Naked mole-rats are becoming very well studied. Researchers are attempting to find the root causes of cancer immunity and exceptional longevity in this species, with an eye to creating beneficial medical biotechnologies for humans. Fight Aging! has seen a couple of items on naked mole-rats already this month, which is illustrative of the present pace:
Present theories are varied, but on the longevity side of the house the consensus appears to lean towards an increased resistance to forms of cellular membrane damage - naked mole rat membranes are built of a more resilient mix of proteins than those of comparable species. This is known as the membrane pacemaker hypothesis of aging:
The membrane pacemaker hypothesis predicts that long-living species will have more peroxidation-resistant membrane lipids than shorter living species. ... Resistance to oxidative damage is of particular importance in mitochondria, cellular power plants that progressive damage themselves with the reactive oxygen species they produce as a byproduct of their operation - and that gives rise to a chain of further biochemical damage that spreads throughout the body, growing ever more harmful as you age. Less damage to the mitochondria should mean slower aging, and thus more resistant mitochondrial membranes should also mean slower aging.
Studies comparing similar-sized species with disparate longevity may elucidate novel mechanisms that abrogate aging and prolong good health. We focus on the longest living rodent, the naked mole-rat. This mouse-sized mammal lives ∼8 times longer than do mice and, despite high levels of oxidative damage evident at a young age, it is not only very resistant to [cancer] but also shows minimal decline in age-associated physiological traits.
Like other experimental animal models of lifespan extension, naked mole-rat fibroblasts are extremely tolerant of a broad spectrum of cytotoxins including heat, heavy metals, DNA-damaging agents and xenobiotics, showing [median lethal dose] values between 2- and 20-fold greater than those of fibroblasts of shorter-lived mice. Our new data reveal that naked mole-rat fibroblasts stop proliferating even at low doses of toxin whereas those mouse fibroblasts that survive treatment rapidly re-enter the cell cycle and may proliferate with DNA damage. Naked mole-rat fibroblasts also show significantly higher constitutive levels of both p53 and Nrf2 protein levels and activity, and this increases even further in response to toxins.
Enhanced cell signaling via p53 and Nrf2 protects cells against proliferating with damage, augments clearance of damaged proteins and organelles and facilitates the maintenance of both genomic and protein integrity. These pathways collectively regulate a myriad of mechanisms which may contribute to the attenuated aging profile and sustained healthspan of the naked mole-rat. Understanding how these are regulated may be also integral to sustaining positive human healthspan well into old age and may elucidate novel therapeutics for delaying the onset and progression of physiological declines that characterize the aging process.
You might also look back a few years at other research into the role of Nrf2 in determining species longevity. The details can be a little overwhelming, but the big picture remains one of damage at the level of cells and protein machinery: less damage and more resilience to damage means a longer life span.