Naked mole-rats age without metabolic decline
The naked mole-rat lives up to ten times longer than comparably sized rodents.
In most mammals, resting metabolic rate (RMR) shifts with age. Maintenance becomes costlier, organs lose efficiency. That pattern appears largely absent in naked mole-rats, according to new findings reported via Fight Aging.
Unusually low and unusually stable
Researchers measured RMR across multiple age groups, while accounting for body mass, social role, and colony-level factors. Body mass was by far the strongest predictor of energy expenditure, consistent with standard allometric scaling across mammals. The average measured RMR was 45.5 ml O₂ per hour, substantially below what predictive models would estimate for animals of this size (ranging from 51.6 to 71.1 ml O₂/hr across ten published models).
Crucially, age had no significant effect on RMR once body mass was controlled for. In most mammals, aging brings measurable shifts in resting metabolism. The study suggests this is consistent with negligible senescence, the near-absence of the biological deterioration that normally accompanies aging in other species.
Underground life as an evolutionary driver
The low RMR fits the animal’s habitat. Stable underground temperatures reduce the need for thermoregulation, lowering energy demands. In an environment where food is scarce and burrowing is costly, minimising resting energy expenditure benefits the whole colony.
What this means for the mole-rat’s exceptional longevity is not fully resolved. The membrane pacemaker hypothesis proposes that the lipid composition of cell membranes determines resistance to oxidative damage. Lower metabolic rate means reduced production of oxidative molecules by mitochondria. Whether this is the primary explanation, or whether other mechanisms are equally important, remains an open question in the field.