Naked mole-rats (NMRs) pose a opportunity for study in the field of aging science. Why do they live eight times longer than similarly-sized rodents? For that matter, what are the mechanisms whereby some other species of animal manage to live far longer than their peers? In the case of mole-rats, it appears not to be related to antioxidants and the free radical theory of aging: "The present study tested if NMRs possess superior antioxidant defenses compared to mice and if age-related interspecies changes in antioxidants were evident. ... It is nonetheless unlikely that antioxidant defenses are responsible for the eight-fold longevity difference between these two species. Maintenance of constant antioxidant defenses with age in NMRs concurs with previous physiological data, suggesting delayed aging in this species."