Even once you get over the idea they look like a saber-toothed sausage, naked mole rats are unbelievably strange creatures. They can barely feel pain, they can happily live with no oxygen for 20 minutes, and they are remarkably resistant to cancer. Much like ants and termites, they are also eusocial animals that live in colonies, with a single “queen” and dozens of subordinate worker mole rats.
A new study published in the journal PNAS has tried to understand how, as mammals, they manage to maintain this unusual social structure. Just like every part of naked mole rat life, it’s weird. Really weird.
It appears that the pregnant queen kick-starts a maternal instinct in her subordinate workers by feeding them her poop. After eating this hormone-laced poop, the workers are driven to become caring towards their queen’s pups, even though they are not necessarily genetically related.
Japanese scientists had noticed that the subordinates' pup care only increased post-partum, rather than when the queen was pregnant, and they suspected that estradiol, an important female sex hormone, was being transferred, but weren't entirely sure how, though they had their suspicions.
“We hypothesize that the increased estradiol in the queen’s feces was disseminated to subordinates through coprophagy [poop eating], which stimulated subordinates’ responses to pup vocalizations,” the authors write in the study.
They reached this discovery by looking at two different groups of workers. For nine days, one group was fed poop from a pregnant queen, while the other was fed poop from a nonpregnant queen. First of all, they noted that the pregnant poop eaters experienced a rise in estradiol. Secondly, this group also reacted strongly to the vocalizations of naked mole pups, linking the two.
Coprophagy, aka the art of poop eating, perhaps seems unusual to us humans, however, it’s surprisingly common in the animal kingdom. Among mammals, coprophagy often takes place between a youngster and their mother. The young eat the poop in order to obtain vital gut bacteria required to properly digest vegetation found in their ecosystem. Dogs, elephants, and even chimps are all known to partake in this behavior.
As you’ve no doubt gathered, the naked mole rat (Heterocephalus glaber) is a truly unique animal. This species of small rodent lives in underground tunnels around the Horn of Africa. Along with the Damaraland mole, they are one of only two known eusocial mammals that live in ant-like colonies. It’s unclear why these two mammals structure their social environment like this, although it’s most likely due to their harsh, limiting, and unpredictable physical environment.
That said, it seems like naked mole rats just like to break all the rules of nature.