Researchers at the Max Delbrück Center for Molecular Medicine in Berlin have identified a specific chemical compound that naked mole-rat queens use to maintain reproductive control over their colonies. The study, published in Ars Technica, reveals that queens produce an abundance of isopropyl myristate, a substance that is nearly undetectable in other members of the colony. This discovery provides a long-sought explanation for how these eusocial mammals enforce a rigid social hierarchy similar to that of bees and ants.
Max Delbrück Center Identifies Chemical Queens Use to Suppress Fertility
The Role of Isopropyl Myristate
Naked mole-rats are one of the few known mammals that exhibit eusociality, a structure where a single breeding queen rules over a colony of infertile workers and soldiers. For decades, scientists hypothesized that the queen maintained her status through physical size or aggression, but researchers found this explanation unsatisfying.
By analyzing 771 odor samples from 351 naked mole-rats, the research team discovered that isopropyl myristate is concentrated in the queen’s vaginal, anal, and mouth secretions. The compound’s levels fluctuate in synchronization with the queen’s reproductive cycle, peaking during ovulation and declining during pregnancy and lactation. Because the molecule is bulky and does not evaporate easily, it functions at close range, requiring the queen to patrol the colony and spread the scent onto tunnel walls and subordinates.
Impact on Colony Behavior and Fertility
The study demonstrates that this chemical serves as a super contraceptive.
When researchers removed a queen from a colony, they typically observed a Game of Thrones
scenario where high-ranking females fought violently to claim the throne. However, when the team dosed the colony with isopropyl myristate daily after the queen’s removal, the fighting ceased.
Everything was peaceful,
said Gary Lewin, a molecular physiologist at the Max Delbrück Center. We had no fights. We had no females emerging as reproductive queens.
Experimental tests further confirmed the compound’s efficacy. When researchers placed mating pairs in cages sprinkled with isopropyl myristate, the animals failed to breed. Conversely, when females were separated from the queen’s scent, their levels of the hormone prolactin—which is associated with reproductive suppression—dropped, and they became capable of mating.
Scientific Implications and Evolutionary Context
The findings suggest that naked mole-rat biology is more closely tied to the social mechanisms of insects than previously assumed. According to Gizmodo, the research team identified that exposure to the scent flips a hormonal switch in subordinates, keeping them infertile.
The discovery also highlights a curious overlap with human biology. Isopropyl myristate is a common ingredient in cosmetics and lotions, serving as a moisturizer and solvent. It has also been detected in the breast secretions of lactating human mothers, though its function in humans remains unknown. This molecule or similar molecules may have effects on reproduction in species other than naked mole rats, maybe even including humans,
Lewin noted. We just don’t know that.
Summary of Findings
| Observation | Result |
|---|---|
| Primary Chemical | Isopropyl myristate |
| Source of Secretion | Vaginal, anal, and mouth secretions |
| Effect on Subordinates | Suppresses reproduction and prevents aggression |
| Impact of Removal | Infertility collapses, leading to competition for the throne |
While the study clarifies the mechanism of reproductive suppression, researchers continue to investigate how the queen’s scent specifically affects the fertility of her subordinates while leaving her own reproductive capacity intact. The research team’s work underscores the complexity of eusocial behavior in mammals and opens new questions regarding whether such chemical signaling exists elsewhere in the mammalian evolutionary tree.
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