This is how ‘Arwen’ turned queen of the rats: the succession to the throne of probably the most fascinating animal with out spilling a drop of blood | Science | EUROtoday

It is, maybe, probably the most extraordinary animal on the face of the Earth. Not solely due to its unusual and placing look; It is wrinkled, pink, nearly hairless, with disproportionate enamel that protrude from its snout and tiny, nearly ineffective eyes. It is, above all, due to what it hides underneath that wrinkled pores and skin. The shaved mouse (Heterocephalus glaber) is a rodent the dimensions of a mouse that lives in underground colonies within the Horn of Africa and likewise in laboratories all over the world as a result of its fascinating qualities: it lives as much as 30 and even 40 years, ten instances longer than its mouse family members. He barely develops most cancers. Their pores and skin is insensitive to acids and doesn’t really feel ache. And it’s the solely mammal that lives in underground colonies, like ants, with a queen, and troopers and staff who reside to serve her. His life has impressed cartoon characters and even comics. A research printed this Wednesday within the journal Science Advances Now provides another chapter to her legend: when the queen of the colony loses energy, her topics don’t kill one another to exchange her. They can do one thing way more stunning. They can wait.

The story begins in July 2019, on the Salk Institute for Biological Studies in La Jolla, California. A colony of six animals arrived at Janelle Ayres’s laboratory: a queen of unknown age named Teré, a male named Paquito, and the primary litter that they had had collectively. The colony acquired the title “Los Amigos” (in Spanish). The infants that had been born had been additionally given names, and a few got here from Tolkien, like Arwen, the attractive elf who ties her future to the human Aragorn. The research’s principal investigator, Ayres, explains that naming people makes it simpler to trace over time and displays “a respectful recognition of their individuality, without losing scientific objectivity.”

During the primary months, Teré behaved like a mannequin queen. It produced litters repeatedly, with intervals of between 76 and 81 days, and between 6 and 10 offspring, with 100% survival. There had been no assaults within the colony. The social construction was clear. But mouse colonies live techniques, and scientists needed to know what occurs when one thing sudden occurs in that system.

In the world of the shaved vole, copy is a single-female affair. Colonies are organized round that single reproductive feminine, the queen, who monopolizes breeding. The queen actively suppresses the ovulation of subordinate females, via intimidation (biting or pushing them), by chemical alerts and, presumably, by physiological mechanisms not but totally understood. It is a organic dictatorship.

What was recognized till now could be that, when the queen dies or disappears, order is violently damaged. Subordinate females compete to imagine the reproductive function, which generates plenty of aggression and steady wars in the direction of succession: blood decides who’s in cost.

But Ayres and his staff suspected there may be one other method. To discover it, they wanted an extended experiment (it took six years), endurance, and a colony that they knew animal by animal. The Friends had been good.

The researchers subjected the colony to 2 sorts of stresses, recognized to disrupt copy in rodents. The first was overcrowding. When the colony reached 39 animals, the queen continued to grow to be pregnant and provides beginning to normal-sized litters, however all of the pups died. The stress affected the newborns, not Teré’s fertility. And no subordinate took benefit of the queen’s reproductive weak point to attempt to take the throne from her.

The second disturbance was extra highly effective: a transfer. In May 2022, all the colony was moved to a different constructing on the identical campus. The environmental situations—temperature, humidity, gentle cycle—had been similar. But one thing modified. Teré’s means to breed utterly ceased. Over the subsequent 12 months, she maintained a secure weight, and medical examinations revealed no proof of being pregnant. A 12 months with out offspring, with no obvious rationalization. And once more, no assaults.

It was throughout this lengthy pause that researchers started to look at one thing new: within the fall of 2023, Teré timidly resumed breeding with litters of 1 or two pups that didn’t survive; But in the meantime, considered one of her daughters, Alexandria, started to indicate indicators of being pregnant. A second breeding feminine had emerged within the colony, one thing that had not been documented earlier than. And with out anybody preventing about it.

That copy in parallel It occurred with none aggression, with out challenges to domination or social instability within the colony. Teré and Alexandria had been, in their very own method, sharing the throne. Alexandria died shortly after, however one other daughter of Teré from the identical litter, Arwenstarted to indicate the identical indicators of being pregnant. In October 2025, Arwen she gave beginning to 2 cubs that survived; the primary to take action since 2023. The researchers documented that Teré displayed “guard” conduct in the direction of Arwen and his litter, with none signal of battle. The succession was full. No aggression or bloodshed. The queen mom He gave energy to his daughter, and he or she took it with no need to take it away.

Ayres is cautious concerning the extent to which this discovering displays what occurs in nature. “Our findings demonstrate that shaved voles are capable of peaceful succession, in addition to the more widely recognized aggressive pathway,” he says. “However, it remains to be determined whether this alternative strategy is employed in natural environments.”

What the research does enable us to affirm is that there’s this flexibility, that “hidden path”, because the authors themselves name it. The findings reveal a “social plasticity,” they are saying, that had by no means been noticed on this animal, historically topic to the sturdy hierarchy of the queen.

What determines which path a colony takes? Ayres has a speculation: “It is reasonable to speculate that succession depends not only on social stability and reproductive competition, but also on a cost-benefit analysis. When the cost of conflict is too high, a peaceful transition may be favored.”