Â鶹ÒùÔº

Naked mole-rats are one of the rare examples of eusocial mammals. Eusocial animal species are those in which a single female within the group is tasked with reproduction, along with a select group of males, while the rest of the group focuses on other tasks related to maintaining the living area, gathering food, or caring for young. This kind of caste system is most often seen in insects, like ants and bees.

Research into the daily lives of naked mole-rats has been somewhat limited due to difficulties in monitoring all colony members simultaneously over long periods in underground burrows. But, a research group in Japan has found a way around this limitation.

In their new study, the group developed and used an automated RFID tracking system to monitor 102 mole-rats across five different colonies. The system enabled a unique view of the fascinating social hierarchy and habits of these strange creatures, which the team then analyzed by applying clustering algorithms to behavioral parameters to identify phenotypes. Their work is now in Science Advances.

The team created five different burrows for the five mole-rat groups in the lab, consisting of nine chambers connected by tunnels. Out of the available chambers, the mole-rats designated each one as either a nest, toilet, or garbage area, while the rest were what the researchers referred to as "other." The authors note that the mole-rats had a preference for keeping the nests in corners, as well as the toilet chambers, while the garbage chamber was usually centrally located. The nests were frequently moved around, however.

The mole-rats were tracked by RFID readers as they moved through the burrows, allowing the researchers to determine when individuals were moving about, which individual was in which location, and to check for behaviors like following others, synchronized activity, or if some individuals stayed near other particular individuals.

The group found an array of distinct behaviors among the different groups. They identified seven distinct behavioral phenotypes: one for breeders and six for nonbreeders. Nonbreeders appeared to be associated with certain locations and some phenotypes exhibited less social interaction—especially between nonbreeder-nonbreeder pairs when compared to breeders. Some phenotypes also exhibited more mobility than others.

"These differences may reflect a form of task allocation. For example, cluster 1 individuals (high mobility and garbage occupancy) may serve as transport specialists, whereas those in cluster 4 (low mobility and frequent occupancy of nonfunctional chambers) may engage primarily in digging tasks. Cluster 5 individuals, who frequently occupied toilet chambers, may contribute to a cleaning-related role. These functional differences among clusters suggest that differentiated behavioral roles may emerge in association with broader life-history traits," the study authors write.

They note a particularly strong bond among all breeders, with high synchrony in their activities, close spatial proximity, and frequent following behavior. But, their interactions with nonbreeders were more dominant.

"Breeders uniquely exhibit frequent short rests, possibly reflecting repeated patrols and dominant interactions. Breeding females patrol burrows and display agonistic dominance toward nonbreeders, paralleling queen aggression in primitively eusocial insects. Because dominant breeder behavior involves a form of following, namely, displacement through shoving, our observation of breeders following nonbreeders supports this interpretation," the study authors say.

Another interesting behavior was revealed during video footage for studying types of interactions. Some of the mole-rats were found to engage in "tail-tugging," often before following the individual whose tail they tugged on. This was more common in some phenotypes than in others.

"In addition, high-mobility nonbreeders (cluster 1) attracted a frequent following. Among nonbreeders, follow events frequently involve tail tugging, where the tail-puller typically becomes the followee. Given this, the frequent followee status of high-mobility nonbreeders suggests that they may commonly initiate tail-tugging interactions," the authors explain.

The study has shed light on the previously unseen social world of naked mole-rats with a novel system for tracking eusocial mammals—with more complex results than expected. However, the researchers involved believe combining RFID with image-based tracking or tracking more diverse groups could potentially reveal even more complex behavioral details.

The study authors also note, "Future studies that integrate experimental manipulations or additional observation methods promise to deepen our understanding of eusociality in this unique mammalian system and uncover underlying mechanisms driving cooperative society."

© 2025 Science X Network