Naked mole rats are not cute, but they attract huge interest for their extraordinary lifespans – which is at least ten times longer than would be expected for mammals of their size. A paper in Proceedings of the Royal Society B argues that their social networks form part of the explanation.
In birds and mammals, the smaller animals usually have shorter lifespans, particularly when compared with closely related species. Most rat species live for no more than a few years – the ones that live longer are suspicious. So the naked mole rat (Heterocephalus glaber), which grows to 8-10 centimeters but lives for 30 years, is truly exceptional.
Medical researchers have been attempting to steal the mole rat's tricks for ourselves. Last year, a factor in the rat's cells was shown to protect the functioning of an enzyme responsible for disposing of damaged proteins. Naked mole rats have also been shown to be more consistent in the transcription of their DNA than comparable species.
Dr. Scott Williams and Dr. Milena Shattuck of New York University decided to consider the mole rat's lifestyle rather than biochemistry. A previously identified aspect of the mole rat's survival is the fact that it spends most of its life underground, protecting it from predators and UV radiation. Other underground species also tend to have longer lives, but they still fall well short of the mole rat.
The researchers wondered if an even more unusual aspect of H. glaber's behavior could contribute. Naked mole rats have specialized roles within their colony, including a queen and a few consorts that do all the breeding, with chemicals in the queen's urine suppressing the fertility of other females. While we are familiar with this type of structure from bees and ants, it is very rare among mammals.
Collating data on the lifespan and lifestyle of 440 mammalian species, Williams and Shattuck found that while body size has the strongest correlation with longevity, sociability and burrowing are important as well.
Even the combination of cooperative breeding and living in burrows will not ensure a species lives as long as mole rats. Meerkats, for example, combine these two and live for around six years in the wild – not bad for their size but still no competition for the much smaller naked mole rat. The naked mole rat has taken this sociability to a greater extreme than other species, however, with the queen spending her time in a special chamber in the burrow breeding with selected males, giving birth and nursing. It seems that somehow the extreme nature of the social structure has paid off.
So what does this mean for humans? We've already done a pretty good job of evading predators, and handing reproduction over to a few members of the community may be a harder sell than pills based on the mole rat's proteins. Still, the naked mole rat may have a message for those preparing for the apocalypse: If you really want to survive a disaster, you need a little help from your friends.