Molecular Medicine in Berlin, found this explanation unsatisfying. ‘We never found that very satisfying as an explanation,’ he told New Scientist. The question demanded a different kind of answer — one that could explain how a single queen maintains control even when she is not physically present.
A study published in Nature on July 15, 2026, provides that answer. The queen produces a single chemical compound called isopropyl myristate, or IPM. This compound is not just present in the queen — it is almost entirely absent from every other colony member. The chemical’s scent alters hormone production in other females, stifling their ability to bear young. The finding resolves what Melissa Holmes, a behavioral neuroscientist at the University of Toronto, Canada, called ‘a longstanding mystery.’ The study is, in her words, a ‘game changer.”
Why only the queen’s scent works
Mohammed Khallaf, a neuroscientist at the Max Delbrück Center, proposed a new approach. Instead of observing behavior, he would identify the molecules that create the mole rats’ scent — what he called the ‘mole rat bouquet.” The team swabbed hundreds of naked mole rats of different social ranks. They analyzed the chemical profiles of queens, workers, and soldiers. One chemical stood out immediately: isopropyl myristate. It was abundant in queens and peaked during ovulation, the period when the queen is most fertile. In other females, the compound was nearly undetectable.
The compound is not just a passive marker of rank. It actively suppresses reproduction. Brain imaging showed that when non-breeding females were exposed to IPM, their olfactory neurons — cells that process incoming smells — became active. The animals could detect the scent. Then the team performed a crucial experiment: they removed some non-breeding females from the colony entirely. In these isolated females, prolactin levels dropped. Those paired with males became pregnant. The same result occurred when the team used a drug to block the ability to smell in other females. Without the sense of smell, the chemical signal could not reach the brain, and reproduction resumed.
The most dramatic experiment came next. The team removed a queen from a colony and applied isopropyl myristate daily to the empty nest. For three months, no female began breeding. There were no fights for succession. ‘We produced peacefulness,’ Lewin said. When the team stopped applying the compound, high-ranking females started fighting within a week. After about three weeks, one female became pregnant — the new queen. The presence of IPM alone, without any queen present, was enough to block reproduction and maintain the colony’s social order. The compound functions as what Lewin called ‘a super-contraceptive, if you’re a mole rat”
The unanswered question of detection
The study raises a question that the researchers themselves cannot yet answer. How does the mole rat’s body detect isopropyl myristate and translate that detection into hormonal changes? The team showed that exposure to IPM alters levels of progesterone and prolactin. But the molecular pathway — the chain of events from nose to brain to ovary — remains unknown. ‘That’s the next project,’ Lewin said.
The compound itself has unusual properties. Isopropyl myristate is volatile, meaning it can evaporate into the air. But it is not highly volatile, so traces left by the queen take time to evaporate. The scent persists for at least a day. This matters because the queen patrols every part of her colony, which in the wild might extend underground for three kilometers. ‘We think the reason she does that is to deposit this molecule around the colony,’ Lewin said. ‘To make sure that every member of her colony is exposed to her scent.’ The compound is also widely used in cosmetics, where it is described as odorless. Lewin noted that some women in his lab thought they could smell something when exposed to it.
Markus Zöttl, a researcher at Linnaeus University in Sweden, called the evidence ‘compelling’ and the study ‘impressive and important.’ Chris Faulkes at Queen Mary University of London agreed, but noted that ‘the paper raises many questions, like any interesting research.” Those questions include how animals detect the compound, and how behavioral interactions and queen dominance interact with the scent. The team also tested other species of mole rats. They did not find isopropyl myristate in any solitary species. They did find it in a few species whose social structure is more like that of naked mole rats. But Zöttl cautioned: ‘I would be cautious about assuming that the same pathway has a comparable function across social mole rats without direct experimental evidence.’ The pathway remains the next frontier — a question that the study itself cannot yet answer.
Sources
1. DOI: 10.1038/d41586-026-02168-2