Theorizing More Broadly on the Topic of the Evolution of Longevity

The evolution of aging and longevity is a field in which it's still comparatively easy to make a mark and carve out an area of new theory. For most species it is still the case that ideas on their longevity are comparative unsettled: why they live as long as they do, what mechanisms may have determined their life span, and how it all fits in to the bigger picture of metabolism and the evolution of specific biological processes. There is far more data than any one group of researchers could hope to organize in a lifetime, and new information continues to flood in ever faster as the biotechnology revolution unfolds.

At some point this rich wealth of data starts to give rise to hypotheses that are more holistic: evolution as a system of systems linked by feedback loops, thousands of species interacting with one another in any given biome, and the evolution of each species highly connected to that of its peers. Embarking upon this level of modeling and understanding, all the way down to biomolecular processes, will keep evolutionary biologists busy for the next century or so, I'd imagine - and give them something to do with the staggering levels of computing power that will be available by that time.

Here is an interesting open access paper that gives a hint of the shape of this sort of future research, whilst considering the evolution of longevity amongst interacting species:

Various organisms (i.e., bacteria, fungi, plants and animals) within an ecosystem can synthesize and release into the environment certain longevity-extending small molecules. Here we hypothesize that these interspecies chemical signals can create [selective] forces driving the ecosystemic evolution of longevity regulation mechanisms.

In our hypothesis, following their release into the environment by one species of the organisms composing an ecosystem, such small molecules can activate anti-aging processes and/or inhibit pro-aging processes in other species within the ecosystem. The organisms that possess the most effective (as compared to their counterparts of the same species) mechanisms for sensing the chemical signals produced and released by other species and for responding to such signals by undergoing certain hormetic and/or [cellular housekeeping related] life-extending changes to their metabolism and physiology are expected to live longer then their counterparts within the ecosystem.

Thus, the ability of a species of the organisms composing an ecosystem to undergo life-extending metabolic or physiological changes in response [to] chemical compounds released to the ecosystem by other species: 1) increases its chances of survival; 2) creates selective forces aimed at maintaining such ability; and 3) enables the evolution of longevity regulation mechanisms.

So the researchers propose that such things as the ability of rapamycin (produced by soil bacteria) to extend life in mice or the beneficial effects of mammalian bile acid on yeast life span are late manifestations of cross-species evolutionary processes that have been going on since the very earliest epoch of multicellular life. The suggestion is that we should expect there to be a wide range of compounds produced by varied species that will have some beneficial effect on the life span of another species (such as by improving cellular housekeeping processes), because the existence of such relationships between species is a fundamental characteristic of diverse ecosystems produced by evolution.

Which is an interesting line of thought, and I look forward to seeing where it leads.

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