When the Salk Institute for Biological Studies in San Diego got their first naked mole rat colony in 2019, the researchers named them the "amigos" — Spanish for "friends."
Naked mole rats are subterranean mammals native to East Africa. Since the 1960s, scientists have studied captive colonies in labs and zoos for their unusual living arrangements and their long, healthy lives.
The Salk colony's name was prescient. A few years later, they exhibited a peaceful transition that bucks the conventional wisdom on how naked mole rat colonies change queens — which is usually through all-out warfare.
"Maybe they heard us and they were like, okay, we'll show you that we're friends," says Shanes Abeywardena, a veterinarian and postdoctoral fellow in scientist Janelle Ayres' lab. Abeywardena and her colleagues documented the nonviolent changing of the queens for the April 15 issue of the journal Science Advances.
The study broadens the understanding of how naked mole rats, often researched for the secrets to their longevity, can use different cooperative strategies to thrive. Unusually for rodents, they can live for more than thirty years, despite having basically no hair or fat and lacking the ability to thermoregulate.
The colony came to San Diego in the summer of 2019, sent by a fellow researcher at The City University of New York, with a clear hierarchy.
"Queen Teré established herself as the original queen and matriarch," Abeywardena says. She arrived with her male consort, whom the researchers dubbed Paquito, and their first litter of four surviving pups.
Naked mole rat colonies are often structured with a single large mating queen and dozens of smaller male and female rats that serve specialized roles such as guarding, gathering food and caregiving.
In naked mole rat colonies, the queen is the largest and the only one that has babies. And Queen Teré kept having more.
A crisis in the colony
When the colony reached 39, there came a whole year when her babies died shortly after birth, likely due to overcrowding.
Abeywardena and her colleagues hypothesized that the naked mole rats felt a strain in their resources and adjusted, perhaps by taking poor care of the newborns. In 2021, the researchers split 20 naked mole rats off to start a separate family they called the Amici colony, and Queen Teré gave birth to a few viable litters.
Then came another disruption: a laboratory construction project forced the colony to move in 2022. "To stress us all out, including the naked mole rats, we had to move them to a different facility," Abeywardena says, "During that time, we noticed that Teré's reproductive capabilities stopped and she wasn't reproducing for a year."
At that point, Abeywardena and her colleagues thought Queen Teré, who was no longer viably reproducing, would be overthrown. "Is there going to be a violent war? Is there going to be aggression?" she says, based on examples from zoos and scientific literature on how new queens typically emerge. "That's what we were expecting — but that wasn't the case."
Instead, two of Teré's daughters started growing bigger and having litters too.
A new queen ascends
One died from internal injuries. But the other, named Arwen became the colony's only birthing queen in 2025. "As this was unfolding, we were just completely shocked," Abeywardena says.
Rather than show the expected aggressive behavior, Teré continued to protect and guard the colony — including her ascending queen daughter — as she ceded the throne.
Teré is spry, still the largest naked mole rat in the group, and just seven years old. She could have more than twenty golden years of retirement, as "Queen Grandmother of the colony," ahead of her, Abeywardena says.
This seemingly unusual peaceful transition has advantages: "Those aggressive fatal queen wars add costs because you risk injury. You risk losing individuals, i.e., workers," Abeywardena says. For naked mole rats, it takes energy and resources to wage civil war.
Regime change via civil war is more commonly seen in the species. Indeed, as the Amigos colony was changing queens peacefully in San Diego, the naked mole rat colony at the Smithsonian's National Zoo in Washington, D.C. was waging a classic bloody coup.
That naked mole rat war has continued, on and off, for more than two years. "We'll go two or three months where it looks like, finally, things are calming down and then — violence," says Kenton Kerns, the curator at the zoo's small mammal house, "Sometimes it might just be low-level fighting, other times it's straight to the death, fatal bites immediately."
But the zoo's previous colony was older and calmer, Kerns says. Some mole rats in that colony were over twenty years old and multiple queens bred side by side.
So the idea of the old and new queen overlapping peacefully, is "very possible," Kerns says, and though it's not considered the norm, it may not be as rare as scientists previously thought.
Kerns says the human understanding of naked mole rats evolves constantly. Some assumptions from the early days of studying them in labs and zoos may have applied only to the specific groups under study.
Decades of observation demonstrate that there's a lot of variety in behavior and biology among individuals and colonies.
Kerns says naked mole rats flaunt all kinds of rules. They're mammals but mostly hairless and cold-blooded, they live a very long time and they're resistant to diseases like cancer.
It makes sense that they would buck social rules too — and in time, scientists may find that more naked mole rats are peace-loving than they thought.
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