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Here is an interesting short blog post by our friend and evolutionary biologists, Josh Mitteldorf which he titles Aging is a Military Coup. In it he suggests two things, which I paraphrase thusly:

  1. Aging is not the passive process we used to think it was. Instead, aging is programmed into the body, and it is often a result of the body actively attacking itself in one way or another - commonly a result of the immune system response to inflammation.
  2. From a multi-level natural selection perspective, this self-destruction by individuals may be the way a community/society clears out its weaker members to make way for a new generation, and thereby promote the flourishing of the group.

I don't think anyone can argue with #1 - aging, at least in the manifest forms Josh enumerates, does appear to be a very active, programmed response. But I'm much more skeptical about #2. It seems plausible, but far from proven. Here is how Josh describes it:

 

If evolution found it necessary to regulate the individual’s life span for the larger good of the community or the ecosystem, there would be no need to invent a new and specialized death program.  It would be far easier to coopt the body’s existing armies, and redirect them in a suicide mission.

 

You can see where Josh gets the "military coup" metaphor in his title. But I think a better analogy is apoptosis. In Josh's model, the individual person is "self destructing" when they get old for the good of the community/society, in the same way an individual cell "self destructs" when it is damaged (via the process called apoptosis) for the good of body.

 

Perhaps resources have been scarce enough in human history that it benefitted the group if older members died off to avoid consuming resources "unproductively". But it's not clear to me that there were enough long-lived, "parasitic" elders in our deep evolutionary history (when our ancestors rarely lived beyond age 30-40) to generate the kind of selection pressure in favor of "human apoptosis" that Josh postulates. Plus there is the "grandmother effect" which suggests older people (particularly women) may have been productive caregivers in a community even after their reproductive years.

 

Regardless of whether his model is right or not, I don't believe that Josh thinks this human apoptosis is a good thing!

 

--Dean
 

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