Unless you’re a scientist researching cancer resistance, anti-aging, high pain tolerance or long-term oxygen deprivation (all traits of this peculiar species), there’s not much to love about naked mole-rats (Heterocephalus glaber), the world’s ugliest rodents. If that lack of love is starting to make you feel sorry for them, this story will quickly put an end to that – a new study found that naked mole-rats war with other colonies over territory, and the victors pillage the nurseries of the defeated, kidnap their young and turn them into slaves. Are these the Vikings of the animal kingdom?
“We report evidence that wild colonies of naked mole‐rats invade neighbouring colonies and thus expand their territories. Furthermore, as has been observed in laboratory colonies, invading colonies may kidnap un‐weaned pups which can subsequently be incorporated into the workforce.”
Stan Braude, professor of the practice of biology at Washington University in St. Louis, has spent over 30 years studying naked mole-rats in eastern Africa, especially in Kenya’s Meru National Park. In his new study published in the Journal of Zoology and reviewed by ScienceAlert, Braude and his colleagues reveal their strange discovery which began in the 1990s when they began marking and tracking naked mole-rats. They initially found that 26 of the colonies being monitored invaded and conquered 13 other colonies, with rats from the defeated never seen again. If that wasn’t interesting (and bad) enough, they subsequently found two rat pups working in a conquering colony that appeared to have come from one of the vanquished. At the time, Braude did not have the technology to verify their identity conclusively. That changed when they could perform a genetic analysis.
"The pups kidnapped by colony QQ became non-reproductive workers, hence their life effort would be categorized as slavery, in the same sense as slave-making ants."
This enslaving trait – seen in some ants and (sadly) in humans but not in other mammals – may be a key to growing naked more rat colonies to their massive sizes in both numbers of rats and enormity of burrows with only one queen doing all of the reproducing.
"The low probability of documenting this phenomenon with our mark-recapture methods, raises the possibility that this behaviour is far more common and may be a significant driver of sociality, and extreme large colony size, in naked mole-rats."
Braude likes that theory, but it’s not without detractors. Evolutionary biologist Chris Faulkes of Queen Mary University of London points out that they’ve only found a small number of enslaved pups and no enslaved adults, causing him to question the frequency of the practice and it’s benefit to colony building. Besides, they have another way of invading and conquering other colonies – dispersal morphing. Colonies are made up of a queen (reproducer) , workers (builders) and dispersers – special mole-rats with extra fat reserves for traveling long distances and high levels of a luteinizing hormone which drives them to find and infiltrate new colonies for the purpose of mating and “dispersing” their genetic material.
Despite residing only in parts of East Africa, naked mole-rats are in no danger of extinction – which may be directly related to slavery and ‘dispersing’.
Don’t get any ideas … it could also be the reason why they’re naked and ugly.