The Greenland shark (Somniosus microcephalus), with an estimated lifespan of up to 500 years, is the longest-living known vertebrate on Earth. It therefore represents an extraordinary model for the study of aging processes. Its extreme longevity is associated with very slow growth, a low metabolic rate, minimal activity, and late sexual maturity, which is only reached after about 150 years. These characteristics make it particularly interesting to scientists, as they may provide clues about how biological systems remain stable over long periods of time.
Studies of long-lived animal species show that they often possess especially effective mechanisms for DNA repair, cancer resistance, and immune system regulation. In the Greenland shark, genetic analyses also suggest that genes associated with anti-inflammatory processes and cellular protection play an important role. Such mechanisms could help limit or repair damage over time.
A recent study led by Alessandro Cellerino examined the heart tissue of the Greenland shark in detail for the first time. The findings revealed that the heart shows clear signs of aging. These include fibrosis, a buildup of connective tissue that can reduce the elasticity of the heart muscle, as well as a strong accumulation of lipofuscin, a pigment that builds up as a byproduct in aging cells. In addition, there were indications of mitochondrial damage and enlarged lysosomes, which are responsible for breaking down cellular components. Elevated levels of 3-nitrotyrosine were also detected, indicating increased oxidative stress.
Remarkably, however, these pronounced signs of aging do not appear to lead to a loss of function. While comparable damage in humans would have serious consequences, the Greenland shark’s heart remains functional. The animals continue to be active and viable. This suggests that while the Greenland shark is not immune to aging, it is able to compensate for its effects.
The findings suggest that its exceptional longevity is primarily due to a high level of biological resilience. This resilience describes the ability of an organism to maintain vital functions despite increasing damage. The Greenland shark appears to have particularly efficient systems that allow it to tolerate cellular damage while maintaining the stability of its organs.
This research provides an important insight: a long life does not depend solely on avoiding aging processes, but rather on how well an organism can cope with them. Understanding these mechanisms could, in the long term, pave new ways for healthy aging in humans.
Heiner Kubny, PolarJournal