Summary: Mice, like people, navigate social hierarchies by reading subtle signals from unfamiliar individuals. A new study from the Francis Crick Institute shows that male mice determine the dominance status of strangers using chemical cues—both airborne odours and contact-dependent scents—rather than fixed behavioural traits or visual attributes.
Researchers used a transparent tunnel or tube test in which two male mice enter from opposite ends and meet in the middle. In these encounters, the animal that perceives itself as lower in rank typically retreats. By testing animals from established social groups against unfamiliar opponents, the team discovered that mice can rapidly infer another animal’s social rank and compare it to their own, leading them either to withdraw or to force the other to retreat.
Key findings:
- Two complementary sensory systems: Mice rely on both the main olfactory system (airborne odours) and the vomeronasal system (contact-dependent chemical cues) to assess another animal’s dominance.
- Flexible, real-time assessment: Dominance is not determined by rigid, fixed behaviours. Instead, mice integrate sensory information in the moment to make a decision to retreat or stand ground.
- Redundancy and compensation: Ablating only one chemosensory system does not eliminate rank recognition; both systems must be disabled to disrupt this ability, showing that they can compensate for one another.
Previous work suggested that social rank might reflect stable behavioural traits or be inferred from physical features such as size or posture. The new Current Biology study challenges those ideas by showing that mice need not have previous encounters with a specific opponent to estimate their dominance. Instead, they use scalable chemical signals—odours detectable at a distance and non-volatile scent markers encountered on contact—to judge an unfamiliar mouse’s place in the hierarchy.
To test whether vision, size or hormone-driven aggression explained the mice’s decisions, the team repeated the tube tests in complete darkness and with castrated males. Rank recognition persisted under both conditions, indicating that visual cues and circulating sex hormones are not required for these rapid dominance judgments.
The critical experiments involved disabling the two primary chemosensory pathways. Removing just the olfactory pathway or just the vomeronasal pathway did not erase the ability to infer rank. Only when both systems were ablated did mice fail to recognize the dominance status of unfamiliar opponents. This reinforced the conclusion that mice integrate multiple chemosensory streams and can rely on one when the other is absent.
These findings place chemosensation at the centre of rapid social evaluation in mice. The results also resonate with human social behaviour: people, too, infer the relative status of unfamiliar others—often using visual and auditory cues such as clothing, facial expression and language—when entering new social environments.
The research points to important neural questions that follow directly from the behavioural results. The next step is to identify the brain circuits that compare self-related information about rank with sensory evidence about an opponent, and then translate that comparison into a decision to retreat or to advance.
Neven Borak, a former PhD student in the State-Dependent Neural Processing Laboratory and first author of the study, said: “We’ve shown that mice weigh up strangers using chemical cues and can detect social status without needing an extensive history of confrontations with those specific opponents. This is a fascinating phenomenon that humans do too, mostly using visual cues. Our work offers an interesting perspective on social mobility: humans, like mice, can enter a new group of people but still maintain understanding of their own social rank and gauge the social status of unfamiliar people.”
Jonny Kohl, Group Leader and senior author, added: “We’ve shown for the first time how mice integrate internal and external information about dominance. This shows that a decision based on relative ranks is made in the brain before mice show either aggressive or submissive behaviour, rather than there being fixed differences in behaviours leading to an aggressive or docile mouse.”
The State-Dependent Neural Processing Laboratory investigates how bodily states—such as stress, sleep or pregnancy—shape neural circuit function. By linking physiological state to social decision-making, the group aims to develop a more integrated understanding of brain physiology in health and disease.
About this sensory and social neuroscience research news
Author: Clare Green
Source: Francis Crick Institute
Contact: Clare Green, Francis Crick Institute
Image: Image credited to Neuroscience News
Original Research: Open access. “Dominance rank inference in mice via chemosensation” by Neven Borak et al., Current Biology. DOI: 10.1016/j.cub.2025.04.063
Abstract
Dominance rank inference in mice via chemosensation
Social dominance hierarchies reduce conflict and organize access to resources in many animal societies. While individuals can track their own rank through prior wins and losses, integrating information about an opponent’s dominance status would allow faster and more efficient decisions. Pheromonal and scent signals—such as molecules concentrated in urine from dominant animals—provide a plausible route for conveying rank information.
Using a tube test in male mice, the study demonstrates that stable hierarchies do not depend on fixed behavioural identities. Instead, mice detect scalable chemical cues about an opponent’s dominance and combine that information with their own status to guide behaviour. Sensory ablation experiments reveal that either the olfactory or vomeronasal system is sufficient for rank assessment, but both systems must be removed to prevent recognition. These results show that male mice use chemosensory signals to infer dominance status during social interactions.