Naked mole-rats are among the strangest mammals on Earth: they live underground in large colonies, exhibit temperature-dependent sex determination, and, most unusually for a mammal, operate with a eusocial structure reminiscent of ants or bees. A single queen monopolizes reproduction while all other females remain infertile, a system that has puzzled biologists since it was first described.
A study published in Nature by Khallaf and colleagues has now identified the chemical signal at the heart of this hierarchy. The answer is surprisingly mundane: isopropyl myristate, a low-volatility ester widely used in cosmetics and plastics manufacturing.
Finding the queen’s signal
The research team, working with 771 samples from 351 animals across multiple colonies, compared the chemical profiles of queens and non-breeding females. Isopropyl myristate (IPM) stood out: it was highly enriched in queens and nearly absent from subordinates.
The compound is most abundant in vaginal, anal, and mouth secretions, and its concentration peaks during ovulation before declining during pregnancy and lactation. IPM was also detected in breeding females of four other Fukomys mole-rat species, with the highest levels in naked mole-rats, paralleling the extreme reproductive skew seen in that species.
How it works
The team demonstrated that IPM is detected by the olfactory system. Electro-olfactogram recordings showed IPM eliciting short-latency field potentials in the olfactory epithelium, and whole-brain FOS imaging confirmed activation of the olfactory bulb. Functional ultrasound imaging revealed robust, spatially structured cerebral blood volume increases in olfactory-related brain regions including the piriform cortex and amygdala.
The behavioral effects are rank-dependent. In two-choice assays, high-ranking animals actively avoided IPM, while low-ranking animals showed no preference. This avoidance required a functioning olfactory system; chemical ablation of olfactory sensory neurons abolished it entirely.
Physiological effects
IPM exposure alters hormone levels in non-breeders. Plasma prolactin rises during queen ovulation (when IPM is highest) and falls when IPM is absent. In isolated opposite-sex pairs, daily IPM application to bedding completely prevented pregnancy; 0 out of 7 females became pregnant, compared with 5 out of 6 in control pairs. Progesterone remained low and no mating behavior was observed.
The mechanism, the authors propose, co-opts an ancient pathway: IPM triggers olfactory detection, which increases prolactin, which in turn inhibits GnRH release, the same pathway that mediates lactational infertility in mammals.
The queen removal experiment
The most striking demonstration came from a colony from which the queen was removed. The team applied IPM to the colony’s bedding daily for 12 weeks. During this period, no aggression was observed among females, prolactin remained high, progesterone stayed low, and body mass remained stable across all females.
When IPM application was withdrawn at week 12, the colony changed rapidly. Prolactin dropped sharply, progesterone rose, and sexual behavior emerged. Within one week, lethal aggression broke out. By week 19, a dominant female had become pregnant and given birth; a new queen had been established.
A mammalian queen pheromone
IPM is the first chemically identified queen signal in a eusocial mammal, serving as a functional analog of insect queen pheromones. The compound’s low volatility means it evaporates slowly, making it well-suited as a persistent environmental signal that can maintain colony-wide suppression without requiring constant re-application by the queen.
The discovery also has implications for understanding social evolution. Naked mole-rats represent an extreme end of mammalian social organization, and the finding that a single, simple chemical can maintain this hierarchy suggests that the mechanisms of reproductive suppression may be more tractable, and more ancient, than previously assumed.
Sources:
1. Khallaf, M.A. et al. “A queen odor mediates reproductive suppression in a eusocial mammal.” Nature (2026). DOI: 10.1038/s41586-026-10772-5
2. Bundell, S. “The simple chemical that lets queen naked mole-rats ‘rule’.” Nature News (15 July 2026). DOI: 10.1038/d41586-026-02186-0