The naked mole rat (Heterocephalus glaber) is an animal disgusting to look at and fascinating in its behavior. It is the only eusocial mammal: it is organized in colonies of up to 300 members in which only a few males are fertile and a female acts as a reproductive queen, in the manner of bees.
The rest build the tunnels where they live, look for food, protect the group and… eat shit. Literally, because that is the biological key that drives subordinate rats of both sexes to care for the offspring of the “alpha female ,” according to a study by biologist Akiyuki Watarai and animal behavior expert Takefumi Kikusui, both from the Azabu University of Japan.
Beta rats lack mature sexual organs and therefore do not produce estrogens, hormones that influence pregnancy and parenting behaviors. When the queen mother is pregnant and when she gives birth, her stools are full of estrogen ; when eaten, the rest of the colony suffers a hormonal high that triggers their maternal instincts.
To reach this conclusion, the researchers recorded the cries of newborn pups and then made them listen to subordinate rats. They found that animals whose queens had just given birth were more attentive to those sounds than those of other groups , suggesting that the pregnancy and delivery of the dominant female activated the caregiving instincts of the rest.
The researchers then analyzed the urine and feces of the subordinate specimens and found that they contained estradiol – a type of estrogen – but only when the queen was pregnant: that is, those hormones came from her. The next step in the study was to administer to the beta rats the hormones present in the queen’s feces: the result was that their estradiol levels rose, and that they began to pay more attention to the calls of the young.
Now, these Japanese scientists have begun to scan the brains of subordinate females, to discover how they change when they become queens, an always bloody process: when the boss dies, her slaves fight – often to the death – to succeed her.
