Methuselah's Zoo

Is the research community doing as much as it might to extract value from the diversity in life span amongst mammals? Certainly there are those scientist who would like to be engaged in a great deal more sequencing and biochemical deciphering of long-lived animals. But on the whole, I think that less is taking place in this area of study than might be. See this paper from a noted gerontologist, for example:

As impressive as the accomplishments of modern molecular biologists have been in finding genetic alterations that lengthen life in short-lived model organisms, they pale in comparison to the remarkable diversity of lifespans produced by evolution. Some animal species are now firmly documented to live for more than four centuries and even some mammals, like the bowhead whale, appear to survive 200 years or more. Another group of species may not be as absolutely long-lived, but they are remarkably long-lived for their body size and metabolic rate. These species include a number of bats, some of which live for at least 40 years in the wild, as well as the naked mole-rat, which is the same size, but lives nearly 10 times as long as the laboratory mouse. Together these exceptionally long-lived organisms have important roles to play in our future understanding of the causal mechanisms and modulation of ageing.

Bats and naked mole-rats in particular have already contributed in the following ways: (1) they have contributed to the abandonment of the rate-of-living theory and weakened enthusiasm for the oxidative stress hypothesis of ageing, (2) they have helped evaluate how the tumour-suppressing role of cellular senescence is affected by the evolution of diverse body sizes as well as diverse longevities, (3) they have shed light on the relationship between specific types of DNA repair and ageing and (4) they have yielded insight into new processes, specifically the maintenance of the proteome and hypotheses concerning how evolution shapes ageing. The continuing acceleration of progress in genome sequencing and development of more and more cross-species investigatory techniques will facilitate even more contributions of these species in the near future.

Why is it that whales, with many more cells than us and longer life spans to boot, aren't riddled with cancers? How is that naked mole-rats seem to evade cancer entirely? What biochemical mechanisms allow humans to live much longer than our closest relatives in the primate kingdom? It is clearly the case that some forms of mammal biochemistry are much more capable of producing long and healthy lives than our own, and that we don't fully understand why yet.

ResearchBlogging.orgAustad SN (2009). Methusaleh's Zoo: How Nature provides us with Clues for Extending Human Health Span. Journal of comparative pathology PMID: 19962715

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